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..be3f0539f25f3c6f64689aeed8577c33bd20ab5c 100644
--- a/src/core/SkRRect.cpp
+++ b/src/core/SkRRect.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkRRect.h"
+#include "SkMatrix.h"
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ -254,6 +255,49 @@ 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 {

[robertphillips, 2013/10/30 23:55:02]

This seems like a complete abrogation of the const contract.

[scroggo, 2013/10/31 17:40:35]

Agreed. This is to be consistent with SkPath::transform. If I change this one,
should I fix SkPath or have them work differently?

+    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;
+    }
+

[robertphillips, 2013/10/30 23:55:02]

Will this do the right thing if the matrix is a reflection and the RR isn't
symmetric?

[scroggo, 2013/10/31 17:40:35]

No. Fixed.

+    // Now scale each corner
+    SkScalar xScale = matrix.getScaleX();
+    if (xScale < 0) {
+        xScale = -xScale;
+    }
+    SkScalar yScale = matrix.getScaleY();
+    if (yScale < 0) {
+        yScale = -yScale;
+    }

[robertphillips, 2013/10/30 23:55:02]

Do we actually need "radii" here? Can't we do this in place in dst?

[scroggo, 2013/10/31 17:40:35]

Done.

+    SkVector radii[4];
+    for (int i = 0; i < 4; ++i) {
+        radii[i].fX = fRadii[i].fX * xScale;
+        radii[i].fY = fRadii[i].fY * yScale;
+    }
+    dst->setRectRadii(newRect, radii);
+    return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkRRect::inset(SkScalar dx, SkScalar dy, SkRRect* dst) const {