397 lines
14 KiB
C++
397 lines
14 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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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#include "StickyScrollContainer.h"
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#include "nsIFrame.h"
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#include "nsIScrollableFrame.h"
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#include "nsLayoutUtils.h"
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#include "RestyleTracker.h"
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namespace mozilla {
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NS_DECLARE_FRAME_PROPERTY_DELETABLE(StickyScrollContainerProperty,
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StickyScrollContainer)
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StickyScrollContainer::StickyScrollContainer(nsIScrollableFrame* aScrollFrame)
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: mScrollFrame(aScrollFrame)
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, mScrollPosition()
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{
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mScrollFrame->AddScrollPositionListener(this);
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}
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StickyScrollContainer::~StickyScrollContainer()
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{
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mScrollFrame->RemoveScrollPositionListener(this);
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}
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// static
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StickyScrollContainer*
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StickyScrollContainer::GetStickyScrollContainerForFrame(nsIFrame* aFrame)
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{
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nsIScrollableFrame* scrollFrame =
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nsLayoutUtils::GetNearestScrollableFrame(aFrame->GetParent(),
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nsLayoutUtils::SCROLLABLE_SAME_DOC |
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nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
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if (!scrollFrame) {
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// We might not find any, for instance in the case of
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// <html style="position: fixed">
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return nullptr;
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}
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nsIFrame* frame = do_QueryFrame(scrollFrame);
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StickyScrollContainer* s =
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frame->GetProperty(StickyScrollContainerProperty());
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if (!s) {
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s = new StickyScrollContainer(scrollFrame);
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frame->SetProperty(StickyScrollContainerProperty(), s);
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}
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return s;
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}
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// static
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void
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StickyScrollContainer::NotifyReparentedFrameAcrossScrollFrameBoundary(nsIFrame* aFrame,
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nsIFrame* aOldParent)
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{
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nsIScrollableFrame* oldScrollFrame =
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nsLayoutUtils::GetNearestScrollableFrame(aOldParent,
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nsLayoutUtils::SCROLLABLE_SAME_DOC |
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nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
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if (!oldScrollFrame) {
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// XXX maybe aFrame has sticky descendants that can be sticky now, but
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// we aren't going to handle that.
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return;
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}
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StickyScrollContainer* oldSSC =
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static_cast<nsIFrame*>(do_QueryFrame(oldScrollFrame))->
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GetProperty(StickyScrollContainerProperty());
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if (!oldSSC) {
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// aOldParent had no sticky descendants, so aFrame doesn't have any sticky
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// descendants, and we're done here.
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return;
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}
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auto i = oldSSC->mFrames.Length();
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while (i-- > 0) {
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nsIFrame* f = oldSSC->mFrames[i];
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StickyScrollContainer* newSSC = GetStickyScrollContainerForFrame(f);
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if (newSSC != oldSSC) {
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oldSSC->RemoveFrame(f);
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if (newSSC) {
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newSSC->AddFrame(f);
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}
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}
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}
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}
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// static
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StickyScrollContainer*
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StickyScrollContainer::GetStickyScrollContainerForScrollFrame(nsIFrame* aFrame)
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{
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return aFrame->GetProperty(StickyScrollContainerProperty());
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}
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static nscoord
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ComputeStickySideOffset(Side aSide, const nsStyleSides& aOffset,
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nscoord aPercentBasis)
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{
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if (eStyleUnit_Auto == aOffset.GetUnit(aSide)) {
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return NS_AUTOOFFSET;
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} else {
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return nsLayoutUtils::ComputeCBDependentValue(aPercentBasis,
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aOffset.Get(aSide));
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}
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}
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// static
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void
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StickyScrollContainer::ComputeStickyOffsets(nsIFrame* aFrame)
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{
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nsIScrollableFrame* scrollableFrame =
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nsLayoutUtils::GetNearestScrollableFrame(aFrame->GetParent(),
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nsLayoutUtils::SCROLLABLE_SAME_DOC |
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nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
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if (!scrollableFrame) {
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// Bail.
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return;
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}
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nsSize scrollContainerSize = scrollableFrame->GetScrolledFrame()->
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GetContentRectRelativeToSelf().Size();
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nsMargin computedOffsets;
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const nsStylePosition* position = aFrame->StylePosition();
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computedOffsets.left = ComputeStickySideOffset(eSideLeft, position->mOffset,
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scrollContainerSize.width);
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computedOffsets.right = ComputeStickySideOffset(eSideRight, position->mOffset,
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scrollContainerSize.width);
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computedOffsets.top = ComputeStickySideOffset(eSideTop, position->mOffset,
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scrollContainerSize.height);
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computedOffsets.bottom = ComputeStickySideOffset(eSideBottom, position->mOffset,
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scrollContainerSize.height);
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// Store the offset
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nsMargin* offsets = aFrame->GetProperty(nsIFrame::ComputedOffsetProperty());
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if (offsets) {
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*offsets = computedOffsets;
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} else {
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aFrame->SetProperty(nsIFrame::ComputedOffsetProperty(),
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new nsMargin(computedOffsets));
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}
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}
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void
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StickyScrollContainer::ComputeStickyLimits(nsIFrame* aFrame, nsRect* aStick,
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nsRect* aContain) const
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{
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NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aFrame),
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"Can't sticky position individual continuations");
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aStick->SetRect(nscoord_MIN/2, nscoord_MIN/2, nscoord_MAX, nscoord_MAX);
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aContain->SetRect(nscoord_MIN/2, nscoord_MIN/2, nscoord_MAX, nscoord_MAX);
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const nsMargin* computedOffsets =
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aFrame->GetProperty(nsIFrame::ComputedOffsetProperty());
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if (!computedOffsets) {
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// We haven't reflowed the scroll frame yet, so offsets haven't been
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// computed. Bail.
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return;
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}
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nsIFrame* scrolledFrame = mScrollFrame->GetScrolledFrame();
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nsIFrame* cbFrame = aFrame->GetContainingBlock();
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NS_ASSERTION(cbFrame == scrolledFrame ||
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nsLayoutUtils::IsProperAncestorFrame(scrolledFrame, cbFrame),
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"Scroll frame should be an ancestor of the containing block");
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nsRect rect =
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nsLayoutUtils::GetAllInFlowRectsUnion(aFrame, aFrame->GetParent());
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// Note: Table row groups aren't supposed to be containing blocks, but we treat
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// them as such anyway.
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// Not having this basically disables position:sticky on table cells, which
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// would be really unfortunate, and doesn't match what other browsers do.
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if (cbFrame != scrolledFrame && cbFrame->GetType() == nsGkAtoms::tableRowGroupFrame) {
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cbFrame = cbFrame->GetContainingBlock();
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}
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// Containing block limits for the position of aFrame relative to its parent.
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// The margin box of the sticky element stays within the content box of the
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// contaning-block element.
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if (cbFrame != scrolledFrame) {
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*aContain = nsLayoutUtils::
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GetAllInFlowRectsUnion(cbFrame, aFrame->GetParent(),
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nsLayoutUtils::RECTS_USE_CONTENT_BOX);
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nsRect marginRect = nsLayoutUtils::
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GetAllInFlowRectsUnion(aFrame, aFrame->GetParent(),
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nsLayoutUtils::RECTS_USE_MARGIN_BOX);
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// Deflate aContain by the difference between the union of aFrame's
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// continuations' margin boxes and the union of their border boxes, so that
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// by keeping aFrame within aContain, we keep the union of the margin boxes
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// within the containing block's content box.
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aContain->Deflate(marginRect - rect);
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// Deflate aContain by the border-box size, to form a constraint on the
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// upper-left corner of aFrame and continuations.
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aContain->Deflate(nsMargin(0, rect.width, rect.height, 0));
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}
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nsMargin sfPadding = scrolledFrame->GetUsedPadding();
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nsPoint sfOffset = aFrame->GetParent()->GetOffsetTo(scrolledFrame);
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// Top
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if (computedOffsets->top != NS_AUTOOFFSET) {
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aStick->SetTopEdge(mScrollPosition.y + sfPadding.top +
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computedOffsets->top - sfOffset.y);
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}
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nsSize sfSize = scrolledFrame->GetContentRectRelativeToSelf().Size();
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// Bottom
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if (computedOffsets->bottom != NS_AUTOOFFSET &&
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(computedOffsets->top == NS_AUTOOFFSET ||
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rect.height <= sfSize.height - computedOffsets->TopBottom())) {
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aStick->SetBottomEdge(mScrollPosition.y + sfPadding.top + sfSize.height -
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computedOffsets->bottom - rect.height - sfOffset.y);
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}
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uint8_t direction = cbFrame->StyleVisibility()->mDirection;
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// Left
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if (computedOffsets->left != NS_AUTOOFFSET &&
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(computedOffsets->right == NS_AUTOOFFSET ||
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direction == NS_STYLE_DIRECTION_LTR ||
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rect.width <= sfSize.width - computedOffsets->LeftRight())) {
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aStick->SetLeftEdge(mScrollPosition.x + sfPadding.left +
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computedOffsets->left - sfOffset.x);
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}
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// Right
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if (computedOffsets->right != NS_AUTOOFFSET &&
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(computedOffsets->left == NS_AUTOOFFSET ||
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direction == NS_STYLE_DIRECTION_RTL ||
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rect.width <= sfSize.width - computedOffsets->LeftRight())) {
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aStick->SetRightEdge(mScrollPosition.x + sfPadding.left + sfSize.width -
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computedOffsets->right - rect.width - sfOffset.x);
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}
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// These limits are for the bounding box of aFrame's continuations. Convert
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// to limits for aFrame itself.
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nsPoint frameOffset = aFrame->GetPosition() - rect.TopLeft();
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aStick->MoveBy(frameOffset);
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aContain->MoveBy(frameOffset);
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}
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nsPoint
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StickyScrollContainer::ComputePosition(nsIFrame* aFrame) const
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{
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nsRect stick;
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nsRect contain;
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ComputeStickyLimits(aFrame, &stick, &contain);
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nsPoint position = aFrame->GetNormalPosition();
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// For each sticky direction (top, bottom, left, right), move the frame along
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// the appropriate axis, based on the scroll position, but limit this to keep
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// the element's margin box within the containing block.
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position.y = std::max(position.y, std::min(stick.y, contain.YMost()));
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position.y = std::min(position.y, std::max(stick.YMost(), contain.y));
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position.x = std::max(position.x, std::min(stick.x, contain.XMost()));
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position.x = std::min(position.x, std::max(stick.XMost(), contain.x));
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return position;
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}
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void
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StickyScrollContainer::GetScrollRanges(nsIFrame* aFrame, nsRect* aOuter,
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nsRect* aInner) const
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{
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// We need to use the first in flow; continuation frames should not move
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// relative to each other and should get identical scroll ranges.
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// Also, ComputeStickyLimits requires this.
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nsIFrame *firstCont =
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nsLayoutUtils::FirstContinuationOrIBSplitSibling(aFrame);
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nsRect stick;
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nsRect contain;
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ComputeStickyLimits(firstCont, &stick, &contain);
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aOuter->SetRect(nscoord_MIN/2, nscoord_MIN/2, nscoord_MAX, nscoord_MAX);
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aInner->SetRect(nscoord_MIN/2, nscoord_MIN/2, nscoord_MAX, nscoord_MAX);
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const nsPoint normalPosition = firstCont->GetNormalPosition();
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// Bottom and top
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if (stick.YMost() != nscoord_MAX/2) {
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aOuter->SetTopEdge(contain.y - stick.YMost());
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aInner->SetTopEdge(normalPosition.y - stick.YMost());
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}
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if (stick.y != nscoord_MIN/2) {
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aInner->SetBottomEdge(normalPosition.y - stick.y);
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aOuter->SetBottomEdge(contain.YMost() - stick.y);
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}
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// Right and left
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if (stick.XMost() != nscoord_MAX/2) {
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aOuter->SetLeftEdge(contain.x - stick.XMost());
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aInner->SetLeftEdge(normalPosition.x - stick.XMost());
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}
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if (stick.x != nscoord_MIN/2) {
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aInner->SetRightEdge(normalPosition.x - stick.x);
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aOuter->SetRightEdge(contain.XMost() - stick.x);
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}
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// Make sure |inner| does not extend outside of |outer|. (The consumers of
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// the Layers API, to which this information is propagated, expect this
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// invariant to hold.) The calculated value of |inner| can sometimes extend
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// outside of |outer|, for example due to margin collapsing, since
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// GetNormalPosition() returns the actual position after margin collapsing,
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// while |contain| is calculated based on the frame's GetUsedMargin() which
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// is pre-collapsing.
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// Note that this doesn't necessarily solve all problems stemming from
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// comparing pre- and post-collapsing margins (TODO: find a proper solution).
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*aInner = aInner->Intersect(*aOuter);
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}
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void
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StickyScrollContainer::PositionContinuations(nsIFrame* aFrame)
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{
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NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aFrame),
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"Should be starting from the first continuation");
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nsPoint translation = ComputePosition(aFrame) - aFrame->GetNormalPosition();
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// Move all continuation frames by the same amount.
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for (nsIFrame* cont = aFrame; cont;
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cont = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(cont)) {
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cont->SetPosition(cont->GetNormalPosition() + translation);
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}
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}
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void
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StickyScrollContainer::UpdatePositions(nsPoint aScrollPosition,
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nsIFrame* aSubtreeRoot)
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{
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#ifdef DEBUG
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{
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nsIFrame* scrollFrameAsFrame = do_QueryFrame(mScrollFrame);
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NS_ASSERTION(!aSubtreeRoot || aSubtreeRoot == scrollFrameAsFrame,
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"If reflowing, should be reflowing the scroll frame");
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}
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#endif
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mScrollPosition = aScrollPosition;
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OverflowChangedTracker oct;
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oct.SetSubtreeRoot(aSubtreeRoot);
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for (nsTArray<nsIFrame*>::size_type i = 0; i < mFrames.Length(); i++) {
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nsIFrame* f = mFrames[i];
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if (!nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(f)) {
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// This frame was added in nsFrame::Init before we knew it wasn't
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// the first ib-split-sibling.
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mFrames.RemoveElementAt(i);
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--i;
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continue;
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}
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if (aSubtreeRoot) {
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// Reflowing the scroll frame, so recompute offsets.
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ComputeStickyOffsets(f);
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}
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// mFrames will only contain first continuations, because we filter in
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// nsIFrame::Init.
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PositionContinuations(f);
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f = f->GetParent();
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if (f != aSubtreeRoot) {
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for (nsIFrame* cont = f; cont;
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cont = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(cont)) {
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oct.AddFrame(cont, OverflowChangedTracker::CHILDREN_CHANGED);
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}
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}
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}
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oct.Flush();
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}
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void
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StickyScrollContainer::ScrollPositionWillChange(nscoord aX, nscoord aY)
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{
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}
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void
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StickyScrollContainer::ScrollPositionDidChange(nscoord aX, nscoord aY)
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{
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UpdatePositions(nsPoint(aX, aY), nullptr);
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}
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} // namespace mozilla
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