Xrender cursor performance / double buffering?

[Jim Gettys]

Jordon Crouse could answer if he's tried to use the alpha blending unit
for the cursor: but he's in the middle of having his office moved this
week, and I don't want to put his private mail address on the list.
                                  - Jim


On Tue, 2007-04-17 at 16:25 +0200, Bert Freudenberg wrote:
> On Apr 17, 2007, at 16:08 , Dan Williams wrote:
> 
> > On Tue, 2007-04-17 at 10:05 -0400, Dan Williams wrote:
> >> On Tue, 2007-04-17 at 12:21 +0200, Bert Freudenberg wrote:
> >>> Hi folks,
> >>>
> >>> for drag'n'dropping an image between an activity and the sugar frame
> >>> I thought it would be nice to just set it as cursor. This way, it
> >>> gets rendered on top of both the activity and the frame.
> >>
> >> Cursors can be hardware accelerated up to a point.  See section  
> >> 6.5.1.3
> >> of the AMD Geode GX2 data book.
> >
> > I hit Ctl+Enter too soon...
> >
> > http://www.amd.com/us-en/ConnectivitySolutions/ProductInformation/ 
> > 0,,50_2330_9863_9864%5E9867,00.html
> >
> > "The GUI supports a 64x64x2-bit hardware cursor overlay."
> >
> > Beyond 64x64, you're not going to get hardware acceleration at all,  
> > and
> > it will be X11 drawing the cursor.  That's gonna be just as slow as
> > anything else you draw from an app.
> >
> >>> Ideas appreciated - or will the LX make this work magically? This is
> >>> a B2.
> >
> > The LX data book says that the LX has the same hardware cursor size as
> > the GX, 64x64.  So I don't think it will help here.
> 
> XO is not using the HW cursor anyway because, as you point out, that  
> only supports 2 bit cursors (1 bit black/white, 1 bit alpha).
> 
> What I was asking is can I make the software cursor faster - for  
> example by using a different format than PictStandardARGB32.  
> Actually, as long as there is no animation behind the large cursor,  
> performance doesn't feel so bad.
> 
> Or, even better, if Xrender would use double-buffering when showing  
> the cursor, this would be much less distracting.
> 
> - Bert -
> 
> 
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-- 
Jim Gettys
One Laptop Per Child