4f gradient negative-dx interval fixup for kMirror_TileMode
4f intervals are meant to be monotonically increasing in X. This means
we invert the point order when dx < 0:
[0...1) -> (1...0]
For kMirror_TileMode, we also append a duplicate/flipped interval
sequence and expand the range to 2:
[0...1) -> [0...1)[1...2)
When dx < 0, the current logic yields
(1...0] -> (1...0](2...1]
which violates the interval monotonicity.
To achieve the proper order, we need to swap the two halves:
(1...0] -> (1...0](2...1] -> (2...1](1...0]
R=reed@google.com
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Review URL: https://codereview.chromium.org/1735773003
1 file changed