Re: CopyBits/QDFlush error

• Subject: Re: CopyBits/QDFlush error
• From: Steve Christensen <email@hidden>
• Date: Fri, 30 May 2003 14:51:14 -0700

I have been having a persistent problem with discrepancies between Quickdraw coordinates and direct-to-buffer coordinates. Does Quickdraw's origin start at 1,1 instead of 0,0 or something? To demonstrate the problem I wrote the following test code:

LockPortBits(ePort);
AAdestAddr = (unsigned char *)GetPixBaseAddr(GetPortPixMap(ePort));
AAdest_rowbytes = (unsigned long)GetPixRowBytes(GetPortPixMap(ePort));
UnlockPortBits(ePort);

// draw a small rectangle between 10,10 and 19,19
for (short y = 10; y < 20; y++) {
AAdestRowStart = (unsigned long *)(AAdestAddr + y*AAdest_rowbytes);
for (short x = 10; x < 20; x++)
*(AAdestRowStart+x) = 0xff000000; // draw a black square
}

// first just flush the whole buffer, to check
if (QDIsPortBuffered(ePort)) {
RgnHandle theRgn;
theRgn = NewRgn();
RectRgn(theRgn, &backRect);
QDSetDirtyRegion(ePort,theRgn);
QDFlushPortBuffer(ePort, theRgn);
DisposeRgn(theRgn);
}

// wait until user presses command key
while (!CheckKey(COMMAND_KEY));

for (short y = 10; y < 20; y++) {
AAdestRowStart = (unsigned long *)(AAdestAddr + y*AAdest_rowbytes);
for (short x = 10; x < 20; x++)
*(AAdestRowStart+x) = 0xffffffff; // now draw with white
}

Thanks very much to anyone who can answer this. It has been driving me crazy.

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