[Xquartz-dev] Porting XCopyArea to plain OS X
pfomichev at elverils.com
Tue May 12 13:31:58 PDT 2009
Dear List members
I've been looking inside the XScreenSaver package to understand some
specifics about X11 stuff and I stumbled upon pretty big performance
problem in port where the author himself acknowledges he is currently
unaware what to do. The author replaced XCopyArea with something like
If source is 'WINDOW'
// get the bits (desired sub-rectangle) out of the NSView via
NSBitmapImageRep *bm = [NSBitmapImageRep alloc];
unsigned char *data = [bm bitmapData];
int bps = [bm bitsPerSample];
int bpp = [bm bitsPerPixel];
int bpl = [bm bytesPerRow];
releaseme = bm;
CGDataProviderCreateWithData(.. data .. )
It's quite an overkill - check http://jwz.livejournal.com/628118.html
for more information.
So the question is - what to do in order to move bits faster in
window backing store or whatever i.e. get as close to the real buffer
as possible. Lots of stuff hint as libXPlugin as a source of
'acceleration' for X Server. Is there any way to get a public API for
it as well as documentation. May be there is some info on
CGBlt_copyBytes function in CoreGraphics as well?
I am also quite at a loss - I looked at SDL code - they use QuickDraw
to get access to video buffer content, yet QuickDraw is deprecated..
So what's the fastest possible memory to draw to window, access and
modify it's internal backing store?
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