Pull in Chromium's version of GatherPixelRefs

include/utils/SkPictureUtils.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPictureUtils_DEFINED
 #define SkPictureUtils_DEFINED
 
 #include "SkPicture.h"
+#include "SkTDArray.h"
 
 class SkData;
 struct SkRect;
 
 class SK_API SkPictureUtils {
 public:
     /**
      *  Given a rectangular visible "window" into the picture, return an array
      *  of SkPixelRefs that might intersect that area. To keep the call fast,
      *  the returned list is not guaranteed to be exact, so it may miss some,
      *  and it may return false positives.
      *
      *  The pixelrefs returned in the SkData are already owned by the picture,
      *  so the returned pointers are only valid while the picture is in scope
      *  and remains unchanged.
      */
     static SkData* GatherPixelRefs(SkPicture* pict, const SkRect& area);
+
+    /**
+     * SkPixelRefContainer provides a base class for more elaborate pixel ref
+     * query structures (e.g., rtrees, quad-trees, etc.)
+     */
+    class SkPixelRefContainer : public SkRefCnt {
+    public:
+        virtual void add(SkPixelRef* pr, const SkRect& rect) = 0;
+
+        // The returned array may contain duplicates
+        virtual void query(const SkRect& queryRect, SkTDArray<SkPixelRef*> *result) = 0;
+
+    private:
+        typedef SkRefCnt INHERITED;
+    };
+
+    // Simple query structure that just stores a linked list of pixel refs
+    // and rects.
+    class SkPixelRefsAndRectsList : public SkPixelRefContainer {
+    public:
+        virtual void add(SkPixelRef* pr, const SkRect& rect) SK_OVERRIDE {
+            PixelRefAndRect *dst = fArray.append();
+
+            dst->fPixelRef = pr;
+            dst->fRect = rect;
+        }
+
+        virtual void query(const SkRect& queryRect, SkTDArray<SkPixelRef*> *result) SK_OVERRIDE {
+            for (int i = 0; i < fArray.count(); ++i) {
+                if (SkRect::Intersects(fArray[i].fRect, queryRect)) {
+                    *result->append() = fArray[i].fPixelRef;
+                }
+            }
+        }
+
+    private:
+        struct PixelRefAndRect {
+            SkPixelRef* fPixelRef;
+            SkRect      fRect;
+        };
+
+        SkTDArray<PixelRefAndRect> fArray;
+
+        typedef SkPixelRefContainer INHERITED;
+    };
+
+    /**
+     *  Fill the provided pixel ref container with the picture's pixel ref
+     *  and rect information.
+     */
+    static void GatherPixelRefsAndRects(SkPicture* pict, SkPixelRefContainer* prCont);
 };
 
 #endif