kam@dlogics.COM (Kevin Mitchell) (12/21/90)
Please help! When using Laserwriter 6.0, printing color pixmaps, I get wierd color changes. Some of my lightest colors have been painted with black on the printer output. Even worse, when the pixmap is next displayed on the screen, the colors have changed there, too! It turns out that the LaserWriter driver is replacing the first entry in my color table with white and the last entry with black. I found this by isolating the change in the color table to some point during the _Copybits call I make when writing to the printer's grafPort. Using StepSpy, I found that the change is made in the PDEF resource for the printer right before the part where it sends out the color values as hex data for the _colorimage_ PostScript call. Why does it do this? There is no reason for a pixmap to require black and white in the "friendly" positions except when it is part of a gDevice. There is even less reason for the LaserWriter driver to insert the black and white colors when it subsequently disassembles the pixmap without help from QuickDraw to obtain the color raster for the PostScript output. There is NO EXCUSE for a printer driver to modify part of a program's data structure without permission. (Who'd ever expect CopyBits to arbitrarily alter a pixmap's color table??!?) The pixmap and color table are of my own construction, and have worked properly on everything else except the LaserWriter driver, including display to the screen and third party color-compatible printer drivers. If anybody knows of a workaround, newer version of the LaserWriter driver that fixes this, a way of submitting this problem to Apple, etc., please let me know. Kevin Mitchell -- Kevin A. Mitchell (312) 266-4485 Datalogics, Inc Internet: kam@dlogics.UUCP 441 W. Huron UUCP: ..!uunet!dlogics!kam Chicago, IL 60610 FAX: (312) 266-4473