Cache blur mask for rects which can not break into nine-patch

src/core/SkMaskFilter.cpp

Index: src/core/SkMaskFilter.cpp
diff --git a/src/core/SkMaskFilter.cpp b/src/core/SkMaskFilter.cpp
index 28c9a381d3162376275a23a5cfea6ebbaae4ead2..db2e7c91486428b3c0b6bf508c6e99e263c33db0 100644
--- a/src/core/SkMaskFilter.cpp
+++ b/src/core/SkMaskFilter.cpp
@@ -10,6 +10,7 @@
 #include "SkMaskFilter.h"
 #include "SkBlitter.h"
 #include "SkDraw.h"
+#include "SkMaskCache.h"
 #include "SkRasterClip.h"
 #include "SkRRect.h"
 #include "SkTypes.h"
@@ -263,9 +264,34 @@ bool SkMaskFilter::filterPath(const SkPath& devPath, const SkMatrix& matrix,
     }
     SkAutoMaskFreeImage autoSrc(srcM.fImage);
 
-    if (!this->filterMask(&dstM, srcM, matrix, NULL)) {
-        return false;
+    BlurRec rec;
+    if (!this->asABlur(&rec)
+        || !rectCount

[reed1, 2014/12/22 21:38:16]

This 4-part predicate may be correct, but it is pretty complex for me to read.
Can it be restructured to make it clearer?

[qiankun, 2014/12/23 10:54:32]

What about the latest implementation?

+        || (this->asABlur(&rec) && !SkMaskCache::FindCachedRects(&dstM, matrix.mapRadius(rec.fSigma), rec.fStyle,
+                                                                 rec.fQuality, rects, rectCount))) {
+        if (!this->filterMask(&dstM, srcM, matrix, NULL)) {
+            return false;
+        }
+        if (this->asABlur(&rec) && rectCount) {
+            SkMaskCache::AddCachedRects(dstM, matrix.mapRadius(rec.fSigma), rec.fStyle, rec.fQuality, rects, rectCount);
+        }
+    } else {
+        // Compute the correct bounds of dst mask if dst mask is got from cache.
+        SkMask tmpSrc, tmpDst;
+        tmpSrc = srcM;
+        tmpSrc.fImage = NULL;
+        if (!this->filterMask(&tmpDst, tmpSrc, matrix, NULL)) {
+            return false;
+        }
+
+        // Fallback to original calculation if size of bounds is different with size of the cached mask.
+        if (dstM.fBounds.width() != tmpDst.fBounds.width() || dstM.fBounds.height() != tmpDst.fBounds.height()) {
+            this->filterMask(&dstM, srcM, matrix, NULL);
+        } else {
+            dstM.fBounds = tmpDst.fBounds;
+        }
     }
+
     SkAutoMaskFreeImage autoDst(dstM.fImage);
 
     // if we get here, we need to (possibly) resolve the clip and blitter