[cairo] nearest neighborhood or bilinear interpolation

Carlos Eduardo Rodrigues Diógenes cerdiogenes at yahoo.com.br
Mon Oct 30 12:15:37 PST 2006

Hello Clemens,

Em Seg, 2006-10-30 às 20:54 +0100, Clemens Eisserer escreveu:
> Hello Carlos,
> > since cairo supports lot's of back-ends, including Xrender and OpenGL,
> > and is very easy to change from one to another, so an initial scale can
> > be done in hardware and more intensive smoothing algorithms can be
> > applied in software, this way when the user is scrolling the mouse
> > around the desktop the magnifier screen get's updated quickly and only
> > when the user stop to move the mouse ore intensive algorithms will be
> > applied.
> Well for now this won't help much, since using OpenGL means (when not
> rendering the whole thing to an OpenGL-window) vram-readbacks and most
> Xorg drivers don't support scaling in hardware. Since some time I try
> to lobby for better 2d drivers (e.g. nvidia drivers do most not-solid
> stuff in software) - it would be great if you could help a bit since
> this would mean overall better 2d drivers.

I don't understand well the issues related with OpenGL. When and why
(it's possible revert this siutation) the vram-readbacks are needed?
Other think, it's really needed to claim for better 2d drivers? The
Xrender driver-hooks can make use of the 3d capacity of the hardware,
isn't is? The Xrender operations can't be mapped to OpenGL? The OpenGL
implementation appear to work reasonably well in the paper "GLITZ -
Hardware Accelerated Image Compositing using OpenGL" for a GeForce
FX-5600. So the path isn't is a Xserver implemented on top of OpenGL?

> It would be great if you could post at
> http://www.nvnews.net/vbulletin/forumdisplay.php?f=14 that you're
> gnome-mag co-author and unhappy with the current situation and that
> you would need hw-accalerated X11 drivers. (Escpecially because
> XRender has the needed Driver-Hooks but drivers are falling back to
> software).
> This forum is read by nvidia developers (semi official driver feedback
> forum). I know its just nvidia ... however it would be great if you
> could take the 3min nonetheless.

Do you think that I must claim for better 2d drivers? The OpenGL
implementations offered by ATI and nvidia aren't good enough?

> Thank you in advance, lg Clemens


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