CURRAN@rcgl1.eng.ohio-state.edu (Curran, Jim) (06/27/89)
Hello, I was wondering if the 32-Bit QD extensions allow me to copy a 24-bit planar image (8 bits of red, 8 bits of blue, 8 bits of green) into an 8 bit pixmap using the CopyBits call. Is there a Tech Note which describes the new Color QuickDraw. Thanks in advance. Jim
oster@dewey.soe.berkeley.edu (David Phillip Oster) (06/28/89)
In article <2497@quanta.eng.ohio-state.edu> CURRAN@rcgl1.eng.ohio-state.edu (Curran, Jim) writes: > I was wondering if the 32-Bit QD extensions allow me to copy >a 24-bit planar image (8 bits of red, 8 bits of blue, 8 bits of green) >into an 8 bit pixmap using the CopyBits call. 1.) you can't get a 24-bit planar image (8 red, 8 green, 8 blue) you must use 32-bits per pixel to hold 24-bit data. (although, there is a new PICT opCode that suppresses the extra byte.) 2.) there is a new CopyBits() transfer mode that, if the destination is thinner than the source, CopyBits() uses dithering to approximate the colors. The dithering algorithm is vaguely similar to Floyd-Steinberg, but it only pushes error terms along the scan-line for speed. This works, even if the destination is an SE/30, so you can at least do someting with color picts on a black & white mac. All in all, it is pretty neat.
andyi@mmm.UUCP (Andy Ihlenfeldt) (06/29/89)
> I was wondering if the 32-Bit QD extensions allow me to copy >a 24-bit planar image (8 bits of red, 8 bits of blue, 8 bits of green) >into an 8 bit pixmap using the CopyBits call. Is there a Tech Note which >describes the new Color QuickDraw. Thanks in advance. Jim - I believe the answer to your question about CopyBits is YES. We created an offscreen 32-bit Pixel Map and then used CopyBits to copy to a window on the MacII monitor which has an 8 bit Pixel Map. There are a couple of "confidential drafts" of tech notes that we somehow got a hold of (don't ask me, I don't know) that describe 32 bit QD and off-screen support. We have problems ourselves though. We have trouble create on-screen 32 bit windows and draw directly into them. Seems strange. We're looking for more leadership from Apple on this one. Jill Sicora c/o Andy Ihlenfeldt andyi@mmm.uucp (612) 736-7143