My testing suggests that EXTEND_PAD is supported by XRender now. The following seems to fix the issue for me:
* Change pat->SetFilter(0) to pat->SetExtend(gfxPattern::EXTEND_PAD) to use EXTEND_PAD for upscaling
* patch cairo to not claim that REPEAT_PAD is unsupported by XRender.
My testing suggests that EXTEND_PAD is supported by XRender now. The following seems to fix the issue for me:
* Change pat->SetFilter(0) to pat->SetExtend( gfxPattern: :EXTEND_ PAD) to use EXTEND_PAD for upscaling
* patch cairo to not claim that REPEAT_PAD is unsupported by XRender.