Dropping X11 VCL backend

[Michael Meeks]

On 29/12/2020 16:29, Thorsten Behrens wrote:
>> XRender. Hopefully I’m reading the code right. If I am reading that
>> right, are there any distributions that ship X11 *without* XRender?
>>
> I believe that's the wrong question to ask - there's always going to
> be a fringe use case where Xrender is not (easily) available. Old, or
> remote X11 comes to mind.

	It would have to be -very- old not to support Xrender, which is also
available via remote protocol; and is ~20 years old. I would say the
probability is near zero of that being useful.

	I'd be well up for killing non-Xrender code-paths if that's easy and
safe - but we should really just go for using statically linked skia's
X11 support and kill that native X11 rendering code in big chunks. Ditto
for the Mac backend, and ultimately for the GDI Windows backend.

	Then with a sane alpha API we could switch to in-line alpha and get
some big performance improvement for rendering.

	I'd love to see someone looking at that. The S390x thing - I saw
problems there related to Skia GPU acceleration on that, but either the
CPU pixel bashing works there - or we can fix it I guess:

	https://bugzilla.mozilla.org/show_bug.cgi?id=1144632

	Looks interesting some years ago.

	There are huge benefits to having a much more powerful single rendering
backend ~everywhere, that removes the need for lots of fallback code.

	So - I'd love to see the existing 'gen' backend switch quietly to using
static skia rendering =)

	My 2 cents,

		Michael.

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