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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "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, nsRect* aOuter, nsRect* 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 */
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