Xrender cursor performance / double buffering?

Jordan Crouse jordan.crouse at amd.com
Tue Apr 17 12:56:33 EDT 2007

On 17/04/07 18:22 +0200, Bert Freudenberg wrote:
> On Apr 17, 2007, at 17:40 , Jordan Crouse wrote:
> > On 17/04/07 17:37 +0200, Bert Freudenberg wrote:
> >
> >> Besides, the OLPC default cursors all use ARGB, not 2 bit.
> >
> > Again, I have to ask.  Why are we purposely hurting ourselves?
> Well, ask Eben, not me ;)
> Seriously, OLPC decided it's a good idea to have antialiased graphics  
> everywhere. So why would you exclude the cursor from that?

Because the hardware doesn't support it, for one.  I would sure love to
read the minutes from the meeting where a risk analysis was done between
2 bit cursors and ARGB, and everybody agreed ARGB was a better choice.
Just because the technology behind 2 bit cursors is ancient, that doesn't
make them unusable for this project.  we have many brilliant graphic artists
working on this - is it really difficult to come up with a set of
good looking 2 bit cursors that doesn't harm the look and feel of Sugar?

Jim has asked several times if the alpha blending unit can be used to help.
I'm not sure if the X software cursor engine has the capacity to use the
EXA composting, and even if it did, it would hurt performance even more on
GX, because the hardware can't composite ARGB32 on native screen mode.  The
LX can, but three months from now, I'll still argue that there is no really
compelling reason to have a ARGB cursor.


Jordan Crouse
Senior Linux Engineer
Advanced Micro Devices, Inc.

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