Add SkRRectsGaussianEdgeMaskFilter

SkRRectsGaussianEdgeShader will be removed once the usage of the
MaskFilter flavor has been propagated to Android

I will complete the raster implementation in a follow up CL.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3632

Change-Id: I42470b17308582b040a5db1a7283c3d717405345
Reviewed-on: https://skia-review.googlesource.com/3632
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/effects/SkRRectsGaussianEdgeMaskFilter.h b/include/effects/SkRRectsGaussianEdgeMaskFilter.h
new file mode 100644
index 0000000000..14e17b3deb
--- /dev/null
+++ b/include/effects/SkRRectsGaussianEdgeMaskFilter.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkRRectsGaussianEdgeMaskFilter_DEFINED
+#define SkRRectsGaussianEdgeMaskFilter_DEFINED
+
+#include "SkMaskFilter.h"
+
+class SkRRect;
+
+class SK_API SkRRectsGaussianEdgeMaskFilter {
+public:
+    /** Returns a mask filter that applies a Gaussian blur depending on distance to the edge
+     *  of the intersection of two round rects.
+     *  Currently this is only useable with round rects that have the same radii at
+     *  all the corners and for which the x & y radii are equal.
+     *  
+     *  In order to minimize fill the coverage geometry that should be drawn should be no larger
+     *  than the intersection of the bounding boxes of the two round rects. Ambitious users can
+     *  omit the center area of the coverage geometry if it is known to be occluded.
+     */
+    static sk_sp<SkMaskFilter> Make(const SkRRect& first,
+                                    const SkRRect& second,
+                                    SkScalar radius);
+
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+
+private:
+    SkRRectsGaussianEdgeMaskFilter(); // can't be instantiated
+};
+
+#endif