Analytic AntiAlias for Convex Shapes

src/core/SkAntiRun.h

Index: src/core/SkAntiRun.h
diff --git a/src/core/SkAntiRun.h b/src/core/SkAntiRun.h
index 8214e28d5b7ee8d8575c082d31b77e9f49388d5a..4537b05ac9e4e2615d75dfc2316816bcb5605d63 100644
--- a/src/core/SkAntiRun.h
+++ b/src/core/SkAntiRun.h
@@ -79,7 +79,7 @@ public:
             runs += x;
             x = 0;
             do {
-                alpha[0] = SkToU8(alpha[0] + maxValue);
+                alpha[0] = SkToU8(SkTMin<int>(0xFF, alpha[0] + maxValue));

[reed1, 2016/08/18 20:31:00]

is this needed today, or just with your CL? If today, lets land this sooner.

[liyuqian, 2016/08/22 15:30:48]

I don't think that the current supersampling algorithm will trigger this because
it's descretized (0 - 16) without many arithmetic operations.

Anyway, I found that I actually triggered this because of some bugs in my code.
I've fixed them and I no longer need this check.

                 int n = runs[0];
                 SkASSERT(n <= middleCount);
                 alpha += n;