freepascal.compiler/docs/graph.tex

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% Documentation for the 'Graph' unit of Free Pascal.
% Michael Van Canneyt, July 1997
\chapter{The GRAPH unit.}
This document describes the \var{GRAPH} unit for Free Pascal, for all
platforms. The unit was first written for \dos by Florian kl\"ampfl. 
This chapter is divided in 4 sections. 
\begin{itemize}
\item The first section gives an introduction to the graph unit.
\item The second section lists the pre-defined constants, types and variables. 
\item The second section describes the functions which appear in the
interface part of the \file{GRAPH} unit.
\item The last part describes some system-specific issues.

\end{itemize}
\section{Introduction}
\label{se:Introduction}
\subsection{Requirements}
The unit Graph exports functions and procedures for graphical output.
It requires at least a VESA compatible VGA-Card or a VGA-Card with software-driver
(min. \textbf{512Kb} video memory).
Before the graph unit can be used, be sure your graphics adapter supports
the VESA-Standard. Otherwise in the most cases you can try to use a VESA-TSR
to make your adapter VESA compatible (e.g. UNIVBE).
\section{Constants, Types and Variables}
\subsection{Types}
\begin{verbatim}
ArcCoordsType = record
 X,Y,Xstart,Ystart,Xend,Yend : Integer;
end;
FillPatternType = Array [1..8] of Byte;
FillSettingsType = Record
 Pattern,Color : Word
end;
LineSettingsType = Record
  LineStyle,Pattern, Width : Word;
end;
PaletteType = Record
 Size : Byte;
 Colors : array[0..MAxColor] of shortint;
end;
PointType = Record
  X,Y : Integer;
end;
TextSettingsType = Record
 Font,Direction, CharSize, Horiz, Vert : Word
end;
ViewPortType = Record
  X1,Y1,X2,Y2 : Integer;
  Clip : Boolean
end;
\end{verbatim}
\section{Functions and procedures}
\begin{procedure}{Arc}
\Declaration
Procedure Arc (X,Y : Integer; start,stop, radius : Word);

\Description
 \var{Arc} draws part of a circle with center at \var{(X,Y)}, radius
\var{radius}, starting from angle \var{start}, stopping at angle \var{stop}.
These  angles are measured
counterclockwise.
\Errors
None.
\SeeAlso
\seep{Circle},\seep{Ellipse} 
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}
\end{procedure}
\begin{procedure}{Bar}
\Declaration
Procedure Bar (X1,Y1,X2,Y2 : Integer);

\Description
Draws a rectangle with corners at \var{(X1,Y1)} and \var{(X2,Y2)} 
and fills it with the current color and fill-style.
\Errors
None.
\SeeAlso
\seep{Bar3D}, 
\seep{Rectangle}
\end{procedure}
\begin{procedure}{Bar3D}
\Declaration
Procedure Bar3D (X1,Y1,X2,Y2 : Integer; depth : Word; Top : Boolean);

\Description
Draws a 3-dimensional Bar  with corners at \var{(X1,Y1)} and \var{(X2,Y2)} 
and fills it with the current color and fill-style.
\var{Depth} specifies the number of pixels used to show the depth of the
bar.
If \var{Top} is true; then a 3-dimensional top is drawn.
\Errors
None.
\SeeAlso
\seep{Bar}, \seep{Rectangle}
\end{procedure}
\begin{procedure}{Circle}
\Declaration
Procedure Circle (X,Y : Integer; Radius : Word);

\Description
 \var{Circle} draws part of a circle with center at \var{(X,Y)}, radius
\var{radius}.
\Errors
None.
\SeeAlso
\seep{Ellipse},\seep{Arc}
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}
\end{procedure}
\begin{procedure}{ClearDevice}
\Declaration
Procedure ClearDevice ;

\Description
Clears the graphical screen (with the current
background color), and sets the pointer at \var{(0,0)}
\Errors
None.
\SeeAlso
\seep{ClearViewPort}, \seep{SetBkColor}
\end{procedure}
\begin{procedure}{ClearViewPort}
\Declaration
Procedure ClearViewPort ;

\Description
Clears the current view-port. The current background color is used as filling
color. The pointer is set at
\var{(0,0)}
\Errors
None.
\SeeAlso
\seep{ClearDevice},\seep{SetViewPort}, \seep{SetBkColor}
\end{procedure}
\begin{procedure}{CloseGraph}
\Declaration
Procedure CloseGraph ;

\Description
Closes the graphical system, and restores the
screen modus which was active before the graphical modus was
activated.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{procedure}
\begin{procedure}{DetectGraph}
\Declaration
Procedure DetectGraph (Var Driver, Modus : Integer);

\Description
 Checks the hardware in the PC and determines the driver and screen-modus to
be used. These are returned in \var{Driver} and \var{Modus}, and can be fed
to \var{InitGraph}. 
See the \var{InitGraph} for a list of drivers and modi.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{procedure}
\begin{procedure}{DrawPoly}
\Declaration
Procedure DrawPoly (NumberOfPoints : Word; Var PolyPoints;

\Description

Draws a polygone with \var{NumberOfPoints} corner points, using the
current color and line-style. PolyPoints is an array of type \var{PointType}.

\Errors
None.
\SeeAlso
\seep{Bar}, seep{Bar3D}, \seep{Rectangle}
\end{procedure}
\begin{procedure}{Ellipse}
\Declaration
Procedure Ellipse (X,Y : Integer; Start,Stop,XRadius,YRadius : Word);

\Description
 \var{Ellipse} draws part of an ellipse with center at \var{(X,Y)}.
\var{XRadius} and \var{Yradius} are the horizontal and vertical radii of the
ellipse. \var{Start} and \var{Stop} are the starting and stopping angles of
the part of the ellipse. 
They are measured counterclockwise from the X-axis.
\Errors
None.
\SeeAlso
\seep{Arc} \seep{Circle}, \seep{FillEllipse}
\end{procedure}
\begin{procedure}{FillEllipse}
\Declaration
Procedure FillEllipse (X,Y : Integer; Xradius,YRadius: Word);

\Description
 \var{Ellipse} draws an ellipse with center at \var{(X,Y)}.
\var{XRadius} and \var{Yradius} are the horizontal and vertical radii of the
ellipse. The ellipse is filled with the current color and fill-style.
\Errors
None.
\SeeAlso
\seep{Arc} \seep{Circle},
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}
\end{procedure}
\begin{procedure}{FillPoly}
\Declaration
Procedure FillPoly (NumberOfPoints : Word; Var PolyPoints);

\Description

Draws a polygone with \var{NumberOfPoints} corner points and fills it
using the current color and line-style. 
PolyPoints is an array of type \var{PointType}.

\Errors
None.
\SeeAlso
\seep{Bar}, seep{Bar3D}, \seep{Rectangle}
\end{procedure}
\begin{procedure}{FloodFill}
\Declaration
Procedure FloodFill (X,Y : Integer; BorderColor : Word);

\Description

Fills the area containing the point \var{(X,Y)}, bounded by the color
\var{BorderColor}.
\Errors
None
\SeeAlso
\seep{SetColor}, \seep{SetBkColor}
\end{procedure}
\begin{procedure}{GetArcCoords}
\Declaration
Procedure GetArcCoords (Var ArcCoords : ArcCoordsType);

\Description
\var{GetArcCoords} returns the coordinates of the latest \var{Arc} or
\var{Ellipse} call.
\Errors
None.
\SeeAlso
\seep{Arc}, \seep{Ellipse}
\end{procedure}
\begin{procedure}{GetAspectRatio}
\Declaration
Procedure GetAspectRatio (Var Xasp,Yasp : Word);

\Description
\var{GetAspectRatio} determines the effective resolution of the screen. The aspect ration can
the be calculated as \var{Xasp/Yasp}.
\Errors
None.
\SeeAlso
\seep{InitGraph},\seep{SetAspectRatio}
\end{procedure}
\begin{function}{GetBkColor}
\Declaration
Function GetBkColor  : Word;

\Description
\var{GetBkColor} returns the current background color (the palette
entry).
\Errors
None.
\SeeAlso
\seef{GetColor},\seep{SetBkColor}
\end{function}
\begin{function}{GetColor}
\Declaration
Function GetColor  : Word;

\Description
\var{GetColor} returns the current drawing color (the palette
entry).
\Errors
None.
\SeeAlso
\seef{GetColor},\seep{SetBkColor}
\end{function}
\begin{procedure}{GetDefaultPalette}
\Declaration
Procedure GetDefaultPalette (Var Palette : PaletteType);

\Description
Returns the
current palette in \var{Palette}.
\Errors
None.
\SeeAlso
\seef{GetColor}, \seef{GetBkColor}
\end{procedure}
\begin{function}{GetDriverName}
\Declaration
Function GetDriverName  : String;

\Description
\var{GetDriverName} returns a string containing the name of the
current driver.
\Errors
None.
\SeeAlso
\seef{GetModeName}, \seep{InitGraph}
\end{function}
\begin{procedure}{GetFillPattern}
\Declaration
Procedure GetFillPattern (Var FillPattern : FillPatternType);

\Description
\var{GetFillPattern} returns an array with the current fill-pattern  in \var{FillPattern}
\Errors
None
\SeeAlso
\seep{SetFillPattern}
\end{procedure}
\begin{procedure}{GetFillSettings}
\Declaration
Procedure GetFillSettings (Var FillInfo : FillSettingsType);

\Description
\var{GetFillSettings} returns the current fill-settings in
\var{FillInfo}
\Errors
None.
\SeeAlso
\seep{SetFillPattern}
\end{procedure}
\begin{function}{GetGraphMode}
\Declaration
Function GetGraphMode  : Integer;

\Description
\var{GetGraphMode} returns the current graphical modus
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{function}
\begin{procedure}{GetImage}
\Declaration
Procedure GetImage (X1,Y1,X2,Y2 : Integer, Var Bitmap;

\Description
\var{GetImage}
Places a copy of the screen area \var{(X1,Y1)} to \var{X2,Y2} in \var{BitMap}
\Errors
Bitmap must have enough room to contain the image.
\SeeAlso
\seef{ImageSize},
\seep{PutImage}
\end{procedure}
\begin{procedure}{GetLineSettings}
\Declaration
Procedure GetLineSettings (Var LineInfo : LineSettingsType);

\Description
\var{GetLineSettings} returns the current Line settings in
\var{LineInfo}
\Errors
None.
\SeeAlso
\seep{SetLineStyle}
\end{procedure}
\begin{function}{GetMaxColor}
\Declaration
Function GetMaxColor  : Word;

\Description
\var{GetMaxColor} returns the maximum
color-number which can be set with \var{SetColor}
\Errors
None.
\SeeAlso
\seep{SetColor},
\seef{GetPaletteSize}
\end{function}
\begin{function}{GetMaxMode}
\Declaration
Function GetMaxMode  : Word;

\Description
\var{GetMaxMode} returns the highest modus for
the current driver.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{function}
\begin{function}{GetMaxX}
\Declaration
Function GetMaxX  : Word;

\Description
\var{GetMaxX} returns the maximum horizontal screen
length
\Errors
None.
\SeeAlso
\seef{GetMaxY}
\end{function}
\begin{function}{GetMaxY}
\Declaration
Function GetMaxY  : Word;

\Description
\var{GetMaxY} returns the maximum number of screen
lines
\Errors
None.
\SeeAlso
\seef{GetMaxY}
\end{function}
\begin{function}{GetModeName}
\Declaration
Function GetModeName (Var modus : Integer) : String;

\Description

Returns a string with the name of modus
\var{Modus}
\Errors
None.
\SeeAlso
\seef{GetDriverName}, \seep{InitGraph}
\end{function}
\begin{procedure}{GetModeRange}
\Declaration
Procedure GetModeRange (Driver : Integer; \\ LoModus, HiModus: Integer);

\Description
\var{GetModeRange} returns the Lowest and Highest modus of the currently
installed driver.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{procedure}
\begin{procedure}{GetPalette}
\Declaration
Procedure GetPalette (Var Palette : PaletteType);

\Description
\var{GetPalette} returns in \var{Palette} the current palette.
\Errors
None.
\SeeAlso
\seef{GetPaletteSize}, \seep{SetPalette}
\end{procedure}
\begin{function}{GetPaletteSize}
\Declaration
Function GetPaletteSize  : Word;

\Description
\var{GetPaletteSize} returns the maximum
number of entries in the current palette.
\Errors
None.
\SeeAlso
\seep{GetPalette},
\seep{SetPalette}
\end{function}
\begin{function}{GetPixel}
\Declaration
Function GetPixel (X,Y : Integer) : Word;

\Description
\var{GetPixel} returns the color
of the point at \var{(X,Y)} 
\Errors
None.
\SeeAlso

\end{function}
\begin{procedure}{GetTextSettings}
\Declaration
Procedure GetTextSettings (Var TextInfo : TextSettingsType);

\Description
\var{GetTextSettings} returns the current text style settings : The font,
direction, size and placement as set with \var{SetTextStyle} and
\var{SetTextJustify}
\Errors
None.
\SeeAlso
\seep{SetTextStyle}, \seep{SetTextJustify}
\end{procedure}
\begin{procedure}{GetViewSettings}
\Declaration
Procedure GetViewSettings (Var ViewPort : ViewPortType);

\Description
\var{GetViewSettings} returns the current view-port and clipping settings in
\var{ViewPort}.
\Errors
None.
\SeeAlso
\seep{SetViewPort}
\end{procedure}
\begin{function}{GetX}
\Declaration
Function GetX  : Integer;

\Description
\var{GetX} returns the X-coordinate of the current position of
the graphical pointer
\Errors
None.
\SeeAlso
\seef{GetY}
\end{function}
\begin{function}{GetY}
\Declaration
Function GetY  : Integer;

\Description
\var{GetY} returns the Y-coordinate of the current position of
the graphical pointer
\Errors
None.
\SeeAlso
\seef{GetX}
\end{function}
\begin{procedure}{GraphDefaults}
\Declaration
Procedure GraphDefaults ;

\Description
\var{GraphDefaults} resets all settings for view-port, palette,
foreground and background pattern, line-style and pattern, filling style,
filling color and pattern, font, text-placement and
text size.
\Errors
None.
\SeeAlso
\seep{SetViewPort}, \seep{SetFillStyle}, \seep{SetColor},
\seep{SetBkColor}, \seep{SetLineStyle}
\end{procedure}
\begin{function}{GraphErrorMsg}
\Declaration
Function GraphErrorMsg (ErrorCode : Integer) : String;

\Description
\var{GraphErrorMsg}
returns a string describing the error \var{Errorcode}. This string can be
used to let the user know what went wrong.
\Errors
None.
\SeeAlso
\seef{GraphResult}
\end{function}
\begin{function}{GraphResult}
\Declaration
Function GraphResult  : Integer;

\Description
\var{GraphResult} returns an error-code for
the last graphical operation. If the returned value is zero, all went well.
A value different from zero means an error has occurred.
Except for all operations which draw something on the screen, 
the following procedures also can produce a \var{GraphResult} different from
zero:
\begin{itemize}
\item \seef{InstallUserFont}
\item \seep{SetLineStyle}
\item \seep{SetWriteMode}
\item \seep{SetFillStyle}
\item \seep{SetTextJustify}
\item \seep{SetGraphMode}
\item \seep{SetTextStyle}
\end{itemize}

\Errors
None.
\SeeAlso
\seef{GraphErrorMsg}
\end{function}
\begin{function}{ImageSize}
\Declaration
Function ImageSize (X1,Y1,X2,Y2 : Integer) : Word;

\Description
\var{ImageSize} returns
the number of bytes needed to store the image in the rectangle defined by
\var{(X1,Y1)} and \var{(X2,Y2)}.
\Errors
None.
\SeeAlso
\seep{GetImage}
\end{function}
\begin{procedure}{InitGraph}
\Declaration
Procedure InitGraph (var GraphDriver,GraphModus : integer;\\
const PathToDriver : string);

\Description

\var{InitGraph} initializes the \var{graph} package.
\var{GraphDriver} has two valid values: \var{GraphDriver=0} which
performs an auto detect and initializes the highest possible mode with the most
colors. 1024x768x64K is the highest possible resolution supported by the
driver, if you need a higher resolution, you must edit \file{MODES.PPI}. 
If you need another mode, then set \var{GraphDriver} to a value different
from zero
and \var{graphmode} to the mode you wish (VESA modes where 640x480x256
is \var {101h} etc.).
\var{PathToDriver} is only needed, if you use the BGI fonts from
Borland.
\Errors
None.
\SeeAlso
Introduction, (page \pageref{se:Introduction}),
\seep{DetectGraph}, \seep{CloseGraph}, \seef{GraphResult}
\end{procedure}
Example:
\begin{verbatim}
var 
   gd,gm : integer; 
   PathToDriver : string; 
begin 
   gd:=detect; { highest possible resolution } 
   gm:=0; { not needed, auto detection } 
   PathToDriver:='C:\PP\BGI'; { path to BGI fonts, 
                                drivers aren't needed } 
   InitGraph(gd,gm,PathToDriver); 
   if GraphResult<>grok then 
     halt; ..... { whatever you need } 
   CloseGraph; { restores the old graphics mode } 
end.
\end{verbatim}
\begin{function}{InstallUserDriver}
\Declaration
Function InstallUserDriver (DriverPath : String; \\AutoDetectPtr: Pointer) : Integer;

\Description
\var{InstallUserDriver} 
adds the device-driver \var{DriverPath} to the list of .BGI
drivers. \var{AutoDetectPtr} is a pointer to a possible auto-detect function.
\Errors
None.
\SeeAlso
\seep{InitGraph}, \seef{InstallUserFont}
\end{function}
\begin{function}{InstallUserFont}
\Declaration
Function InstallUserFont (FontPath : String) : Integer;

\Description
\var{InstallUserFont} adds the font in \var{FontPath} to the list of fonts
of the .BGI system.
\Errors
None.
\SeeAlso
\seep{InitGraph}, \seef{InstallUserDriver}
\end{function}
\begin{procedure}{Line}
\Declaration
Procedure Line (X1,Y1,X2,Y2 : Integer);

\Description
\var{Line} draws a line starting from
\var{(X1,Y1} to \var{(X2,Y2)}, in the current line style and color. The
current position is put to \var{(X2,Y2)}
\Errors
None.
\SeeAlso
\seep{LineRel},\seep{LineTo}
\end{procedure}
\begin{procedure}{LineRel}
\Declaration
Procedure LineRel (DX,DY : Integer);

\Description
\var{LineRel} draws a line starting from
the current pointer position to the point\var{(DX,DY}, \textbf{relative} to the
current position, in the current line style and color. The Current Position
is set to the endpoint of the line.
\Errors
None.
\SeeAlso
\seep{Line}, \seep{LineTo}
\end{procedure}
\begin{procedure}{LineTo}
\Declaration
Procedure LineTo (DX,DY : Integer);

\Description
\var{LineTo} draws a line starting from
the current pointer position to the point\var{(DX,DY}, \textbf{relative} to the
current position, in the current line style and color. The Current position
is set to the end of the line.
\Errors
None.
\SeeAlso
\seep{LineRel},\seep{Line}
\end{procedure}
\begin{procedure}{MoveRel}
\Declaration
Procedure MoveRel (DX,DY : Integer;

\Description
\var{MoveRel} moves the pointer to the
point \var{(DX,DY)}, relative to the current pointer
position
\Errors
None.
\SeeAlso
\seep{MoveTo}
\end{procedure}
\begin{procedure}{MoveTo}
\Declaration
Procedure MoveTo (X,Y : Integer;

\Description
\var{MoveTo} moves the pointer to the
point \var{(X,Y)}.
\Errors
None.
\SeeAlso
\seep{MoveRel}
\end{procedure}
\begin{procedure}{OutText}
\Declaration
Procedure OutText (Const TextString : String);

\Description
\var{OutText} puts \var{TextString} on the screen, at the current pointer
position, using the current font and text settings. The current position is
moved to the end of the text.
\Errors
None.
\SeeAlso
\seep{OutTextXY}
\end{procedure}
\begin{procedure}{OutTextXY}
\Declaration
Procedure OutTextXY (X,Y : Integer; Const TextString : String);

\Description
\var{OutText} puts \var{TextString} on the screen, at position \var{(X,Y)},
using the current font and text settings. The current position is
moved to the end of the text.
\Errors
None.
\SeeAlso
\seep{OutText}
\end{procedure}
\begin{procedure}{PieSlice}
\Declaration
Procedure PieSlice (X,Y : Integer; \\ Start,Stop,Radius : Word);

\Description
\var{PieSlice}
draws and fills a sector of a circle with center \var{(X,Y)} and radius 
\var{Radius}, starting at angle \var{Start} and ending at angle \var{Stop}.
\Errors
None.
\SeeAlso
\seep{Arc}, \seep{Circle}, \seep{Sector}
\end{procedure}
\begin{procedure}{PutImage}
\Declaration
Procedure PutImage (X1,Y1 : Integer; Var Bitmap; How : word) ;

\Description
\var{PutImage}
Places the bitmap in \var{Bitmap} on the screen at \var{(X1,Y1)}. \var{How}
determines how the bitmap will be placed on the screen. Possible values are :
\begin{itemize}
\item CopyPut
\item XORPut
\item ORPut
\item AndPut
\item NotPut
\end{itemize}
\Errors
None
\SeeAlso
\seef{ImageSize},\seep{GetImage}
\end{procedure}
\begin{procedure}{PutPixel}
\Declaration
Procedure PutPixel (X,Y : Integer; Color : Word);

\Description
Puts a point at
\var{(X,Y)} using color \var{Color}
\Errors
None.
\SeeAlso
\seef{GetPixel}
\end{procedure}
\begin{procedure}{Rectangle}
\Declaration
Procedure Rectangle (X1,Y1,X2,Y2 : Integer);

\Description
Draws a rectangle with
corners at \var{(X1,Y1)} and \var{(X2,Y2)}, using the current color and
style.
\Errors
None.
\SeeAlso
\seep{Bar}, \seep{Bar3D}
\end{procedure}
\begin{function}{RegisterBGIDriver}
\Declaration
Function RegisterBGIDriver (Driver : Pointer) : Integer;

\Description
Registers a user-defined BGI driver
\Errors
None.
\SeeAlso
\seef{InstallUserDriver},
\seef{RegisterBGIFont}
\end{function}
\begin{function}{RegisterBGIFont}
\Declaration
Function RegisterBGIFont (Font : Pointer) : Integer;

\Description
Registers a user-defined BGI driver
\Errors
None.
\SeeAlso
\seef{InstallUserFont},
\seef{RegisterBGIDriver}
\end{function}
\begin{procedure}{RestoreCRTMode}
\Declaration
Procedure RestoreCRTMode ;

\Description
Restores the screen modus which was active before
the graphical modus was started.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{procedure}
\begin{procedure}{Sector}
\Declaration
Procedure Sector (X,Y : Integer; \\ Start,Stop,XRadius,YRadius : Word);

\Description
\var{Sector}
draws and fills a sector of an ellipse  with center \var{(X,Y)} and radii 
\var{XRadius} and \var{YRadius}, starting at angle \var{Start} and ending at angle \var{Stop}.
\Errors
None.
\SeeAlso
\seep{Arc}, \seep{Circle}, \seep{PieSlice}
\end{procedure}
\begin{procedure}{SetActivePage}
\Declaration
Procedure SetActivePage (Page : Word);

\Description
Sets \var{Page} as the active page 
for all graphical output.
\Errors
None.
\SeeAlso

\end{procedure}
\begin{procedure}{SetAllPallette}
\Declaration
Procedure SetAllPallette (Var Palette);

\Description
Sets the current palette to
\var{Palette}. \var{Palette} is an untyped variable, usually pointing to a
record of type \var{PaletteType}
\Errors
None.
\SeeAlso
\seep{GetPalette}
\end{procedure}
\begin{procedure}{SetAspectRatio}
\Declaration
Procedure SetAspectRatio (Xasp,Yasp : Word);

\Description
Sets the aspect ratio of the
current screen to \var{Xasp/Yasp}.
\Errors
None
\SeeAlso
\seep{InitGraph}, \seep{GetAspectRatio}
\end{procedure}
\begin{procedure}{SetBkColor}
\Declaration
Procedure SetBkColor (Color : Word);

\Description
Sets the background color to
\var{Color}.
\Errors
None.
\SeeAlso
\seef{GetBkColor}, \seep{SetColor}
\end{procedure}
\begin{procedure}{SetColor}
\Declaration
Procedure SetColor (Color : Word);

\Description
Sets the foreground color to
\var{Color}.
\Errors
None.
\SeeAlso
\seef{GetColor}, \seep{SetBkColor}
\end{procedure}
\begin{procedure}{SetFillPattern}
\Declaration
Procedure SetFillPattern (FillPattern : FillPatternType,\\ Color : Word);

\Description
\var{SetFillPattern} sets the current fill-pattern to \var{FillPattern}, and
the filling color to \var{Color}
The pattern is an 8x8 raster, corresponding to the 64 bits in
\var{FillPattern}.
\Errors
None
\SeeAlso
\seep{GetFillPattern}, \seep{SetFillStyle}
\end{procedure}
\begin{procedure}{SetFillStyle}
\Declaration
Procedure SetFillStyle (Pattern,Color : word);

\Description
\var{SetFillStyle} sets the filling pattern and color to one of the
predefined filling patterns. \var{Pattern} can be one of the following predefined
constants :
\begin{itemize}
\item \var{EmptyFill  } Uses backgroundcolor.
\item \var{SolidFill  } Uses filling color
\item \var{LineFill   } Fills with horizontal lines.
\item \var{ltSlashFill} Fills with lines from left-under to top-right.
\item \var{SlashFill  } Idem as previous, thick lines.
\item \var{BkSlashFill} Fills with thick lines from left-Top to bottom-right.
\item \var{LtBkSlashFill} Idem as previous, normal lines.
\item \var{HatchFill}  Fills with a hatch-like pattern.
\item \var{XHatchFill} Fills with a hatch pattern, rotated 45 degrees.
\item \var{InterLeaveFill} 
\item \var{WideDotFill} Fills with dots, wide spacing.
\item \var{CloseDotFill} Fills with dots, narrow spacing.
\item \var{UserFill} Fills with a user-defined pattern.
\end{itemize}

\Errors
None.
\SeeAlso
\seep{SetFillPattern}
\end{procedure}
\begin{procedure}{SetGraphBufSize}
\Declaration
Procedure SetGraphBufSize (BufSize : Word);

\Description
\var{SetGraphBufSize} 
sets the graphical buffer size. The default size is 4Kb
\Errors
None.
\SeeAlso

\end{procedure}
\begin{procedure}{SetGraphMode}
\Declaration
Procedure SetGraphMode (Mode : Integer);

\Description
\var{SetGraphMode} sets the
graphical mode and clears the screen.
\Errors
None.
\SeeAlso
\seep{InitGraph}
\end{procedure}
\begin{procedure}{SetLineStyle}
\Declaration
Procedure SetLineStyle (LineStyle,Pattern,Width :
Word);

\Description
\var{SetLineStyle}
sets the drawing style for lines. You can specify a \var{LineStyle} which is
one of the following pre-defined constants:
\begin{itemize}
\item \var{Solidln=0;} draws a solid line.
\item \var{Dottedln=1;} Draws a dotted line.
\item \var{Centerln=2;} draws a non-broken centered line.
\item \var{Dashedln=3;} draws a dashed line.
\item \var{UserBitln=4;} Draws a User-defined bit pattern.
\end{itemize}
If \var{UserBitln} is specified then \var{Pattern} contains the bit pattern.
In all another cases, \var{Pattern} is ignored. The parameter \var{Width} 
indicates how thick the line should be. You can specify one of the following
pre-defined constants:
\begin{itemize}
\item \var{NormWidth=1}
\item \var{ThickWidth=3}
\end{itemize}

\Errors
None.
\SeeAlso
\seep{GetLineSettings}
\end{procedure}
\begin{procedure}{SetPalette}
\Declaration
Procedure SetPalette (ColorNr : Word; NewColor : ShortInt);

\Description
\var{SetPalette} changes the \var{ColorNr}-th entry in the palette to
\var{NewColor}
\Errors
None.
\SeeAlso
\seep{SetAllPallette},\seep{SetRGBPalette}
\end{procedure}
\begin{procedure}{SetRGBPalette}
\Declaration
Procedure SetRGBPalette (ColorNr,Red,Green,Blue : Integer);

\Description
\var{SetRGBPalette} sets the \var{ColorNr}-th entry in the palette to the
color with RGB-values \var{Red, Green Blue}.
\Errors
None.
\SeeAlso
\seep{SetAllPallette},
\seep{SetPalette}
\end{procedure}
\begin{procedure}{SetTextJustify}
\Declaration
Procedure SetTextJustify (Horizontal,Vertical : Word);

\Description
\var{SetTextJustify} controls the placement of new text, relative to the 
(graphical) cursor position. \var{Horizontal} controls horizontal placement, and can be
one of the following pre-defined constants:
\begin{itemize}
\item \var{LeftText=0;} Text is set left of the pointer.
\item \var{CenterText=1;} Text is set centered horizontally on the pointer.
\item \var{RightText=2;} Text is set to the right of the pointer.
\end{itemize}
\var{Vertical} controls the vertical placement of the text, relative to the
(graphical) cursor position. Its value can be one of the following
pre-defined constants :
\begin{itemize}
\item \var{BottomText=0;} Text is placed under the pointer.
\item \var{CenterText=1;} Text is placed centered vertically on the pointer.
\item \var{TopText=2;}Text is placed above the pointer.
\end{itemize}

\Errors
None.
\SeeAlso
\seep{OutText}, \seep{OutTextXY}
\end{procedure}
\begin{procedure}{SetTextStyle}
\Declaration
Procedure SetTextStyle (Font,Direction,Magnitude : Word);

\Description
\var{SetTextStyle} controls the style of text to be put on the screen.
pre-defined constants for \var{Font} are:
\begin{itemize}
\item \var{DefaultFont=0;}
\item \var{TriplexFont=2;}
\item \var{SmallFont=2;}
\item \var{SansSerifFont=3;}
\item \var{GothicFont=4;}
\end{itemize}
Pre-defined constants for \var{Direction} are :
\begin{itemize}
\item \var{HorizDir=0;}
\item \var{VertDir=1;}
\end{itemize}
\Errors
None.
\SeeAlso
\seep{GetTextSettings} 
\end{procedure}
\begin{procedure}{SetUserCharSize}
\Declaration
Procedure SetUserCharSize (Xasp1,Xasp2,Yasp1,Yasp2 : Word);

\Description
Sets the width and height of vector-fonts. The horizontal size is given
by \var{Xasp1/Xasp2}, and the vertical size by \var{Yasp1/Yasp2}.
\Errors
None.
\SeeAlso
\seep{SetTextStyle}
\end{procedure}
\begin{procedure}{SetViewPort}
\Declaration
Procedure SetViewPort (X1,Y1,X2,Y2 : Integer; Clip : Boolean);

\Description
Sets the current graphical view-port (window) to the rectangle defined by
the top-left corner \var{(X1,Y1)} and the bottom-right corner \var{(X2,Y2)}.
If \var{Clip} is true, anything drawn outside the view-port (window) will be
clipped (i.e. not drawn). Coordinates specified after this call are relative
to the top-left corner of the view-port.
\Errors
None.
\SeeAlso
\seep{GetViewSettings}
\end{procedure}
\begin{procedure}{SetVisualPage}
\Declaration
Procedure SetVisualPage (Page : Word);

\Description
\var{SetVisualPage} sets the video page to page number \var{Page}. 
\Errors
None
\SeeAlso
\seep{SetActivePage}
\end{procedure}
\begin{procedure}{SetWriteMode}
\Declaration
Procedure SetWriteMode (Mode : Integer);

\Description
\var{SetWriteMode} controls the drawing of lines on the screen. It controls
the binary operation used when drawing lines on the screen. \var{Mode} can
be one of the following pre-defined constants:
\begin{itemize}
\item CopyPut=0;
\item XORPut=1;
\end{itemize}
\Errors
None.
\SeeAlso

\end{procedure}
\begin{function}{TextHeight}
\Declaration
Function TextHeight (S : String) : Word;

\Description
\var{TextHeight} returns the height (in pixels) of the string \var{S} in
the current font and text-size.

\Errors
None.
\SeeAlso
\seef{TextWidth}
\end{function}
\begin{function}{TextWidth}
\Declaration
Function TextWidth (S : String) : Word;

\Description
\var{TextHeight} returns the width (in pixels) of the string \var{S} in
the current font and text-size.

\Errors
None.
\SeeAlso
\seef{TextHeight}
\end{function}

% Target specific issues.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Target specific issues}                                                                                                                                                                                                                                                               
In what follows we describe some things that are different on the various
platforms:

\subsection{\dos}
\subsection{\windows}
\subsection{\linux}