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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef ScrollAnchor_h | 5 #ifndef ScrollAnchor_h |
6 #define ScrollAnchor_h | 6 #define ScrollAnchor_h |
7 | 7 |
8 #include "core/CoreExport.h" | 8 #include "core/CoreExport.h" |
9 #include "platform/geometry/LayoutPoint.h" | 9 #include "platform/geometry/LayoutPoint.h" |
10 #include "platform/heap/Handle.h" | 10 #include "platform/heap/Handle.h" |
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24 ~ScrollAnchor(); | 24 ~ScrollAnchor(); |
25 | 25 |
26 // The scroller that is scrolled to componsate for layout movements. Note | 26 // The scroller that is scrolled to componsate for layout movements. Note |
27 // that the scroller can only be initialized once. | 27 // that the scroller can only be initialized once. |
28 void setScroller(ScrollableArea*); | 28 void setScroller(ScrollableArea*); |
29 | 29 |
30 // Returns true if the underlying scroller is set. | 30 // Returns true if the underlying scroller is set. |
31 bool hasScroller() const { return m_scroller; } | 31 bool hasScroller() const { return m_scroller; } |
32 | 32 |
33 // The LayoutObject we are currently anchored to. Lazily computed during | 33 // The LayoutObject we are currently anchored to. Lazily computed during |
34 // save() and cached until the next call to clear(). | 34 // notifyBeforeLayout() and cached until the next call to clear(). |
35 LayoutObject* anchorObject() const { return m_anchorObject; } | 35 LayoutObject* anchorObject() const { return m_anchorObject; } |
36 | 36 |
37 // Indicates that the next save() should compute a new anchor for the | 37 // Indicates that this ScrollAnchor, and all ancestor ScrollAnchors, should |
38 // containing scroller and all ancestor scrollers. | 38 // compute new anchor nodes on their next notifyBeforeLayout(). |
39 void clear(); | 39 void clear(); |
40 | 40 |
41 // Indicates that the next save() should compute a new anchor for the | 41 // Indicates that this ScrollAnchor should compute a new anchor node on the |
42 // containing scroller. | 42 // next call to notifyBeforeLayout(). |
43 void clearSelf(); | 43 void clearSelf(); |
44 | 44 |
45 // Records the anchor's location in relation to the scroller. Should be | 45 // Records the anchor's location in relation to the scroller. Should be |
46 // called when the scroller is about to be laid out. | 46 // called when the scroller is about to be laid out. |
47 void save(); | 47 void notifyBeforeLayout(); |
48 | 48 |
49 // Scrolls to compensate for any change in the anchor's relative location | 49 // Scrolls to compensate for any change in the anchor's relative location. |
50 // since the most recent call to save(). Should be called immediately after | 50 // Should be called at the end of the animation frame. |
51 // the scroller has been laid out. | 51 void adjust(); |
52 void restore(); | |
53 | 52 |
54 enum class Corner { | 53 enum class Corner { |
55 TopLeft = 0, | 54 TopLeft = 0, |
56 TopRight, | 55 TopRight, |
57 }; | 56 }; |
58 // Which corner of the anchor object we are currently anchored to. | 57 // Which corner of the anchor object we are currently anchored to. |
59 // Only meaningful if anchorObject() is non-null. | 58 // Only meaningful if anchorObject() is non-null. |
60 Corner corner() const { return m_corner; } | 59 Corner corner() const { return m_corner; } |
61 | 60 |
62 // Checks if we hold any references to the specified object. | 61 // Checks if we hold any references to the specified object. |
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84 : status(s), viable(true), corner(c) {} | 83 : status(s), viable(true), corner(c) {} |
85 | 84 |
86 WalkStatus status; | 85 WalkStatus status; |
87 bool viable; | 86 bool viable; |
88 Corner corner; | 87 Corner corner; |
89 }; | 88 }; |
90 ExamineResult examine(const LayoutObject*) const; | 89 ExamineResult examine(const LayoutObject*) const; |
91 | 90 |
92 IntSize computeAdjustment() const; | 91 IntSize computeAdjustment() const; |
93 | 92 |
94 // The scroller that owns and is adjusted by this ScrollAnchor. | 93 // The scroller to be adjusted by this ScrollAnchor. This is also the scroller |
| 94 // that owns us, unless it is the RootFrameViewport in which case we are owned |
| 95 // by the layout viewport. |
95 Member<ScrollableArea> m_scroller; | 96 Member<ScrollableArea> m_scroller; |
96 | 97 |
97 // The LayoutObject we should anchor to. | 98 // The LayoutObject we should anchor to. |
98 LayoutObject* m_anchorObject; | 99 LayoutObject* m_anchorObject; |
99 | 100 |
100 // Which corner of m_anchorObject's bounding box to anchor to. | 101 // Which corner of m_anchorObject's bounding box to anchor to. |
101 Corner m_corner; | 102 Corner m_corner; |
102 | 103 |
103 // Location of m_layoutObject relative to scroller at time of save(). | 104 // Location of m_layoutObject relative to scroller at time of |
| 105 // notifyBeforeLayout(). |
104 LayoutPoint m_savedRelativeOffset; | 106 LayoutPoint m_savedRelativeOffset; |
105 | 107 |
106 // We suppress scroll anchoring after a style change on the anchor node or | 108 // We suppress scroll anchoring after a style change on the anchor node or |
107 // one of its ancestors, if that change might have caused the node to move. | 109 // one of its ancestors, if that change might have caused the node to move. |
108 // This bit tracks whether we have had a scroll-anchor-disabling style | 110 // This bit tracks whether we have had a scroll-anchor-disabling style |
109 // change since the last layout. It is recomputed in save(), and used to | 111 // change since the last layout. It is recomputed in notifyBeforeLayout(), |
110 // suppress the adjustment in restore(). More at http://bit.ly/sanaclap. | 112 // and used to suppress adjustment in adjust(). See http://bit.ly/sanaclap. |
111 bool m_scrollAnchorDisablingStyleChanged; | 113 bool m_scrollAnchorDisablingStyleChanged; |
112 | 114 |
113 // True iff save has been called, and restore has not been called since | 115 // True iff an adjustment check has been queued with the FrameView but not yet |
114 // the call to save. In this state, additional calls to save are ignored, | 116 // performed. |
115 // to make things easier for multi-pass layout modes such as flexbox. | 117 bool m_queued; |
116 // TODO(skobes): explore anchoring at frame boundaries instead of layouts, | |
117 // which would allow this field to be removed. | |
118 bool m_saved; | |
119 }; | 118 }; |
120 | 119 |
121 } // namespace blink | 120 } // namespace blink |
122 | 121 |
123 #endif // ScrollAnchor_h | 122 #endif // ScrollAnchor_h |
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