Mail Archives: djgpp/1998/01/06/06:22:50
On Tue, 6 Jan 1998, Anthony.Appleyard wrote:
> keep flashing in and out of view. How can I tell the PC's graphics card not to
> redisplay the screen while I am writing a display to it?
I don't think you can. The video circuitry is scanning the video ram
dedicated to the currently-displayed page at its own rate and displays
whatever it finds there. The only ways of preventing it which are known
to me are (1) to prepare the display on a different page, then flip pages
when it is ready; or (2) turn off the screen while you update it. The
second way will probably cause worse flickering than writing directly to
the screen without waiting.
Another technique is to wait for the retrace time (when the CRT beam
moves from the lower-right corner to the upper-left, for the next scan)
and only update them, since at that time, the display is automatically
turned off.
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