Keith Packard <[EMAIL PROTECTED]> wrote: > I think the interfaces currently provided by XAA will probably remain > usable, so you might as well implement them.
Ok. > Plus, we should have XAA expose special higher level functions for > glyph rendering to the driver so that the graphics card can use the > higher level data structures to speed this operation, rather than > having the MI layer break the text operation into a (long) sequence > of primitive Composite operations. Yes, most definitely. The current mechanism is not exactly efficient, and in fact is the reason why I want to hook some functions at a higher level so we can make this faster. Also when it comes to rendering text, one of the fastest ways of doing this is the way that OS/2 does it. Instead of caching any glyphs in offscreen video memory (terribly wasteful of offscreen video memory and no faster than using system memory bitmaps), you maintain a single large bitmap that matches the physical resolution of the screen (ie: 1280x1024 mono bitmap). When you need to draw text, you render the text into the mono bitmap in software at the necessary place on the screen, and when that is done pass the entire bitmap to be drawn to the hardware with a clip rectangle that covers just the text you just rendered into the bitmap. The clipping is real easy to do in the software setup stages for text rendering, and then you can blit the entire string to the hardware in one shot. So fast, efficient text could be done in XFree86 if a single function was used to transfer an entire bitmap in the driver code (pre-clipping could easily be done before the driver code is called), and some high level code to maintain and render the glyphs into the pre-allocated large bitmap. > > Also I have been wondering about the accelerated anti-aliased text. Is > > all anti-aliased text in XFree86 done via the XRENDER extension and alpha > > blits? It is possible to implement accelerated anti-aliased text using > > simple 4-8 levels of mono bitmap blits using FreeType (that is what we > > used for it in our MGL graphics library). > > Yes, all AA text is done with the Render glyph operations which > are defined in terms of the basic image composition primitive. > Once you have hardware acceleration for image compositing, that's > going to be a lot faster than any non-standard rendering path. Granted, if you have hardware alpha blits that will be the fastest way to do this. But if you don't have hardware alpha blits (and lots of cards supported by XFree86 do not), you can still speed up anti-aliased text quite a lot by using a 4 or 8 level scheme using multiple mono bitmaps. 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
