Why does the GTK3 vcl sal plugin default to SvpSalGraphics / software rendering?

Tomaž Vajngerl quikee at gmail.com
Wed Feb 14 11:01:40 UTC 2018


On Wed, Feb 14, 2018 at 6:44 PM, Clemens Eisserer <linuxhippy at gmail.com> wrote:
> Hi,
> While investigaing, I found that with the GTK3 backend all rendering
> is done with SvpSalGraphics in software / on the CPU.
> I wonder what was the relationale behind this decision? And is this
> the right mailing list to ask vcl implementation details?

Not sure what you mean software - it is using cairo, which is used for
canvas in GTK 2/3 for example. Whatever that triggers on cairo's
backend could be done in software and some code paths could trigger
code path in X which could be performed on the GPU using Glamor (and
the GPU data upload would kill any performance advantage you would get
from doing that). Under wayland however there is no such thing -
either you're doing it in software or do it yourself (or a library
that does it) in OpenGL / Vulkan. So the rationale is simple - that's
how rendering is done in GTK3, until GTK4 comes out and its sexy
scenegraph API.

> Best regards, Clemens

Regards, Tomaž

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