Add SkRRect::transform.

src/core/SkRRect.cpp

Index: src/core/SkRRect.cpp
diff --git a/src/core/SkRRect.cpp b/src/core/SkRRect.cpp
index 75af106b7b6eaf81183ce1b977afa27231577aa3..ec4d686530fd2786b0548ebc6daf3c55729b0f2f 100644
--- a/src/core/SkRRect.cpp
+++ b/src/core/SkRRect.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkRRect.h"
+#include "SkMatrix.h"
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ -254,6 +255,85 @@ void SkRRect::computeType() const {
     fType = kComplex_Type;
 }
 
+static bool matrix_only_scale_and_translate(const SkMatrix& matrix) {
+    const SkMatrix::TypeMask m = (SkMatrix::TypeMask) (SkMatrix::kAffine_Mask
+                                    | SkMatrix::kPerspective_Mask);
+    return (matrix.getType() & m) == 0;
+}
+
+bool SkRRect::transform(const SkMatrix& matrix, SkRRect* dst) const {
+    if (NULL == dst) {
+        dst = const_cast<SkRRect*>(this);
+    }
+
+    if (matrix.isIdentity()) {
+        *dst = *this;
+        return true;
+    }
+
+    if (!matrix_only_scale_and_translate(matrix)) {
+        return false;
+    }
+
+    SkRect newRect;
+    if (!matrix.mapRect(&newRect, fRect)) {
+        return false;
+    }
+
+    dst->fRect = newRect;
+
+    // Now scale each corner
+    SkScalar xScale = matrix.getScaleX();
+    if (xScale < 0) {
+        xScale = -xScale;
+        // Each x radius will swap with its horizontal opposite.
+        const SkScalar upperLeftXRadius = this->radii(kUpperLeft_Corner).fX;
+        const SkScalar upperRightXRadius = this->radii(kUpperRight_Corner).fX;
+        dst->fRadii[(int) kUpperRight_Corner].fX = SkScalarMul(xScale, upperLeftXRadius);
+        dst->fRadii[(int) kUpperLeft_Corner].fX = SkScalarMul(xScale, upperRightXRadius);
+
+        const SkScalar lowerLeftXRadius = this->radii(kLowerLeft_Corner).fX;
+        const SkScalar lowerRightXRadius = this->radii(kLowerRight_Corner).fX;
+        dst->fRadii[(int) kLowerRight_Corner].fX = SkScalarMul(xScale, lowerLeftXRadius);
+        dst->fRadii[(int) kLowerLeft_Corner].fX = SkScalarMul(xScale, lowerRightXRadius);
+    } else {
+        dst->fRadii[(int) kUpperLeft_Corner].fX = SkScalarMul(xScale,
+                this->radii(kUpperLeft_Corner).fX);
+        dst->fRadii[(int) kUpperRight_Corner].fX = SkScalarMul(xScale,
+                this->radii(kUpperRight_Corner).fX);
+        dst->fRadii[(int) kLowerRight_Corner].fX = SkScalarMul(xScale,
+                this->radii(kLowerRight_Corner).fX);
+        dst->fRadii[(int) kLowerLeft_Corner].fX = SkScalarMul(xScale,
+                this->radii(kLowerLeft_Corner).fX);
+    }
+
+    SkScalar yScale = matrix.getScaleY();
+    if (yScale < 0) {
+        yScale = -yScale;
+        // Each y radius will swap with its vertical opposite.
+        const SkScalar upperLeftYRadius = this->radii(kUpperLeft_Corner).fY;
+        const SkScalar lowerLeftYRadius = this->radii(kLowerLeft_Corner).fY;
+        dst->fRadii[(int) kLowerLeft_Corner].fY = SkScalarMul(yScale, upperLeftYRadius);
+        dst->fRadii[(int) kUpperLeft_Corner].fY = SkScalarMul(yScale, lowerLeftYRadius);
+
+        const SkScalar upperRightYRadius = this->radii(kUpperRight_Corner).fY;
+        const SkScalar lowerRightYRadius = this->radii(kLowerRight_Corner).fY;
+        dst->fRadii[(int) kLowerRight_Corner].fY = SkScalarMul(yScale, upperRightYRadius);
+        dst->fRadii[(int) kUpperRight_Corner].fY = SkScalarMul(yScale, lowerRightYRadius);
+    } else {
+        dst->fRadii[(int) kUpperLeft_Corner].fY = SkScalarMul(yScale,
+                this->radii(kUpperLeft_Corner).fY);
+        dst->fRadii[(int) kUpperRight_Corner].fY = SkScalarMul(yScale,
+                this->radii(kUpperRight_Corner).fY);
+        dst->fRadii[(int) kLowerRight_Corner].fY = SkScalarMul(yScale,
+                this->radii(kLowerRight_Corner).fY);
+        dst->fRadii[(int) kLowerLeft_Corner].fY = SkScalarMul(yScale,
+                this->radii(kLowerLeft_Corner).fY);
+    }
+
+    return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkRRect::inset(SkScalar dx, SkScalar dy, SkRRect* dst) const {