galfar.imaginglib/Source/Imaging.pas

{
  $Id$
  Vampyre Imaging Library
  by Marek Mauder 
  http://imaginglib.sourceforge.net

  The contents of this file are used with permission, subject to the Mozilla
  Public License Version 1.1 (the "License"); you may not use this file except
  in compliance with the License. You may obtain a copy of the License at
  http://www.mozilla.org/MPL/MPL-1.1.html

  Software distributed under the License is distributed on an "AS IS" basis,
  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
  the specific language governing rights and limitations under the License.

  Alternatively, the contents of this file may be used under the terms of the
  GNU Lesser General Public License (the  "LGPL License"), in which case the
  provisions of the LGPL License are applicable instead of those above.
  If you wish to allow use of your version of this file only under the terms
  of the LGPL License and not to allow others to use your version of this file
  under the MPL, indicate your decision by deleting  the provisions above and
  replace  them with the notice and other provisions required by the LGPL
  License.  If you do not delete the provisions above, a recipient may use
  your version of this file under either the MPL or the LGPL License.

  For more information about the LGPL: http://www.gnu.org/copyleft/lesser.html
}

{ This unit is heart of Imaging library. It contains basic functions for
  manipulating image data as well as various image file format support.}
unit Imaging;

{$I ImagingOptions.inc}

interface

uses
  ImagingTypes, SysUtils, Classes;

type
  { Default Imaging excepton class.}
  EImagingError = class(Exception);

  { Dynamic array of TImageData records.}
  TDynImageDataArray = array of TImageData;


{ ------------------------------------------------------------------------
                       Low Level Interface Functions
  ------------------------------------------------------------------------}

{ General Functions }

{ Initializes image (all is set to zeroes). Call this for each image
  before using it (before calling every other function) to be sure there
  are no random-filled bytes (which would cause errors later).}
procedure InitImage(var Image: TImageData);
{ Creates empty image of given dimensions and format. Image is filled with
  transparent black color (A=0, R=0, G=0, B=0).}
function NewImage(Width, Height: LongInt; Format: TImageFormat;
  var Image: TImageData): Boolean;
{ Returns True if given TImageData record is valid.}
function TestImage(const Image: TImageData): Boolean;
{ Frees given image data. Ater this call image is in the same state
  as after calling InitImage. If image is not valid (dost not pass TestImage
  test) it is only zeroed by calling InitImage.}
procedure FreeImage(var Image: TImageData);
{ Call FreeImage() on all images in given dynamic array and sets its
  length to zero.}
procedure FreeImagesInArray(var Images: TDynImageDataArray);
{ Returns True if all TImageData records in given array are valid. Returns False
  if at least one is invalid or if array is empty.}
function TestImagesInArray(const Images: TDynImageDataArray): Boolean;
{ Checks given file for every supported image file format and if
  the file is in one of them returns its string identifier
  (which can be used in LoadFromStream/LoadFromMem type functions).
  If file is not in any of the supported formats empty string is returned.}
function DetermineFileFormat(const FileName: string): string;
{ Checks given stream for every supported image file format and if
  the stream is in one of them returns its string identifier
  (which can be used in LoadFromStream/LoadFromMem type functions).
  If stream is not in any of the supported formats empty string is returned.}
function DetermineStreamFormat(Stream: TStream): string;
{ Checks given memory for every supported image file format and if
  the memory is in one of them returns its string identifier
  (which can be used in LoadFromStream/LoadFromMem type functions).
  If memory is not in any of the supported formats empty string is returned.}
function DetermineMemoryFormat(Data: Pointer; Size: LongInt): string;
{ Checks that an apropriate file format is supported purely from inspecting
  the given file name's extension (not contents of the file itself).
  The file need not exist.}
function IsFileFormatSupported(const FileName: string): Boolean;
{ Enumerates all registered image file formats. Descriptive name,
  default extension, masks (like '*.jpg,*.jfif') and some capabilities
  of each format are returned. To enumerate all formats start with Index at 0 and
  call EnumFileFormats with given Index in loop until it returns False (Index is
  automatically increased by 1 in function's body on successful call).}
function EnumFileFormats(var Index: LongInt; var Name, DefaultExt, Masks: string;
  var CanSaveImages, IsMultiImageFormat: Boolean): Boolean;

{ Loading Functions }

{ Loads single image from given file.}
function LoadImageFromFile(const FileName: string; var Image: TImageData): Boolean;
{ Loads single image from given stream. If function fails stream position
  is not changed.}
function LoadImageFromStream(Stream: TStream; var Image: TImageData): Boolean;
{ Loads single image from given memory location.}
function LoadImageFromMemory(Data: Pointer; Size: LongInt; var Image: TImageData): Boolean;
{ Loads multiple images from given file.}
function LoadMultiImageFromFile(const FileName: string;
  var Images: TDynImageDataArray): Boolean;
{ Loads multiple images from given stream. If function fails stream position
  is not changed.}
function LoadMultiImageFromStream(Stream: TStream;
  var Images: TDynImageDataArray): Boolean;
{ Loads multiple images from given memory location.}
function LoadMultiImageFromMemory(Data: Pointer; Size: LongInt;
  var Images: TDynImageDataArray): Boolean;

{ Saving Functions }

{ Saves single image to given file.}
function SaveImageToFile(const FileName: string; const Image: TImageData): Boolean;
{ Saves single image to given stream. If function fails stream position
  is not changed. Ext identifies desired image file format (jpg, png, dds, ...).}
function SaveImageToStream(const Ext: string; Stream: TStream;
  const Image: TImageData): Boolean;
{ Saves single image to given memory location. Memory must be allocated and its
  size is passed in Size parameter in which number of written bytes is returned.
  Ext identifies desired image file format (jpg, png, dds, ...).}
function SaveImageToMemory(const Ext: string; Data: Pointer; var Size: LongInt;
  const Image: TImageData): Boolean;
{ Saves multiple images to given file. If format supports
  only single level images and there are multiple images to be saved,
  they are saved as sequence of files img000.jpg, img001.jpg ....).}
function SaveMultiImageToFile(const FileName: string;
  const Images: TDynImageDataArray): Boolean;
{ Saves multiple images to given stream. If format supports
  only single level images and there are multiple images to be saved,
  they are saved one after another to the stream. If function fails stream
  position is not changed. Ext identifies desired image file format (jpg, png, dds, ...).}
function SaveMultiImageToStream(const Ext: string; Stream: TStream;
  const Images: TDynImageDataArray): Boolean;
{ Saves multiple images to given memory location. If format supports
  only single level images and there are multiple images to be saved,
  they are saved one after another to the memory. Memory must be allocated and
  its size is passed in Size parameter in which number of written bytes is returned.
  Ext identifies desired image file format (jpg, png, dds, ...).}
function SaveMultiImageToMemory(const Ext: string; Data: Pointer;
  var Size: LongInt; const Images: TDynImageDataArray): Boolean;

{ Manipulation Functions }

{ Creates identical copy of image data. Clone should be initialized
  by InitImage or it should be vaild image which will be freed by CloneImage.}
function CloneImage(const Image: TImageData; var Clone: TImageData): Boolean;
{ Converts image to the given format.}
function ConvertImage(var Image: TImageData; DestFormat: TImageFormat): Boolean;
{ Flips given image. Reverses the image along its horizontal axis — the top
  becomes the bottom and vice versa.}
function FlipImage(var Image: TImageData): Boolean;
{ Mirrors given image. Reverses the image along its vertical axis — the left
  side becomes the right and vice versa.}
function MirrorImage(var Image: TImageData): Boolean;
{ Resizes given image to new dimensions. Nearest, bilinear, or bicubic filtering
  can be used. Input Image must already be created - use NewImage to create new images.}
function ResizeImage(var Image: TImageData; NewWidth, NewHeight: LongInt;
  Filter: TResizeFilter): Boolean;
{ Swaps SrcChannel and DstChannel color or alpha channels of image.
  Use ChannelRed, ChannelBlue, ChannelGreen, ChannelAlpha constants to
  identify channels.}
function SwapChannels(var Image: TImageData; SrcChannel, DstChannel: LongInt): Boolean;
{ Reduces the number of colors of the Image. Currently MaxColors must be in
  range <2, 4096>. Color reduction works also for alpha channel. Note that for
  large images and big number of colors it can be very slow.
  Output format of the image is the same as input format.}
function ReduceColors(var Image: TImageData; MaxColors: LongInt): Boolean;
{ Generates mipmaps for image. Levels is the number of desired mipmaps levels
  with zero (or some invalid number) meaning all possible levels.}
function GenerateMipMaps(const Image: TImageData; Levels: LongInt;
  var MipMaps: TDynImageDataArray): Boolean;
{ Maps image to existing palette producing image in ifIndex8 format.
  Pal must be allocated to at least Entries * SizeOf(TColor32Rec) bytes.
  As resulting image is in 8bit indexed format Entries must be lower or
  equal to 256.}
function MapImageToPalette(var Image: TImageData; Pal: PPalette32;
  Entries: LongInt): Boolean;
{ Splits image into XChunks x YChunks subimages. Default size of each chunk is
  ChunkWidth x ChunkHeight. If PreserveSize si True chunks at the edges of
  the image are also ChunkWidth x ChunkHeight sized and empty space is filled
  with Fill pixels. After calling this function XChunks contains number of
  chunks along x axis and YChunks along y axis. To access chunk [X, Y] use this
  index: Chunks[Y * XChunks + X].}
function SplitImage(var Image: TImageData; var Chunks: TDynImageDataArray;
  ChunkWidth, ChunkHeight: LongInt; var XChunks, YChunks: LongInt;
  PreserveSize: Boolean; Fill: Pointer): Boolean;
{ Creates palette with MaxColors based on the colors of images in Images array.
  Use it when you want to convert several images to indexed format using
  single palette for all of them. If ConvertImages is True images in array
  are converted to indexed format using resulting palette. if it is False
  images are left intact and only resulting palatte is returned in Pal.
  Pal must be allocated to have at least MaxColors entries.}
function MakePaletteForImages(var Images: TDynImageDataArray; Pal: PPalette32;
  MaxColors: LongInt; ConvertImages: Boolean): Boolean;
{ Rotates image by Angle degrees counterclockwise. All angles are allowed.}
function RotateImage(var Image: TImageData; Angle: Single): Boolean;

{ Drawing/Pixel functions }

{ Copies rectangular part of SrcImage to DstImage. No blending is performed -
  alpha is simply copied to destination image. Operates also with
  negative X and Y coordinates.
  Note that copying is fastest for images in the same data format
  (and slowest for images in special formats).}
function CopyRect(const SrcImage: TImageData; SrcX, SrcY, Width, Height: LongInt;
  var DstImage: TImageData; DstX, DstY: LongInt): Boolean;
{ Fills given rectangle of image with given pixel fill data. Fill should point
  to the pixel in the same format as the given image is in.}
function FillRect(var Image: TImageData; X, Y, Width, Height: LongInt; FillColor: Pointer): Boolean;
{ Replaces pixels with OldPixel in the given rectangle by NewPixel.
  OldPixel and NewPixel should point to the pixels in the same format
  as the given image is in.}
function ReplaceColor(var Image: TImageData; X, Y, Width, Height: LongInt;
  OldColor, NewColor: Pointer): Boolean;
{ Stretches the contents of the source rectangle to the destination rectangle
  with optional resampling. No blending is performed - alpha is
  simply copied/resampled to destination image. Note that stretching is
  fastest for images in the same data format (and slowest for
  images in special formats).}
function StretchRect(const SrcImage: TImageData; SrcX, SrcY, SrcWidth,
  SrcHeight: LongInt; var DstImage: TImageData; DstX, DstY, DstWidth,
  DstHeight: LongInt; Filter: TResizeFilter): Boolean;
{ Copies pixel of Image at [X, Y] to memory pointed at by Pixel. Doesn't
  work with special formats.}
procedure GetPixelDirect(const Image: TImageData; X, Y: LongInt; Pixel: Pointer);
{ Copies pixel from memory pointed at by Pixel to Image at position [X, Y].
  Doesn't work with special formats.}
procedure SetPixelDirect(const Image: TImageData; X, Y: LongInt; Pixel: Pointer);
{ Function for getting pixel colors. Native pixel is read from Image and
  then translated to 32 bit ARGB. Works for all image formats (except special)
  so it is not very fast.}
function GetPixel32(const Image: TImageData; X, Y: LongInt): TColor32Rec;
{ Procedure for setting pixel colors. Input 32 bit ARGB color is translated to
  native format and then written to Image. Works for all image formats (except special)
  so it is not very fast.}
procedure SetPixel32(const Image: TImageData; X, Y: LongInt; const Color: TColor32Rec);
{ Function for getting pixel colors. Native pixel is read from Image and
  then translated to FP ARGB. Works for all image formats (except special)
  so it is not very fast.}
function GetPixelFP(const Image: TImageData; X, Y: LongInt): TColorFPRec;
{ Procedure for setting pixel colors. Input FP ARGB color is translated to
  native format and then written to Image. Works for all image formats (except special)
  so it is not very fast.}
procedure SetPixelFP(const Image: TImageData; X, Y: LongInt; const Color: TColorFPRec); 

{ Palette Functions }

{ Allocates new palette with Entries ARGB color entries.}
procedure NewPalette(Entries: LongInt; var Pal: PPalette32);
{ Frees given palette.}
procedure FreePalette(var Pal: PPalette32);
{ Copies Count palette entries from SrcPal starting at index SrcIdx to
  DstPal at index DstPal.}
procedure CopyPalette(SrcPal, DstPal: PPalette32; SrcIdx, DstIdx, Count: LongInt);
{ Returns index of color in palette or index of nearest color if exact match
  is not found. Pal must have at least Entries color entries.}
function FindColor(Pal: PPalette32; Entries: LongInt; Color: TColor32): LongInt;
{ Creates grayscale palette where each color channel has the same value.
  Pal must have at least Entries color entries.}
procedure FillGrayscalePalette(Pal: PPalette32; Entries: LongInt);
{ Creates palette with given bitcount for each channel.
  2^(RBits + GBits + BBits) should be equl to Entries. Examples:
  (3, 3, 2) will create palette with all possible colors of R3G3B2 format
  and (8, 0, 0) will create palette with 256 shades of red.
  Pal must be allocated to at least Entries * SizeOf(TColor32Rec) bytes.}
procedure FillCustomPalette(Pal: PPalette32; Entries: LongInt; RBits, GBits,
  BBits: Byte; Alpha: Byte = $FF);
{ Swaps SrcChannel and DstChannel color or alpha channels of palette.
  Use ChannelRed, ChannelBlue, ChannelGreen, ChannelAlpha constants to
  identify channels. Pal must be allocated to at least
  Entries * SizeOf(TColor32Rec) bytes.}
procedure SwapChannelsOfPalette(Pal: PPalette32; Entries, SrcChannel,
  DstChannel: LongInt);

{ Options Functions }

{ Sets value of integer option specified by OptionId parameter.
  Option Ids are constans starting ImagingXXX.}
function SetOption(OptionId, Value: LongInt): Boolean;
{ Returns value of integer option specified by OptionId parameter. If OptionId is
  invalid, InvalidOption is returned. Option Ids are constans
  starting ImagingXXX.}
function GetOption(OptionId: LongInt): LongInt;
{ Pushes current values of all options on the stack. Returns True
  if successfull (max stack depth is 8 now). }
function PushOptions: Boolean;
{ Pops back values of all options from the top of the stack. Returns True
  if successfull (max stack depth is 8 now). }
function PopOptions: Boolean;

{ Image Format Functions }

{ Returns short information about given image format.}
function GetImageFormatInfo(Format: TImageFormat; out Info: TImageFormatInfo): Boolean;
{ Returns size in bytes of Width x Height area of pixels. Works for all formats.}
function GetPixelsSize(Format: TImageFormat; Width, Height: LongInt): LongInt;

{ IO Functions }

{ User can set his own file IO functions used when loading from/saving to
  files by this function.}
procedure SetUserFileIO(OpenReadProc: TOpenReadProc; OpenWriteProc:
  TOpenWriteProc; CloseProc: TCloseProc; EofProc: TEofProc; SeekProc:
  TSeekProc; TellProc: TTellProc; ReadProc: TReadProc; WriteProc: TWriteProc);
{ Sets file IO functions to Imaging default.}
procedure ResetFileIO;


{ ------------------------------------------------------------------------
                           Other Imaging Stuff
  ------------------------------------------------------------------------}

type
  { Set of TImageFormat enum.}
  TImageFormats = set of TImageFormat;

  { Record containg set of IO functions internaly used by image loaders/savers.}
  TIOFunctions = record
    OpenRead: TOpenReadProc;
    OpenWrite: TOpenWriteProc;
    Close: TCloseProc;
    Eof: TEofProc;
    Seek: TSeekProc;
    Tell: TTellProc;
    Read: TReadProc;
    Write: TWriteProc;
  end;
  PIOFunctions = ^TIOFunctions;

  { Base class for various image file format loaders/savers which
    descend from this class. If you want to add support for new image file
    format the best way is probably to look at TImageFileFormat descendants'
    implementations that are already part of Imaging.}
  {$TYPEINFO ON}
  TImageFileFormat = class(TObject)
  private
    FExtensions: TStringList;
    FMasks: TStringList;
    { Does various checks and actions before LoadData method is called.}
    function PrepareLoad(Handle: TImagingHandle; var Images: TDynImageDataArray;
      OnlyFirstFrame: Boolean): Boolean;
    { Processes some actions according to result of LoadData.}
    function PostLoadCheck(var Images: TDynImageDataArray; LoadResult: Boolean): Boolean;
    { Helper function to be called in SaveData methods of descendants (ensures proper
      index and sets FFirstIdx and FLastIdx for multi-images).}
    function PrepareSave(Handle: TImagingHandle; const Images: TDynImageDataArray;
      var Index: LongInt): Boolean;
  protected
    FName: string;
    FCanLoad: Boolean;
    FCanSave: Boolean;
    FIsMultiImageFormat: Boolean;
    FSupportedFormats: TImageFormats;
    FFirstIdx, FLastIdx: LongInt;
    { Defines filename masks for this image file format. AMasks should be
      in format '*.ext1,*.ext2,umajo.*'.}
    procedure AddMasks(const AMasks: string);
    function GetFormatInfo(Format: TImageFormat): TImageFormatInfo;
    { Returns set of TImageData formats that can be saved in this file format
      without need for conversion.}
    function GetSupportedFormats: TImageFormats; virtual;
    { Method which must be overrided in descendants if they' are be capable
      of loading images. Images are already freed and length is set to zero
      whenever this method gets called. Also Handle is assured to be valid
      and contains data that passed TestFormat method's check.}
    function LoadData(Handle: TImagingHandle; var Images: TDynImageDataArray;
      OnlyFirstFrame: Boolean): Boolean; virtual;
    { Method which must be overrided in descendants if they are be capable
      of saving images. Images are checked to have length >0 and
      that they contain valid images. For single-image file formats
      Index contain valid index to Images array (to image which should be saved).
      Multi-image formats should use FFirstIdx and FLastIdx fields to
      to get all images that are to be saved.}
    function SaveData(Handle: TImagingHandle; const Images: TDynImageDataArray;
      Index: LongInt): Boolean; virtual;
    { This method is called internaly by MakeCompatible when input image
      is in format not supported by this file format. Image is clone of
      MakeCompatible's input and Info is its extended format info.}
    procedure ConvertToSupported(var Image: TImageData;
      const Info: TImageFormatInfo); virtual;
    { Returns True if given image is supported for saving by this file format.
      Most file formats don't need to override this method. It checks
      (in this base class) if Image's format is in SupportedFromats set.
      But you may override it if you want further checks
      (proper widht and height for example).}
    function IsSupported(const Image: TImageData): Boolean; virtual;
  public
    constructor Create; virtual;
    destructor Destroy; override;

    { Loads images from file source.}
    function LoadFromFile(const FileName: string; var Images: TDynImageDataArray;
      OnlyFirstLevel: Boolean = False): Boolean;
    { Loads images from stream source.}
    function LoadFromStream(Stream: TStream; var Images: TDynImageDataArray;
      OnlyFirstLevel: Boolean = False): Boolean;
    { Loads images from memory source.}
    function LoadFromMemory(Data: Pointer; Size: LongInt;
      var Images: TDynImageDataArray; OnlyFirstLevel: Boolean = False): Boolean;

    { Saves images to file. If format supports only single level images and
      there are multiple images to be saved, they are saved as sequence of
      independent images (for example SaveToFile saves sequence of
      files img000.jpg, img001.jpg ....).}
    function SaveToFile(const FileName: string; const Images: TDynImageDataArray;
      OnlyFirstLevel: Boolean = False): Boolean;
    { Saves images to stream. If format supports only single level images and
      there are multiple images to be saved, they are saved as sequence of
      independent images.}
    function SaveToStream(Stream: TStream; const Images: TDynImageDataArray;
      OnlyFirstLevel: Boolean = False): Boolean;
    { Saves images to memory. If format supports only single level images and
      there are multiple images to be saved, they are saved as sequence of
      independent images. Data must be already allocated and their size passed
      as Size parameter, number of written bytes is then returned in the same
      parameter.}
    function SaveToMemory(Data: Pointer; var Size: LongInt;
      const Images: TDynImageDataArray; OnlyFirstLevel: Boolean = False): Boolean;

    { Makes Image compatible with this file format (that means it is in one
      of data formats in Supported formats set). If input is already
      in supported format then Compatible just use value from input
      (Compatible := Image) so must not free it after you are done with it
      (image bits pointer points to input image's bits).
      If input is not in supported format then it is cloned to Compatible
      and concerted to one of supported formats (which one dependeds on
      this file format). If image is cloned MustBeFreed is set to True
      to indicated that you must free Compatible after you are done with it.}
    function MakeCompatible(const Image: TImageData; var Compatible: TImageData;
      out MustBeFreed: Boolean): Boolean;   
    { Returns True if data located in source identified by Handle
      represent valid image in current format.}
    function TestFormat(Handle: TImagingHandle): Boolean; virtual;
    { Resturns True if the given FileName matches filter for this file format.
      For most formats it just checks filename extensions.
      It uses filename masks in from Masks property so it can recognize
      filenames like this 'umajoXXXumajo.j0j' if one of themasks is
      'umajo*umajo.j?j'.}
    function TestFileName(const FileName: string): Boolean;
    { Descendants use this method to check if their options (registered with
      constant Ids for SetOption/GetOption interface or accessible as properties
      of descendants) have valid values and make necessary changes.}
    procedure CheckOptionsValidity; virtual;

    { Description of this format.}
    property Name: string read FName;
    { Indicates whether images in this format can be loaded.}
    property CanLoad: Boolean read FCanLoad;
    { Indicates whether images in this format can be saved.}
    property CanSave: Boolean read FCanSave;
    { Indicates whether images in this format can contain multiple image levels.}
    property IsMultiImageFormat: Boolean read FIsMultiImageFormat;
    { List of filename extensions for this format.}
    property Extensions: TStringList read FExtensions;
    { List of filename mask that are used to associate filenames
      with TImageFileFormat descendants. Typical mask looks like
      '*.bmp' or 'texture.*' (supports file formats which use filename instead
      of extension to identify image files).}
    property Masks: TStringList read FMasks;
    { Set of TImageFormats supported by saving functions of this format. Images
      can be saved only in one those formats.}
    property SupportedFormats: TImageFormats read GetSupportedFormats;
  end;
  {$TYPEINFO OFF}

  { Class reference for TImageFileFormat class}
  TImageFileFormatClass = class of TImageFileFormat;

{ Returns symbolic name of given format.}
function GetFormatName(Format: TImageFormat): string;
{ Returns string with information about given Image.}
function ImageToStr(const Image: TImageData): string;
{ Returns Imaging version string in format 'Major.Minor.Patch'.}
function GetVersionStr: string;
{ If Condition is True then TruePart is retured, otherwise FalsePart is returned.}
function IffFormat(Condition: Boolean; const TruePart, FalsePart: TImageFormat): TImageFormat;
{ Registers new image loader/saver so it can be used by LoadFrom/SaveTo
  functions.}
procedure RegisterImageFileFormat(AClass: TImageFileFormatClass);
{ Registers new option so it can be used by SetOption and GetOption functions.
  Returns True if registration was succesful - that is Id is valid and is
  not already taken by another option.}
function RegisterOption(OptionId: LongInt; Variable: PLongInt): Boolean;
{ Returns image format loader/saver according to given extension
  or nil if not found.}
function FindImageFileFormatByExt(const Ext: string): TImageFileFormat;
{ Returns image format loader/saver according to given filename
  or nil if not found.}
function FindImageFileFormatByName(const FileName: string): TImageFileFormat;
{ Returns image format loader/saver based on its class
  or nil if not found or not registered.}
function FindImageFileFormatByClass(AClass: TImageFileFormatClass): TImageFileFormat;
{ Returns number of registered image file format loaders/saver.}
function GetFileFormatCount: LongInt;
{ Returns image file format loader/saver at given index. Index must be
  in range [0..GetFileFormatCount - 1] otherwise nil is returned.}
function GetFileFormatAtIndex(Index: LongInt): TImageFileFormat;
{ Returns filter string for usage with open and save picture dialogs
  which contains all registered image file formats.
  Set OpenFileFilter to True if you want filter for open dialog
  and to False if you want save dialog filter (formats that cannot save to files
  are not added then).
  For open dialog filter for all known graphic files
  (like All(*.jpg;*.png;....) is added too at the first index.}
function GetImageFileFormatsFilter(OpenFileFilter: Boolean): string;
{ Returns file extension (without dot) of image format selected
  by given filter index. Used filter string is defined by GetImageFileFormatsFilter
  function. This function can be used with save dialogs (with filters created
  by GetImageFileFormatsFilter) to get the extension of file format selected
  in dialog quickly. Index is in range 1..N (as FilterIndex property
  of TOpenDialog/TSaveDialog)}
function GetFilterIndexExtension(Index: LongInt; OpenFileFilter: Boolean): string;
{ Returns filter index of image file format of file specified by FileName. Used filter
  string is defined by GetImageFileFormatsFilter function.
  Returned index is in range 1..N (as FilterIndex property of TOpenDialog/TSaveDialog)}
function GetFileNameFilterIndex(const FileName: string; OpenFileFilter: Boolean): LongInt;
{ Returns current IO functions.}
function GetIO: TIOFunctions;
{ Raises EImagingError with given message.}
procedure RaiseImaging(const Msg: string; const Args: array of const);

implementation

uses
{$IFNDEF DONT_LINK_BITMAP}
  ImagingBitmap,
{$ENDIF}
{$IFNDEF DONT_LINK_JPEG}
  ImagingJpeg,
{$ENDIF}
{$IF not Defined(DONT_LINK_PNG) or not Defined(DONT_LINK_MNG) or not Defined(DONT_LINK_JNG)}
  ImagingNetworkGraphics,
{$IFEND}
{$IFNDEF DONT_LINK_GIF}
  ImagingGif,
{$ENDIF}
{$IFNDEF DONT_LINK_DDS}
  ImagingDds,
{$ENDIF}
{$IFNDEF DONT_LINK_TARGA}
  ImagingTarga,
{$ENDIF}
{$IFNDEF DONT_LINK_PNM}
  ImagingPortableMaps,
{$ENDIF}
{$IFNDEF DONT_LINK_EXTRAS}
  ImagingExtras,
{$ENDIF}
  ImagingFormats, ImagingUtility, ImagingIO;

resourcestring
  SImagingTitle = 'Vampyre Imaging Library';
  SExceptMsg = 'Exception Message';
  SAllFilter = 'All Images';
  SUnknownFormat = 'Unknown and unsupported format';
  SErrorFreeImage = 'Error while freeing image. %s';
  SErrorCloneImage = 'Error while cloning image. %s';
  SErrorFlipImage = 'Error while flipping image. %s';
  SErrorMirrorImage = 'Error while mirroring image. %s';
  SErrorResizeImage = 'Error while resizing image.  %s';
  SErrorSwapImage = 'Error while swapping channels of image. %s';
  SFileFormatCanNotLoad = 'Image Format "%s" does not support loading images.';
  SFileFormatCanNotSave = 'Image Format "%s" does not support saving images.';
  SErrorNewImage = 'Error while creating image data with params: Width=%d ' +
    'Height=%d Format=%s.';
  SErrorConvertImage = 'Error while converting image to format "%s". %s';
  SImageInfo = 'Image @%p info: Width = %dpx, Height = %dpx, ' +
    'Format = %s, Size = %.0n %s, Bits @%p, Palette @%p.';
  SImageInfoInvalid = 'Access violation encountered when getting info on ' +
    'image at address %p.';
  SFileNotValid = 'File "%s" is not valid image in "%s" format.';
  SStreamNotValid = 'Stream %p does not contain valid image in "%s" format.';
  SMemoryNotValid = 'Memory %p (%d Bytes) does not contain valid image ' +
    'in "%s" format.';
  SErrorLoadingFile = 'Error while loading images from file "%s" (file format: %s).';
  SErrorLoadingStream = 'Error while loading images from stream %p (file format: %s).';
  SErrorLoadingMemory = 'Error while loading images from memory %p (%d Bytes) (file format: %s).';
  SErrorSavingFile = 'Error while saving images to file "%s" (file format: %s).';
  SErrorSavingStream = 'Error while saving images to stream %p (file format: %s).';
  SErrorSavingMemory = 'Error while saving images to memory %p (%d Bytes) (file format: %s).';
  SErrorFindColor = 'Error while finding color in palette @%p with %d entries.';
  SErrorGrayscalePalette = 'Error while filling grayscale palette @%p with %d entries.';
  SErrorCustomPalette = 'Error while filling custom palette @%p with %d entries.';
  SErrorSwapPalette = 'Error while swapping channels of palette @%p with %d entries.';
  SErrorReduceColors = 'Error while reducing number of colors of image to %d. %s';
  SErrorGenerateMipMaps = 'Error while generating %d mipmap levels for image %s';
  SImagesNotValid = 'One or more images are not valid.';
  SErrorCopyRect = 'Error while copying rect from image %s to image %s.';
  SErrorMapImage = 'Error while mapping image %s to palette.';
  SErrorFillRect = 'Error while filling rectangle X:%d Y:%d W:%d H:%d in image %s';
  SErrorSplitImage = 'Error while splitting image %s to %dx%d sized chunks.';
  SErrorMakePaletteForImages = 'Error while making %d color palette for %d images.';
  SErrorNewPalette = 'Error while creating new palette with %d entries';
  SErrorFreePalette = 'Error while freeing palette @%p';
  SErrorCopyPalette = 'Error while copying %d entries from palette @%p to @%p';
  SErrorReplaceColor = 'Error while replacing colors in rectangle X:%d Y:%d W:%d H:%d of image %s';
  SErrorRotateImage = 'Error while rotating image %s by %.2n degrees';
  SErrorStretchRect = 'Error while stretching rect from image %s to image %s.';
  SErrorEmptyStream = 'Input stream has no data. Check Position property.';

const
  // initial size of array with options information
  InitialOptions = 256;
  // max depth of the option stack
  OptionStackDepth = 8;
  // do not change the default format now, its too late
  DefaultImageFormat: TImageFormat = ifA8R8G8B8;

type
  TOptionArray = array of PLongInt;
  TOptionValueArray = array of LongInt;

  TOptionStack = class(TObject)
  private
    FStack: array[0..OptionStackDepth - 1] of TOptionValueArray;
    FPosition: LongInt;
  public
    constructor Create;
    destructor Destroy; override;
    function Push: Boolean;
    function Pop: Boolean;
  end;

var
  // currently set IO functions
  IO: TIOFunctions;
  // list with all registered TImageFileFormat classes
  ImageFileFormats: TList = nil;
  // array with registered options (pointers to their values)
  Options: TOptionArray = nil;
  // array containing addional infomation about every image format
  ImageFormatInfos: TImageFormatInfoArray;
  // stack used by PushOptions/PopOtions functions
  OptionStack: TOptionStack = nil;
var
  // variable for ImagingColorReduction option
  ColorReductionMask: LongInt = $FF;
  // variable for ImagingLoadOverrideFormat option
  LoadOverrideFormat: TImageFormat = ifUnknown;
  // variable for ImagingSaveOverrideFormat option
  SaveOverrideFormat: TImageFormat = ifUnknown;
  // variable for ImagingSaveOverrideFormat option
  MipMapFilter: TSamplingFilter = sfLinear;


{ Internal unit functions }

{ Modifies option value to be in the allowed range. Works only
  for options registered in this unit.}
function CheckOptionValue(OptionId, Value: LongInt): LongInt; forward;
{ Sets IO functions to file IO.}
procedure SetFileIO; forward;
{ Sets IO functions to stream IO.}
procedure SetStreamIO; forward;
{ Sets IO functions to memory IO.}
procedure SetMemoryIO; forward;
{ Inits image format infos array.}
procedure InitImageFormats; forward;
{ Freew image format infos array.}
procedure FreeImageFileFormats; forward;
{ Creates options array and stack.}
procedure InitOptions; forward;
{ Frees options array and stack.}
procedure FreeOptions; forward;

{$IFDEF USE_INLINE}
{ Those inline functions are copied here from ImagingFormats
  because Delphi 9/10 cannot inline them if they are declared in
  circularly dependent units.}

procedure CopyPixel(Src, Dest: Pointer; BytesPerPixel: LongInt); inline;
begin
  case BytesPerPixel of
    1: PByte(Dest)^ := PByte(Src)^;
    2: PWord(Dest)^ := PWord(Src)^;
    3: PColor24Rec(Dest)^ := PColor24Rec(Src)^;
    4: PLongWord(Dest)^ := PLongWord(Src)^;
    6: PColor48Rec(Dest)^ := PColor48Rec(Src)^;
    8: PInt64(Dest)^ := PInt64(Src)^;
    16: PColorFPRec(Dest)^ := PColorFPRec(Src)^;
  end;
end;

function ComparePixels(PixelA, PixelB: Pointer; BytesPerPixel: LongInt): Boolean; inline;
begin
  case BytesPerPixel of
    1: Result := PByte(PixelA)^ = PByte(PixelB)^;
    2: Result := PWord(PixelA)^ = PWord(PixelB)^;
    3: Result := (PWord(PixelA)^ = PWord(PixelB)^) and
         (PColor24Rec(PixelA).R = PColor24Rec(PixelB).R);
    4: Result := PLongWord(PixelA)^ = PLongWord(PixelB)^;
    6: Result := (PLongWord(PixelA)^ = PLongWord(PixelB)^) and
         (PColor48Rec(PixelA).R = PColor48Rec(PixelB).R);
    8: Result := PInt64(PixelA)^ = PInt64(PixelB)^;
    16: Result := (PFloatHelper(PixelA).Data2 = PFloatHelper(PixelB).Data2) and
          (PFloatHelper(PixelA).Data1 = PFloatHelper(PixelB).Data1);
  else
    Result := False;
  end;
end;
{$ENDIF}

{ ------------------------------------------------------------------------
                       Low Level Interface Functions
  ------------------------------------------------------------------------}

{ General Functions }

procedure InitImage(var Image: TImageData);
begin
  FillChar(Image, SizeOf(Image), 0);
end;

function NewImage(Width, Height: LongInt; Format: TImageFormat; var Image:
  TImageData): Boolean;
var
  FInfo: PImageFormatInfo;
begin
  Assert((Width > 0) and (Height >0));
  Assert(IsImageFormatValid(Format));
  Result := False;
  FreeImage(Image);
  try
    Image.Width := Width;
    Image.Height := Height;
    // Select default data format if selected
    if (Format = ifDefault)  then
      Image.Format := DefaultImageFormat
    else
      Image.Format := Format;
    // Get extended format info
    FInfo := ImageFormatInfos[Image.Format];
    if FInfo = nil then
    begin
      InitImage(Image);
      Exit;
    end;
    // Check image dimensions and calculate its size in bytes
    FInfo.CheckDimensions(FInfo.Format, Image.Width, Image.Height);
    Image.Size := FInfo.GetPixelsSize(FInfo.Format, Image.Width, Image.Height);
    if Image.Size = 0 then
    begin
      InitImage(Image);
      Exit;
    end;
    // Image bits are allocated and set to zeroes
    GetMem(Image.Bits, Image.Size);
    FillChar(Image.Bits^, Image.Size, 0);
    // Palette is allocated and set to zeroes
    if FInfo.PaletteEntries > 0 then
    begin
      GetMem(Image.Palette, FInfo.PaletteEntries * SizeOf(TColor32Rec));
      FillChar(Image.Palette^, FInfo.PaletteEntries * SizeOf(TColor32Rec), 0);
    end;
    Result := TestImage(Image);
  except
    RaiseImaging(SErrorNewImage, [Width, Height, GetFormatName(Format)]);
  end;
end;

function TestImage(const Image: TImageData): Boolean;
begin
  try
    Result := (LongInt(Image.Format) >= LongInt(Low(TImageFormat))) and
      (LongInt(Image.Format) <= LongInt(High(TImageFormat))) and
      (ImageFormatInfos[Image.Format] <> nil) and
      (Assigned(ImageFormatInfos[Image.Format].GetPixelsSize) and
      (ImageFormatInfos[Image.Format].GetPixelsSize(Image.Format,
      Image.Width, Image.Height) = Image.Size));
  except
    // Possible int overflows or other errors 
    Result := False;
  end;
end;

procedure FreeImage(var Image: TImageData);
begin
  try
    if TestImage(Image) then
    begin
      FreeMemNil(Image.Bits);
      FreeMemNil(Image.Palette);
    end;
    InitImage(Image);
  except
    RaiseImaging(SErrorFreeImage, [ImageToStr(Image)]);
  end;
end;

procedure FreeImagesInArray(var Images: TDynImageDataArray);
var
  I: LongInt;
begin
  if Length(Images) > 0 then
  begin
    for I := 0 to Length(Images) - 1 do
      FreeImage(Images[I]);
    SetLength(Images, 0);
  end;
end;

function TestImagesInArray(const Images: TDynImageDataArray): Boolean;
var
  I: LongInt;
begin
  if Length(Images) > 0 then
  begin
    Result := True;
    for I := 0 to Length(Images) - 1 do
    begin
      Result := Result and TestImage(Images[I]);
      if not Result then
        Break;
    end;
  end
  else
    Result := False;
end;

function DetermineFileFormat(const FileName: string): string;
var
  I: LongInt;
  Fmt: TImageFileFormat;
  Handle: TImagingHandle;
begin
  Assert(FileName <> '');
  Result := '';
  SetFileIO;
  try
    Handle := IO.OpenRead(PChar(FileName));
    try
      // First file format according to FileName and test if the data in
      // file is really in that format
      for I := 0 to ImageFileFormats.Count - 1 do
      begin
        Fmt := TImageFileFormat(ImageFileFormats[I]);
        if Fmt.TestFileName(FileName) and Fmt.TestFormat(Handle) then
        begin
          Result := Fmt.Extensions[0];
          Exit;
        end;
      end;
      // No file format was found with filename search so try data-based search
      for I := 0 to ImageFileFormats.Count - 1 do
      begin
        Fmt := TImageFileFormat(ImageFileFormats[I]);
        if Fmt.TestFormat(Handle) then
        begin
          Result := Fmt.Extensions[0];
          Exit;
        end;
      end;
    finally
      IO.Close(Handle);
    end;
  except
    Result := '';
  end;
end;

function DetermineStreamFormat(Stream: TStream): string;
var
  I: LongInt;
  Fmt: TImageFileFormat;
  Handle: TImagingHandle;
begin
  Assert(Stream <> nil);
  Result := '';
  SetStreamIO;
  try
    Handle := IO.OpenRead(Pointer(Stream));
    try
      for I := 0 to ImageFileFormats.Count - 1 do
      begin
        Fmt := TImageFileFormat(ImageFileFormats[I]);
        if Fmt.TestFormat(Handle) then
        begin
          Result := Fmt.Extensions[0];
          Exit;
        end;
      end;
    finally
      IO.Close(Handle);
    end;
  except
    Result := '';
  end;
end;

function DetermineMemoryFormat(Data: Pointer; Size: LongInt): string;
var
  I: LongInt;
  Fmt: TImageFileFormat;
  Handle: TImagingHandle;
  IORec: TMemoryIORec;
begin
  Assert((Data <> nil) and (Size > 0));
  Result := '';
  SetMemoryIO;
  IORec.Data := Data;
  IORec.Position := 0;
  IORec.Size := Size;
  try
    Handle := IO.OpenRead(@IORec);
    try
      for I := 0 to ImageFileFormats.Count - 1 do
      begin
        Fmt := TImageFileFormat(ImageFileFormats[I]);
        if Fmt.TestFormat(Handle) then
        begin
          Result := Fmt.Extensions[0];
          Exit;
        end;
      end;
    finally
      IO.Close(Handle);
    end;
  except
    Result := '';
  end;
end;

function IsFileFormatSupported(const FileName: string): Boolean;
begin
  Result := FindImageFileFormatByName(FileName) <> nil;
end;

function EnumFileFormats(var Index: LongInt; var Name, DefaultExt, Masks: string;
  var CanSaveImages, IsMultiImageFormat: Boolean): Boolean;
var
  FileFmt: TImageFileFormat;
begin
  FileFmt := GetFileFormatAtIndex(Index);
  Result := FileFmt <> nil;
  if Result then
  begin
    Name := FileFmt.Name;
    DefaultExt := FileFmt.Extensions[0];
    Masks := FileFmt.Masks.DelimitedText; 
    CanSaveImages := FileFmt.CanSave;
    IsMultiImageFormat := FileFmt.IsMultiImageFormat;
    Inc(Index);
  end
  else
  begin
    Name := '';
    DefaultExt := '';
    Masks := '';
    CanSaveImages := False;
    IsMultiImageFormat := False;
  end;
end;

{ Loading Functions }

function LoadImageFromFile(const FileName: string; var Image: TImageData):
  Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
  I: LongInt;
begin
  Assert(FileName <> '');
  Result := False;
  Format := FindImageFileFormatByExt(DetermineFileFormat(FileName));
  if Format <> nil then
  begin
    FreeImage(Image);
    Result := Format.LoadFromFile(FileName, IArray, True);
    if Result and (Length(IArray) > 0) then
    begin
      Image := IArray[0];
      for I := 1 to Length(IArray) - 1 do
        FreeImage(IArray[I]);
    end
    else
      Result := False;
  end;
end;

function LoadImageFromStream(Stream: TStream; var Image: TImageData): Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
  I: LongInt;
begin
  Assert(Stream <> nil);
  if Stream.Size - Stream.Position = 0 then
    RaiseImaging(SErrorEmptyStream, []);
  Result := False;
  Format := FindImageFileFormatByExt(DetermineStreamFormat(Stream));
  if Format <> nil then
  begin
    FreeImage(Image);
    Result := Format.LoadFromStream(Stream, IArray, True);
    if Result and (Length(IArray) > 0) then
    begin
      Image := IArray[0];
      for I := 1 to Length(IArray) - 1 do
        FreeImage(IArray[I]);
    end
    else
      Result := False;
  end;
end;

function LoadImageFromMemory(Data: Pointer; Size: LongInt; var Image: TImageData): Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
  I: LongInt;
begin
  Assert((Data <> nil) and (Size > 0));
  Result := False;
  Format := FindImageFileFormatByExt(DetermineMemoryFormat(Data, Size));
  if Format <> nil then
  begin
    FreeImage(Image);
    Result := Format.LoadFromMemory(Data, Size, IArray, True);
    if Result and (Length(IArray) > 0) then
    begin
      Image := IArray[0];
      for I := 1 to Length(IArray) - 1 do
        FreeImage(IArray[I]);
    end
    else
      Result := False;
  end;
end;

function LoadMultiImageFromFile(const FileName: string; var Images:
  TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert(FileName <> '');
  Result := False;
  Format := FindImageFileFormatByExt(DetermineFileFormat(FileName));
  if Format <> nil then
  begin
    FreeImagesInArray(Images);
    Result := Format.LoadFromFile(FileName, Images);
  end;
end;

function LoadMultiImageFromStream(Stream: TStream; var Images: TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert(Stream <> nil);
  if Stream.Size - Stream.Position = 0 then
    RaiseImaging(SErrorEmptyStream, []);
  Result := False;
  Format := FindImageFileFormatByExt(DetermineStreamFormat(Stream));
  if Format <> nil then
  begin
    FreeImagesInArray(Images);
    Result := Format.LoadFromStream(Stream, Images);
  end;
end;

function LoadMultiImageFromMemory(Data: Pointer; Size: LongInt;
  var Images: TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert((Data <> nil) and (Size > 0));
  Result := False;
  Format := FindImageFileFormatByExt(DetermineMemoryFormat(Data, Size));
  if Format <> nil then
  begin
    FreeImagesInArray(Images);
    Result := Format.LoadFromMemory(Data, Size, Images);
  end;
end;

{ Saving Functions }

function SaveImageToFile(const FileName: string; const Image: TImageData): Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
begin
  Assert(FileName <> '');
  Result := False;
  Format := FindImageFileFormatByName(FileName);
  if Format <> nil then
  begin
    SetLength(IArray, 1);
    IArray[0] := Image;
    Result := Format.SaveToFile(FileName, IArray, True);
  end;
end;

function SaveImageToStream(const Ext: string; Stream: TStream;
  const Image: TImageData): Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
begin
  Assert((Ext <> '') and (Stream <> nil));
  Result := False;
  Format := FindImageFileFormatByExt(Ext);
  if Format <> nil then
  begin
    SetLength(IArray, 1);
    IArray[0] := Image;
    Result := Format.SaveToStream(Stream, IArray, True);
  end;
end;

function SaveImageToMemory(const Ext: string; Data: Pointer; var Size: LongInt;
  const Image: TImageData): Boolean;
var
  Format: TImageFileFormat;
  IArray: TDynImageDataArray;
begin
  Assert((Ext <> '') and (Data <> nil) and (Size > 0));
  Result := False;
  Format := FindImageFileFormatByExt(Ext);
  if Format <> nil then
  begin
    SetLength(IArray, 1);
    IArray[0] := Image;
    Result := Format.SaveToMemory(Data, Size, IArray, True);
  end;
end;

function SaveMultiImageToFile(const FileName: string;
  const Images: TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert(FileName <> '');
  Result := False;
  Format := FindImageFileFormatByName(FileName);
  if Format <> nil then
    Result := Format.SaveToFile(FileName, Images);
end;

function SaveMultiImageToStream(const Ext: string; Stream: TStream;
  const Images: TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert((Ext <> '') and (Stream <> nil));
  Result := False;
  Format := FindImageFileFormatByExt(Ext);
  if Format <> nil then
    Result := Format.SaveToStream(Stream, Images);
end;

function SaveMultiImageToMemory(const Ext: string; Data: Pointer;
  var Size: LongInt; const Images: TDynImageDataArray): Boolean;
var
  Format: TImageFileFormat;
begin
  Assert((Ext <> '') and (Data <> nil) and (Size > 0));
  Result := False;
  Format := FindImageFileFormatByExt(Ext);
  if Format <> nil then
    Result := Format.SaveToMemory(Data, Size, Images);
end;

{ Manipulation Functions }

function CloneImage(const Image: TImageData; var Clone: TImageData): Boolean;
var
  Info: PImageFormatInfo;
begin
  Result := False;
  if TestImage(Image) then
  try
    if TestImage(Clone) and (Image.Bits <> Clone.Bits) then
      FreeImage(Clone)
    else
      InitImage(Clone);

    Info := ImageFormatInfos[Image.Format];
    Clone.Width := Image.Width;
    Clone.Height := Image.Height;
    Clone.Format := Image.Format;
    Clone.Size := Image.Size;

    if Info.PaletteEntries > 0 then
    begin
      GetMem(Clone.Palette, Info.PaletteEntries * SizeOf(TColor32Rec));
      Move(Image.Palette^, Clone.Palette^, Info.PaletteEntries *
        SizeOf(TColor32Rec));
    end;

    GetMem(Clone.Bits, Clone.Size);
    Move(Image.Bits^, Clone.Bits^, Clone.Size);
    Result := True;
  except
    RaiseImaging(SErrorCloneImage, [ImageToStr(Image)]);
  end;
end;

function ConvertImage(var Image: TImageData; DestFormat: TImageFormat): Boolean;
var
  NewData: Pointer;
  NewPal: PPalette32;
  NewSize, NumPixels: LongInt;
  SrcInfo, DstInfo: PImageFormatInfo;
begin
  Assert(IsImageFormatValid(DestFormat));
  Result := False;
  if TestImage(Image) then
  with Image do
  try
    // If default format is set we use DefaultImageFormat
    if DestFormat = ifDefault then
      DestFormat := DefaultImageFormat;
    SrcInfo := ImageFormatInfos[Format];
    DstInfo := ImageFormatInfos[DestFormat];
    if SrcInfo = DstInfo then
    begin
      // There is nothing to convert - src is alredy in dest format
      Result := True;
      Exit;
    end;
    // Exit Src or Dest format is invalid 
    if (SrcInfo = nil) or (DstInfo = nil) then Exit;
    // If dest format is just src with swapped channels we call
    // SwapChannels instead
    if (SrcInfo.RBSwapFormat = DestFormat) and
      (DstInfo.RBSwapFormat = SrcInfo.Format) then
    begin
      Result := SwapChannels(Image, ChannelRed, ChannelBlue);
      Image.Format := SrcInfo.RBSwapFormat;
      Exit;
    end;

    if (not SrcInfo.IsSpecial) and (not DstInfo.IsSpecial) then
    begin
      NumPixels := Width * Height;
      NewSize := NumPixels * DstInfo.BytesPerPixel;
      GetMem(NewData, NewSize);
      FillChar(NewData^, NewSize, 0);
      GetMem(NewPal, DstInfo.PaletteEntries * SizeOf(TColor32Rec));
      FillChar(NewPal^, DstInfo.PaletteEntries * SizeOf(TColor32Rec), 0);

      if SrcInfo.IsIndexed then
      begin
        // Source: indexed format
        if DstInfo.IsIndexed then
          IndexToIndex(NumPixels, Bits, NewData, SrcInfo, DstInfo, Palette, NewPal)
        else if DstInfo.HasGrayChannel then
          IndexToGray(NumPixels, Bits, NewData, SrcInfo, DstInfo, Palette)
        else if DstInfo.IsFloatingPoint then
          IndexToFloat(NumPixels, Bits, NewData, SrcInfo, DstInfo, Palette)
        else
          IndexToChannel(NumPixels, Bits, NewData, SrcInfo, DstInfo, Palette);
      end
      else if SrcInfo.HasGrayChannel then
      begin
        // Source: grayscale format
        if DstInfo.IsIndexed then
          GrayToIndex(NumPixels, Bits, NewData, SrcInfo, DstInfo, NewPal)
        else if DstInfo.HasGrayChannel then
          GrayToGray(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else if DstInfo.IsFloatingPoint then
          GrayToFloat(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else
          GrayToChannel(NumPixels, Bits, NewData, SrcInfo, DstInfo);
      end
      else if SrcInfo.IsFloatingPoint then
      begin
        // Source: floating point format
        if DstInfo.IsIndexed then
          FloatToIndex(NumPixels, Bits, NewData, SrcInfo, DstInfo, NewPal)
        else if DstInfo.HasGrayChannel then
          FloatToGray(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else if DstInfo.IsFloatingPoint then
          FloatToFloat(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else
          FloatToChannel(NumPixels, Bits, NewData, SrcInfo, DstInfo);
      end
      else
      begin
        // Source: standard multi channel image
        if DstInfo.IsIndexed then
          ChannelToIndex(NumPixels, Bits, NewData, SrcInfo, DstInfo, NewPal)
        else if DstInfo.HasGrayChannel then
          ChannelToGray(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else if DstInfo.IsFloatingPoint then
          ChannelToFloat(NumPixels, Bits, NewData, SrcInfo, DstInfo)
        else
          ChannelToChannel(NumPixels, Bits, NewData, SrcInfo, DstInfo);
      end;

      FreeMemNil(Bits);
      FreeMemNil(Palette);
      Format := DestFormat;
      Bits := NewData;
      Size := NewSize;
      Palette := NewPal;
    end
    else
      ConvertSpecial(Image, SrcInfo, DstInfo);

    Assert(SrcInfo.Format <> Image.Format);

    Result := True;
  except
    RaiseImaging(SErrorConvertImage, [GetFormatName(DestFormat), ImageToStr(Image)]);
  end;
end;

function FlipImage(var Image: TImageData): Boolean;
var
  P1, P2, Buff: Pointer;
  WidthBytes, I: LongInt;
  OldFmt: TImageFormat;
begin
  Result := False;
  OldFmt := Image.Format;
  if TestImage(Image) then
  with Image do
  try
    if ImageFormatInfos[OldFmt].IsSpecial then
      ConvertImage(Image, ifDefault);

    WidthBytes := Width * ImageFormatInfos[Format].BytesPerPixel;
    GetMem(Buff, WidthBytes);
    try
      // Swap all scanlines of image
      for I := 0 to Height div 2 - 1 do
      begin
        P1 := @PByteArray(Bits)[I * WidthBytes];
        P2 := @PByteArray(Bits)[(Height - I - 1) * WidthBytes];
        Move(P1^, Buff^, WidthBytes);
        Move(P2^, P1^, WidthBytes);
        Move(Buff^, P2^, WidthBytes);
      end;
    finally
      FreeMemNil(Buff);
    end;

    if OldFmt <> Format then
      ConvertImage(Image, OldFmt);

    Result := True;  
  except
    RaiseImaging(SErrorFlipImage, [ImageToStr(Image)]);
  end;
end;

function MirrorImage(var Image: TImageData): Boolean;
var
  Scanline: PByte;
  Buff: TColorFPRec;
  Bpp, Y, X, WidthDiv2, WidthBytes, XLeft, XRight: LongInt;
  OldFmt: TImageFormat;
begin
  Result := False;
  OldFmt := Image.Format;
  if TestImage(Image) then
  with Image do
  try
    if ImageFormatInfos[OldFmt].IsSpecial then
      ConvertImage(Image, ifDefault);

    Bpp := ImageFormatInfos[Format].BytesPerPixel;
    WidthDiv2 := Width div 2;
    WidthBytes := Width * Bpp;
    // Mirror all pixels on each scanline of image
    for Y := 0 to Height - 1 do
    begin
      Scanline := @PByteArray(Bits)[Y * WidthBytes];
      XLeft := 0;
      XRight := (Width - 1) * Bpp;
      for X := 0 to WidthDiv2 - 1 do
      begin
        CopyPixel(@PByteArray(Scanline)[XLeft], @Buff, Bpp);
        CopyPixel(@PByteArray(Scanline)[XRight],
          @PByteArray(Scanline)[XLeft], Bpp);
        CopyPixel(@Buff, @PByteArray(Scanline)[XRight], Bpp);
        Inc(XLeft, Bpp);
        Dec(XRight, Bpp);
      end;
    end;

    if OldFmt <> Format then
      ConvertImage(Image, OldFmt);

    Result := True;
  except
    RaiseImaging(SErrorMirrorImage, [ImageToStr(Image)]);
  end;
end;

function ResizeImage(var Image: TImageData; NewWidth, NewHeight: LongInt;
  Filter: TResizeFilter): Boolean;
var
  WorkImage: TImageData;
begin
  Assert((NewWidth > 0) and (NewHeight > 0));
  Result := False;
  if TestImage(Image) and ((Image.Width <> NewWidth) or (Image.Height <> NewHeight)) then
  try
    InitImage(WorkImage);
    // Create new image with desired dimensions
    NewImage(NewWidth, NewHeight, Image.Format, WorkImage);
    // Stretch pixels from old image to new one
    StretchRect(Image, 0, 0, Image.Width, Image.Height,
      WorkImage, 0, 0, WorkImage.Width, WorkImage.Height, Filter);
    // Free old image and assign new image to it
    FreeMemNil(Image.Bits);
    if Image.Palette <> nil then
    begin
      FreeMem(WorkImage.Palette);
      WorkImage.Palette := Image.Palette;
    end;
    Image := WorkImage;
    Result := True;
  except
    RaiseImaging(SErrorResizeImage, [ImageToStr(Image)]);
  end;
end;

function SwapChannels(var Image: TImageData; SrcChannel, DstChannel: LongInt): Boolean;
var
  I, NumPixels: LongInt;
  Info: PImageFormatInfo;
  Swap, Alpha: Word;
  Data: PByte;
  Pix64: TColor64Rec;
  PixF: TColorFPRec;
  SwapF: Single;
begin
  Assert((SrcChannel in [0..3]) and (DstChannel in [0..3]));
  Result := False;
  if TestImage(Image) and (SrcChannel <> DstChannel) then
  with Image do
  try
    NumPixels := Width * Height;
    Info := ImageFormatInfos[Format];
    Data := Bits;

    if (Info.Format = ifR8G8B8) or ((Info.Format = ifA8R8G8B8) and
       (SrcChannel <> ChannelAlpha) and (DstChannel <> ChannelAlpha)) then
    begin
      // Swap channels of most common formats R8G8B8 and A8R8G8B8 (no alpha)
      for I := 0 to NumPixels - 1 do
      with PColor24Rec(Data)^ do
      begin
        Swap := Channels[SrcChannel];
        Channels[SrcChannel] := Channels[DstChannel];
        Channels[DstChannel] := Swap;
        Inc(Data, Info.BytesPerPixel);
      end;
    end
    else if Info.IsIndexed then
    begin
      // Swap palette channels of indexed images
      SwapChannelsOfPalette(Palette, Info.PaletteEntries, SrcChannel, DstChannel)
    end
    else if Info.IsFloatingPoint then
    begin
      // Swap channels of floating point images
      for I := 0 to NumPixels - 1 do
      begin
        FloatGetSrcPixel(Data, Info, PixF);
        with PixF do
        begin
          SwapF := Channels[SrcChannel];
          Channels[SrcChannel] := Channels[DstChannel];
          Channels[DstChannel] := SwapF;
        end;
        FloatSetDstPixel(Data, Info, PixF);
        Inc(Data, Info.BytesPerPixel);
      end;
    end
    else if Info.IsSpecial then
    begin
      // Swap channels of special format images
      ConvertImage(Image, ifDefault);
      SwapChannels(Image, SrcChannel, DstChannel);
      ConvertImage(Image, Info.Format);
    end
    else if Info.HasGrayChannel and Info.HasAlphaChannel and
      ((SrcChannel = ChannelAlpha) or (DstChannel = ChannelAlpha)) then
    begin
      for I := 0 to NumPixels - 1 do
      begin
        // If we have grayscale image with alpha and alpha is channel
        // to be swapped, we swap it. No other alternative for gray images,
        // just alpha and something
        GrayGetSrcPixel(Data, Info, Pix64, Alpha);
        Swap := Alpha;
        Alpha := Pix64.A;
        Pix64.A := Swap;
        GraySetDstPixel(Data, Info, Pix64, Alpha);
        Inc(Data, Info.BytesPerPixel);
      end;
    end
    else
    begin
      // Then do general swap on other channel image formats
      for I := 0 to NumPixels - 1 do
      begin
        ChannelGetSrcPixel(Data, Info, Pix64);
        with Pix64 do
        begin
          Swap := Channels[SrcChannel];
          Channels[SrcChannel] := Channels[DstChannel];
          Channels[DstChannel] := Swap;
        end;
        ChannelSetDstPixel(Data, Info, Pix64);
        Inc(Data, Info.BytesPerPixel);
      end;
    end;

    Result := True;
  except
    RaiseImaging(SErrorSwapImage, [ImageToStr(Image)]);
  end;
end;

function ReduceColors(var Image: TImageData; MaxColors: LongInt): Boolean;
var
  TmpInfo: TImageFormatInfo;
  Data, Index: PWord;
  I, NumPixels: LongInt;
  Pal: PPalette32;
  Col:PColor32Rec;
  OldFmt: TImageFormat;
begin
  Result := False;
  if TestImage(Image) then
  with Image do
  try
    // First create temp image info and allocate output bits and palette
    MaxColors := ClampInt(MaxColors, 2, High(Word));
    OldFmt := Format;
    FillChar(TmpInfo, SizeOf(TmpInfo), 0);
    TmpInfo.PaletteEntries := MaxColors;
    TmpInfo.BytesPerPixel := 2;
    NumPixels := Width * Height;
    GetMem(Data, NumPixels * TmpInfo.BytesPerPixel);
    GetMem(Pal, MaxColors * SizeOf(TColor32Rec));
    ConvertImage(Image, ifA8R8G8B8);
    // We use median cut algorithm to create reduced palette and to
    // fill Data with indices to this palette
    ReduceColorsMedianCut(NumPixels, Bits, PByte(Data),
      ImageFormatInfos[Format], @TmpInfo, MaxColors, ColorReductionMask, Pal);
    Col := Bits;
    Index := Data;
    // Then we write reduced colors to the input image
    for I := 0 to NumPixels - 1 do
    begin
      Col.Color := Pal[Index^].Color;
      Inc(Col);
      Inc(Index);
    end;
    FreeMemNil(Data);
    FreeMemNil(Pal);
    // And convert it to its original format
    ConvertImage(Image, OldFmt);
    Result := True;
  except
    RaiseImaging(SErrorReduceColors, [MaxColors, ImageToStr(Image)]);
  end;
end;

function GenerateMipMaps(const Image: TImageData; Levels: LongInt;
  var MipMaps: TDynImageDataArray): Boolean;
var
  Width, Height, I, Count: LongInt;
  Info: TImageFormatInfo;
  CompatibleCopy: TImageData;
begin
  Result := False;
  if TestImage(Image) then
  try
    Width := Image.Width;
    Height := Image.Height;
    // We compute number of possible mipmap levels and if
    // the given levels are invalid or zero we use this value
    Count := GetNumMipMapLevels(Width, Height);
    if (Levels <= 0) or (Levels > Count) then
      Levels := Count;

    // If we have special format image we create copy to allow pixel access.
    // This is also done in FillMipMapLevel which is called for each level
    // but then the main big image would be converted to compatible
    // for every level.
    GetImageFormatInfo(Image.Format, Info);
    if Info.IsSpecial then
    begin
      InitImage(CompatibleCopy);
      CloneImage(Image, CompatibleCopy);
      ConvertImage(CompatibleCopy, ifDefault);
    end
    else
      CompatibleCopy := Image;

    FreeImagesInArray(MipMaps);
    SetLength(MipMaps, Levels);
    CloneImage(Image, MipMaps[0]);

    for I := 1 to Levels - 1 do
    begin
      Width := Width shr 1;
      Height := Height shr 1;
      if Width < 1 then Width := 1;
      if Height < 1 then Height := 1;
      FillMipMapLevel(CompatibleCopy, Width, Height, MipMaps[I]);
    end;

    if CompatibleCopy.Format <> MipMaps[0].Format then
    begin
      // Must convert smaller levels to proper format
      for I := 1 to High(MipMaps) do
        ConvertImage(MipMaps[I], MipMaps[0].Format);
      FreeImage(CompatibleCopy);
    end;

    Result := True;
  except
    RaiseImaging(SErrorGenerateMipMaps, [Levels, ImageToStr(Image)]);
  end;
end;

function MapImageToPalette(var Image: TImageData; Pal: PPalette32;
  Entries: LongInt): Boolean;

  function FindNearestColor(Pal: PPalette32; Entries: LongInt; Col: TColor32Rec): LongInt;
  var
    I, MinDif, Dif: LongInt;
  begin
    Result := 0;
    MinDif := 1020;
    for I := 0 to Entries - 1 do
    with Pal[I] do
    begin
      Dif := Abs(R - Col.R);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(G - Col.G);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(B - Col.B);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(A - Col.A);
      if Dif < MinDif then
      begin
        MinDif := Dif;
        Result := I;
      end;
    end;
  end;

var
  I, MaxEntries: LongInt;
  PIndex: PByte;
  PColor: PColor32Rec;
  CloneARGB: TImageData;
  Info: PImageFormatInfo;
begin
  Assert((Entries >= 2) and (Entries <= 256));
  Result := False;

  if TestImage(Image) then
  try
    // We create clone of source image in A8R8G8B8 and
    // then recreate source image in ifIndex8 format
    // with palette taken from Pal parameter
    InitImage(CloneARGB);
    CloneImage(Image, CloneARGB);
    ConvertImage(CloneARGB, ifA8R8G8B8);
    FreeImage(Image);
    NewImage(CloneARGB.Width, CloneARGB.Height, ifIndex8, Image);

    Info := ImageFormatInfos[Image.Format];
    MaxEntries := Min(Info.PaletteEntries, Entries);
    Move(Pal^, Image.Palette^, MaxEntries * SizeOf(TColor32Rec));
    PIndex := Image.Bits;
    PColor := CloneARGB.Bits;

    // For every pixel of ARGB clone we find closest color in
    // given palette and assign its index to resulting image's pixel
    // procedure used here is very slow but simple and memory usage friendly
    // (contrary to other methods)
    for I := 0 to Image.Width * Image.Height - 1 do
    begin
      PIndex^ := Byte(FindNearestColor(Image.Palette, MaxEntries, PColor^));
      Inc(PIndex);
      Inc(PColor);
    end;

    FreeImage(CloneARGB);
    Result := True;
  except
    RaiseImaging(SErrorMapImage, [ImageToStr(Image)]);
  end;
end;

function SplitImage(var Image: TImageData; var Chunks: TDynImageDataArray;
  ChunkWidth, ChunkHeight: LongInt; var XChunks, YChunks: LongInt;
  PreserveSize: Boolean; Fill: Pointer): Boolean;
var
  X, Y, XTrunc, YTrunc: LongInt;
  NotOnEdge: Boolean;
  Info: PImageFormatInfo;
  OldFmt: TImageFormat;
begin
  Assert((ChunkWidth > 0) and (ChunkHeight > 0));
  Result := False;
  OldFmt := Image.Format;
  FreeImagesInArray(Chunks);

  if TestImage(Image) then
  try
    Info := ImageFormatInfos[Image.Format];
    if Info.IsSpecial then
      ConvertImage(Image, ifDefault);

    // We compute make sure that chunks are not larger than source image or negative
    ChunkWidth := ClampInt(ChunkWidth, 0, Image.Width);
    ChunkHeight := ClampInt(ChunkHeight, 0, Image.Height);
    // Number of chunks along X and Y axes is computed
    XChunks := Trunc(Ceil(Image.Width / ChunkWidth));
    YChunks := Trunc(Ceil(Image.Height / ChunkHeight));
    SetLength(Chunks, XChunks * YChunks);

    // For every chunk we create new image and copy a portion of
    // the source image to it. If chunk is on the edge of the source image
    // we fill enpty space with Fill pixel data if PreserveSize is set or
    // make the chunk smaller if it is not set
    for Y := 0 to YChunks - 1 do
      for X := 0 to XChunks - 1 do
      begin
        // Determine if current chunk is on the edge of original image
        NotOnEdge := ((X < XChunks - 1) and (Y < YChunks - 1)) or
          ((Image.Width mod ChunkWidth = 0) and (Image.Height mod ChunkHeight = 0));

        if PreserveSize or NotOnEdge then
        begin
          // We should preserve chunk sizes or we are somewhere inside original image
          NewImage(ChunkWidth, ChunkHeight, Image.Format, Chunks[Y * XChunks + X]);
          if (not NotOnEdge) and (Fill <> nil) then
            FillRect(Chunks[Y * XChunks + X], 0, 0, ChunkWidth, ChunkHeight, Fill);
          CopyRect(Image, X * ChunkWidth, Y * ChunkHeight, ChunkWidth, ChunkHeight,
            Chunks[Y * XChunks + X], 0, 0);
        end
        else
        begin
          // Create smaller edge chunk
          XTrunc := Image.Width - (Image.Width div ChunkWidth) * ChunkWidth;
          YTrunc := Image.Height - (Image.Height div ChunkHeight) * ChunkHeight;
          NewImage(XTrunc, YTrunc, Image.Format, Chunks[Y * XChunks + X]);
          CopyRect(Image, X * ChunkWidth, Y * ChunkHeight, XTrunc, YTrunc,
            Chunks[Y * XChunks + X], 0, 0);
        end;
        
        // If source image is in indexed format we copy its palette to chunk
        if Info.IsIndexed then
        begin
          Move(Image.Palette^, Chunks[Y * XChunks + X].Palette^,
            Info.PaletteEntries * SizeOf(TColor32Rec));
        end;
      end;

    if OldFmt <> Image.Format then
    begin
      ConvertImage(Image, OldFmt);
      for X := 0 to Length(Chunks) - 1 do
        ConvertImage(Chunks[X], OldFmt);
    end;

    Result := True;
  except
    RaiseImaging(SErrorSplitImage, [ImageToStr(Image), ChunkWidth, ChunkHeight]);
  end;
end;

function MakePaletteForImages(var Images: TDynImageDataArray; Pal: PPalette32;
  MaxColors: LongInt; ConvertImages: Boolean): Boolean;
var
  I: Integer;
  SrcInfo, DstInfo: PImageFormatInfo;
  Target, TempImage: TImageData;
  DstFormat: TImageFormat;
begin
  Assert((Pal <> nil) and (MaxColors > 0));
  Result := False;
  InitImage(TempImage);

  if TestImagesInArray(Images) then
  try
    // Null the color histogram
    ReduceColorsMedianCut(0, nil, nil, nil, nil, 0, 0, nil, [raCreateHistogram]);
    for I := 0 to Length(Images) - 1 do
    begin
      SrcInfo := ImageFormatInfos[Images[I].Format];
      if SrcInfo.IsIndexed or SrcInfo.IsSpecial then
      begin
        // create temp image in supported format for updating histogram
        CloneImage(Images[I], TempImage);
        ConvertImage(TempImage, ifA8R8G8B8);
        SrcInfo := ImageFormatInfos[TempImage.Format];
      end
      else
        TempImage := Images[I];

      // Update histogram with colors of each input image
      ReduceColorsMedianCut(TempImage.Width * TempImage.Height, TempImage.Bits,
        nil, SrcInfo, nil, MaxColors, ColorReductionMask, nil, [raUpdateHistogram]);

      if Images[I].Bits <> TempImage.Bits then
        FreeImage(TempImage);
    end;
    // Construct reduced color map from the histogram
    ReduceColorsMedianCut(0, nil, nil, nil, nil, MaxColors, ColorReductionMask,
      Pal, [raMakeColorMap]);

    if ConvertImages then
    begin
      DstFormat := ifIndex8;
      DstInfo := ImageFormatInfos[DstFormat];
      MaxColors := Min(DstInfo.PaletteEntries, MaxColors);

      for I := 0 to Length(Images) - 1 do
      begin
        SrcInfo := ImageFormatInfos[Images[I].Format];
        if SrcInfo.IsIndexed or SrcInfo.IsSpecial then
        begin
          // If source image is in format not supported by ReduceColorsMedianCut
          // we convert it
          ConvertImage(Images[I], ifA8R8G8B8);
          SrcInfo := ImageFormatInfos[Images[I].Format];
        end;

        InitImage(Target);
        NewImage(Images[I].Width, Images[I].Height, DstFormat, Target);
        // We map each input image to reduced palette and replace
        // image in array with mapped image
        ReduceColorsMedianCut(Images[I].Width * Images[I].Height, Images[I].Bits,
          Target.Bits, SrcInfo, DstInfo, MaxColors, 0, nil, [raMapImage]);
        Move(Pal^, Target.Palette^, MaxColors * SizeOf(TColor32Rec));

        FreeImage(Images[I]);
        Images[I] := Target;
      end;
    end;
    Result := True;
  except
    RaiseImaging(SErrorMakePaletteForImages, [MaxColors, Length(Images)]);
  end;
end;

function RotateImage(var Image: TImageData; Angle: Single): Boolean;
var
  OldFmt: TImageFormat;

  procedure XShear(var Src, Dst: TImageData; Row, Offset, Weight, Bpp: Integer);
  var
    I, J, XPos: Integer;
    PixSrc, PixLeft, PixOldLeft: TColor32Rec;
    LineDst: PByteArray;
    SrcPtr: PColor32;
  begin
    SrcPtr := @PByteArray(Src.Bits)[Row * Src.Width * Bpp];
    LineDst := @PByteArray(Dst.Bits)[Row * Dst.Width * Bpp];
    PixOldLeft.Color := 0;

    for I := 0 to Src.Width - 1 do
    begin
      CopyPixel(SrcPtr, @PixSrc, Bpp);
      for J := 0 to Bpp - 1 do
        PixLeft.Channels[J] := MulDiv(PixSrc.Channels[J], Weight, 256);

      XPos := I + Offset;
      if (XPos >= 0) and (XPos < Dst.Width) then
      begin
        for J := 0 to Bpp - 1 do
          PixSrc.Channels[J] := PixSrc.Channels[J] - (PixLeft.Channels[J] - PixOldLeft.Channels[J]);
        CopyPixel(@PixSrc, @LineDst[XPos * Bpp], Bpp);
      end;
      PixOldLeft := PixLeft;
      Inc(PByte(SrcPtr), Bpp);
    end;

    XPos := Src.Width + Offset;
    if XPos < Dst.Width then
      CopyPixel(@PixOldLeft, @LineDst[XPos * Bpp], Bpp);
  end;

  procedure YShear(var Src, Dst: TImageData; Col, Offset, Weight, Bpp: Integer);
  var
    I, J, YPos: Integer;
    PixSrc, PixLeft, PixOldLeft: TColor32Rec;
    SrcPtr: PByte;
  begin
    SrcPtr := @PByteArray(Src.Bits)[Col * Bpp];
    PixOldLeft.Color := 0;

    for I := 0 to Src.Height - 1 do
    begin
      CopyPixel(SrcPtr, @PixSrc, Bpp);
      for J := 0 to Bpp - 1 do
        PixLeft.Channels[J] := MulDiv(PixSrc.Channels[J], Weight, 256);

      YPos := I + Offset;
      if (YPos >= 0) and (YPos < Dst.Height) then
      begin
        for J := 0 to Bpp - 1 do
          PixSrc.Channels[J] := PixSrc.Channels[J] - (PixLeft.Channels[J] - PixOldLeft.Channels[J]);
        CopyPixel(@PixSrc, @PByteArray(Dst.Bits)[(YPos * Dst.Width + Col) * Bpp], Bpp);
      end;
      PixOldLeft := PixLeft;
      Inc(SrcPtr, Src.Width * Bpp);
    end;

    YPos := Src.Height + Offset;
    if YPos < Dst.Height then
      CopyPixel(@PixOldLeft, @PByteArray(Dst.Bits)[(YPos * Dst.Width + Col) * Bpp], Bpp);
  end;

  procedure Rotate45(var Image: TImageData; Angle: Single);
  var
    TempImage1, TempImage2: TImageData;
    AngleRad, AngleTan, AngleSin, AngleCos, Shear: Single;
    I, DstWidth, DstHeight, SrcWidth, SrcHeight, Bpp: Integer;
    SrcFmt, TempFormat: TImageFormat;
    Info: TImageFormatInfo;
  begin
    AngleRad := Angle * Pi / 180;
    AngleSin := Sin(AngleRad);
    AngleCos := Cos(AngleRad);
    AngleTan := Sin(AngleRad / 2) / Cos(AngleRad / 2);
    SrcWidth := Image.Width;
    SrcHeight := Image.Height;
    SrcFmt := Image.Format;

    if not (SrcFmt in [ifR8G8B8..ifX8R8G8B8, ifGray8..ifGray32, ifA16Gray16]) then
      ConvertImage(Image, ifA8R8G8B8);

    TempFormat := Image.Format;
    GetImageFormatInfo(TempFormat, Info);
    Bpp := Info.BytesPerPixel;

    // 1st shear (horizontal)
    DstWidth := Trunc(SrcWidth + SrcHeight * Abs(AngleTan) + 0.5);
    DstHeight := SrcHeight;
    NewImage(DstWidth, DstHeight, TempFormat, TempImage1);

    for I := 0 to DstHeight - 1 do
    begin
      if AngleTan >= 0 then
        Shear := (I + 0.5) * AngleTan
      else
        Shear := (I - DstHeight + 0.5) * AngleTan;
      XShear(Image, TempImage1, I, Floor(Shear), Trunc(255 * (Shear - Floor(Shear)) + 1), Bpp);
    end;

    // 2nd shear  (vertical)
    FreeImage(Image);
    DstHeight := Trunc(SrcWidth * Abs(AngleSin) + SrcHeight * AngleCos + 0.5) + 1;
    NewImage(DstWidth, DstHeight, TempFormat, TempImage2);

    if AngleSin >= 0 then
      Shear := (SrcWidth - 1) * AngleSin
    else
      Shear := (SrcWidth - DstWidth) * -AngleSin;

    for I := 0 to DstWidth - 1 do
    begin
      YShear(TempImage1, TempImage2, I, Floor(Shear), Trunc(255 * (Shear - Floor(Shear)) + 1), Bpp);
      Shear := Shear - AngleSin;
    end;

    // 3rd shear (horizontal)
    FreeImage(TempImage1);
    DstWidth := Trunc(SrcHeight * Abs(AngleSin) + SrcWidth * AngleCos + 0.5) + 1;
    NewImage(DstWidth, DstHeight, TempFormat, Image);

    if AngleSin >= 0 then
      Shear := (SrcWidth - 1) * AngleSin * -AngleTan
    else
      Shear := ((SrcWidth - 1) * -AngleSin + (1 - DstHeight)) * AngleTan;

    for I := 0 to DstHeight - 1 do
    begin
      XShear(TempImage2, Image, I, Floor(Shear), Trunc(255 * (Shear - Floor(Shear)) + 1), Bpp);
      Shear := Shear + AngleTan;
    end;

    FreeImage(TempImage2);
    if Image.Format <> SrcFmt then
      ConvertImage(Image, SrcFmt);
  end;

  procedure RotateMul90(var Image: TImageData; Angle: Integer);
  var
    RotImage: TImageData;
    X, Y, BytesPerPixel: Integer;
    RotPix, Pix: PByte;
  begin
    InitImage(RotImage);
    BytesPerPixel := ImageFormatInfos[Image.Format].BytesPerPixel;

    if ((Angle = 90) or (Angle = 270)) and (Image.Width <> Image.Height) then
      NewImage(Image.Height, Image.Width, Image.Format, RotImage)
    else
      NewImage(Image.Width, Image.Height, Image.Format, RotImage);

    RotPix := RotImage.Bits;
    case Angle of
      90:
        begin
          for Y := 0 to RotImage.Height - 1 do
          begin
            Pix := @PByteArray(Image.Bits)[(Image.Width - Y - 1) * BytesPerPixel];
            for X := 0 to RotImage.Width - 1 do
            begin
              CopyPixel(Pix, RotPix, BytesPerPixel);
              Inc(RotPix, BytesPerPixel);
              Inc(Pix, Image.Width * BytesPerPixel);
            end;
          end;
        end;
      180:
        begin
          Pix := @PByteArray(Image.Bits)[((Image.Height - 1) * Image.Width +
            (Image.Width - 1)) * BytesPerPixel];
          for Y := 0 to RotImage.Height - 1 do
            for X := 0 to RotImage.Width - 1 do
            begin
              CopyPixel(Pix, RotPix, BytesPerPixel);
              Inc(RotPix, BytesPerPixel);
              Dec(Pix, BytesPerPixel);
            end;
        end;
      270:
        begin
          for Y := 0 to RotImage.Height - 1 do
          begin
            Pix := @PByteArray(Image.Bits)[((Image.Height - 1) * Image.Width + Y) * BytesPerPixel];
            for X := 0 to RotImage.Width - 1 do
            begin
              CopyPixel(Pix, RotPix, BytesPerPixel);
              Inc(RotPix, BytesPerPixel);
              Dec(Pix, Image.Width * BytesPerPixel);
            end;
          end;
        end;
    end;

    FreeMemNil(Image.Bits);
    RotImage.Palette := Image.Palette;
    Image := RotImage;
  end;

begin
  Result := False;

  if TestImage(Image) then
  try
    while Angle >= 360 do
      Angle := Angle - 360;
    while Angle < 0 do
      Angle := Angle + 360;

    if (Angle = 0) or (Abs(Angle) = 360) then
    begin
      Result := True;
      Exit;
    end;

    OldFmt := Image.Format;
    if ImageFormatInfos[Image.Format].IsSpecial then
      ConvertImage(Image, ifDefault);

    if (Angle > 45) and (Angle <= 135) then
    begin
      RotateMul90(Image, 90);
      Angle := Angle - 90;
    end
    else if (Angle > 135) and (Angle <= 225) then
    begin
      RotateMul90(Image, 180);
      Angle := Angle - 180;
    end
    else if (Angle > 225) and (Angle <= 315) then
    begin
      RotateMul90(Image, 270);
      Angle := Angle - 270;
    end;

    if Angle <> 0 then
      Rotate45(Image, Angle);

    if OldFmt <> Image.Format then
      ConvertImage(Image, OldFmt);

    Result := True;
  except
    RaiseImaging(SErrorRotateImage, [ImageToStr(Image), Angle]);
  end;
end;

{ Drawing/Pixel functions }

function CopyRect(const SrcImage: TImageData; SrcX, SrcY, Width, Height: LongInt;
  var DstImage: TImageData; DstX, DstY: LongInt): Boolean;
var
  Info: PImageFormatInfo;
  I, SrcWidthBytes, DstWidthBytes, MoveBytes: LongInt;
  SrcPointer, DstPointer: PByte;
  WorkImage: TImageData;
  OldFormat: TImageFormat;
begin
  Result := False;
  OldFormat := ifUnknown;
  if TestImage(SrcImage) and TestImage(DstImage) then
  try
    // Make sure we are still copying image to image, not invalid pointer to protected memory
    ClipCopyBounds(SrcX, SrcY, Width, Height, DstX, DstY, SrcImage.Width, SrcImage.Height,
      Rect(0, 0, DstImage.Width, DstImage.Height));

    if (Width > 0) and (Height > 0) then
    begin
      Info := ImageFormatInfos[DstImage.Format];
      if Info.IsSpecial then
      begin
        // If dest image is in special format we convert it to default
        OldFormat := Info.Format;
        ConvertImage(DstImage, ifDefault);
        Info := ImageFormatInfos[DstImage.Format];
      end;
      if SrcImage.Format <> DstImage.Format then
      begin
        // If images are in different format source is converted to dest's format
        InitImage(WorkImage);
        CloneImage(SrcImage, WorkImage);
        ConvertImage(WorkImage, DstImage.Format);
      end
      else
        WorkImage := SrcImage;

      MoveBytes := Width * Info.BytesPerPixel;
      DstWidthBytes := DstImage.Width * Info.BytesPerPixel;
      DstPointer := @PByteArray(DstImage.Bits)[DstY * DstWidthBytes +
        DstX * Info.BytesPerPixel];
      SrcWidthBytes := WorkImage.Width * Info.BytesPerPixel;
      SrcPointer := @PByteArray(WorkImage.Bits)[SrcY * SrcWidthBytes +
        SrcX * Info.BytesPerPixel];

      for I := 0 to Height - 1 do
      begin
        Move(SrcPointer^, DstPointer^, MoveBytes);
        Inc(SrcPointer, SrcWidthBytes);
        Inc(DstPointer, DstWidthBytes);
      end;
      // If dest image was in special format we convert it back
      if OldFormat <> ifUnknown then
        ConvertImage(DstImage, OldFormat);
      // Working image must be freed if it is not the same as source image
      if WorkImage.Bits <> SrcImage.Bits then
        FreeImage(WorkImage);

      Result := True;
    end;
  except
    RaiseImaging(SErrorCopyRect, [ImageToStr(SrcImage), ImageToStr(DstImage)]);
  end;
end;

function FillRect(var Image: TImageData; X, Y, Width, Height: LongInt;
  FillColor: Pointer): Boolean;
var
  Info: PImageFormatInfo;
  I, J, ImageWidthBytes, RectWidthBytes, Bpp: Longint;
  LinePointer, PixPointer: PByte;
  OldFmt: TImageFormat;
begin
  Result := False;
  if TestImage(Image) then
  try
    ClipRectBounds(X, Y, Width, Height, Rect(0, 0, Image.Width, Image.Height));

    if (Width > 0) and (Height > 0) then
    begin
      OldFmt := Image.Format;
      if ImageFormatInfos[OldFmt].IsSpecial then
        ConvertImage(Image, ifDefault);

      Info := ImageFormatInfos[Image.Format];
      Bpp := Info.BytesPerPixel;
      ImageWidthBytes := Image.Width * Bpp;
      RectWidthBytes := Width * Bpp;
      LinePointer := @PByteArray(Image.Bits)[Y * ImageWidthBytes + X * Bpp];

      for I := 0 to Height - 1 do
      begin
        case Bpp of
          1: FillMemoryByte(LinePointer, RectWidthBytes, PByte(FillColor)^);
          2: FillMemoryWord(LinePointer, RectWidthBytes, PWord(FillColor)^);
          4: FillMemoryLongWord(LinePointer, RectWidthBytes, PLongWord(FillColor)^);
        else
          PixPointer := LinePointer;
          for J := 0 to Width - 1 do
          begin
            CopyPixel(FillColor, PixPointer, Bpp);
            Inc(PixPointer, Bpp);
          end;
        end;
        Inc(LinePointer, ImageWidthBytes);
      end;

      if OldFmt <> Image.Format then
        ConvertImage(Image, OldFmt);
    end;

    Result := True;
  except
    RaiseImaging(SErrorFillRect, [X, Y, Width, Height, ImageToStr(Image)]);
  end;
end;

function ReplaceColor(var Image: TImageData; X, Y, Width, Height: LongInt;
  OldColor, NewColor: Pointer): Boolean;
var
  Info: PImageFormatInfo;
  I, J, WidthBytes, Bpp: Longint;
  LinePointer, PixPointer: PByte;
  OldFmt: TImageFormat;
begin
  Assert((OldColor <> nil) and (NewColor <> nil));
  Result := False;
  if TestImage(Image) then
  try
    ClipRectBounds(X, Y, Width, Height, Rect(0, 0, Image.Width, Image.Height));

    if (Width > 0) and (Height > 0) then
    begin
      OldFmt := Image.Format;
      if ImageFormatInfos[OldFmt].IsSpecial then
        ConvertImage(Image, ifDefault);

      Info := ImageFormatInfos[Image.Format];
      Bpp := Info.BytesPerPixel;
      WidthBytes := Image.Width * Bpp;
      LinePointer := @PByteArray(Image.Bits)[Y * WidthBytes + X * Bpp];

      for I := 0 to Height - 1 do
      begin
        PixPointer := LinePointer;
        for J := 0 to Width - 1 do
        begin
          if ComparePixels(PixPointer, OldColor, Bpp) then
            CopyPixel(NewColor, PixPointer, Bpp);
          Inc(PixPointer, Bpp);
        end;
        Inc(LinePointer, WidthBytes);
      end;

      if OldFmt <> Image.Format then
        ConvertImage(Image, OldFmt);
    end;

    Result := True;
  except
    RaiseImaging(SErrorReplaceColor, [X, Y, Width, Height, ImageToStr(Image)]);
  end;
end;

function StretchRect(const SrcImage: TImageData; SrcX, SrcY, SrcWidth,
  SrcHeight: LongInt; var DstImage: TImageData; DstX, DstY, DstWidth,
  DstHeight: LongInt; Filter: TResizeFilter): Boolean;
var
  Info: PImageFormatInfo;
  WorkImage: TImageData;
  OldFormat: TImageFormat;
begin
  Result := False;
  OldFormat := ifUnknown;
  if TestImage(SrcImage) and TestImage(DstImage) then
  try
    // Make sure we are still copying image to image, not invalid pointer to protected memory
    ClipStretchBounds(SrcX, SrcY, SrcWidth, SrcHeight, DstX, DstY, DstWidth, DstHeight,
      SrcImage.Width, SrcImage.Height, Rect(0, 0, DstImage.Width, DstImage.Height));

    if (SrcWidth = DstWidth) and (SrcHeight = DstHeight) then
    begin
      // If source and dest rectangles have the same size call CopyRect
      Result := CopyRect(SrcImage, SrcX, SrcY, SrcWidth, SrcHeight, DstImage, DstX, DstY);
    end
    else if (SrcWidth > 0) and (SrcHeight > 0) and (DstWidth > 0) and (DstHeight > 0) then
    begin
      // If source and dest rectangles don't have the same size we do stretch
      Info := ImageFormatInfos[DstImage.Format];

      if Info.IsSpecial then
      begin
        // If dest image is in special format we convert it to default
        OldFormat := Info.Format;
        ConvertImage(DstImage, ifDefault);
        Info := ImageFormatInfos[DstImage.Format];
      end;

      if SrcImage.Format <> DstImage.Format then
      begin
        // If images are in different format source is converted to dest's format
        InitImage(WorkImage);
        CloneImage(SrcImage, WorkImage);
        ConvertImage(WorkImage, DstImage.Format);
      end
      else
        WorkImage := SrcImage;

      // Only pixel resize is supported for indexed images
      if Info.IsIndexed then
        Filter := rfNearest;

      case Filter of
        rfNearest: StretchNearest(WorkImage, SrcX, SrcY, SrcWidth, SrcHeight,
          DstImage, DstX, DstY, DstWidth, DstHeight);
        rfBilinear: StretchResample(WorkImage, SrcX, SrcY, SrcWidth, SrcHeight,
          DstImage, DstX, DstY, DstWidth, DstHeight, sfLinear);
        rfBicubic: StretchResample(WorkImage, SrcX, SrcY, SrcWidth, SrcHeight,
          DstImage, DstX, DstY, DstWidth, DstHeight, sfCatmullRom);
      end;

      // If dest image was in special format we convert it back
      if OldFormat <> ifUnknown then
        ConvertImage(DstImage, OldFormat);
      // Working image must be freed if it is not the same as source image
      if WorkImage.Bits <> SrcImage.Bits then
        FreeImage(WorkImage);

      Result := True;
    end;
  except
    RaiseImaging(SErrorStretchRect, [ImageToStr(SrcImage), ImageToStr(DstImage)]);
  end;
end;

procedure GetPixelDirect(const Image: TImageData; X, Y: LongInt; Pixel: Pointer);
var
  BytesPerPixel: LongInt;
begin
  Assert(Pixel <> nil);
  BytesPerPixel := ImageFormatInfos[Image.Format].BytesPerPixel;
  CopyPixel(@PByteArray(Image.Bits)[(Y * Image.Width + X) * BytesPerPixel],
    Pixel, BytesPerPixel);
end;

procedure SetPixelDirect(const Image: TImageData; X, Y: LongInt; Pixel: Pointer);
var
  BytesPerPixel: LongInt;
begin
  Assert(Pixel <> nil);
  BytesPerPixel := ImageFormatInfos[Image.Format].BytesPerPixel;
  CopyPixel(Pixel, @PByteArray(Image.Bits)[(Y * Image.Width + X) * BytesPerPixel],
    BytesPerPixel);
end;

function GetPixel32(const Image: TImageData; X, Y: LongInt): TColor32Rec;
var
  Info: PImageFormatInfo;
  Data: PByte;
begin
  Info := ImageFormatInfos[Image.Format];
  Data := @PByteArray(Image.Bits)[(Y * Image.Width + X) * Info.BytesPerPixel];
  Result := GetPixel32Generic(Data, Info, Image.Palette);
end;

procedure SetPixel32(const Image: TImageData; X, Y: LongInt; const Color: TColor32Rec);
var
  Info: PImageFormatInfo;
  Data: PByte;
begin
  Info := ImageFormatInfos[Image.Format];
  Data := @PByteArray(Image.Bits)[(Y * Image.Width + X) * Info.BytesPerPixel];
  SetPixel32Generic(Data, Info, Image.Palette, Color);
end;

function GetPixelFP(const Image: TImageData; X, Y: LongInt): TColorFPRec;
var
  Info: PImageFormatInfo;
  Data: PByte;
begin
  Info := ImageFormatInfos[Image.Format];
  Data := @PByteArray(Image.Bits)[(Y * Image.Width + X) * Info.BytesPerPixel];
  Result := GetPixelFPGeneric(Data, Info, Image.Palette);
end;

procedure SetPixelFP(const Image: TImageData; X, Y: LongInt; const Color: TColorFPRec);
var
  Info: PImageFormatInfo;
  Data: PByte;
begin
  Info := ImageFormatInfos[Image.Format];
  Data := @PByteArray(Image.Bits)[(Y * Image.Width + X) * Info.BytesPerPixel];
  SetPixelFPGeneric(Data, Info, Image.Palette, Color);
end;

{ Palette Functions }

procedure NewPalette(Entries: LongInt; var Pal: PPalette32);
begin
  Assert((Entries > 2) and (Entries <= 65535));
  try
    GetMem(Pal, Entries * SizeOf(TColor32Rec));
    FillChar(Pal^, Entries * SizeOf(TColor32Rec), $FF);
  except
    RaiseImaging(SErrorNewPalette, [Entries]);
  end;
end;

procedure FreePalette(var Pal: PPalette32);
begin
  try
    FreeMemNil(Pal);
  except
    RaiseImaging(SErrorFreePalette, [Pal]);
  end;
end;

procedure CopyPalette(SrcPal, DstPal: PPalette32; SrcIdx, DstIdx, Count: LongInt);
begin
  Assert((SrcPal <> nil) and (DstPal <> nil));
  Assert((SrcIdx >= 0) and (DstIdx >= 0) and (Count >= 0));
  try
    Move(SrcPal[SrcIdx], DstPal[DstIdx], Count * SizeOf(TColor32Rec));
  except
    RaiseImaging(SErrorCopyPalette, [Count, SrcPal, DstPal]);
  end;
end;

function FindColor(Pal: PPalette32; Entries: LongInt; Color: TColor32):
  LongInt;
var
  Col: TColor32Rec;
  I, MinDif, Dif: LongInt;
begin
  Assert(Pal <> nil);
  Result := -1;
  Col.Color := Color;
  try
    // First try to find exact match
    for I := 0 to Entries - 1 do
    with Pal[I] do
    begin
      if (A = Col.A) and (R = Col.R) and
        (G = Col.G) and (B = Col.B) then
      begin
        Result := I;
        Exit;
      end;
    end;

    // If exact match was not found, find nearest color
    MinDif := 1020;
    for I := 0 to Entries - 1 do
    with Pal[I] do
    begin
      Dif := Abs(R - Col.R);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(G - Col.G);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(B - Col.B);
      if Dif > MinDif then Continue;
      Dif := Dif + Abs(A - Col.A);
      if Dif < MinDif then
      begin
        MinDif := Dif;
        Result := I;
      end;
    end;
  except
    RaiseImaging(SErrorFindColor, [Pal, Entries]);
  end;
end;

procedure FillGrayscalePalette(Pal: PPalette32; Entries: LongInt);
var
  I: LongInt;
begin
  Assert(Pal <> nil);
  try
    for I := 0 to Entries - 1 do
    with Pal[I] do
    begin
      A := $FF;
      R := Byte(I);
      G := Byte(I);
      B := Byte(I);
    end;
  except
    RaiseImaging(SErrorGrayscalePalette, [Pal, Entries]);
  end;
end;

procedure FillCustomPalette(Pal: PPalette32; Entries: LongInt; RBits, GBits,
  BBits: Byte; Alpha: Byte = $FF);
var
  I, TotalBits, MaxEntries: LongInt;
begin
  Assert(Pal <> nil);
  TotalBits := RBits + GBits + BBits;
  MaxEntries := Min(Pow2Int(TotalBits), Entries);
  FillChar(Pal^, Entries * SizeOf(TColor32Rec), 0);
  try
    for I := 0 to MaxEntries - 1 do
    with Pal[I] do
    begin
      A := Alpha;
      if RBits > 0 then
        R := ((I shr Max(0, GBits + BBits - 1)) and (1 shl RBits - 1)) * 255 div (1 shl RBits - 1);
      if GBits > 0 then
        G := ((I shr Max(0, BBits - 1)) and (1 shl GBits - 1)) * 255 div (1 shl GBits - 1);
      if BBits > 0 then
        B := ((I shr 0) and (1 shl BBits - 1)) * 255 div (1 shl BBits - 1);
    end;
  except
    RaiseImaging(SErrorCustomPalette, [Pal, Entries]);
  end;
end;

procedure SwapChannelsOfPalette(Pal: PPalette32; Entries, SrcChannel,
  DstChannel: LongInt);
var
  I: LongInt;
  Swap: Byte;
begin
  Assert(Pal <> nil);
  Assert((SrcChannel in [0..3]) and (DstChannel in [0..3]));
  try
    for I := 0 to Entries - 1 do
    with Pal[I] do
    begin
      Swap := Channels[SrcChannel];
      Channels[SrcChannel] := Channels[DstChannel];
      Channels[DstChannel] := Swap;
    end;
  except
    RaiseImaging(SErrorSwapPalette, [Pal, Entries]);
  end;
end;

{ Options Functions }

function SetOption(OptionId, Value: LongInt): Boolean;
begin
  Result := False;
  if (OptionId >= 0) and (OptionId < Length(Options)) and
    (Options[OptionID] <> nil) then
  begin
    Options[OptionID]^ := CheckOptionValue(OptionId, Value);
    Result := True;
  end;
end;

function GetOption(OptionId: LongInt): LongInt;
begin
  Result := InvalidOption;
  if (OptionId >= 0) and (OptionId < Length(Options)) and
    (Options[OptionID] <> nil) then
  begin
    Result := Options[OptionID]^;
  end;
end;

function PushOptions: Boolean;
begin
  Result := OptionStack.Push;
end;

function PopOptions: Boolean;
begin
  Result := OptionStack.Pop;
end;

{ Image Format Functions }

function GetImageFormatInfo(Format: TImageFormat; out Info: TImageFormatInfo): Boolean;
begin
  FillChar(Info, SizeOf(Info), 0);
  if ImageFormatInfos[Format] <> nil then
  begin
    Info := ImageFormatInfos[Format]^;
    Result := True;
  end
  else
    Result := False;
end;

function GetPixelsSize(Format: TImageFormat; Width, Height: LongInt): LongInt;
begin
  if ImageFormatInfos[Format] <> nil then
    Result := ImageFormatInfos[Format].GetPixelsSize(Format, Width, Height)
  else
    Result := 0;
end;

{ IO Functions }

procedure SetUserFileIO(OpenReadProc: TOpenReadProc; OpenWriteProc:
  TOpenWriteProc;
  CloseProc: TCloseProc; EofProc: TEofProc; SeekProc: TSeekProc; TellProc:
  TTellProc; ReadProc: TReadProc; WriteProc: TWriteProc);
begin
  FileIO.OpenRead := OpenReadProc;
  FileIO.OpenWrite := OpenWriteProc;
  FileIO.Close := CloseProc;
  FileIO.Eof := EofProc;
  FileIO.Seek := SeekProc;
  FileIO.Tell := TellProc;
  FileIO.Read := ReadProc;
  FileIO.Write := WriteProc;
end;

procedure ResetFileIO;
begin
  FileIO := OriginalFileIO;
end;


{ ------------------------------------------------------------------------
                           Other Imaging Stuff
  ------------------------------------------------------------------------}

function GetFormatName(Format: TImageFormat): string;
begin
  if ImageFormatInfos[Format] <> nil then
    Result := ImageFormatInfos[Format].Name
  else
    Result := SUnknownFormat;
end;

function ImageToStr(const Image: TImageData): string;
var
  ImgSize: Integer;
begin
  if TestImage(Image) then
  with Image do
  begin
    ImgSize := Size;
    if ImgSize > 8192 then
      ImgSize := ImgSize div 1024;
    Result := SysUtils.Format(SImageInfo, [@Image, Width, Height,
      GetFormatName(Format), ImgSize + 0.0, Iff(ImgSize = Size, 'B', 'KiB'), Bits,
      Palette]);
  end
  else
    Result := SysUtils.Format(SImageInfoInvalid, [@Image]);
end;

function GetVersionStr: string;
begin
  Result := Format('%.1d.%.2d.%.1d', [ImagingVersionMajor,
    ImagingVersionMinor, ImagingVersionPatch]);
end;

function IffFormat(Condition: Boolean; const TruePart, FalsePart: TImageFormat): TImageFormat;
begin
  if Condition then
    Result := TruePart
  else
    Result := FalsePart;
end;

procedure RegisterImageFileFormat(AClass: TImageFileFormatClass);
begin
  Assert(AClass <> nil);
  if ImageFileFormats = nil then
    ImageFileFormats := TList.Create;
  if ImageFileFormats <> nil then
    ImageFileFormats.Add(AClass.Create);
end;

function RegisterOption(OptionId: LongInt; Variable: PLongInt): Boolean;
begin
  Result := False;
  if Options = nil then
    InitOptions;

  Assert(Variable <> nil);

  if OptionId >= Length(Options) then
    SetLength(Options, OptionId + InitialOptions);
  if (OptionId >= 0) and (OptionId < Length(Options)) {and (Options[OptionId] = nil) - must be able to override existing } then
  begin
    Options[OptionId] := Variable;
    Result := True;
  end;
end;

function FindImageFileFormatByExt(const Ext: string): TImageFileFormat;
var
  I: LongInt;
begin
  Result := nil;
  for I := ImageFileFormats.Count - 1 downto 0 do
    if TImageFileFormat(ImageFileFormats[I]).Extensions.IndexOf(Ext) >= 0 then
    begin
      Result := TImageFileFormat(ImageFileFormats[I]);
      Exit;
    end;
end;

function FindImageFileFormatByName(const FileName: string): TImageFileFormat;
var
  I: LongInt;
begin
  Result := nil;
  for I := ImageFileFormats.Count - 1 downto 0 do
    if TImageFileFormat(ImageFileFormats[I]).TestFileName(FileName) then
    begin
      Result := TImageFileFormat(ImageFileFormats[I]);
      Exit;
    end;
end;

function FindImageFileFormatByClass(AClass: TImageFileFormatClass): TImageFileFormat;
var
  I: LongInt;
begin
  Result := nil;
  for I := 0 to ImageFileFormats.Count - 1 do
    if TImageFileFormat(ImageFileFormats[I]) is AClass then
    begin
      Result := TObject(ImageFileFormats[I]) as TImageFileFormat;
      Break;
    end;
end;

function GetFileFormatCount: LongInt;
begin
  Result := ImageFileFormats.Count;
end;

function GetFileFormatAtIndex(Index: LongInt): TImageFileFormat;
begin
  if (Index >= 0) and (Index < ImageFileFormats.Count) then
    Result := TImageFileFormat(ImageFileFormats[Index])
  else
    Result := nil;
end;

function GetImageFileFormatsFilter(OpenFileFilter: Boolean): string;
var
  I, J, Count: LongInt;
  Descriptions: string;
  Filters, CurFilter: string;
  FileFormat: TImageFileFormat;
begin
  Descriptions := '';
  Filters := '';
  Count := 0;

  for I := 0 to ImageFileFormats.Count - 1 do
  begin
    FileFormat := TObject(ImageFileFormats[I]) as TImageFileFormat;

    // If we are creating filter for save dialog and this format cannot save
    // files the we skip it
    if not OpenFileFilter and not FileFormat.CanSave then
      Continue;

    CurFilter := '';
    for J := 0 to FileFormat.Masks.Count - 1 do
    begin
      CurFilter := CurFilter + FileFormat.Masks[J];
      if J < FileFormat.Masks.Count - 1 then
        CurFilter := CurFilter + ';';
    end;

    FmtStr(Descriptions, '%s%s (%s)|%2:s', [Descriptions, FileFormat.Name, CurFilter]);
    if Filters <> '' then
      FmtStr(Filters, '%s;%s', [Filters, CurFilter])
    else
      Filters := CurFilter;

    if I < ImageFileFormats.Count - 1 then
        Descriptions := Descriptions + '|';

    Inc(Count);
  end;

  if (Count > 1) and OpenFileFilter then
    FmtStr(Descriptions, '%s (%s)|%1:s|%s', [SAllFilter, Filters, Descriptions]);

  Result := Descriptions;
end;

function GetFilterIndexExtension(Index: LongInt; OpenFileFilter: Boolean): string;
var
  I, Count: LongInt;
  FileFormat: TImageFileFormat;
begin
  // -1 because filter indices are in 1..n range
  Index := Index - 1;
  Result := '';
  if OpenFileFilter then
  begin
    if Index > 0 then
      Index := Index - 1;
  end;

  if (Index >= 0) and (Index < ImageFileFormats.Count) then
  begin
    Count := 0;
    for I := 0 to ImageFileFormats.Count - 1 do
    begin
      FileFormat := TObject(ImageFileFormats[I]) as TImageFileFormat;
      if not OpenFileFilter and not FileFormat.CanSave then
        Continue;
      if Index = Count then
      begin
        if FileFormat.Extensions.Count > 0 then
          Result := FileFormat.Extensions[0];
        Exit;
      end;
      Inc(Count);
    end;
  end;
end;

function GetFileNameFilterIndex(const FileName: string; OpenFileFilter: Boolean): LongInt;
var
  I: LongInt;
  FileFormat: TImageFileFormat;
begin
  Result := 0;
  for I := 0 to ImageFileFormats.Count - 1 do
  begin
    FileFormat := TObject(ImageFileFormats[I]) as TImageFileFormat;
    if not OpenFileFilter and not FileFormat.CanSave then
      Continue;
    if FileFormat.TestFileName(FileName) then
    begin
      // +1 because filter indices are in 1..n range
      Inc(Result);
      if OpenFileFilter then
        Inc(Result);
      Exit;
    end;
    Inc(Result);
  end;
  Result := -1;
end;

function GetIO: TIOFunctions;
begin
  Result := IO;
end;

procedure RaiseImaging(const Msg: string; const Args: array of const);
var
  WholeMsg: string;
begin
  WholeMsg := Msg;
  if GetExceptObject <> nil then
    WholeMsg := WholeMsg + ' ' + SExceptMsg + ': ' +
      GetExceptObject.Message;
  raise EImagingError.CreateFmt(WholeMsg, Args);
end;

{ Internal unit functions }

function CheckOptionValue(OptionId, Value: LongInt): LongInt;
begin
  case OptionId of
    ImagingColorReductionMask:
      Result := ClampInt(Value, 0, $FF);
    ImagingLoadOverrideFormat, ImagingSaveOverrideFormat:
      Result := Iff(ImagingFormats.IsImageFormatValid(TImageFormat(Value)),
        Value, LongInt(ifUnknown));
    ImagingMipMapFilter: Result := ClampInt(Value, Ord(Low(TSamplingFilter)),
        Ord(High(TSamplingFilter)));
  else
    Result := Value;
  end;
end;

procedure SetFileIO;
begin
  IO := FileIO;
end;

procedure SetStreamIO;
begin
  IO := StreamIO;
end;

procedure SetMemoryIO;
begin
  IO := MemoryIO;
end;

procedure InitImageFormats;
begin
  ImagingFormats.InitImageFormats(ImageFormatInfos);
end;

procedure FreeImageFileFormats;
var
  I: LongInt;
begin
  if ImageFileFormats <> nil then
    for I := 0 to ImageFileFormats.Count - 1 do
      TImageFileFormat(ImageFileFormats[I]).Free;
  FreeAndNil(ImageFileFormats);
end;

procedure InitOptions;
begin
  SetLength(Options, InitialOptions);
  OptionStack := TOptionStack.Create;
end;

procedure FreeOptions;
begin
  SetLength(Options, 0);
  FreeAndNil(OptionStack);
end;

{
  TImageFileFormat class implementation
}

constructor TImageFileFormat.Create;
begin
  inherited Create;
  FName := SUnknownFormat;
  FExtensions := TStringList.Create;
  FMasks := TStringList.Create;
end;

destructor TImageFileFormat.Destroy;
begin
  FExtensions.Free;
  FMasks.Free;
  inherited Destroy;
end;

function TImageFileFormat.PrepareLoad(Handle: TImagingHandle;
  var Images: TDynImageDataArray; OnlyFirstFrame: Boolean): Boolean;
begin
  FreeImagesInArray(Images);
  SetLength(Images, 0);
  Result := Handle <> nil;
end;

function TImageFileFormat.PostLoadCheck(var Images: TDynImageDataArray;
  LoadResult: Boolean): Boolean;
var
  I: LongInt;
begin
  if not LoadResult then
  begin
    FreeImagesInArray(Images);
    SetLength(Images, 0);
    Result := False;
  end
  else
  begin
    Result := (Length(Images) > 0) and TestImagesInArray(Images);

    if Result then
    begin
      // Convert to overriden format if it is set
      if LoadOverrideFormat <> ifUnknown then
        for I := Low(Images) to High(Images) do
          ConvertImage(Images[I], LoadOverrideFormat);
    end;
  end;
end;

function TImageFileFormat.PrepareSave(Handle: TImagingHandle;
  const Images: TDynImageDataArray; var Index: Integer): Boolean;
var
  Len, I: LongInt;
begin
  CheckOptionsValidity;
  Result := False;
  if FCanSave then
  begin
    Len := Length(Images);
    Assert(Len > 0);

    // If there are no images to be saved exit
    if Len = 0 then Exit;

    // Check index of image to be saved (-1 as index means save all images)
    if FIsMultiImageFormat then
    begin
      if (Index >= Len) then
        Index := 0;

      if Index < 0 then
      begin
        Index := 0;
        FFirstIdx := 0;
        FLastIdx := Len - 1;
      end
      else
      begin
        FFirstIdx := Index;
        FLastIdx := Index;
      end;

      for I := FFirstIdx to FLastIdx - 1 do
        if not TestImage(Images[I]) then
          Exit;
    end
    else
    begin
      if (Index >= Len) or (Index < 0) then
        Index := 0;
      if not TestImage(Images[Index]) then
        Exit;
    end;

    Result := True;
  end;
end;

procedure TImageFileFormat.AddMasks(const AMasks: string);
var
  I: LongInt;
  Ext: string;
begin
  FExtensions.Clear;
  FMasks.CommaText := AMasks;
  FMasks.Delimiter := ';';

  for I := 0 to FMasks.Count - 1 do
  begin
    FMasks[I] := Trim(FMasks[I]);
    Ext := GetFileExt(FMasks[I]);
    if (Ext <> '') and (Ext <> '*') then
      FExtensions.Add(Ext);
  end;
end;

function TImageFileFormat.GetFormatInfo(Format: TImageFormat): TImageFormatInfo;
begin
  Result := ImageFormatInfos[Format]^;
end;

function TImageFileFormat.GetSupportedFormats: TImageFormats;
begin
  Result := FSupportedFormats;
end;

function TImageFileFormat.LoadData(Handle: TImagingHandle;
  var Images: TDynImageDataArray; OnlyFirstFrame: Boolean): Boolean;
begin
  Result := False;
  RaiseImaging(SFileFormatCanNotLoad, [FName]);
end;

function TImageFileFormat.SaveData(Handle: TImagingHandle;
  const Images: TDynImageDataArray; Index: LongInt): Boolean;
begin
  Result := False;
  RaiseImaging(SFileFormatCanNotSave, [FName]);
end;

procedure TImageFileFormat.ConvertToSupported(var Image: TImageData;
  const Info: TImageFormatInfo);
begin
end;

function TImageFileFormat.IsSupported(const Image: TImageData): Boolean;
begin
  Result := Image.Format in GetSupportedFormats;
end;

function TImageFileFormat.LoadFromFile(const FileName: string;
  var Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
begin
  Result := False;
  if FCanLoad then
  try
    // Set IO ops to file ops and open given file
    SetFileIO;
    Handle := IO.OpenRead(PChar(FileName));
    try
      // Test if file contains valid image and if so then load it
      if TestFormat(Handle) then
      begin
        Result := PrepareLoad(Handle, Images, OnlyFirstLevel) and
          LoadData(Handle, Images, OnlyFirstlevel);
        Result := Result and PostLoadCheck(Images, Result);
      end
      else
        RaiseImaging(SFileNotValid, [FileName, Name]);
    finally
      IO.Close(Handle);
    end;
  except
    RaiseImaging(SErrorLoadingFile, [FileName, FExtensions[0]]);
  end;
end;

function TImageFileFormat.LoadFromStream(Stream: TStream;
  var Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
  OldPosition: Int64;
begin
  Result := False;
  OldPosition := Stream.Position;
  if FCanLoad then
  try
    // Set IO ops to stream ops and "open" given memory
    SetStreamIO;
    Handle := IO.OpenRead(Pointer(Stream));
    try
      // Test if stream contains valid image and if so then load it
      if TestFormat(Handle) then
      begin
        Result := PrepareLoad(Handle, Images, OnlyFirstLevel) and
          LoadData(Handle, Images, OnlyFirstlevel);
        Result := Result and PostLoadCheck(Images, Result);
      end
      else
        RaiseImaging(SStreamNotValid, [@Stream, Name]);
    finally
      IO.Close(Handle);
    end;
  except
    Stream.Position := OldPosition;
    RaiseImaging(SErrorLoadingStream, [@Stream, FExtensions[0]]);
  end;
end;

function TImageFileFormat.LoadFromMemory(Data: Pointer; Size: LongInt; var
  Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
  IORec: TMemoryIORec;
begin
  Result := False;
  if FCanLoad then
  try
    // Set IO ops to memory ops and "open" given memory
    SetMemoryIO;
    IORec := PrepareMemIO(Data, Size);
    Handle := IO.OpenRead(@IORec);
    try
      // Test if memory contains valid image and if so then load it
      if TestFormat(Handle) then
      begin
        Result := PrepareLoad(Handle, Images, OnlyFirstLevel) and
          LoadData(Handle, Images, OnlyFirstlevel);
        Result := Result and PostLoadCheck(Images, Result);
      end
      else
        RaiseImaging(SMemoryNotValid, [Data, Size, Name]);
    finally
      IO.Close(Handle);
    end;
  except
    RaiseImaging(SErrorLoadingMemory, [Data, Size, FExtensions[0]]);
  end;
end;

function TImageFileFormat.SaveToFile(const FileName: string;
  const Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
  Len, Index, I: LongInt;
  Ext, FName: string;
begin
  Result := False;
  if FCanSave and TestImagesInArray(Images) then
  try
    SetFileIO;
    Len := Length(Images);
    if FIsMultiImageFormat or
      (not FIsMultiImageFormat and (OnlyFirstLevel or (Len = 1))) then
    begin
      Handle := IO.OpenWrite(PChar(FileName));
      try
        if OnlyFirstLevel then
          Index := 0
        else
          Index := -1;
        // Write multi image to one file
        Result := PrepareSave(Handle, Images, Index) and SaveData(Handle, Images, Index);
      finally
        IO.Close(Handle);
      end;
    end
    else
    begin
      // Write multi image to file sequence
      Ext := ExtractFileExt(FileName);
      FName := ChangeFileExt(FileName, '');
      Result := True;
      for I := 0 to Len - 1 do
      begin
        Handle := IO.OpenWrite(PChar(Format(FName + '%.3d' + Ext, [I])));
        try
          Index := I;
          Result := Result and PrepareSave(Handle, Images, Index) and
            SaveData(Handle, Images, Index);
          if not Result then
            Break;
        finally
          IO.Close(Handle);
        end;
      end;
    end;
  except
    RaiseImaging(SErrorSavingFile, [FileName, FExtensions[0]]);
  end;
end;

function TImageFileFormat.SaveToStream(Stream: TStream;
  const Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
  Len, Index, I: LongInt;
  OldPosition: Int64;
begin
  Result := False;
  OldPosition := Stream.Position;
  if FCanSave and TestImagesInArray(Images) then
  try
    SetStreamIO;
    Handle := IO.OpenWrite(PChar(Stream));
    try
      if FIsMultiImageFormat or OnlyFirstLevel then
      begin
        if OnlyFirstLevel then
          Index := 0
        else
          Index := -1;
        // Write multi image in one run
        Result := PrepareSave(Handle, Images, Index) and SaveData(Handle, Images, Index);
      end
      else
      begin
        // Write multi image to sequence
        Result := True;
        Len := Length(Images);
        for I := 0 to Len - 1 do
        begin
          Index := I;
          Result := Result and PrepareSave(Handle, Images, Index) and
            SaveData(Handle, Images, Index);
          if not Result then
            Break;
        end;
      end;
    finally
      IO.Close(Handle);
    end;
  except
    Stream.Position := OldPosition;
    RaiseImaging(SErrorSavingStream, [@Stream, FExtensions[0]]);
  end;
end;

function TImageFileFormat.SaveToMemory(Data: Pointer; var Size: LongInt;
  const Images: TDynImageDataArray; OnlyFirstLevel: Boolean): Boolean;
var
  Handle: TImagingHandle;
  Len, Index, I: LongInt;
  IORec: TMemoryIORec;
begin
  Result := False;
  if FCanSave and TestImagesInArray(Images) then
  try
    SetMemoryIO;
    IORec := PrepareMemIO(Data, Size);
    Handle := IO.OpenWrite(PChar(@IORec));
    try
      if FIsMultiImageFormat or OnlyFirstLevel then
      begin
        if OnlyFirstLevel then
          Index := 0
        else
          Index := -1;
        // Write multi image in one run
        Result := PrepareSave(Handle, Images, Index) and SaveData(Handle, Images, Index);
      end
      else
      begin
        // Write multi image to sequence
        Result := True;
        Len := Length(Images);
        for I := 0 to Len - 1 do
        begin
          Index := I;
          Result := Result and PrepareSave(Handle, Images, Index) and
            SaveData(Handle, Images, Index);
          if not Result then
            Break;
        end;
      end;
      Size := IORec.Position;
    finally
      IO.Close(Handle);
    end;
  except
    RaiseImaging(SErrorSavingMemory, [Data, Size, FExtensions[0]]);
  end;
end;

function TImageFileFormat.MakeCompatible(const Image: TImageData;
  var Compatible: TImageData; out MustBeFreed: Boolean): Boolean;
begin
  InitImage(Compatible);

  if SaveOverrideFormat <> ifUnknown then
  begin
    // Save format override is active. Clone input and convert it to override format.
    CloneImage(Image, Compatible);
    ConvertImage(Compatible, SaveOverrideFormat);
    // Now check if override format is supported by file format. If it is not
    // then file format specific conversion (virtual method) is called.
    Result := IsSupported(Compatible);
    if not Result then
    begin
      ConvertToSupported(Compatible, GetFormatInfo(Compatible.Format));
      Result := IsSupported(Compatible);
    end;
  end     // Add IsCompatible function! not only checking by Format
  else if IsSupported(Image) then
  begin
    // No save format override and input is in format supported by this
    // file format. Just copy Image's fields to Compatible
    Compatible := Image;
    Result := True;
  end
  else
  begin
    // No override and input's format is not compatible with file format.
    // Clone it and the call file format specific conversion (virtual method).
    CloneImage(Image, Compatible);
    ConvertToSupported(Compatible, GetFormatInfo(Compatible.Format));
    Result := IsSupported(Compatible);
  end;
  // Tell the user that he must free Compatible after he's done with it
  // (if necessary).
  MustBeFreed := Image.Bits <> Compatible.Bits;
end;

function TImageFileFormat.TestFormat(Handle: TImagingHandle): Boolean;
begin
  Result := False;
end;

function TImageFileFormat.TestFileName(const FileName: string): Boolean;
var
  I: LongInt;
  OnlyName: string;
begin
  OnlyName := ExtractFileName(FileName);
  // For each mask test if filename matches it 
  for I := 0 to FMasks.Count - 1 do
    if MatchFileNameMask(OnlyName, FMasks[I], False) then
    begin
      Result := True;
      Exit;
    end;
  Result := False;
end;

procedure TImageFileFormat.CheckOptionsValidity;
begin
end;

{ TOptionStack  class implementation }

constructor TOptionStack.Create;
begin
  inherited Create;
  FPosition := -1;
end;

destructor TOptionStack.Destroy;
var
  I: LongInt;
begin
  for I := 0 to OptionStackDepth - 1 do
    SetLength(FStack[I], 0);
  inherited Destroy;
end;

function TOptionStack.Pop: Boolean;
var
  I: LongInt;
begin
  Result := False;
  if FPosition >= 0  then
  begin
    SetLength(Options, Length(FStack[FPosition]));
    for I := 0 to Length(FStack[FPosition]) - 1 do
      if Options[I] <> nil then
        Options[I]^ := FStack[FPosition, I];
    Dec(FPosition);
    Result := True;
  end;
end;

function TOptionStack.Push: Boolean;
var
  I: LongInt;
begin
  Result := False;
  if FPosition < OptionStackDepth - 1 then
  begin
    Inc(FPosition);
    SetLength(FStack[FPosition], Length(Options));
    for I := 0 to Length(Options) - 1 do
      if Options[I] <> nil then
        FStack[FPosition, I] := Options[I]^;
    Result := True;
  end;
end;

initialization
{$IFDEF MEMCHECK}
  {$IF CompilerVersion >= 18}
    System.ReportMemoryLeaksOnShutdown := True;
  {$IFEND}
{$ENDIF}
  if ImageFileFormats = nil then
    ImageFileFormats := TList.Create;
  InitImageFormats;
  RegisterOption(ImagingColorReductionMask, @ColorReductionMask);
  RegisterOption(ImagingLoadOverrideFormat, @LoadOverrideFormat);
  RegisterOption(ImagingSaveOverrideFormat, @SaveOverrideFormat);
  RegisterOption(ImagingMipMapFilter, @MipMapFilter);
finalization
  FreeOptions;
  FreeImageFileFormats;

{
  File Notes:

  -- TODOS ----------------------------------------------------
    - nothing now

  -- 0.26.3 Changes/Bug Fixes ---------------------------------
    - Extended RotateImage to allow arbitrary angle rotations.
    - Reversed the order file formats list is searched so
      if you register a new one it will be found sooner than
      built in formats.
    - Fixed memory leak in ResizeImage ocurring when resizing
      indexed images.

  -- 0.26.1 Changes/Bug Fixes ---------------------------------
    - Added position/size checks to LoadFromStream functions.
    - Changed conditional compilation in impl. uses section to reflect changes
      in LINK symbols.

  -- 0.24.3 Changes/Bug Fixes ---------------------------------
    - GenerateMipMaps now generates all smaller levels from
      original big image (better results when using more advanced filters).
      Also conversion to compatible image format is now done here not
      in FillMipMapLevel (that is called for every mipmap level).

  -- 0.23 Changes/Bug Fixes -----------------------------------
    - MakePaletteForImages now works correctly for indexed and special format images
    - Fixed bug in StretchRect: Image was not properly stretched if
      src and dst dimensions differed only in height.
    - ConvertImage now fills new image with zeroes to avoid random data in
      some conversions (RGB->XRGB)
    - Changed RegisterOption procedure to function
    - Changed bunch of palette functions from low level interface to procedure
      (there was no reason for them to be functions).
    - Changed FreeImage and FreeImagesInArray functions to procedures.
    - Added many assertions, come try-finally, other checks, and small code
      and doc changes.

  -- 0.21 Changes/Bug Fixes -----------------------------------
    - GenerateMipMaps threw failed assertion when input was indexed or special,
      fixed.
    - Added CheckOptionsValidity to TImageFileFormat and its decendants.
    - Unit ImagingExtras which registers file formats in Extras package
      is now automatically added to uses clause if LINK_EXTRAS symbol is
      defined in ImagingOptions.inc file.
    - Added EnumFileFormats function to low level interface.
    - Fixed bug in SwapChannels which could cause AV when swapping alpha
      channel of A8R8G8B8 images.
    - Converting loaded images to ImagingOverrideFormat is now done
      in PostLoadCheck method to avoid code duplicity.
    - Added GetFileFormatCount and GetFileFormatAtIndex functions
    - Bug in ConvertImage: if some format was converted to similar format
      only with swapped channels (R16G16B16<>B16G16R16) then channels were
      swapped correctly but new data format (swapped one) was not set.
    - Made TImageFileFormat.MakeCompatible public non-virtual method
      (and modified its function). Created new virtual
      ConvertToSupported which should be overriden by descendants.
      Main reason for doint this is to avoid duplicate code that was in all
      TImageFileFormat's descendants.
    - Changed TImageFileFormat.GetFormatInfo's result type to TImageFormatInfo.
    - Split overloaded FindImageFileFormat functions to
      FindImageFileFormatByClass and FindImageFileFormatByExt and created new
      FindImageFileFormatByName which operates on whole filenames.
    - Function GetExtensionFilterIndex renamed to GetFileNameFilterIndex
      (because it now works with filenames not extensions).
    - DetermineFileFormat now first searches by filename and if not found
      then by data.
    - Added TestFileName method to TImageFileFormat.
    - Updated GetImageFileFormatsFilter to uses Masks instead of Extensions
      property of TImageFileFormat. Also you can now request
      OpenDialog and SaveDialog type filters
    - Added Masks property and AddMasks method to TImageFileFormat.
      AddMasks replaces AddExtensions, it uses filename masks instead
      of sime filename extensions to identify supported files.
    - Changed TImageFileFormat.LoadData procedure to function and
      moved varios duplicate code from its descandats (check index,...)
      here to TImageFileFormat helper methods.
    - Changed TImageFileFormat.SaveData procedure to function and
      moved varios duplicate code from its descandats (check index,...)
      here to TImageFileFormat helper methods.
    - Removed RAISE_EXCEPTIONS define, exceptions are now raised everytime
    - Added MustBeFreed parameter to TImageFileFormat.MakeComptible method
      that indicates that compatible image returned by this method must be
      freed after its usage.

  -- 0.19 Changes/Bug Fixes -----------------------------------
    - fixed bug in NewImage: if given format was ifDefault it wasn't
      replaced with DefaultImageFormat constant which caused problems later
      in other units 
    - fixed bug in RotateImage which caused that rotated special format
      images were whole black
    - LoadImageFromXXX and LoadMultiImageFromXXX now use DetermineXXXFormat
      when choosing proper loader, this eliminated need for Ext parameter
      in stream and memory loading functions
    - added GetVersionStr function
    - fixed bug in ResizeImage which caued indexed images to lose their
      palette during process resulting in whole black image
    - Clipping in ...Rect functions now uses clipping procs from ImagingUtility,
      it also works better
    - FillRect optimization for 8, 16, and 32 bit formats
    - added pixel set/get functions to low level interface:
      GetPixelDirect, SetPixelDirect, GetPixel32, SetPixel32,
      GetPixelFP, SetPixelFP
    - removed GetPixelBytes low level intf function - redundant
      (same data can be obtained by GetImageFormatInfo)
    - made small changes in many parts of library to compile
      on AMD64 CPU (Linux with FPC)
    - changed InitImage to procedure (function was pointless)
    - Method TestFormat of TImageFileFormat class made public
      (was protected)
    - added function IsFileFormatSupported to low level interface
      (contributed by Paul Michell)
    - fixed some missing format arguments from error strings
      which caused Format function to raise exception
    - removed forgotten debug code that disabled filtered resizing of images with
      channel bitcounts > 8

  -- 0.17 Changes/Bug Fixes -----------------------------------
    - changed order of parameters of CopyRect function  
    - GenerateMipMaps now filters mipmap levels
    - ResizeImage functions was extended to allow bilinear and bicubic filtering
    - added StretchRect function to low level interface
    - added functions GetImageFileFormatsFilter, GetFilterIndexExtension,
      and GetExtensionFilterIndex

  -- 0.15 Changes/Bug Fixes -----------------------------------
    - added function RotateImage to low level interface
    - moved TImageFormatInfo record and types required by it to
      ImagingTypes unit, changed GetImageFormatInfo low level
      interface function to return TImageFormatInfo instead of short info
    - added checking of options values validity before they are used
    - fixed possible memory leak in CloneImage
    - added ReplaceColor function to low level interface
    - new function FindImageFileFormat by class added

  -- 0.13 Changes/Bug Fixes -----------------------------------
    - added DetermineFileFormat, DetermineStreamFormat, DetermineMemoryFormat,
      GetPixelsSize functions to low level interface
    - added NewPalette, CopyPalette, FreePalette functions
      to low level interface
    - added MapImageToPalette, FillRect, SplitImage, MakePaletteForImages
      functions to low level interface
    - fixed buggy FillCustomPalette function (possible div by zero and others)
    - added CopyRect function to low level interface
    - Member functions of TImageFormatInfo record implemented for all formats
    - before saving images TestImagesInArray is called now
    - added TestImagesInArray function to low level interface
    - added GenerateMipMaps function to low level interface
    - stream position in load/save from/to stream is now set to position before
      function was called if error occurs
    - when error occured during load/save from/to file file handle
      was not released
    - CloneImage returned always False

}
end.