Separable mask blurs: Add compile-time flag. Fix reversed offsets in asymmetrical blurs (this bug cancels itself out, but I thought it might be confusing for future readers). Use correct stride in asymmetrical blurs (this is a real bug).

Review URL: https://codereview.appspot.com/6782089

git-svn-id: http://skia.googlecode.com/svn/trunk@6508 2bbb7eff-a529-9590-31e7-b0007b416f81

5 files changed, 23 insertions, 8 deletions

diff --git a/include/effects/SkBlurDrawLooper.h b/include/effects/SkBlurDrawLooper.h
index fa730e382c..eeed1b6c20 100644
--- a/include/effects/SkBlurDrawLooper.h
+++ b/include/effects/SkBlurDrawLooper.h
@@ -31,8 +31,10 @@ public:
         kIgnoreTransform_BlurFlag   = 0x01,
         kOverrideColor_BlurFlag     = 0x02,
         kHighQuality_BlurFlag       = 0x04,
+        /** faster, but may discretize the radius */
+        kCoarseRadius_BlurFlag      = 0x08,
         /** mask for all blur flags */
-        kAll_BlurFlag = 0x07
+        kAll_BlurFlag               = 0x0F
     };
 
     SkBlurDrawLooper(SkScalar radius, SkScalar dx, SkScalar dy, SkColor color,
diff --git a/include/effects/SkBlurMaskFilter.h b/include/effects/SkBlurMaskFilter.h
index 2ab321aa7a..e957a9ddd4 100644
--- a/include/effects/SkBlurMaskFilter.h
+++ b/include/effects/SkBlurMaskFilter.h
@@ -29,8 +29,10 @@ public:
         kIgnoreTransform_BlurFlag   = 0x01,
         /** Use a smother, higher qulity blur algorithm */
         kHighQuality_BlurFlag       = 0x02,
+        /** Do faster blurs by rounding the radius to a set of sub-integer values */
+        kCoarseRadius_BlurFlag      = 0x04,
         /** mask for all blur flags */
-        kAll_BlurFlag = 0x03
+        kAll_BlurFlag = 0x07
     };
 
     /** Create a blur maskfilter.
diff --git a/src/effects/SkBlurDrawLooper.cpp b/src/effects/SkBlurDrawLooper.cpp
index e6e2ffdd8c..8854225636 100644
--- a/src/effects/SkBlurDrawLooper.cpp
+++ b/src/effects/SkBlurDrawLooper.cpp
@@ -27,6 +27,10 @@ SkBlurDrawLooper::SkBlurDrawLooper(SkScalar radius, SkScalar dx, SkScalar dy,
             SkBlurMaskFilter::kHighQuality_BlurFlag :
             SkBlurMaskFilter::kNone_BlurFlag;
 
+        blurFlags |= flags & kCoarseRadius_BlurFlag ?
+            SkBlurMaskFilter::kCoarseRadius_BlurFlag :
+            SkBlurMaskFilter::kNone_BlurFlag;
+
         fBlur = SkBlurMaskFilter::Create(radius,
                                          SkBlurMaskFilter::kNormal_BlurStyle,
                                          blurFlags);
diff --git a/src/effects/SkBlurMask.cpp b/src/effects/SkBlurMask.cpp
index e762ae6f65..4873685dc3 100644
--- a/src/effects/SkBlurMask.cpp
+++ b/src/effects/SkBlurMask.cpp
@@ -34,8 +34,9 @@ static int boxBlur(const uint8_t* src, int src_y_stride, uint8_t* dst,
         uint8_t* dptr = dst + y * dst_y_stride;
         const uint8_t* right = src + y * src_y_stride;
         const uint8_t* left = right;
-        for (int x = 0; x < leftRadius - rightRadius; x++) {
-            *dptr++ = 0;
+        for (int x = 0; x < rightRadius - leftRadius; x++) {
+            *dptr = 0;
+            dptr += dst_x_stride;
         }
         for (int x = 0; x < border; ++x) {
             sum += *right++;
@@ -57,8 +58,9 @@ static int boxBlur(const uint8_t* src, int src_y_stride, uint8_t* dst,
             sum -= *left++;
             dptr += dst_x_stride;
         }
-        for (int x = 0; x < rightRadius - leftRadius; x++) {
-            *dptr++ = 0;
+        for (int x = 0; x < leftRadius - rightRadius; x++) {
+            *dptr = 0;
+            dptr += dst_x_stride;
         }
         SkASSERT(sum == 0);
     }
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index 6cc19c16ab..2e031d8056 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -97,8 +97,13 @@ bool SkBlurMaskFilterImpl::filterMask(SkMask* dst, const SkMask& src,
         (fBlurFlags & SkBlurMaskFilter::kHighQuality_BlurFlag) ?
             SkBlurMask::kHigh_Quality : SkBlurMask::kLow_Quality;
 
-    return SkBlurMask::Blur(dst, src, radius, (SkBlurMask::Style)fBlurStyle,
-                            blurQuality, margin);
+    if (fBlurFlags & SkBlurMaskFilter::kCoarseRadius_BlurFlag) {
+        return SkBlurMask::BlurSeparable(dst, src, radius, (SkBlurMask::Style)fBlurStyle,
+                                blurQuality, margin);
+    } else {
+        return SkBlurMask::Blur(dst, src, radius, (SkBlurMask::Style)fBlurStyle,
+                                blurQuality, margin);
+    }
 }
 
 #include "SkCanvas.h"