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Subject:
Scrolling
From: "Frank W. Miller" ####@####.#### Date: 6 Oct 1999 01:32:57 -0000 Message-Id: <199910060117.VAA25495@macalpine.cornfed.com> Just one more item before I release my 16-color bare hardware VGA driver. I wonder if anyone has done fast scrolling. Right now, I'm redrawing from the text buffer but that isnt going to make it. Would a scanline read followed by a scanline write be faster? Later, FM -- Frank W. Miller Cornfed Systems Inc www.cornfed.com | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subject:
RE: Scrolling
From: Greg Haerr ####@####.#### Date: 6 Oct 1999 16:12:07 -0000 Message-Id: <01BF0FE2.F0DF8830.greg@censoft.com> : Just one more item before I release my 16-color bare hardware VGA driver. : I wonder if anyone has done fast scrolling. Right now, I'm redrawing : from the text buffer but that isnt going to make it. Would a scanline : read followed by a scanline write be faster? Frank - there are two ways this could be done. The best way is that we need bitblt, something I'm planning on adding soon, but I want to use it in conjunction with off screen drawing capabilities, so it's an architecture change. The other issue is that currently the text draw routine checks each and every pixel for clipping before output. There is a piece of commented out code that I've left for a fast driver entry point to output text without clipping, when the mid level can allow it. This is in GdText. So another answer is to (almost) duplicate the GdText code in a new driver entry point for fast text drawing, called when clipping is not needed. I can do all this for you if you like, go ahead and release your driver, and I'll take a look at it. Greg | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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