Date: Fri, 18 Jun 93 12:18:45 GMT
From: Joe Clark <joe AT ziggy DOT larc DOT nasa DOT gov>
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Save/Restore screen captures with LIBGRX


I have an application that currently works under TurboC and 
have been trying to port it to djgpp.  It's basically (right now)
for a pulldown menu that will read an initialization
file to change the items/options without recompiling.  In other
words, it involves a lot of graphics and mouse input. But I digress...

My question is I need to save the background before drawing a 
pulldown menu so that I can restore it when the pulldown menu
goes away.  I used getimage() and putimage() in TurboC and couldn't
figure out how to do it since the Libgrx documentation is a little
thin on the subject.  For example, my code looks something like:

draw_pulldown()
{
 ...

 <figure out which pulldown to draw>

 <determine the pulldown vertices - xleft, xright, ytop, ybottom>

 save_backgrnd(xleft, ytop, xright, ybottom);

 <drawing routines for pulldown>

 ...

}

// ...meanwhile, in another file
manage_mouse()
{
 ...

 <need exists to erase the pulldown menu and restore original background>

 restore_backgrnd();

 ...

}


The point being that the functions to save and restore the background
are seperate, and may be called at unpredicatable times from other
files.  The way I do this now is to make the area saved a global pointer.

Does anybody have a small code fragment that does something similar
to this in Libgrx that I can look at. I assume I need to use GrBitBlt().

Thanks,

-Joe


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* Joe Clark                     |  Internet : joe AT ziggy DOT larc DOT nasa DOT gov *
* NASA Langley Research Center  |                                     *
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