Extremely confused, GWorlds and CopyBits
Extremely confused, GWorlds and CopyBits
- Subject: Extremely confused, GWorlds and CopyBits
- From: Sailor Quasar <email@hidden>
- Date: Sun, 11 Jan 2004 11:23:45 -0500
I apologize profusely for the cross-post, but while this problem
involves a NSQuickDrawView, I expect my issue is in NewGWorldFormPtr()
somewhere, so I'm not entirely sure which list is appropriate between
Carbon and Cocoa. Please reply to only one list.
I have an NSQuickDrawView with a set size of 1024x768, inside an
NSScrollView (and hence an NSClipView too, of course). In my concrete
subclass, I set up two GWorlds for backing stores (yes, I'm aware of
double-buffering etc.; my drawing algorithms require extra backing
stores for now). These are based on memory buffers that I allocate
myself like so:
backingPtr = (char *)calloc(1024 * 768, 3);
backingPtr2 = (char *)calloc(1024 * 768, 3);
I then call NewGWorldFromPtr():
SetRect(&r, 0, 0, 1023, 767);
NewGWorldFromPtr(&backingStore, k24RGBPixelFormat, &r, NULL, NULL, 0,
backingPtr, 1024 * 3);
NewGWorldFromPtr(&backingStore2, k24RGBPixelFormat, &r, NULL, NULL, 0,
backingPtr2, 1024 * 3);
From here on, very strange things indeed go on. If I stick with
NewGWorldFromPtr(), any drawing I do gets mirrored approx. 512 pixels
to the right and exactly one pixel up from the original drawing, to the
point of wrapping around a second time if the original picture gets too
wide. If I switch to QTNewGWorldFromPtr(), my CopyBits() which draws
the backing store into the view immediately crashes (badly enough that
gdb gets an internal error and SIGABRTs in PB), unless I double the
amount of memory allocated for the buffers of the gworlds, in which
case my code acts as if the view is something around half its original
_height_. This is the CopyBits() call:
SetRect(&r, 0, 0, 1023, 767);
CopyBits(GetPortBitMapForCopyBits((CGrafPtr)backingStore2),
GetPortBitMapForCopyBits((CGrafPtr)[self qdPort]),
&r, &r,
srcCopy, NULL);
(where, for the Carbon people, [self qdPort] gives me access to the
window's CGrafPtr with an origin relative to the upper left of my view)
It's reasonably obvious that I've got a rowBytes issue or something,
but for the life of me I can not figure out what the heck it is. 24-bit
RGB should yield 3 bytes per pixel, times the width of the image, hence
1024 * 3. Someone please point out to me whatever my glaringly obvious
error is.
-- Sailor Quasar, guardian of Leraz's memory
"A face of stone may hide a soul with the deepest Love of all"
Email: email@hidden
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