qml: fix VideoGridItem image has wrong width
PreserveAspectFit (default) or preserving the
aspect ratio in general is not necessary here.
I'm not sure what is the reason for this, the source size aspect ratio is 1.60747663551401869159, while the actual image size aspect ratio is 1.6. I initially thought that this was the reason, but apparently it is not.
The source size aspect ratio should be the same of the image aspect ratio, but I don't plan to fix it here.
I suspect that this has something to do with
Image's vertex shader [1] which does some kind of
alignment so Image painted size does not reflect
the absolute reality which ShaderEffect uses as
basis for its own alignment.
For example, when the image's size is 456 x 283.35
its painted size is 453.04 x 283.35 (source size is
865 x 538). Even though PreserveAspectFit is used,
the painted size aspect ratio does not seem to match
source size aspect ratio.
Request review @chub.