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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, under \dos.
The unit was first written for \dos by Florian kl\"ampfl. 

This chapter is divided in three 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.
\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}
\procedure{Arc}{(X,Y : Integer; start,stop, radius : Word)}
{ \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.}{None.}{\seep{Circle},\seep{Ellipse} 
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}}

\procedure{Bar}{(X1,Y1,X2,Y2 : Integer)}
{Draws a rectangle with corners at \var{(X1,Y1)} and \var{(X2,Y2)} 
and fills it with the current color and fill-style.}{None.}{\seep{Bar3D}, 
\seep{Rectangle}}

\procedure{Bar3D}{(X1,Y1,X2,Y2 : Integer; depth : Word; Top : Boolean)}
{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.}
{None.}{\seep{Bar}, \seep{Rectangle}}

\procedure{Circle}{(X,Y : Integer; Radius : Word)}
{ \var{Circle} draws part of a circle with center at \var{(X,Y)}, radius
\var{radius}.}{None.}{\seep{Ellipse},\seep{Arc}
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}}

\procedure{ClearDevice}{}{Clears the graphical screen (with the current
background color), and sets the pointer at \var{(0,0)}}{None.}
{\seep{ClearViewPort}, \seep{SetBkColor}}

\procedure{ClearViewPort}{}
{Clears the current view-port. The current background color is used as filling
color. The pointer is set at
\var{(0,0)}}{None.}{\seep{ClearDevice},\seep{SetViewPort}, \seep{SetBkColor}}

\procedure{CloseGraph}{}{Closes the graphical system, and restores the
screen modus which was active before the graphical modus was
activated.}{None.}{\seep{InitGraph}}

\procedure{DetectGraph}{(Var Driver, Modus : Integer)}
{ 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.}
{None.}{\seep{InitGraph}}

\procedure{DrawPoly}{(NumberOfPoints : Word; Var PolyPoints}{
Draws a polygone with \var{NumberOfPoints} corner points, using the
current color and line-style. PolyPoints is an array of type \var{PointType}.
}{None.}{\seep{Bar}, seep{Bar3D}, \seep{Rectangle}}

\procedure{Ellipse}{(X,Y : Integer; Start,Stop,XRadius,YRadius : Word)}
{ \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.}
{None.}{\seep{Arc} \seep{Circle}, \seep{FillEllipse}}

\procedure{FillEllipse}{(X,Y : Integer; Xradius,YRadius: Word)}
{ \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.}
{None.}{\seep{Arc} \seep{Circle},
\seep{GetArcCoords},\seep{PieSlice}, \seep{Sector}}

\procedure{FillPoly}{(NumberOfPoints : Word; Var PolyPoints)}{
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}.
}{None.}{\seep{Bar}, seep{Bar3D}, \seep{Rectangle}}

\procedure{FloodFill}{(X,Y : Integer; BorderColor : Word)}{
Fills the area containing the point \var{(X,Y)}, bounded by the color
\var{BorderColor}.}{None}{\seep{SetColor}, \seep{SetBkColor}}

\procedure{GetArcCoords}{(Var ArcCoords : ArcCoordsType)}
{\var{GetArcCoords} returns the coordinates of the latest \var{Arc} or
\var{Ellipse} call.}
{None.}{\seep{Arc}, \seep{Ellipse}}

\procedure{GetAspectRatio}{(Var Xasp,Yasp : Word)}
{\var{GetAspectRatio} determines the effective resolution of the screen. The aspect ration can
the be calculated as \var{Xasp/Yasp}.}{None.}{\seep{InitGraph},\seep{SetAspectRatio}}

\Function{GetBkColor}{Word}{\var{GetBkColor} returns the current background color (the palette
entry).}{None.}{\seef{GetColor},\seep{SetBkColor}}

\Function{GetColor}{Word}{\var{GetColor} returns the current drawing color (the palette
entry).}{None.}{\seef{GetColor},\seep{SetBkColor}}

\procedure {GetDefaultPalette}{(Var Palette : PaletteType)}{Returns the
current palette in \var{Palette}.}{None.}{\seef{GetColor}, \seef{GetBkColor}}

\Function{GetDriverName}{String}{\var{GetDriverName} returns a string containing the name of the
current driver.}{None.}{\seef{GetModeName}, \seep{InitGraph}}

\procedure{GetFillPattern}{(Var FillPattern : FillPatternType)}
{\var{GetFillPattern} returns an array with the current fill-pattern  in \var{FillPattern}}
{None}{\seep{SetFillPattern}}

\procedure{GetFillSettings}{(Var FillInfo : FillSettingsType)}
{\var{GetFillSettings} returns the current fill-settings in
\var{FillInfo}}{None.}{\seep{SetFillPattern}}

\Function{GetGraphMode}{Integer}{\var{GetGraphMode} returns the current graphical modus}
{None.}{\seep{InitGraph}}

\procedure{GetImage}{(X1,Y1,X2,Y2 : Integer, Var Bitmap}{\var{GetImage}
Places a copy of the screen area \var{(X1,Y1)} to \var{X2,Y2} in \var{BitMap}}
{Bitmap must have enough room to contain the image.}{\seef{ImageSize},
\seep{PutImage}}

\procedure{GetLineSettings}{(Var LineInfo : LineSettingsType)}
{\var{GetLineSettings} returns the current Line settings in
\var{LineInfo}}{None.}{\seep{SetLineStyle}}

\Function{GetMaxColor}{Word}{\var{GetMaxColor} returns the maximum
color-number which can be set with \var{SetColor}}{None.}{\seep{SetColor},
\seef{GetPaletteSize}}

\Function{GetMaxMode}{Word}{\var{GetMaxMode} returns the highest modus for
the current driver.}{None.}{\seep{InitGraph}}

\Function{GetMaxX}{Word}{\var{GetMaxX} returns the maximum horizontal screen
length}{None.}{\seef{GetMaxY}}

\Function{GetMaxY}{Word}{\var{GetMaxY} returns the maximum number of screen
lines}{None.}{\seef{GetMaxY}}

\function{GetModeName}{(Var modus : Integer)}{String}{
Returns a string with the name of modus
\var{Modus}}{None.}{\seef{GetDriverName}, \seep{InitGraph}}

\procedure{GetModeRange}{(Driver : Integer; \\ LoModus, HiModus: Integer)}
{\var{GetModeRange} returns the Lowest and Highest modus of the currently
installed driver.}{None.}{\seep{InitGraph}}

\procedure{GetPalette}{(Var Palette : PaletteType)}
{\var{GetPalette} returns in \var{Palette} the current palette.}
{None.}{\seef{GetPaletteSize}, \seep{SetPalette}}

\Function{GetPaletteSize}{Word}{\var{GetPaletteSize} returns the maximum
number of entries in the current palette.}{None.}{\seep{GetPalette},
\seep{SetPalette}}

\function{GetPixel}{(X,Y : Integer)}{Word}{\var{GetPixel} returns the color
of the point at \var{(X,Y)} }{None.}{}

\procedure{GetTextSettings}{(Var TextInfo : TextSettingsType)}
{\var{GetTextSettings} returns the current text style settings : The font,
direction, size and placement as set with \var{SetTextStyle} and
\var{SetTextJustify}}{None.}{\seep{SetTextStyle}, \seep{SetTextJustify}}

\procedure{GetViewSettings}{(Var ViewPort : ViewPortType)}
{\var{GetViewSettings} returns the current view-port and clipping settings in
\var{ViewPort}.}{None.}{\seep{SetViewPort}}

\Function{GetX}{Integer}{\var{GetX} returns the X-coordinate of the current position of
the graphical pointer}{None.}{\seef{GetY}}

\Function{GetY}{Integer}{\var{GetY} returns the Y-coordinate of the current position of
the graphical pointer}{None.}{\seef{GetX}}

\Procedure{GraphDefaults}{\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.}{None.}{\seep{SetViewPort}, \seep{SetFillStyle}, \seep{SetColor},
\seep{SetBkColor}, \seep{SetLineStyle}}

\function{GraphErrorMsg}{(ErrorCode : Integer)}{String}{\var{GraphErrorMsg}
returns a string describing the error \var{Errorcode}. This string can be
used to let the user know what went wrong.}{None.}{\seef{GraphResult}}

\Function{GraphResult}{Integer}{\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}
}{None.}{\seef{GraphErrorMsg}}

\function{ImageSize}{(X1,Y1,X2,Y2 : Integer)}{Word}{\var{ImageSize} returns
the number of bytes needed to store the image in the rectangle defined by
\var{(X1,Y1)} and \var{(X2,Y2)}.}{None.}{\seep{GetImage}}

\procedure{InitGraph}{(var GraphDriver,GraphModus : integer;\\
const PathToDriver : string)}{
\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.}{None.}{Introduction, (page \pageref{se:Introduction}),
\seep{DetectGraph}, \seep{CloseGraph}, \seef{GraphResult}}

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}

\function{InstallUserDriver}{(DriverPath : String; \\AutoDetectPtr: Pointer)}
{Integer}{\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.}
{None.}{\seep{InitGraph}, \seef{InstallUserFont}}

\function{InstallUserFont}{(FontPath : String)}{Integer}
{\var{InstallUserFont} adds the font in \var{FontPath} to the list of fonts
of the .BGI system.}
{None.}{\seep{InitGraph}, \seef{InstallUserDriver}}

\procedure{Line}{(X1,Y1,X2,Y2 : Integer)}{\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)}}{None.}
{\seep{LineRel},\seep{LineTo}}

\procedure{LineRel}{(DX,DY : Integer)}{\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.}{None.}
{\seep{Line}, \seep{LineTo}}

\procedure{LineTo}{(DX,DY : Integer)}{\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.}{None.}
{\seep{LineRel},\seep{Line}}

\procedure{MoveRel}{(DX,DY : Integer}{\var{MoveRel} moves the pointer to the
point \var{(DX,DY)}, relative to the current pointer
position}{None.}{\seep{MoveTo}}

\procedure{MoveTo}{(X,Y : Integer}{\var{MoveTo} moves the pointer to the
point \var{(X,Y)}.}{None.}{\seep{MoveRel}}

\procedure{OutText}{(Const TextString : String)}
{\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.}
{None.}{\seep{OutTextXY}}

\procedure{OutTextXY}{(X,Y : Integer; Const TextString : String)}
{\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.}
{None.}{\seep{OutText}}

\procedure{PieSlice}{(X,Y : Integer; \\ Start,Stop,Radius : Word)}{\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}.}
{None.}{\seep{Arc}, \seep{Circle}, \seep{Sector}}

\procedure{PutImage}{(X1,Y1 : Integer; Var Bitmap; How : word) }{\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}}
{None}{\seef{ImageSize},\seep{GetImage}}

\procedure{PutPixel}{(X,Y : Integer; Color : Word)}{Puts a point at
\var{(X,Y)} using color \var{Color}}{None.}{\seef{GetPixel}}

\procedure{Rectangle}{(X1,Y1,X2,Y2 : Integer)}{Draws a rectangle with
corners at \var{(X1,Y1)} and \var{(X2,Y2)}, using the current color and
style.}{None.}{\seep{Bar}, \seep{Bar3D}}

\function{RegisterBGIDriver}{(Driver : Pointer)}{Integer}
{Registers a user-defined BGI driver}{None.}{\seef{InstallUserDriver},
\seef{RegisterBGIFont}}

\function{RegisterBGIFont}{(Font : Pointer)}{Integer}
{Registers a user-defined BGI driver}{None.}{\seef{InstallUserFont},
\seef{RegisterBGIDriver}}

\Procedure{RestoreCRTMode}{Restores the screen modus which was active before
the graphical modus was started.}{None.}{\seep{InitGraph}}

\procedure{Sector}{(X,Y : Integer; \\ Start,Stop,XRadius,YRadius : Word)}{\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}.}
{None.}{\seep{Arc}, \seep{Circle}, \seep{PieSlice}}

\procedure{SetActivePage}{(Page : Word)}{Sets \var{Page} as the active page 
for all graphical output.}{None.}{}

\procedure{SetAllPallette}{(Var Palette)}{Sets the current palette to
\var{Palette}. \var{Palette} is an untyped variable, usually pointing to a
record of type \var{PaletteType}}{None.}{\seep{GetPalette}}

\procedure{SetAspectRatio}{(Xasp,Yasp : Word)}{Sets the aspect ratio of the
current screen to \var{Xasp/Yasp}.}
{None}{\seep{InitGraph}, \seep{GetAspectRatio}}

\procedure{SetBkColor}{(Color : Word)}{Sets the background color to
\var{Color}.}{None.}{\seef{GetBkColor}, \seep{SetColor}}

\procedure{SetColor}{(Color : Word)}{Sets the foreground color to
\var{Color}.}{None.}{\seef{GetColor}, \seep{SetBkColor}}

\procedure{SetFillPattern}{(FillPattern : FillPatternType,\\ Color : Word)}
{\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}.}{None}{\seep{GetFillPattern}, \seep{SetFillStyle}}

\procedure{SetFillStyle}{(Pattern,Color : word)}
{\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}
}{None.}{\seep{SetFillPattern}}

\procedure{SetGraphBufSize}{(BufSize : Word)}{\var{SetGraphBufSize} 
sets the graphical buffer size. The default size is 4Kb}{None.}{}

\procedure{SetGraphMode}{(Mode : Integer)}{\var{SetGraphMode} sets the
graphical mode and clears the screen.}{None.}{\seep{InitGraph}}

\procedure{SetLineStyle}{(LineStyle,Pattern,Width :
Word)}{\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}
}{None.}{\seep{GetLineSettings}}

\procedure{SetPalette}{(ColorNr : Word; NewColor : ShortInt)}
{\var{SetPalette} changes the \var{ColorNr}-th entry in the palette to
\var{NewColor}}{None.}{\seep{SetAllPallette},\seep{SetRGBPalette}}

\procedure{SetRGBPalette}{(ColorNr,Red,Green,Blue : Integer)}
{\var{SetRGBPalette} sets the \var{ColorNr}-th entry in the palette to the
color with RGB-values \var{Red, Green Blue}.}{None.}{\seep{SetAllPallette},
\seep{SetPalette}}

\procedure{SetTextJustify}{(Horizontal,Vertical : Word)}
{\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}
}{None.}{\seep{OutText}, \seep{OutTextXY}}

\procedure{SetTextStyle}{(Font,Direction,Magnitude : Word)}
{\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}}{None.}{\seep{GetTextSettings}} 

\procedure{SetUserCharSize}{(Xasp1,Xasp2,Yasp1,Yasp2 : Word)}
{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}.}{None.}
{\seep{SetTextStyle}}

\procedure{SetViewPort}{(X1,Y1,X2,Y2 : Integer; Clip : Boolean)}
{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.}{None.}{\seep{GetViewSettings}}

\procedure{SetVisualPage}{(Page : Word)}
{\var{SetVisualPage} sets the video page to page number \var{Page}. }
{None}{\seep{SetActivePage}}

\procedure{SetWriteMode}{(Mode : Integer)}
{\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}}{None.}{}

\function{TextHeight}{(S : String)}{Word}
{\var{TextHeight} returns the height (in pixels) of the string \var{S} in
the current font and text-size.
}{None.}{\seef{TextWidth}}

\function{TextWidth}{(S : String)}{Word}
{\var{TextHeight} returns the width (in pixels) of the string \var{S} in
the current font and text-size.
}{None.}{\seef{TextHeight}}