chromium/third_party/blink/renderer/core/frame/root_frame_viewport.h

// Copyright 2015 The Chromium Authors
// 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_FRAME_ROOT_FRAME_VIEWPORT_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_ROOT_FRAME_VIEWPORT_H_

#include "base/gtest_prod_util.h"
#include "base/task/single_thread_task_runner.h"
#include "third_party/blink/public/mojom/scroll/scroll_into_view_params.mojom-blink-forward.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/scroll/scrollable_area.h"
#include "third_party/blink/renderer/platform/graphics/overlay_scrollbar_clip_behavior.h"
#include "third_party/blink/renderer/platform/wtf/casting.h"

namespace blink {

class LocalFrameView;
struct PhysicalRect;

// ScrollableArea for the root frame's viewport. This class ties together the
// concepts of layout and visual viewports, used in pinch-to-zoom. This class
// takes two ScrollableAreas, one for the visual viewport and one for the
// layout viewport, and delegates and composes the ScrollableArea API as needed
// between them. For most scrolling APIs, this class will split the scroll up
// between the two viewports in accord with the pinch-zoom semantics. For other
// APIs that don't make sense on the combined viewport, the call is delegated to
// the layout viewport. Thus, we could say this class is a decorator on the
// LocalFrameView scrollable area that adds pinch-zoom semantics to scrolling.
class CORE_EXPORT RootFrameViewport final
    : public GarbageCollected<RootFrameViewport>,
      public ScrollableArea { … };

template <>
struct DowncastTraits<RootFrameViewport> { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_ROOT_FRAME_VIEWPORT_H_