[Xorg-driver-geode] Glyph rendering

[Jonathan Morton]

On Mon, 2010-07-12 at 18:06 +0800, Huang, FrankR wrote:
> Our driver is in low performance in glyph rendering.
> Based on the debug and discussion with Michel, There are three operation:

> 1)Op:PictOpAdd, Src:PICT_a8r8g8b8 Mask:0 Dest:PICT_a8

Extract the Alpha component from the source, and add it to the
destination.

> 2)Op:PictOpAdd, Src:PICT_a8 Mask:0 Dest:PICT_a8r8g8b8

Add the source to the Alpha component of the destination.

Both of the above fall obviously out of the general XRender rules, where
missing image components are taken from the ARGB (1,0,0,0) vector during
fetch, and discarded during store.

> 3)Op:PictOpOver, Src:PICT_a8r8g8b8 Mask:PICT_a8r8g8b8 Dst:PICT_r5g6b5

Is Component Alpha turned on for this?  If not, extract the Alpha
component from the mask and otherwise treat as for A8 mask.

It's not entirely clear to me why the above operations would be commonly
encountered.  Possibly some optimisation of higher software layers would
be appropriate.

-- 
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From: Jonathan Morton
      jonathan.morton at movial.com