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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SCROLLING_VIEWPORT_SCROLL_CALLBACK_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SCROLLING_VIEWPORT_SCROLL_CALLBACK_H_
#include "third_party/blink/renderer/core/page/scrolling/scroll_state_callback.h"
#include "third_party/blink/renderer/core/scroll/scroll_types.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
namespace blink {
class BrowserControls;
class ScrollableArea;
class ScrollState;
class OverscrollController;
class RootFrameViewport;
// ViewportScrollCallback is a ScrollStateCallback, meaning that it's applied
// during the applyScroll step of ScrollCustomization. It implements viewport
// actions like moving browser controls and showing overscroll glow as well as
// scrolling the Element.
//
// ScrollCustomization generally relies on using the nativeApplyScroll to
// scroll the element; however, the rootScroller may need to execute actions
// both before and after the native scroll which is currently unsupported.
// Because of this, the ViewportScrollCallback can scroll the Element directly.
// This is accomplished by passing the ScrollableArea directly using
// setScroller() which RootScrollerController will call to set the appropriate
// ScrollableArea to use.
class ViewportScrollCallback : public ScrollStateCallback {
public:
// ViewportScrollCallback does not assume ownership of BrowserControls or of
// OverscrollController.
ViewportScrollCallback(BrowserControls*,
OverscrollController*,
RootFrameViewport&);
~ViewportScrollCallback() override;
void Invoke(ScrollState*) override;
void SetScroller(ScrollableArea*);
void Trace(blink::Visitor*) override;
private:
bool ShouldScrollBrowserControls(const ScrollOffset&,
ScrollGranularity) const;
bool ScrollBrowserControls(ScrollState&);
ScrollResult PerformNativeScroll(ScrollState&);
WeakMember<BrowserControls> browser_controls_;
WeakMember<OverscrollController> overscroll_controller_;
WeakMember<RootFrameViewport> root_frame_viewport_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SCROLLING_VIEWPORT_SCROLL_CALLBACK_H_
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