tree 627a4da69f842186616299f89d10b4a47b0db0f5
parent e78c45720c450ce81f17c669d3ea2e0e8e9c369e
author Nigel Tao <nigeltao@golang.org> 1476425525 +1100
committer Nigel Tao <nigeltao@golang.org> 1476483913 +0000

vector: fix overflow when rasterizing a 30 degree line.

There are some obvious TODOs, but they will be follow-up commits.

This is about correctness, not performance, but for the record:

name                              old time/op  new time/op   delta
GlyphAlpha16Over-8                3.16µs ± 0%   3.38µs ± 0%   +6.96%         (p=0.000 n=9+10)
GlyphAlpha16Src-8                 3.06µs ± 0%   3.28µs ± 0%   +7.21%        (p=0.000 n=10+10)
GlyphAlpha32Over-8                4.92µs ± 1%   5.23µs ± 1%   +6.24%        (p=0.000 n=10+10)
GlyphAlpha32Src-8                 4.53µs ± 1%   4.83µs ± 0%   +6.69%        (p=0.000 n=10+10)
GlyphAlpha64Over-8                9.60µs ± 1%  10.21µs ± 0%   +6.36%        (p=0.000 n=10+10)
GlyphAlpha64Src-8                 8.04µs ± 0%   8.68µs ± 1%   +7.99%         (p=0.000 n=9+10)
GlyphAlpha128Over-8               23.1µs ± 0%   24.2µs ± 1%   +5.08%         (p=0.000 n=9+10)
GlyphAlpha128Src-8                16.8µs ± 0%   18.0µs ± 1%   +6.76%        (p=0.000 n=10+10)
GlyphAlpha256Over-8               68.6µs ± 1%   70.3µs ± 0%   +2.50%        (p=0.000 n=10+10)
GlyphAlpha256Src-8                43.6µs ± 0%   45.4µs ± 0%   +4.08%         (p=0.000 n=10+8)
GlyphRGBA16Over-8                 4.92µs ± 0%   5.14µs ± 0%   +4.48%          (p=0.000 n=9+9)
GlyphRGBA16Src-8                  4.39µs ± 0%   4.59µs ± 0%   +4.60%          (p=0.000 n=8+9)
GlyphRGBA32Over-8                 11.8µs ± 0%   12.2µs ± 1%   +2.89%         (p=0.000 n=9+10)
GlyphRGBA32Src-8                  9.79µs ± 1%  10.03µs ± 0%   +2.49%         (p=0.000 n=10+7)
GlyphRGBA64Over-8                 36.7µs ± 1%   37.5µs ± 1%   +2.23%        (p=0.000 n=10+10)
GlyphRGBA64Src-8                  28.5µs ± 0%   29.1µs ± 0%   +2.09%        (p=0.000 n=10+10)
GlyphRGBA128Over-8                 133µs ± 0%    135µs ± 0%   +1.51%         (p=0.000 n=10+9)
GlyphRGBA128Src-8                 99.1µs ± 0%  100.5µs ± 1%   +1.47%         (p=0.000 n=9+10)
GlyphRGBA256Over-8                 505µs ± 0%    511µs ± 0%   +1.18%         (p=0.000 n=9+10)
GlyphRGBA256Src-8                  372µs ± 0%    374µs ± 0%   +0.69%         (p=0.000 n=9+10)

Change-Id: Ice1d77de5bc2649f8cd88366bcae3c00e78d65c2
Reviewed-on: https://go-review.googlesource.com/31113
Reviewed-by: David Crawshaw <crawshaw@golang.org>