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/* -*- 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 */
* 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 {
* 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;
const nsTArray<nsIFrame*>& GetFrames() const { return mFrames; }
* Returns true if the frame is "stuck" in the y direction, ie it's acting
* like fixed position. aFrame should be in GetFrames().
bool IsStuckInYDirection(nsIFrame* aFrame) const;
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 */