Borland Graphics Interface
The Borland Graphics Interface is a graphics library used by DOS programs, which includes the ability to use loadable drivers. These drivers have the file extension .BGI.
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Identification
Files begin with 'P' 'K' 0x08 0x08 -- this is shared with the CHR font files used by BGI. The four-byte signature is followed by either 'BGI Device Driver' or 'SVGA 256 Colour BGI Device Driver'.
Main Entry
The first 160 bytes of the driver file are a header. This is followed by the driver code segment. Far calls will be made to this address with SI containing the function number to execute.
Bitmap images
BGI contains getimage() and putimage() functions to save and load images. The images thus saved have a 4-byte header (two little-endian words giving the image's width and height) followed by the image data, in a form specific to the driver used. A 16-colour VGA image will contain four monochrome bitmaps for the four planes. These images, with a .ICN extension, are used as icons by RIPscrip 1.x and Counterpoint.
Specifications
- ftp://ftp.musoftware.de/pub/uz/bgi/ contains documentation and source code for creating BGI drivers, along with several complete drivers.
