While most callers of decomposeScale only depend on the scale factors
that are returned, image filter decomposition depends on the remaining
matrix as well. Hence, the following necessary updates to work with
the new behavior of decomposeScale:
* Update imagefilter DAG sample to reflect prescaling
* Correct embedded matrix in SkApplyCTMToFilter
* Add comment to clipRectBounds() clarifying coordinate spaces and image filters
But, we want to have decomposeScale using preScale() because it then
produces a remainder matrix that can be used as the transform for the
image filter draw, instead of wrapping the image filter in an
SkMatrixImageFilter as currently done by SkApplyCTMToFilter.
Bug: skia:7211
Change-Id: If14570afb4189cebc75f3815e8ccdde05cb074e1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/228438
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
aa861a1907