Do not lose existing paint shaders when drawing alpha images
This fixes the case where SkBitmapDevice or SkDraw falls back to use an SkShader
to draw the image. Previously it just assigned a new shader to a paint clone,
which worked fine with color images that are defined to ignore any set shader.
However, with alpha images it would overwrite the effect. This changes it to
compose the image shader with the original shader.
It fixes the behavior of GMs bleed_alpha_image_shader, bleed_alpha_bmp_shader,
and alpha_image.
Bug: skia:
Change-Id: Iaf0552ddb9991dd8d414b76f625a45cd167b7070
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/190677
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Mike Reed <reed@google.com>
5 files changed
