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+{ Copyright (C) 2003 Mattias Gaertner
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+
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+ This library is free software; you can redistribute it and/or modify it
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+ under the terms of the GNU Library General Public License as published by
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+ the Free Software Foundation; either version 2 of the License, or (at your
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+ option) any later version.
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+
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+ This program is distributed in the hope that it will be useful, but WITHOUT
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+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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+ FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
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+ for more details.
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+
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+ You should have received a copy of the GNU Library General Public License
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+ along with this library; if not, write to the Free Software Foundation,
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+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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+
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+ ToDo:
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+ - grayscale
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+ - palette
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+}
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+unit FPReadJPEG;
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+
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+{$mode objfpc}{$H+}
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+
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+interface
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+
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+uses
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+ Classes, SysUtils, FPImage, JPEGLib, JdAPImin, JDataSrc, JdAPIstd, JmoreCfg;
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+
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+type
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+ { TFPReaderJPEG }
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+ { This is a FPImage reader for jpeg images. }
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+
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+ TFPReaderJPEG = class;
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+
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+ PFPJPEGProgressManager = ^TFPJPEGProgressManager;
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+ TFPJPEGProgressManager = record
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+ pub : jpeg_progress_mgr;
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+ instance: TObject;
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+ last_pass: Integer;
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+ last_pct: Integer;
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+ last_time: Integer;
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+ last_scanline: Integer;
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+ end;
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+
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+ TJPEGScale = (jsFullSize, jsHalf, jsQuarter, jsEighth);
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+ TJPEGReadPerformance = (jpBestQuality, jpBestSpeed);
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+
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+ TFPReaderJPEG = class(TFPCustomImageReader)
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+ private
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+ FSmoothing: boolean;
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+ FWidth: Integer;
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+ FHeight: Integer;
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+ FGrayscale: boolean;
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+ FProgressiveEncoding: boolean;
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+ FError: jpeg_error_mgr;
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+ FProgressMgr: TFPJPEGProgressManager;
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+ FInfo: jpeg_decompress_struct;
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+ FScale: TJPEGScale;
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+ FPerformance: TJPEGReadPerformance;
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+ procedure SetPerformance(const AValue: TJPEGReadPerformance);
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+ procedure SetSmoothing(const AValue: boolean);
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+ protected
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+ procedure InternalRead(Str: TStream; Img: TFPCustomImage); override;
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+ function InternalCheck(Str: TStream): boolean; override;
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+ public
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+ constructor Create; override;
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+ destructor Destroy; override;
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+ property GrayScale: boolean read FGrayscale;
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+ property ProgressiveEncoding: boolean read FProgressiveEncoding;
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+ property Smoothing: boolean read FSmoothing write SetSmoothing;
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+ property Performance: TJPEGReadPerformance read FPerformance write SetPerformance;
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+ end;
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+
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+implementation
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+
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+procedure ReadCompleteStreamToStream(SrcStream, DestStream: TStream;
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+ StartSize: integer);
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+var
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+ NewLength: Integer;
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+ ReadLen: Integer;
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+ Buffer: string;
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+begin
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+ if (SrcStream is TMemoryStream) or (SrcStream is TFileStream)
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+ or (SrcStream is TStringStream)
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+ then begin
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+ // read as one block
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+ DestStream.CopyFrom(SrcStream,SrcStream.Size-SrcStream.Position);
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+ end else begin
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+ // read exponential
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+ if StartSize<=0 then StartSize:=1024;
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+ SetLength(Buffer,StartSize);
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+ NewLength:=0;
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+ repeat
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+ ReadLen:=SrcStream.Read(Buffer[NewLength+1],length(Buffer)-NewLength);
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+ inc(NewLength,ReadLen);
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+ if NewLength<length(Buffer) then break;
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+ SetLength(Buffer,length(Buffer)*2);
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+ until false;
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+ if NewLength>0 then
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+ DestStream.Write(Buffer[1],NewLength);
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+ end;
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+end;
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+
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+procedure JPEGError(CurInfo: j_common_ptr);
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+begin
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+ if CurInfo=nil then exit;
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+ writeln('JPEGError ',CurInfo^.err^.msg_code,' ');
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+ raise Exception.CreateFmt('JPEG error',[CurInfo^.err^.msg_code]);
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+end;
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+
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+procedure EmitMessage(CurInfo: j_common_ptr; msg_level: Integer);
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+begin
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+ if CurInfo=nil then exit;
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+ if msg_level=0 then ;
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+end;
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+
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+procedure OutputMessage(CurInfo: j_common_ptr);
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+begin
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+ if CurInfo=nil then exit;
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+end;
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+
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+procedure FormatMessage(CurInfo: j_common_ptr; var buffer: string);
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+begin
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+ if CurInfo=nil then exit;
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+ writeln('FormatMessage ',buffer);
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+end;
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+
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+procedure ResetErrorMgr(CurInfo: j_common_ptr);
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+begin
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+ if CurInfo=nil then exit;
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+ CurInfo^.err^.num_warnings := 0;
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+ CurInfo^.err^.msg_code := 0;
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+end;
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+
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+
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+var
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+ jpeg_std_error: jpeg_error_mgr;
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+
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+procedure ProgressCallback(CurInfo: j_common_ptr);
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+begin
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+ if CurInfo=nil then exit;
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+ // ToDo
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+end;
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+
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+{ TFPReaderJPEG }
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+
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+procedure TFPReaderJPEG.SetSmoothing(const AValue: boolean);
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+begin
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+ if FSmoothing=AValue then exit;
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+ FSmoothing:=AValue;
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+end;
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+
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+procedure TFPReaderJPEG.SetPerformance(const AValue: TJPEGReadPerformance);
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+begin
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+ if FPerformance=AValue then exit;
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+ FPerformance:=AValue;
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+end;
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+
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+procedure TFPReaderJPEG.InternalRead(Str: TStream; Img: TFPCustomImage);
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+var
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+ MemStream: TMemoryStream;
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+
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+ procedure SetSource;
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+ begin
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+ MemStream.Position:=0;
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+ jpeg_stdio_src(@FInfo, @MemStream);
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+ end;
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+
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+ procedure ReadHeader;
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+ begin
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+ jpeg_read_header(@FInfo, TRUE);
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+ FWidth := FInfo.image_width;
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+ FHeight := FInfo.image_height;
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+ FGrayscale := FInfo.jpeg_color_space = JCS_GRAYSCALE;
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+ FProgressiveEncoding := jpeg_has_multiple_scans(@FInfo);
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+ end;
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+
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+ procedure InitReadingPixels;
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+ begin
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+ FInfo.scale_num := 1;
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+ FInfo.scale_denom := 1;// shl Byte(FScale);
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+ FInfo.do_block_smoothing := FSmoothing;
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+
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+ if FGrayscale then FInfo.out_color_space := JCS_GRAYSCALE;
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+ if (FInfo.out_color_space = JCS_GRAYSCALE) then begin
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+ FInfo.quantize_colors := True;
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+ FInfo.desired_number_of_colors := 236;
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+ end;
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+
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+ if FPerformance = jpBestSpeed then begin
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+ FInfo.dct_method := JDCT_IFAST;
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+ FInfo.two_pass_quantize := False;
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+ FInfo.dither_mode := JDITHER_ORDERED;
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+ // FInfo.do_fancy_upsampling := False; can create an AV inside jpeglib
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+ end;
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+
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+ if FProgressiveEncoding then begin
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+ FInfo.enable_2pass_quant := FInfo.two_pass_quantize;
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+ FInfo.buffered_image := True;
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+ end;
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+ end;
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+
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+ procedure ReadPixels;
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+ var
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+ Continue: Boolean;
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+ SampArray: JSAMPARRAY;
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+ SampRow: JSAMPROW;
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+ Color: TFPColor;
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+ LinesRead: Cardinal;
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+ x: Integer;
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+ y: Integer;
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+ begin
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+ InitReadingPixels;
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+
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+ Continue:=true;
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+ Progress(psStarting, 0, False, Rect(0,0,0,0), '', Continue);
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+ if not Continue then exit;
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+
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+ jpeg_start_decompress(@FInfo);
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+
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+ Img.SetSize(FInfo.output_width,FInfo.output_height);
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+
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+ // read one line per call
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+ GetMem(SampArray,SizeOf(JSAMPROW));
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+ GetMem(SampRow,FInfo.output_width*FInfo.output_components);
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+ SampArray^[0]:=SampRow;
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+ try
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+ Color.Alpha:=alphaOpaque;
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+ y:=0;
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+ while (FInfo.output_scanline < FInfo.output_height) do begin
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+ LinesRead := jpeg_read_scanlines(@FInfo, SampArray, 1);
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+ if LinesRead<1 then break;
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+ for x:=0 to FInfo.output_width-1 do begin
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+ Color.Red:=SampRow^[x*3+0] shl 8;
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+ Color.Green:=SampRow^[x*3+1] shl 8;
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+ Color.Blue:=SampRow^[x*3+2] shl 8;
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+ Img.Colors[x,y]:=Color;
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+ end;
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+ inc(y);
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+ end;
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+ finally
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+ FreeMem(SampRow);
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+ FreeMem(SampArray);
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+ end;
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+
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+ if FInfo.buffered_image then jpeg_finish_output(@FInfo);
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+ jpeg_finish_decompress(@FInfo);
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+
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+ Progress(psEnding, 100, false, Rect(0,0,0,0), '', Continue);
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+ end;
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+
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+begin
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+ FWidth:=0;
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+ FHeight:=0;
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+ MemStream:=nil;
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+ FillChar(FInfo,SizeOf(FInfo),0);
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+ try
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+ if Str is TMemoryStream then
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+ MemStream:=TMemoryStream(Str)
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+ else begin
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+ MemStream:=TMemoryStream.Create;
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+ ReadCompleteStreamToStream(Str,MemStream,1024);
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+ MemStream.Position:=0;
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+ end;
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+ if MemStream.Size > 0 then begin
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+ FError:=jpeg_std_error;
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+ FInfo.err := @FError;
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+ jpeg_CreateDecompress(@FInfo, JPEG_LIB_VERSION, SizeOf(FInfo));
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+ try
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+ FProgressMgr.pub.progress_monitor := @ProgressCallback;
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+ FProgressMgr.instance := Self;
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+ FInfo.progress := @FProgressMgr;
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+ SetSource;
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+ ReadHeader;
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+ ReadPixels;
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+ finally
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+ jpeg_Destroy_Decompress(@FInfo);
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+ end;
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+ end;
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+ finally
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+ if (MemStream<>nil) and (MemStream<>Str) then
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+ MemStream.Free;
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+ end;
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+end;
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+
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+function TFPReaderJPEG.InternalCheck(Str: TStream): boolean;
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+begin
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+ // ToDo: read header and check
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+ Result:=false;
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+ if Str=nil then exit;
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+ Result:=true;
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+end;
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+
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+constructor TFPReaderJPEG.Create;
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+begin
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+ FScale:=jsFullSize;
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+ FPerformance:=jpBestSpeed;
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+ inherited Create;
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+end;
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+
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+destructor TFPReaderJPEG.Destroy;
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+begin
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+ inherited Destroy;
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+end;
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+
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+initialization
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+ with jpeg_std_error do begin
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+ error_exit:=@JPEGError;
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+ emit_message:=@EmitMessage;
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+ output_message:=@OutputMessage;
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+ format_message:=@FormatMessage;
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+ reset_error_mgr:=@ResetErrorMgr;
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+ end;
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+
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+end.
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+
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michael