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Fix LinearGradient4fContext::shadeSpanInternal fuzz

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shadeSpanInternal() converts the count to float -> for ridiculously
wide devices, it may not be represented exactly -> we end up potentially
overflowing the dest buffer.

Refactor to stay in int -- this works because SkScalarTruncToInt now
saturates, and it also appears to be marginally faster.

Bug: skia:8536
Change-Id: Ia0b39543ef347332f545af11eabae84c63813fcd
Reviewed-on: https://skia-review.googlesource.com/c/169740
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
This commit is contained in:
Florin Malita 2018-11-08 12:00:20 -05:00 committed by Skia Commit-Bot
parent 389528d8d8
commit 909e61c26c
1 changed files with 1 additions and 2 deletions
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3
src/shaders/gradients/Sk4fLinearGradient.cpp
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@ -242,8 +242,7 @@ LinearGradient4fContext::shadeSpanInternal(int x, int y, dstType dst[], int coun
while (count > 0) { while (count > 0) {
// What we really want here is SkTPin(advance, 1, count) // What we really want here is SkTPin(advance, 1, count)
// but that's a significant perf hit for >> stops; investigate. // but that's a significant perf hit for >> stops; investigate.
const int n = SkScalarTruncToInt( const int n = SkTMin(SkScalarTruncToInt(proc.currentAdvance() + 1), count);
SkTMin<SkScalar>(proc.currentAdvance() + 1, SkIntToScalar(count)));
// The current interval advance can be +inf (e.g. when reaching // The current interval advance can be +inf (e.g. when reaching
// the clamp mode end intervals) - when that happens, we expect to // the clamp mode end intervals) - when that happens, we expect to