Mark Vojkovich <[EMAIL PROTECTED]> wrote: > > Yes, it does! Now that I am learning more about this I am happy to see > > that someone saw fit to make it so XAA drivers can hook stuff at many > > levels. Very cool. It should be better documented though ;-) > > I think there are very few reasons to hook stuff at higher levels. > I don't believe you have a reason to do so.
We do. We have our own device driver abstraction layer and using the low level XAA functions does not map at all well to our driver modle. Hence hooking at the next level up (MID) will allow us to avoid the overheads of translating between the low level XAA model and our driver model. > XAA's catch-all for non-AA text rendering renders each glyph > with WriteBitmap. If the driver didn't provide WriteBitmap, XAA > would provide one that used the driver's CPUToScreenColorExpansion > routines. Right, so we need to hook WriteBitmap to make things faster with our driver model since our driver model essentially implements a WriteBitmap style interface (not a line by line interface that the low level code uses). > If the conditions were appropriate XAA would pre-composite the > whole string and pass the result as a single bitmap. Definately a good performance optimisation. > I don't think you'll be able to write non-AA code that renders > quicker than XAA, but you'll certainly risk rendering it > incorrectly. Our benchmarks have already shown that our code is faster than the standard XAA functions. So if we hook out WriteBitmap it will be faster ;-) > XAA only provides two low-level Render-related primitives. The > "8 bit Alpha texture + color" and the "Generic color texture > composite" functions. It's difficult to abstract things much > beyond that since different graphics engines diverge quite a bit at > this level. XAA 3 (XFree86 5's XAA) doesn't even try. Yep, been there and looked at that. About the only thing conistent that you can handle without image re-packing is 32bit ARGB style alpha blits. Thanks for the info, it is highly appreciated! Regards, --- Kendall Bennett Chief Executive Officer SciTech Software, Inc. Phone: (530) 894 8400 http://www.scitechsoft.com ~ SciTech SNAP - The future of device driver technology! ~ _______________________________________________ Devel mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/devel
