Fix scaling with large magnification
Fix scaling with large magnification

When scaling part of an image we need to specify the source
coordinates in transformed coordinates. For large magnifications this
means we will get pretty large values.

Now, if e.g. src_x * transform is larger than 32765, then the
coordinate ends up outside the pixman 16bit image size, so the
rendering will not work.

The fix is to make the src_x/y offset part of the transformation.
This means its automatically transformed by the correct scaling, and
the coordinates passed into pixman are not (typically) over 16bit.

alon/spice-server,SPICE/spice,alon/spice-server,dezelin/spice,ya-mouse/spice,fgouget/spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,dezelin/spice,alon/spice-server,virtualAMP/spiceplay,mathslinux/spice,elmarco/spice,mathslinux/spice,Fantu/spice,mathslinux/spice,Fantu/spice,dezelin/spice,ya-mouse/spice,alon/spice-server,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,SPICE/spice,virtualAMP/spiceplay,dezelin/spice,fgouget/spice,elmarco/spice,Fantu/spice,freedesktop-unofficial-mirror/spice__spice,elmarco/spice,elmarco/spice,alon/spice-server,Fantu/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,SPICE/spice,virtualAMP/spiceplay,virtualAMP/spiceplay,dezelin/spice,elmarco/spice,mathslinux/spice,mathslinux/spice