Implement cc::FilterOperations::MapRect.

cc/output/filter_operation.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_OUTPUT_FILTER_OPERATION_H_
 #define CC_OUTPUT_FILTER_OPERATION_H_
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkImageFilter.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "third_party/skia/include/core/SkScalar.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }
 class Value;
 }
 
+namespace gfx {
+class Rect;
+}
+
 namespace cc {
 
 class CC_EXPORT FilterOperation {
  public:
   enum FilterType {
     GRAYSCALE,
     SEPIA,
     SATURATE,
     HUE_ROTATE,
     INVERT,
@@ skipping 183 matching lines @@
   // |from| or |to| (but not both) is null, it is treated as a no-op filter of
   // the same type as the other given filter. If both |from| and |to| are null,
   // or if |from| and |to| are non-null but of different types, returns a
   // no-op filter.
   static FilterOperation Blend(const FilterOperation* from,
                                const FilterOperation* to,
                                double progress);
 
   void AsValueInto(base::trace_event::TracedValue* value) const;
 
+  // Maps "forward" to determine which pixels in a destination rect are affected
+  // by pixels in the source rect.
+  gfx::Rect MapRect(const gfx::Rect& rect) const;
+
  private:
   FilterOperation(FilterType type, float amount);
 
   FilterOperation(FilterType type,
                   const gfx::Point& offset,
                   float stdDeviation,
                   SkColor color);
 
   FilterOperation(FilterType, SkScalar matrix[20]);
 
@@ skipping 14 matching lines @@
   SkColor drop_shadow_color_;
   skia::RefPtr<SkImageFilter> image_filter_;
   SkScalar matrix_[20];
   int zoom_inset_;
   SkRegion region_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_FILTER_OPERATION_H_