🚀 go-pugleaf

In article <JARI.KARJALA.91May27134636@superman.hut.fi>, Jari.Karjala@niksula.hut.fi writes:
|>
|>When I set the graphics mode through BGI's initgraph() function, I can
|>singlestep through the following code with Turbo Debugger and the
|>graphics/text screen is flipped correctly. But if I replace the
|>initgraph() with my own function to set the graphics mode (and don't
|>link with graphics.lib), TD no longer notices the mode change and
|>thinks it is still in text mode (and of course the result is not very
|
|>
|>The question is: what does initgraph do to tell TD that now we are
|>in graphics mode? Or is there some hidden function in the BGI library
|>which is used by the debugger?

As far as I know, most graphics libraries require a call to a function such
as initgraph() or OpenGraphics() or InitGraphics() or something like that since
graphics stuff is dependent on certain global variables.  My guess would be
that the BGI routines have global variables describing the current page,
current mode, type of video adapter, amount of memory, etc. and all of these
are determined via initgraph().  If you want to write your own graphics 
routines I would do it completely, rather than deal with trying to make your
library work with someone elses (conflicts will arise more than likely).

Brian

/*
Brian Hook -- MS-DOS Programmer for Contract
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