BitmapRegionSampler (uses SkImageDecoder) will often scale
to a power of 2 regardless of the sampleSize requested.
This is skbug.com/4319.
Consider a 60x60 image.
To decode a subset with sample size 3, we might ask for the
following.
[x, y, w, h] = [-15, -15, 30, 30]
sampleSize = 3
Since w = 30 and h = 30, this should give us a 10x10
result. Only the bottom right 5x5 quadrant of this 10x10
subset will actually be in the image. We should get a 5
pixel border on the top and left because we ask for 15
extra pixels on the top and left.
Unfortunately, SkImageDecoder will take our requested
sample size of 3, and then decide to use a sample size of
2. Not only will it scale the image by 2, but it will also
scale the border by 2. So while we are expecting pixel
data to begin at offset (5, 5) of the result bitmap, it
actually begins at offset (7, 7). Making things worse,
the pixels between (5, 5) and (7, 7) are uninitialized,
causing problems on Gold.
Options for fixing this include:
(1) Not testing decodes with a border.
(2) Changing the test to check the size of the output
bitmap.
(3) Disable the tests.
I think it's best to just disable these tests. We know
they don't work, so why do we need to see the results on
Gold?
BUG=skia:4319
Review URL: https://codereview.chromium.org/1313233007
6efbe05377