This graphics unit for Turbo Pascal 4.0 was written and placed in the public
domain by Anthony Li.


Using the GRAPHICS unit:
------------------------

Refer for the example file GRMAKE.PAS for instructions on creating the files
FONTS.TPU and DRIVERS.TPU.


The following constants are defined for greater clarity (in my opinion) than
TP's constants:


My name for it TP's name for it
-------------- ----------------
NoGraphicsError = grOk;
GeneralGraphicsError = grError;
GraphicsDriverNotInstalled = grNoInitGraph;
GraphicsAdaptorNotDetected = grNotDetected;
GraphicsDriverFileNotFound = grFileNotFound;
InvalidGraphicsDriver = grInvalidDriver;
NotEnoughMemoryForGraphics = grNoLoadMem;
NoMemoryForScanFill = grNoScanMem;
NoMemoryForFloodFill = grNoFloodMem;
GraphicsFontFileNotFound = grFontNotFound;
NotEnoughMemoryForFont = grNoFontMem;
InvalidGraphicsFontFile = grInvalidFont;
InvalidGraphicsFontNumber = grInvalidFontNum;
GraphicsModeIsInvalid = grInvalidMode;
GraphicsIOError = grIOError;
InvalidGraphicsDevice = grInvalidDeviceNum;

LeftJustify = 0;
CenterJustify = 1;
RightJustify = 2;
BottomJustify = 0;
TopJustify = 2;
HorizontalText = 0;
VerticalText = 1;
NormalSizeText = 1;
LargestSizeText = 10;


TYPE
TypeBitImage = RECORD (* Definition of bit Images - *)
ImagePtr : Pointer; (* The ones used by GetImage *)
SizeOfImage : WORD (* and PutImage. *)
END;


VAR
GraphicsAdaptor, (* These variables are updated as *)
GraphicsMode : INTEGER; (* the graphics environment is *)
LastGraphicsErrorCode : INTEGER; (* initialized and manipulated. *)

(*-------------------------------------------------------------------------*)
PROCEDURE EnterGraphicsMode ( GraphicsAdaptorToTry,
GraphicsModeToTry : INTEGER);

Attempts to use the graphics mode for the given graphics adaptor.
Check the variable LastGraphicsErrorCode to see if the attempt
was successful.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE ExitGraphicsMode;

Exits graphics mode and returns to text mode.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE SelectFont ( FontNumber,
Direction,
SizeFactor,
HorizontalJustification,
VerticalJustification : INTEGER);

Sets the current font for use with OutText, OutTextXY, etc.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE GetBitImage (VAR ImageHolder : TypeBitImage;
LeftColumn,
TopRow,
RightColumn,
BottomRow : INTEGER);

Gets a bit image from the screen. Works like TP's GetImage, but this
is easier to use.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE PutBitImage (VAR ImageToShow : TypeBitImage;
LeftColumn,
TopRow,
BitMask : INTEGER);

Writes a bit image onto the screen. Works like TP's PutImage.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE ReleaseBitImageMemory (VAR ImageToKill : TypeBitImage);

"Kills" a bit image, releasing the memory that it used.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE ResetBitImageFile (VAR BitImageFile : FILE;
Filename : STRING);

Opens a file for reading bit images.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE RewriteBitImageFile (VAR BitImageFile : FILE;
Filename : STRING);

Opens a file for writing bit images.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE WriteBitImageToFile (VAR TargetFile : FILE;
VAR ImageToWrite : TypeBitImage);

Writes a bit image to a bit image file that is already open.
(*-------------------------------------------------------------------------*)


(*-------------------------------------------------------------------------*)
PROCEDURE ReadBitImageFromFile (VAR SourceFile : FILE;
VAR ImageHolder : TypeBitImage);

Reads a bit image from an open bit image file to a bit image.
(*-------------------------------------------------------------------------*)