Avoid regenerating cached textblobs on integer scrolls

src/gpu/GrAtlasTextContext.h

Index: src/gpu/GrAtlasTextContext.h
diff --git a/src/gpu/GrAtlasTextContext.h b/src/gpu/GrAtlasTextContext.h
index 86810ff21b6209703a2368b6fb6efffaf7458416..2f4779f03c7aa723ac58b09b54f325ebc119fe6c 100644
--- a/src/gpu/GrAtlasTextContext.h
+++ b/src/gpu/GrAtlasTextContext.h
@@ -13,12 +13,13 @@
 #include "GrBatchAtlas.h"
 #include "GrGeometryProcessor.h"
 #include "SkDescriptor.h"
+#include "GrMemoryPool.h"
 #include "SkTextBlob.h"
-#include "SkTDynamicHash.h"
 #include "SkTInternalLList.h"
 
 class GrBatchTextStrike;
 class GrPipelineBuilder;
+class GrTextBlobCache;
 
 /*
  * This class implements GrTextContext using standard bitmap fonts, and can also process textblobs.
@@ -28,8 +29,6 @@ class GrAtlasTextContext : public GrTextContext {
 public:
     static GrAtlasTextContext* Create(GrContext*, SkGpuDevice*, const SkDeviceProperties&);
 
-    virtual ~GrAtlasTextContext();
-
 private:
     GrAtlasTextContext(GrContext*, SkGpuDevice*, const SkDeviceProperties&);
 
@@ -126,13 +125,13 @@ private:
         };
 
         SkTArray<BigGlyph> fBigGlyphs;
+        GrColor fColor; // the original color on the paint
         SkMatrix fViewMatrix;
         SkScalar fX;
         SkScalar fY;
         SkPaint::Style fStyle;
         int fRunCount;
         uint32_t fUniqueID;
-        size_t fSize;
         GrMemoryPool* fPool;
 
         // all glyph / vertex offsets are into these pools.
@@ -166,8 +165,6 @@ private:
     typedef BitmapTextBlob::Run Run;
     typedef Run::SubRunInfo PerSubRunInfo;
 
-    BitmapTextBlob* CreateBlob(int glyphCount, int runCount, GrMemoryPool*);
-
     void appendGlyph(BitmapTextBlob*, int runIndex, GrGlyph::PackedID, int left, int top,
                      GrColor color, GrFontScaler*, const SkIRect& clipRect);
 
@@ -175,14 +172,15 @@ private:
                                 const SkMatrix& viewMatrix, const SkIRect& clipBounds, SkScalar x,
                                 SkScalar y);
     inline void flushRun(GrDrawTarget*, GrPipelineBuilder*, BitmapTextBlob*, int run, GrColor,
-                         uint8_t paintAlpha);
+                         uint8_t paintAlpha, SkScalar transX, SkScalar transY);
     inline void flushBigGlyphs(BitmapTextBlob* cacheBlob, GrRenderTarget* rt,
-                               const GrPaint& grPaint, const GrClip& clip);
+                               const GrPaint& grPaint, const GrClip& clip,
+                               SkScalar transX, SkScalar transY);
 
     // We have to flush SkTextBlobs differently from drawText / drawPosText
     void flush(GrDrawTarget*, const SkTextBlob*, BitmapTextBlob*, GrRenderTarget*, const SkPaint&,
                const GrPaint&, SkDrawFilter*, const GrClip&, const SkMatrix& viewMatrix,
-               const SkIRect& clipBounds, SkScalar x, SkScalar y);
+               const SkIRect& clipBounds, SkScalar x, SkScalar y, SkScalar transX, SkScalar transY);
     void flush(GrDrawTarget*, BitmapTextBlob*, GrRenderTarget*, const SkPaint&,
                const GrPaint&, const GrClip&, const SkMatrix& viewMatrix);
 
@@ -197,18 +195,15 @@ private:
 
     // sets up the descriptor on the blob and returns a detached cache.  Client must attach
     inline SkGlyphCache* setupCache(Run*, const SkPaint&, const SkMatrix& viewMatrix);
-    static inline bool MustRegenerateBlob(const BitmapTextBlob&, const SkPaint&,
+    static inline bool MustRegenerateBlob(SkScalar* outTransX, SkScalar* outTransY,
+                                          const BitmapTextBlob&, const SkPaint&,
                                           const SkMatrix& viewMatrix, SkScalar x, SkScalar y);
     void regenerateTextBlob(BitmapTextBlob* bmp, const SkPaint& skPaint, const SkMatrix& viewMatrix,
                             const SkTextBlob* blob, SkScalar x, SkScalar y,
                             SkDrawFilter* drawFilter, const SkIRect& clipRect);
 
-    // TODO this currently only uses the public interface of SkTextBlob, however, I may need to add
-    // functionality to it while looping over the runs so I'm putting this here for the time being.
-    // If this lands in Chrome without changes, move it to SkTextBlob.
-    static inline void BlobGlyphCount(int* glyphCount, int* runCount, const SkTextBlob*);
-
     GrBatchTextStrike* fCurrStrike;
+    GrTextBlobCache* fCache;
 
     friend class GrTextBlobCache;
     friend class BitmapTextBatch;