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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_RENDERER_PAINT_AGGREGATOR_H_
      6 #define CONTENT_RENDERER_PAINT_AGGREGATOR_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/basictypes.h"
     11 #include "content/common/content_export.h"
     12 #include "ui/gfx/rect.h"
     13 #include "ui/gfx/vector2d.h"
     14 
     15 namespace content {
     16 
     17 // This class is responsible for aggregating multiple invalidation and scroll
     18 // commands to produce a scroll and repaint sequence.
     19 class CONTENT_EXPORT PaintAggregator {
     20  public:
     21   // This structure describes an aggregation of InvalidateRect and ScrollRect
     22   // calls.  If |scroll_rect| is non-empty, then that rect should be scrolled
     23   // by the amount specified by |scroll_delta|.  If |paint_rects| is non-empty,
     24   // then those rects should be repainted.  If |scroll_rect| and |paint_rects|
     25   // are non-empty, then scrolling should be performed before repainting.
     26   // |scroll_delta| can only specify scrolling in one direction (i.e., the x
     27   // and y members cannot both be non-zero).
     28   struct CONTENT_EXPORT PendingUpdate {
     29     PendingUpdate();
     30     ~PendingUpdate();
     31 
     32     // Returns the rect damaged by scrolling within |scroll_rect| by
     33     // |scroll_delta|.  This rect must be repainted.
     34     gfx::Rect GetScrollDamage() const;
     35 
     36     // Returns the smallest rect containing all paint rects.
     37     gfx::Rect GetPaintBounds() const;
     38 
     39     gfx::Vector2d scroll_delta;
     40     gfx::Rect scroll_rect;
     41     std::vector<gfx::Rect> paint_rects;
     42   };
     43 
     44   // There is a PendingUpdate if InvalidateRect or ScrollRect were called and
     45   // ClearPendingUpdate was not called.
     46   bool HasPendingUpdate() const;
     47   void ClearPendingUpdate();
     48 
     49   // Fills |update| and clears the pending update.
     50   void PopPendingUpdate(PendingUpdate* update);
     51 
     52   // The given rect should be repainted.
     53   void InvalidateRect(const gfx::Rect& rect);
     54 
     55   // The given rect should be scrolled by the given amounts.
     56   void ScrollRect(const gfx::Vector2d& delta, const gfx::Rect& clip_rect);
     57 
     58  private:
     59   gfx::Rect ScrollPaintRect(const gfx::Rect& paint_rect,
     60                             const gfx::Vector2d& delta) const;
     61   bool ShouldInvalidateScrollRect(const gfx::Rect& rect) const;
     62   void InvalidateScrollRect();
     63   void CombinePaintRects();
     64 
     65   PendingUpdate update_;
     66 };
     67 
     68 }  // namespace content
     69 
     70 #endif  // CONTENT_RENDERER_PAINT_AGGREGATOR_H_
     71