Add an average mode for sigma < 2

The original code had an optimization when sigma < 2 that averaged
pixels instead of Gaussian bluring them. This CL adds that
behavior back to the new implementation.

Add the flag SK_LEGACY_USE_GAUSS_FOR_SMALL_RADII to control the
new behavior.

BUG=chromium:745290

Change-Id: I6e7417ce7f42949f88376b549743a9f047667f09
Reviewed-on: https://skia-review.googlesource.com/34624
Commit-Queue: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/core/SkMaskBlurFilter.h b/src/core/SkMaskBlurFilter.h
index c530488efb..000d9493a0 100644
--- a/src/core/SkMaskBlurFilter.h
+++ b/src/core/SkMaskBlurFilter.h
@@ -37,8 +37,13 @@ public:
         // A factor used to simulate division using multiplication and shift.
         uint64_t scaledWeight() const;
 
+        // Returned when sigma < 2.
+        bool isSmall() const;
+
     private:
+        const bool     fIsSmall;
         const uint32_t fFilterWindow;
+        const uint64_t fWeight;
         const uint64_t fScaledWeight;
     };
 
@@ -59,6 +64,14 @@ private:
                      const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
                            uint8_t* dst, size_t dstStride,       uint8_t* dstEnd) const;
 
+    void blurOneScanBox(FilterInfo gen,
+                        const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
+                              uint8_t* dst, size_t dstStride,       uint8_t* dstEnd) const;
+
+    void blurOneScanGauss(FilterInfo gen,
+                          const uint8_t* src, size_t srcStride, const uint8_t* srcEnd,
+                                uint8_t* dst, size_t dstStride,       uint8_t* dstEnd) const;
+
 
     const FilterInfo            fInfoW,
                                 fInfoH;