Fix quickReject computation for blurs

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
===================================================================
--- src/effects/SkBlurMaskFilter.cpp	(revision 9604)
+++ src/effects/SkBlurMaskFilter.cpp	(working copy)
@@ -97,11 +97,7 @@
         radius = matrix.mapRadius(fRadius);
     }
 
-    // To avoid unseemly allocation requests (esp. for finite platforms like
-    // handset) we limit the radius so something manageable. (as opposed to
-    // a request like 10,000)
-    static const SkScalar MAX_RADIUS = SkIntToScalar(128);
-    radius = SkMinScalar(radius, MAX_RADIUS);
+    radius = SkMinScalar(radius, SkBlurMask::kMAX_BLUR_RADIUS);
     SkBlurMask::Quality blurQuality =
         (fBlurFlags & SkBlurMaskFilter::kHighQuality_BlurFlag) ?
             SkBlurMask::kHigh_Quality : SkBlurMask::kLow_Quality;
@@ -120,11 +116,7 @@
         radius = matrix.mapRadius(fRadius);
     }
 
-    // To avoid unseemly allocation requests (esp. for finite platforms like
-    // handset) we limit the radius so something manageable. (as opposed to
-    // a request like 10,000)
-    static const SkScalar MAX_RADIUS = SkIntToScalar(128);
-    radius = SkMinScalar(radius, MAX_RADIUS);
+    radius = SkMinScalar(radius, SkBlurMask::kMAX_BLUR_RADIUS);
 
     return SkBlurMask::BlurRect(dst, r, radius, (SkBlurMask::Style)fBlurStyle,
                                 margin, createMode);
@@ -300,8 +292,27 @@
 
 void SkBlurMaskFilterImpl::computeFastBounds(const SkRect& src,
                                              SkRect* dst) const {
-    dst->set(src.fLeft - fRadius, src.fTop - fRadius,
-             src.fRight + fRadius, src.fBottom + fRadius);
+    SkScalar gpuPad, rasterPad;
+
+    {
+        // GPU path

[Stephen White, 2013/06/14 19:37:38]

I guess there's no way to pass the device down here, so it can do a
device-specific thing?

+        SkScalar sigma = SkScalarMul(fRadius, SkBlurMask::kBLUR_SIGMA_SCALE);
+        gpuPad = sigma * 3.0f;
+    }
+
+    {
+        // raster path
+        SkScalar radius = SkScalarMul(fRadius, SkBlurMask::kBlurRadiusFudgeFactor);
+ 
+        radius = (radius + .5f) * 2.f;
+
+        rasterPad = SkIntToScalar(SkScalarRoundToInt(radius * 3)/2);
+    }
+
+    SkScalar pad = SkMaxScalar(gpuPad, rasterPad);
+
+    dst->set(src.fLeft  - pad, src.fTop    - pad,
+             src.fRight + pad, src.fBottom + pad);
 }
 
 SkBlurMaskFilterImpl::SkBlurMaskFilterImpl(SkFlattenableReadBuffer& buffer)
@@ -332,6 +343,9 @@
         info->fRadius = fRadius;
         info->fIgnoreTransform = SkToBool(fBlurFlags & SkBlurMaskFilter::kIgnoreTransform_BlurFlag);
         info->fHighQuality = SkToBool(fBlurFlags & SkBlurMaskFilter::kHighQuality_BlurFlag);
+
+        info->fSigmaFraction = SkBlurMask::kBLUR_SIGMA_SCALE;
+        info->fMaxRadius = SkBlurMask::kMAX_BLUR_RADIUS;
     }
     return gBlurStyle2BlurType[fBlurStyle];
 }