root_scroller_controller.h | Explore in Territory

// Copyright 2016 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_PAGE_SCROLLING_ROOT_SCROLLER_CONTROLLER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SCROLLING_ROOT_SCROLLER_CONTROLLER_H_

#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_hash_set.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"

namespace blink {

class Document;
class Element;
class HTMLFrameOwnerElement;
class Node;

// Manages the root scroller associated with a given document. The root
// scroller causes browser controls movement, overscroll effects and prevents
// chaining scrolls up further in the DOM. It can be set from script using
// document.setRootScroller. High-level details are available in README.md.
//
// There are two notions of a root scroller in this class: m_rootScroller and
// m_effectiveRootScroller. The former is the Element that was set as the root
// scroller using document.setRootScroller. If the page didn't set a root
// scroller this will be nullptr. The "effective" root scroller is the current
// Node we're using internally to apply viewport scrolling actions.  Both these
// elements come from this controller's associated Document. The final "global"
// root scroller, the one whose scrolling hides browser controls, may be in a
// different frame.
//
// If the currently set m_rootScroller is a valid element to become the root
// scroller, it will be promoted to the effective root scroller. If it is not
// valid, the effective root scroller will fall back to the document Node. The
// rules for what makes an element a valid root scroller are set in
// isValidRootScroller(). The validity of the current root scroller is
// re-checked after layout as part of the document lifecycle.
class CORE_EXPORT RootScrollerController
    : public GarbageCollected<RootScrollerController> { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_PAGE_SCROLLING_ROOT_SCROLLER_CONTROLLER_H_
chromium/third_party/blink/renderer/core/page/scrolling/root_scroller_controller.h
