drawBitmapRect() should not touch the CTM when mask filters are present

src/core/SkBitmapDevice.cpp

Index: src/core/SkBitmapDevice.cpp
diff --git a/src/core/SkBitmapDevice.cpp b/src/core/SkBitmapDevice.cpp
index 3f3e5fd84e47b1d75434754fc9df5b2da834b9f7..4f8074d3a672ea0df255a09cc540b5c726e552fa 100644
--- a/src/core/SkBitmapDevice.cpp
+++ b/src/core/SkBitmapDevice.cpp
@@ -233,6 +233,15 @@ void SkBitmapDevice::drawBitmap(const SkDraw& draw, const SkBitmap& bitmap,
     draw.drawBitmap(bitmap, matrix, nullptr, paint);
 }
 
+static inline bool CanApplyDstMatrixAsCTM(const SkMatrix& m, const SkPaint& paint) {
+    if (!paint.getMaskFilter()) {

[f(malita), 2016/08/26 19:19:10]

Is there anything else downstream that may care about the CTM?

+        return true;
+    }
+
+    // Some mask filters parameters (sigma) depend on the CTM/scale.
+    return m.getType() <= SkMatrix::kTranslate_Mask;
+}
+
 void SkBitmapDevice::drawBitmapRect(const SkDraw& draw, const SkBitmap& bitmap,
                                     const SkRect* src, const SkRect& dst,
                                     const SkPaint& paint, SkCanvas::SrcRectConstraint constraint) {
@@ -309,8 +318,10 @@ void SkBitmapDevice::drawBitmapRect(const SkDraw& draw, const SkBitmap& bitmap,
         // We can go faster by just calling drawBitmap, which will concat the
         // matrix with the CTM, and try to call drawSprite if it can. If not,
         // it will make a shader and call drawRect, as we do below.
-        draw.drawBitmap(*bitmapPtr, matrix, dstPtr, paint);
-        return;
+        if (CanApplyDstMatrixAsCTM(matrix, paint)) {
+            draw.drawBitmap(*bitmapPtr, matrix, dstPtr, paint);
+            return;
+        }
     }
 
     USE_SHADER: