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1 // Copyright 2016 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 TopDocumentRootScrollerController_h | |
6 #define TopDocumentRootScrollerController_h | |
7 | |
8 #include "core/CoreExport.h" | |
9 #include "core/page/scrolling/RootScrollerController.h" | |
10 #include "platform/heap/Handle.h" | |
11 | |
12 namespace blink { | |
13 | |
14 class Document; | |
15 class Element; | |
16 class GraphicsLayer; | |
17 class ScrollStateCallback; | |
18 class ViewportScrollCallback; | |
19 | |
20 // The RootScrollerController used to manage the root scroller for the top | |
21 // level Document on a page. In addition to the regular RootScroller duties | |
22 // such as keeping track of which Element is set as root scroller and which is | |
23 // the effective root scroller, this class is also responsible for setting the | |
24 // ViewportApplyScroll on the one Element on a page that should apply viewport | |
25 // scrolling actions. | |
26 class CORE_EXPORT TopDocumentRootScrollerController | |
27 : public RootScrollerController { | |
28 public: | |
29 static TopDocumentRootScrollerController* create(Document&); | |
30 | |
31 DECLARE_VIRTUAL_TRACE(); | |
32 | |
33 // This class needs to be informed of changes to compositing so that it can | |
34 // update the compositor when the effective root scroller changes. | |
35 void didUpdateCompositing() override; | |
36 | |
37 // This class needs to be informed when the document has been attached to a | |
38 // FrameView so that we can initialize the viewport scroll callback. | |
39 void didAttachDocument() override; | |
40 | |
41 // Returns true if the given ScrollStateCallback is the ViewportScrollCallba
ck managed | |
42 // by this class. | |
43 // TODO(bokan): Temporarily needed to allow ScrollCustomization to | |
44 // differentiate between real custom callback and the built-in viewport | |
45 // apply scroll. crbug.com/623079. | |
46 bool isViewportScrollCallback( | |
47 const ScrollStateCallback*) const override; | |
48 | |
49 protected: | |
50 TopDocumentRootScrollerController(Document&); | |
51 | |
52 // Ensures the effective root scroller is currently valid and replaces it | |
53 // with the default if not. | |
54 void updateEffectiveRootScroller() override; | |
55 | |
56 private: | |
57 // Ensures that the element that should be used as the root scroller on the | |
58 // page has the m_viewportApplyScroll callback set on it. | |
59 void setViewportApplyScrollOnRootScroller(); | |
60 | |
61 // The apply-scroll callback that moves top controls and produces | |
62 // overscroll effects. This class makes sure this callback is set on the | |
63 // appropriate root scroller element. | |
64 Member<ViewportScrollCallback> m_viewportApplyScroll; | |
65 | |
66 // Tracks which element currently has the m_viewportApplyScroll set to it. | |
67 WeakMember<Element> m_currentViewportApplyScrollHost; | |
68 }; | |
69 | |
70 } // namespace blink | |
71 | |
72 #endif // RootScrollerController_h | |
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