Re: Question with regards to componentAlpha

Around 15 o'clock on Sep 14, Thomas Roell wrote:

> Ah, that is true. Forgot about color index rendering. BTW, why did you
> decide to have the alpha channel of color index mode (PseudoColor) to
> be 0, while for example r5g6b5 has a alpha value of 1.0 ?

Indexed formats have an alpha value for each pixel; you'll see in the 
current render/miindex.c that the sample implementation sets alpha to 1 
for each pixel.

> Well we got here with "x11perf -aa10text" on a specifc platform 
> in SW mode around 60000 glyphs per second, while we got 2480000 glyphs
> per second in HW. The SW solution was barely usable for scrolling in a
> terminal. The fbpict.c code was rated at 41000 glyphs per seceond.

I think your definition of "barely usable" and other peoples aren't quite 
the same.  I've been using X for a while, and 40000 glyphs/sec provides 
adequate, if not blinding performance for daily work.  Certainly it would 
be nicer to have hardware acceleration for all operations, but when the 
necessary operation doesn't match the hardware, then it will go a lot 
slower.  Fortunately, CPUs are fast enough to provide a level of 
performance acceptable to most people.

Please feel free to propose an alternative which provides for per-component
rendering for text and graphics operations.

> For SW I agree. For HW you still owe me at least one example. My point
> of criticism here is really that we need to live with what we got in
> terms of HW. 

I don't have permission to publish any examples of per-component capable 
hardware.

Keith Packard        XFree86 Core Team        HP Cambridge Research Lab