tree fa6394fa20aa2c2bf26f1aa9efa88d0ff2da5122
parent d18b1b5adc15afd9b57ddecf779dccbcc85098f1
author tomhudson <tomhudson@google.com> 1449513485 -0800
committer Commit bot <commit-bot@chromium.org> 1449513485 -0800

Fix up signed-integer-overflow warnings

When checking whether a matrix was a pure scale, we subtracted
0x3f800000 from the diagonals; if the diagonal value was already
very negative, we'd underflow. Replace subtraction with XOR.

When dealing with repeating tiled bitmaps, when the bitmap was
very large, we'd multiply an offset by 65535, possibly causing
underflow. Throw in a cast to long (casting to unsigned also
silences the warning and wouldn't involve extension, but I can't
convince myself that it's correct).

BUG=skia:4635
R=mtklein@google.com

Review URL: https://codereview.chromium.org/1504933002