layout/generic/StickyScrollContainer.h
author Nika Layzell <nika@thelayzells.com>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 507828 5e6dae0c1e5a4939ccd406f14607f7fafffd45a7
parent 462050 e3135a56a12503df3ab8e5b9ee1aaad002a1da2e
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1448426 - Wrap windows.h to avoid problematic define statements, r=froydnj,glandium By default, windows.h exposes a large number of problematic define statements which are UpperCamelCase, such as a define from `CreateWindow` to `CreateWindow{A,W}`. As many of these names are generic (e.g. CreateFile, CreateWindow), they can mess up Gecko code that may legitimately have its own methods with the same names. The header also defines some traditional SCREAMING_SNAKE_CASE defines which can mess up our code by conflicting with local values. This patch adds a simple code generator which generates wrappers for these defines, and uses them to wrap the windows.h wrapper using the `stl_wrappers` mechanism, allowing us to use windows.h in more places. Differential Revision: https://phabricator.services.mozilla.com/D10932

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**
 * compute sticky positioning, both during reflow and when the scrolling
 * container scrolls
 */

#ifndef StickyScrollContainer_h
#define StickyScrollContainer_h

#include "nsPoint.h"
#include "nsRectAbsolute.h"
#include "nsTArray.h"
#include "nsIScrollPositionListener.h"

struct nsRect;
class nsIFrame;
class nsIScrollableFrame;

namespace mozilla {

class StickyScrollContainer final : public nsIScrollPositionListener
{
public:
  /**
   * Find (and create if necessary) the StickyScrollContainer associated with
   * the scroll container of the given frame, if a scroll container exists.
   */
  static StickyScrollContainer* GetStickyScrollContainerForFrame(nsIFrame* aFrame);

  /**
   * Find the StickyScrollContainer associated with the given scroll frame,
   * if it exists.
   */
  static StickyScrollContainer* GetStickyScrollContainerForScrollFrame(nsIFrame* aScrollFrame);

  /**
   * aFrame may have moved into or out of a scroll frame's frame subtree.
   */
  static void NotifyReparentedFrameAcrossScrollFrameBoundary(nsIFrame* aFrame,
                                                             nsIFrame* aOldParent);

  void AddFrame(nsIFrame* aFrame) {
    mFrames.AppendElement(aFrame);
  }
  void RemoveFrame(nsIFrame* aFrame) {
    mFrames.RemoveElement(aFrame);
  }

  nsIScrollableFrame* ScrollFrame() const {
    return mScrollFrame;
  }

  // Compute the offsets for a sticky position element
  static void ComputeStickyOffsets(nsIFrame* aFrame);

  /**
   * Compute the position of a sticky positioned frame, based on information
   * stored in its properties along with our scroll frame and scroll position.
   */
  nsPoint ComputePosition(nsIFrame* aFrame) const;

  /**
   * Compute where a frame should not scroll with the page, represented by the
   * difference of two rectangles.
   */
  void GetScrollRanges(nsIFrame* aFrame, nsRectAbsolute* aOuter, nsRectAbsolute* aInner) const;

  /**
   * Compute and set the position of a frame and its following continuations.
   */
  void PositionContinuations(nsIFrame* aFrame);

  /**
   * Compute and set the position of all sticky frames, given the current
   * scroll position of the scroll frame. If not in reflow, aSubtreeRoot should
   * be null; otherwise, overflow-area updates will be limited to not affect
   * aSubtreeRoot or its ancestors.
   */
  void UpdatePositions(nsPoint aScrollPosition, nsIFrame* aSubtreeRoot);

  // nsIScrollPositionListener
  virtual void ScrollPositionWillChange(nscoord aX, nscoord aY) override;
  virtual void ScrollPositionDidChange(nscoord aX, nscoord aY) override;

  ~StickyScrollContainer();

private:
  explicit StickyScrollContainer(nsIScrollableFrame* aScrollFrame);

  /**
   * Compute two rectangles that determine sticky positioning: |aStick|, based
   * on the scroll container, and |aContain|, based on the containing block.
   * Sticky positioning keeps the frame position (its upper-left corner) always
   * within |aContain| and secondarily within |aStick|.
   */
  void ComputeStickyLimits(nsIFrame* aFrame, nsRect* aStick,
                           nsRect* aContain) const;

  nsIScrollableFrame* const mScrollFrame;
  nsTArray<nsIFrame*> mFrames;
  nsPoint mScrollPosition;
};

} // namespace mozilla

#endif /* StickyScrollContainer_h */