forked from mirrors/gecko-dev
6b840f5edf
Differential Revision: https://phabricator.services.mozilla.com/D48618 --HG-- extra : moz-landing-system : lando
115 lines
3.8 KiB
C++
115 lines
3.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* compute sticky positioning, both during reflow and when the scrolling
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* container scrolls
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*/
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#ifndef StickyScrollContainer_h
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#define StickyScrollContainer_h
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#include "nsPoint.h"
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#include "nsRectAbsolute.h"
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#include "nsTArray.h"
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#include "nsIScrollPositionListener.h"
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struct nsRect;
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class nsIFrame;
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class nsIScrollableFrame;
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namespace mozilla {
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class StickyScrollContainer final : public nsIScrollPositionListener {
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public:
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/**
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* Find (and create if necessary) the StickyScrollContainer associated with
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* the scroll container of the given frame, if a scroll container exists.
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*/
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static StickyScrollContainer* GetStickyScrollContainerForFrame(
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nsIFrame* aFrame);
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/**
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* Find the StickyScrollContainer associated with the given scroll frame,
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* if it exists.
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*/
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static StickyScrollContainer* GetStickyScrollContainerForScrollFrame(
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nsIFrame* aScrollFrame);
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/**
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* aFrame may have moved into or out of a scroll frame's frame subtree.
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*/
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static void NotifyReparentedFrameAcrossScrollFrameBoundary(
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nsIFrame* aFrame, nsIFrame* aOldParent);
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void AddFrame(nsIFrame* aFrame) { mFrames.AppendElement(aFrame); }
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void RemoveFrame(nsIFrame* aFrame) { mFrames.RemoveElement(aFrame); }
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nsIScrollableFrame* ScrollFrame() const { return mScrollFrame; }
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// Compute the offsets for a sticky position element
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static void ComputeStickyOffsets(nsIFrame* aFrame);
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/**
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* Compute the position of a sticky positioned frame, based on information
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* stored in its properties along with our scroll frame and scroll position.
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*/
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nsPoint ComputePosition(nsIFrame* aFrame) const;
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/**
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* Compute where a frame should not scroll with the page, represented by the
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* difference of two rectangles.
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*/
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void GetScrollRanges(nsIFrame* aFrame, nsRectAbsolute* aOuter,
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nsRectAbsolute* aInner) const;
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/**
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* Compute and set the position of a frame and its following continuations.
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*/
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void PositionContinuations(nsIFrame* aFrame);
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/**
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* Compute and set the position of all sticky frames, given the current
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* scroll position of the scroll frame. If not in reflow, aSubtreeRoot should
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* be null; otherwise, overflow-area updates will be limited to not affect
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* aSubtreeRoot or its ancestors.
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*/
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void UpdatePositions(nsPoint aScrollPosition, nsIFrame* aSubtreeRoot);
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// nsIScrollPositionListener
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virtual void ScrollPositionWillChange(nscoord aX, nscoord aY) override;
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virtual void ScrollPositionDidChange(nscoord aX, nscoord aY) override;
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~StickyScrollContainer();
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const nsTArray<nsIFrame*>& GetFrames() const { return mFrames; }
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/**
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* Returns true if the frame is "stuck" in the y direction, ie it's acting
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* like fixed position. aFrame should be in GetFrames().
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*/
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bool IsStuckInYDirection(nsIFrame* aFrame) const;
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private:
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explicit StickyScrollContainer(nsIScrollableFrame* aScrollFrame);
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/**
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* Compute two rectangles that determine sticky positioning: |aStick|, based
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* on the scroll container, and |aContain|, based on the containing block.
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* Sticky positioning keeps the frame position (its upper-left corner) always
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* within |aContain| and secondarily within |aStick|.
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*/
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void ComputeStickyLimits(nsIFrame* aFrame, nsRect* aStick,
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nsRect* aContain) const;
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nsIScrollableFrame* const mScrollFrame;
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nsTArray<nsIFrame*> mFrames;
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nsPoint mScrollPosition;
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};
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} // namespace mozilla
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#endif /* StickyScrollContainer_h */
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