1/*
2 * Copyright (C) 2011 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef PaintAggregator_h
32#define PaintAggregator_h
33
34#include "platform/geometry/IntPoint.h"
35#include "platform/geometry/IntRect.h"
36#include "wtf/Vector.h"
37
38namespace blink {
39
40// This class is responsible for aggregating multiple invalidation and scroll
41// commands to produce a scroll and repaint sequence.
42class PaintAggregator {
43public:
44    // This structure describes an aggregation of invalidateRect and scrollRect
45    // calls. If |scrollRect| is non-empty, then that rect should be scrolled
46    // by the amount specified by |scrollDelta|. If |paintRects| is non-empty,
47    // then those rects should be repainted. If |scrollRect| and |paintRects|
48    // are non-empty, then scrolling should be performed before repainting.
49    // |scrollDelta| can only specify scrolling in one direction (i.e., the x
50    // and y members cannot both be non-zero).
51    struct PendingUpdate {
52        PendingUpdate();
53        ~PendingUpdate();
54
55        // Returns the rect damaged by scrolling within |scrollRect| by
56        // |scrollDelta|. This rect must be repainted.
57        blink::IntRect calculateScrollDamage() const;
58
59        // Returns the smallest rect containing all paint rects.
60        blink::IntRect calculatePaintBounds() const;
61
62        blink::IntPoint scrollDelta;
63        blink::IntRect scrollRect;
64        WTF::Vector<blink::IntRect> paintRects;
65    };
66
67    // There is a PendingUpdate if invalidateRect or scrollRect were called and
68    // ClearPendingUpdate was not called.
69    bool hasPendingUpdate() const;
70    void clearPendingUpdate();
71
72    // Fills |update| and clears the pending update.
73    void popPendingUpdate(PendingUpdate*);
74
75    // The given rect should be repainted.
76    void invalidateRect(const blink::IntRect&);
77
78    // The given rect should be scrolled by the given amounts.
79    void scrollRect(int dx, int dy, const blink::IntRect& clipRect);
80
81private:
82    blink::IntRect scrollPaintRect(const blink::IntRect& paintRect, int dx, int dy) const;
83    bool shouldInvalidateScrollRect(const blink::IntRect&) const;
84    void invalidateScrollRect();
85    void combinePaintRects();
86
87    PendingUpdate m_update;
88};
89
90} // namespace blink
91
92#endif
93