content/renderer/paint_aggregator.h

   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_