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00acdab2d5
Convert `nsIScrollableFrame` to `ScrollContainerFrame` for all the APIs in nsLayoutUtils, and then adapt other callers until everything compiles. In `nsLayoutUtils::CalculateBasicFrameMetrics()`'s documentation, s/ComputeFrameMetrics/ComputeScrollMetadata/ because the method was renamed in https://hg.mozilla.org/mozilla-central/rev/cb2023f50288 Differential Revision: https://phabricator.services.mozilla.com/D211493
788 lines
34 KiB
C++
788 lines
34 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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#include "ScrollSnap.h"
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#include "FrameMetrics.h"
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#include "mozilla/ScrollContainerFrame.h"
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#include "mozilla/ScrollSnapInfo.h"
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#include "mozilla/ServoStyleConsts.h"
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#include "nsIFrame.h"
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#include "nsLayoutUtils.h"
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#include "nsPresContext.h"
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#include "nsTArray.h"
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#include "mozilla/StaticPrefs_layout.h"
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namespace mozilla {
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/**
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* Keeps track of the current best edge to snap to. The criteria for
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* adding an edge depends on the scrolling unit.
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*/
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class CalcSnapPoints final {
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using SnapTarget = ScrollSnapInfo::SnapTarget;
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public:
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CalcSnapPoints(ScrollUnit aUnit, ScrollSnapFlags aSnapFlags,
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const nsPoint& aDestination, const nsPoint& aStartPos);
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struct SnapPosition : public SnapTarget {
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SnapPosition(const SnapTarget& aSnapTarget, nscoord aPosition,
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nscoord aDistanceOnOtherAxis)
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: SnapTarget(aSnapTarget),
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mPosition(aPosition),
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mDistanceOnOtherAxis(aDistanceOnOtherAxis) {}
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nscoord mPosition;
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// The distance from the scroll destination to this snap position on the
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// other axis. This value is used if there are multiple SnapPositions on
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// this axis, but the positions on the other axis are different.
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nscoord mDistanceOnOtherAxis;
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};
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void AddHorizontalEdge(const SnapTarget& aTarget);
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void AddVerticalEdge(const SnapTarget& aTarget);
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struct CandidateTracker {
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// keeps track of the position of the current second best edge on the
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// opposite side of the best edge on this axis.
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// We use NSCoordSaturatingSubtract to calculate the distance between a
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// given position and this second best edge position so that it can be an
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// uninitialized value as the maximum possible value, because the first
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// distance calculation would always be nscoord_MAX.
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nscoord mSecondBestEdge = nscoord_MAX;
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// Assuming in most cases there's no multiple coincide snap points.
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AutoTArray<ScrollSnapTargetId, 1> mTargetIds;
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// keeps track of the positions of the current best edge on this axis.
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// NOTE: Each SnapPosition.mPosition points the same snap position on this
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// axis but other member variables of SnapPosition may have different
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// values.
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AutoTArray<SnapPosition, 1> mBestEdges;
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bool EdgeFound() const { return !mBestEdges.IsEmpty(); }
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};
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void AddEdge(const SnapPosition& aEdge, nscoord aDestination,
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nscoord aStartPos, nscoord aScrollingDirection,
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CandidateTracker* aCandidateTracker);
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SnapDestination GetBestEdge(const nsSize& aSnapportSize) const;
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nscoord XDistanceBetweenBestAndSecondEdge() const {
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return std::abs(NSCoordSaturatingSubtract(
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mTrackerOnX.mSecondBestEdge,
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mTrackerOnX.EdgeFound() ? mTrackerOnX.mBestEdges[0].mPosition
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: mDestination.x,
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nscoord_MAX));
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}
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nscoord YDistanceBetweenBestAndSecondEdge() const {
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return std::abs(NSCoordSaturatingSubtract(
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mTrackerOnY.mSecondBestEdge,
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mTrackerOnY.EdgeFound() ? mTrackerOnY.mBestEdges[0].mPosition
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: mDestination.y,
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nscoord_MAX));
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}
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const nsPoint& Destination() const { return mDestination; }
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protected:
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ScrollUnit mUnit;
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ScrollSnapFlags mSnapFlags;
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nsPoint mDestination; // gives the position after scrolling but before
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// snapping
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nsPoint mStartPos; // gives the position before scrolling
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nsIntPoint mScrollingDirection; // always -1, 0, or 1
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CandidateTracker mTrackerOnX;
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CandidateTracker mTrackerOnY;
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};
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CalcSnapPoints::CalcSnapPoints(ScrollUnit aUnit, ScrollSnapFlags aSnapFlags,
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const nsPoint& aDestination,
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const nsPoint& aStartPos)
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: mUnit(aUnit),
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mSnapFlags(aSnapFlags),
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mDestination(aDestination),
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mStartPos(aStartPos) {
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MOZ_ASSERT(aSnapFlags != ScrollSnapFlags::Disabled);
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nsPoint direction = aDestination - aStartPos;
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mScrollingDirection = nsIntPoint(0, 0);
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if (direction.x < 0) {
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mScrollingDirection.x = -1;
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}
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if (direction.x > 0) {
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mScrollingDirection.x = 1;
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}
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if (direction.y < 0) {
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mScrollingDirection.y = -1;
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}
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if (direction.y > 0) {
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mScrollingDirection.y = 1;
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}
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}
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SnapDestination CalcSnapPoints::GetBestEdge(const nsSize& aSnapportSize) const {
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if (mTrackerOnX.EdgeFound() && mTrackerOnY.EdgeFound()) {
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nsPoint bestCandidate(mTrackerOnX.mBestEdges[0].mPosition,
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mTrackerOnY.mBestEdges[0].mPosition);
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nsRect snappedPort = nsRect(bestCandidate, aSnapportSize);
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// If we've found the candidates on both axes, it's possible some of
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// candidates will be outside of the snapport if we snap to the point
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// (mTrackerOnX.mBestEdges[0].mPosition,
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// mTrackerOnY.mBestEdges[0].mPosition). So we need to get the intersection
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// of the snap area of each snap target element on each axis and the
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// snapport to tell whether it's outside of the snapport or not.
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//
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// Also if at least either one of the elements will be outside of the
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// snapport if we snap to (mTrackerOnX.mBestEdges[0].mPosition,
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// mTrackerOnY.mBestEdges[0].mPosition). We need to choose one of
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// combinations of the candidates which is closest to the destination.
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//
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// So here we iterate over mTrackerOnX and mTrackerOnY just once
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// respectively for both purposes to avoid iterating over them again and
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// again.
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//
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// NOTE: Ideally we have to iterate over every possible combinations of
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// (mTrackerOnX.mBestEdges[i].mSnapPoint.mY,
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// mTrackerOnY.mBestEdges[j].mSnapPoint.mX) and tell whether the given
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// combination will be visible in the snapport or not (maybe we should
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// choose the one that the visible area, i.e., the intersection area of
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// the snap target elements and the snapport, is the largest one rather than
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// the closest one?). But it will be inefficient, so here we will not
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// iterate all the combinations, we just iterate all the snap target
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// elements in each axis respectively.
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AutoTArray<ScrollSnapTargetId, 1> visibleTargetIdsOnX;
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nscoord minimumDistanceOnY = nscoord_MAX;
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size_t minimumXIndex = 0;
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AutoTArray<ScrollSnapTargetId, 1> minimumDistanceTargetIdsOnX;
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for (size_t i = 0; i < mTrackerOnX.mBestEdges.Length(); i++) {
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const auto& targetX = mTrackerOnX.mBestEdges[i];
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if (targetX.mSnapArea.Intersects(snappedPort)) {
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visibleTargetIdsOnX.AppendElement(targetX.mTargetId);
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}
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if (targetX.mDistanceOnOtherAxis < minimumDistanceOnY) {
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minimumDistanceOnY = targetX.mDistanceOnOtherAxis;
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minimumXIndex = i;
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minimumDistanceTargetIdsOnX =
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AutoTArray<ScrollSnapTargetId, 1>{targetX.mTargetId};
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} else if (minimumDistanceOnY != nscoord_MAX &&
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targetX.mDistanceOnOtherAxis == minimumDistanceOnY) {
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minimumDistanceTargetIdsOnX.AppendElement(targetX.mTargetId);
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}
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}
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AutoTArray<ScrollSnapTargetId, 1> visibleTargetIdsOnY;
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nscoord minimumDistanceOnX = nscoord_MAX;
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size_t minimumYIndex = 0;
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AutoTArray<ScrollSnapTargetId, 1> minimumDistanceTargetIdsOnY;
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for (size_t i = 0; i < mTrackerOnY.mBestEdges.Length(); i++) {
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const auto& targetY = mTrackerOnY.mBestEdges[i];
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if (targetY.mSnapArea.Intersects(snappedPort)) {
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visibleTargetIdsOnY.AppendElement(targetY.mTargetId);
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}
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if (targetY.mDistanceOnOtherAxis < minimumDistanceOnX) {
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minimumDistanceOnX = targetY.mDistanceOnOtherAxis;
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minimumYIndex = i;
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minimumDistanceTargetIdsOnY =
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AutoTArray<ScrollSnapTargetId, 1>{targetY.mTargetId};
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} else if (minimumDistanceOnX != nscoord_MAX &&
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targetY.mDistanceOnOtherAxis == minimumDistanceOnX) {
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minimumDistanceTargetIdsOnY.AppendElement(targetY.mTargetId);
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}
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}
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// If we have the target ids on both axes, it means the target elements
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// (ids) specifying the best edge on X axis and the target elements
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// specifying the best edge on Y axis are visible if we snap to the best
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// edge. Thus they are valid snap positions.
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if (!visibleTargetIdsOnX.IsEmpty() && !visibleTargetIdsOnY.IsEmpty()) {
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return SnapDestination{
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bestCandidate,
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ScrollSnapTargetIds{visibleTargetIdsOnX, visibleTargetIdsOnY}};
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}
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// Now we've already known that snapping to
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// (mTrackerOnX.mBestEdges[0].mPosition,
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// mTrackerOnY.mBestEdges[0].mPosition) will make all candidates of
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// mTrackerX or mTrackerY (or both) outside of the snapport. We need to
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// choose another combination where candidates of both mTrackerX/Y are
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// inside the snapport.
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// There are three possibilities;
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// 1) There's no candidate on X axis in mTrackerOnY (that means
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// each candidate's scroll-snap-align is `none` on X axis), but there's
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// any candidate in mTrackerOnX, the closest candidates of mTrackerOnX
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// should be used.
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// 2) There's no candidate on Y axis in mTrackerOnX (that means
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// each candidate's scroll-snap-align is `none` on Y axis), but there's
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// any candidate in mTrackerOnY, the closest candidates of mTrackerOnY
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// should be used.
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// 3) There are candidates on both axes. Choosing a combination such as
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// (mTrackerOnX.mBestEdges[i].mSnapPoint.mX,
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// mTrackerOnY.mBestEdges[i].mSnapPoint.mY)
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// would require us to iterate over the candidates again if the
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// combination position is outside the snapport, which we don't want to
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// do. Instead, we choose either one of the axis' candidates.
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if ((minimumDistanceOnX == nscoord_MAX) &&
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minimumDistanceOnY != nscoord_MAX) {
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bestCandidate.y = *mTrackerOnX.mBestEdges[minimumXIndex].mSnapPoint.mY;
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return SnapDestination{bestCandidate,
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ScrollSnapTargetIds{minimumDistanceTargetIdsOnX,
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minimumDistanceTargetIdsOnX}};
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}
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if (minimumDistanceOnX != nscoord_MAX &&
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minimumDistanceOnY == nscoord_MAX) {
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bestCandidate.x = *mTrackerOnY.mBestEdges[minimumYIndex].mSnapPoint.mX;
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return SnapDestination{bestCandidate,
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ScrollSnapTargetIds{minimumDistanceTargetIdsOnY,
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minimumDistanceTargetIdsOnY}};
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}
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if (minimumDistanceOnX != nscoord_MAX &&
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minimumDistanceOnY != nscoord_MAX) {
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// If we've found candidates on both axes, choose the closest point either
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// on X axis or Y axis from the scroll destination. I.e. choose
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// `minimumXIndex` one or `minimumYIndex` one to make at least one of
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// snap target elements visible inside the snapport.
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//
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// For example,
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// [bestCandidate.x, mTrackerOnX.mBestEdges[minimumXIndex].mSnapPoint.mY]
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// is a candidate generated from a single element, thus snapping to the
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// point would definitely make the element visible inside the snapport.
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if (hypotf(NSCoordToFloat(mDestination.x -
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mTrackerOnX.mBestEdges[0].mPosition),
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NSCoordToFloat(minimumDistanceOnY)) <
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hypotf(NSCoordToFloat(minimumDistanceOnX),
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NSCoordToFloat(mDestination.y -
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mTrackerOnY.mBestEdges[0].mPosition))) {
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bestCandidate.y = *mTrackerOnX.mBestEdges[minimumXIndex].mSnapPoint.mY;
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} else {
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bestCandidate.x = *mTrackerOnY.mBestEdges[minimumYIndex].mSnapPoint.mX;
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}
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return SnapDestination{bestCandidate,
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ScrollSnapTargetIds{minimumDistanceTargetIdsOnX,
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minimumDistanceTargetIdsOnY}};
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}
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MOZ_ASSERT_UNREACHABLE("There's at least one candidate on either axis");
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// `minimumDistanceOnX == nscoord_MAX && minimumDistanceOnY == nscoord_MAX`
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// should not happen but we fall back for safety.
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}
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return SnapDestination{
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nsPoint(
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mTrackerOnX.EdgeFound() ? mTrackerOnX.mBestEdges[0].mPosition
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// In the case of IntendedEndPosition (i.e. the destination point is
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// explicitely specied, e.g. scrollTo) use the destination point if we
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// didn't find any candidates.
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: !(mSnapFlags & ScrollSnapFlags::IntendedDirection) ? mDestination.x
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: mStartPos.x,
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mTrackerOnY.EdgeFound() ? mTrackerOnY.mBestEdges[0].mPosition
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// Same as above X axis case, use the destination point if we didn't
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// find any candidates.
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: !(mSnapFlags & ScrollSnapFlags::IntendedDirection) ? mDestination.y
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: mStartPos.y),
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ScrollSnapTargetIds{mTrackerOnX.mTargetIds, mTrackerOnY.mTargetIds}};
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}
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void CalcSnapPoints::AddHorizontalEdge(const SnapTarget& aTarget) {
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MOZ_ASSERT(aTarget.mSnapPoint.mY);
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AddEdge(SnapPosition{aTarget, *aTarget.mSnapPoint.mY,
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aTarget.mSnapPoint.mX
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? std::abs(mDestination.x - *aTarget.mSnapPoint.mX)
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: nscoord_MAX},
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mDestination.y, mStartPos.y, mScrollingDirection.y, &mTrackerOnY);
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}
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void CalcSnapPoints::AddVerticalEdge(const SnapTarget& aTarget) {
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MOZ_ASSERT(aTarget.mSnapPoint.mX);
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AddEdge(SnapPosition{aTarget, *aTarget.mSnapPoint.mX,
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aTarget.mSnapPoint.mY
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? std::abs(mDestination.y - *aTarget.mSnapPoint.mY)
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: nscoord_MAX},
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mDestination.x, mStartPos.x, mScrollingDirection.x, &mTrackerOnX);
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}
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void CalcSnapPoints::AddEdge(const SnapPosition& aEdge, nscoord aDestination,
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nscoord aStartPos, nscoord aScrollingDirection,
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CandidateTracker* aCandidateTracker) {
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if (mSnapFlags & ScrollSnapFlags::IntendedDirection) {
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// In the case of intended direction, we only want to snap to points ahead
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// of the direction we are scrolling.
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if (aScrollingDirection == 0 ||
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(aEdge.mPosition - aStartPos) * aScrollingDirection <= 0) {
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// The scroll direction is neutral - will not hit a snap point, or the
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// edge is not in the direction we are scrolling, skip it.
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return;
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}
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}
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if (!aCandidateTracker->EdgeFound()) {
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aCandidateTracker->mBestEdges = AutoTArray<SnapPosition, 1>{aEdge};
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aCandidateTracker->mTargetIds =
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AutoTArray<ScrollSnapTargetId, 1>{aEdge.mTargetId};
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return;
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}
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auto isPreferredStopAlways = [&](const SnapPosition& aSnapPosition) -> bool {
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MOZ_ASSERT(mSnapFlags & ScrollSnapFlags::IntendedDirection);
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// In the case of intended direction scroll operations, `scroll-snap-stop:
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// always` snap points in between the start point and the scroll destination
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// are preferable preferable. In other words any `scroll-snap-stop: always`
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// snap points can be handled as if it's `scroll-snap-stop: normal`.
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return aSnapPosition.mScrollSnapStop == StyleScrollSnapStop::Always &&
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std::abs(aSnapPosition.mPosition - aStartPos) <
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std::abs(aDestination - aStartPos);
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};
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const bool isOnOppositeSide =
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((aEdge.mPosition - aDestination) > 0) !=
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((aCandidateTracker->mBestEdges[0].mPosition - aDestination) > 0);
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const nscoord distanceFromStart = aEdge.mPosition - aStartPos;
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// A utility function to update the best and the second best edges in the
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// given conditions.
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// |aIsCloserThanBest| True if the current candidate is closer than the best
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// edge.
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// |aIsCloserThanSecond| True if the current candidate is closer than
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// the second best edge.
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const nscoord distanceFromDestination = aEdge.mPosition - aDestination;
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auto updateBestEdges = [&](bool aIsCloserThanBest, bool aIsCloserThanSecond) {
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if (aIsCloserThanBest) {
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if (mSnapFlags & ScrollSnapFlags::IntendedDirection &&
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isPreferredStopAlways(aEdge)) {
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// In the case of intended direction scroll operations and the new best
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// candidate is `scroll-snap-stop: always` and if it's closer to the
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// start position than the destination, thus we won't use the second
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// best edge since even if the snap port of the best edge covers entire
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// snapport, the `scroll-snap-stop: always` snap point is preferred than
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// any points.
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// NOTE: We've already ignored snap points behind start points so that
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// we can use std::abs here in the comparison.
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//
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// For example, if there's a `scroll-snap-stop: always` in between the
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// start point and destination, no `snap-overflow` mechanism should
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// happen, if there's `scroll-snap-stop: always` further than the
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// destination, `snap-overflow` might happen something like below
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// diagram.
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// start always dest other always
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// |------------|---------|------|
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aCandidateTracker->mSecondBestEdge = aEdge.mPosition;
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} else if (isOnOppositeSide) {
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// Replace the second best edge with the current best edge only if the
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// new best edge (aEdge) is on the opposite side of the current best
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// edge.
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aCandidateTracker->mSecondBestEdge =
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aCandidateTracker->mBestEdges[0].mPosition;
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}
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aCandidateTracker->mBestEdges = AutoTArray<SnapPosition, 1>{aEdge};
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aCandidateTracker->mTargetIds =
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AutoTArray<ScrollSnapTargetId, 1>{aEdge.mTargetId};
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} else {
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if (aEdge.mPosition == aCandidateTracker->mBestEdges[0].mPosition) {
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aCandidateTracker->mTargetIds.AppendElement(aEdge.mTargetId);
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aCandidateTracker->mBestEdges.AppendElement(aEdge);
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}
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if (aIsCloserThanSecond && isOnOppositeSide) {
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aCandidateTracker->mSecondBestEdge = aEdge.mPosition;
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}
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}
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};
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bool isCandidateOfBest = false;
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bool isCandidateOfSecondBest = false;
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switch (mUnit) {
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case ScrollUnit::DEVICE_PIXELS:
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case ScrollUnit::LINES:
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case ScrollUnit::WHOLE: {
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isCandidateOfBest =
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std::abs(distanceFromDestination) <
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std::abs(aCandidateTracker->mBestEdges[0].mPosition - aDestination);
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isCandidateOfSecondBest =
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std::abs(distanceFromDestination) <
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std::abs(NSCoordSaturatingSubtract(aCandidateTracker->mSecondBestEdge,
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aDestination, nscoord_MAX));
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break;
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}
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case ScrollUnit::PAGES: {
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// distance to the edge from the scrolling destination in the direction of
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|
// scrolling
|
|
nscoord overshoot = distanceFromDestination * aScrollingDirection;
|
|
// distance to the current best edge from the scrolling destination in the
|
|
// direction of scrolling
|
|
nscoord curOvershoot =
|
|
(aCandidateTracker->mBestEdges[0].mPosition - aDestination) *
|
|
aScrollingDirection;
|
|
|
|
nscoord secondOvershoot =
|
|
NSCoordSaturatingSubtract(aCandidateTracker->mSecondBestEdge,
|
|
aDestination, nscoord_MAX) *
|
|
aScrollingDirection;
|
|
|
|
// edges between the current position and the scrolling destination are
|
|
// favoured to preserve context
|
|
if (overshoot < 0) {
|
|
isCandidateOfBest = overshoot > curOvershoot || curOvershoot >= 0;
|
|
isCandidateOfSecondBest =
|
|
overshoot > secondOvershoot || secondOvershoot >= 0;
|
|
}
|
|
// if there are no edges between the current position and the scrolling
|
|
// destination the closest edge beyond the destination is used
|
|
if (overshoot > 0) {
|
|
isCandidateOfBest = overshoot < curOvershoot;
|
|
isCandidateOfSecondBest = overshoot < secondOvershoot;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (mSnapFlags & ScrollSnapFlags::IntendedDirection) {
|
|
if (isPreferredStopAlways(aEdge)) {
|
|
// If the given position is `scroll-snap-stop: always` and if the position
|
|
// is in between the start and the destination positions, update the best
|
|
// position based on the distance from the __start__ point.
|
|
isCandidateOfBest =
|
|
std::abs(distanceFromStart) <
|
|
std::abs(aCandidateTracker->mBestEdges[0].mPosition - aStartPos);
|
|
} else if (isPreferredStopAlways(aCandidateTracker->mBestEdges[0])) {
|
|
// If we've found a preferable `scroll-snap-stop:always` position as the
|
|
// best, do not update it unless the given position is also
|
|
// `scroll-snap-stop: always`.
|
|
isCandidateOfBest = false;
|
|
}
|
|
}
|
|
|
|
updateBestEdges(isCandidateOfBest, isCandidateOfSecondBest);
|
|
}
|
|
|
|
static void ProcessSnapPositions(CalcSnapPoints& aCalcSnapPoints,
|
|
const ScrollSnapInfo& aSnapInfo) {
|
|
aSnapInfo.ForEachValidTargetFor(
|
|
aCalcSnapPoints.Destination(), [&](const auto& aTarget) -> bool {
|
|
if (aTarget.mSnapPoint.mX && aSnapInfo.mScrollSnapStrictnessX !=
|
|
StyleScrollSnapStrictness::None) {
|
|
aCalcSnapPoints.AddVerticalEdge(aTarget);
|
|
}
|
|
if (aTarget.mSnapPoint.mY && aSnapInfo.mScrollSnapStrictnessY !=
|
|
StyleScrollSnapStrictness::None) {
|
|
aCalcSnapPoints.AddHorizontalEdge(aTarget);
|
|
}
|
|
return true;
|
|
});
|
|
}
|
|
|
|
Maybe<SnapDestination> ScrollSnapUtils::GetSnapPointForDestination(
|
|
const ScrollSnapInfo& aSnapInfo, ScrollUnit aUnit,
|
|
ScrollSnapFlags aSnapFlags, const nsRect& aScrollRange,
|
|
const nsPoint& aStartPos, const nsPoint& aDestination) {
|
|
if (aSnapInfo.mScrollSnapStrictnessY == StyleScrollSnapStrictness::None &&
|
|
aSnapInfo.mScrollSnapStrictnessX == StyleScrollSnapStrictness::None) {
|
|
return Nothing();
|
|
}
|
|
|
|
if (!aSnapInfo.HasSnapPositions()) {
|
|
return Nothing();
|
|
}
|
|
|
|
CalcSnapPoints calcSnapPoints(aUnit, aSnapFlags, aDestination, aStartPos);
|
|
|
|
ProcessSnapPositions(calcSnapPoints, aSnapInfo);
|
|
|
|
// If the distance between the first and the second candidate snap points
|
|
// is larger than the snapport size and the snapport is covered by larger
|
|
// elements, any points inside the covering area should be valid snap
|
|
// points.
|
|
// https://drafts.csswg.org/css-scroll-snap-1/#snap-overflow
|
|
// NOTE: |aDestination| sometimes points outside of the scroll range, e.g.
|
|
// by the APZC fling, so for the overflow checks we need to clamp it.
|
|
nsPoint clampedDestination = aScrollRange.ClampPoint(aDestination);
|
|
for (auto range : aSnapInfo.mXRangeWiderThanSnapport) {
|
|
if (range.IsValid(clampedDestination.x, aSnapInfo.mSnapportSize.width) &&
|
|
calcSnapPoints.XDistanceBetweenBestAndSecondEdge() >
|
|
aSnapInfo.mSnapportSize.width) {
|
|
calcSnapPoints.AddVerticalEdge(ScrollSnapInfo::SnapTarget{
|
|
Some(clampedDestination.x), Nothing(), range.mSnapArea,
|
|
StyleScrollSnapStop::Normal, range.mTargetId});
|
|
break;
|
|
}
|
|
}
|
|
for (auto range : aSnapInfo.mYRangeWiderThanSnapport) {
|
|
if (range.IsValid(clampedDestination.y, aSnapInfo.mSnapportSize.height) &&
|
|
calcSnapPoints.YDistanceBetweenBestAndSecondEdge() >
|
|
aSnapInfo.mSnapportSize.height) {
|
|
calcSnapPoints.AddHorizontalEdge(ScrollSnapInfo::SnapTarget{
|
|
Nothing(), Some(clampedDestination.y), range.mSnapArea,
|
|
StyleScrollSnapStop::Normal, range.mTargetId});
|
|
break;
|
|
}
|
|
}
|
|
|
|
bool snapped = false;
|
|
auto finalPos = calcSnapPoints.GetBestEdge(aSnapInfo.mSnapportSize);
|
|
constexpr float proximityRatio = 0.3;
|
|
if (aSnapInfo.mScrollSnapStrictnessY ==
|
|
StyleScrollSnapStrictness::Proximity &&
|
|
std::abs(aDestination.y - finalPos.mPosition.y) >
|
|
aSnapInfo.mSnapportSize.height * proximityRatio) {
|
|
finalPos.mPosition.y = aDestination.y;
|
|
} else if (aSnapInfo.mScrollSnapStrictnessY !=
|
|
StyleScrollSnapStrictness::None &&
|
|
aDestination.y != finalPos.mPosition.y) {
|
|
snapped = true;
|
|
}
|
|
if (aSnapInfo.mScrollSnapStrictnessX ==
|
|
StyleScrollSnapStrictness::Proximity &&
|
|
std::abs(aDestination.x - finalPos.mPosition.x) >
|
|
aSnapInfo.mSnapportSize.width * proximityRatio) {
|
|
finalPos.mPosition.x = aDestination.x;
|
|
} else if (aSnapInfo.mScrollSnapStrictnessX !=
|
|
StyleScrollSnapStrictness::None &&
|
|
aDestination.x != finalPos.mPosition.x) {
|
|
snapped = true;
|
|
}
|
|
return snapped ? Some(finalPos) : Nothing();
|
|
}
|
|
|
|
ScrollSnapTargetId ScrollSnapUtils::GetTargetIdFor(const nsIFrame* aFrame) {
|
|
MOZ_ASSERT(aFrame && aFrame->GetContent());
|
|
return ScrollSnapTargetId{reinterpret_cast<uintptr_t>(aFrame->GetContent())};
|
|
}
|
|
|
|
static std::pair<Maybe<nscoord>, Maybe<nscoord>> GetCandidateInLastTargets(
|
|
const ScrollSnapInfo& aSnapInfo, const nsPoint& aCurrentPosition,
|
|
const UniquePtr<ScrollSnapTargetIds>& aLastSnapTargetIds,
|
|
const nsIContent* aFocusedContent) {
|
|
ScrollSnapTargetId targetIdForFocusedContent = ScrollSnapTargetId::None;
|
|
if (aFocusedContent && aFocusedContent->GetPrimaryFrame()) {
|
|
targetIdForFocusedContent =
|
|
ScrollSnapUtils::GetTargetIdFor(aFocusedContent->GetPrimaryFrame());
|
|
}
|
|
|
|
// Note: Below algorithm doesn't care about cases where the last snap point
|
|
// was on an element larger than the snapport since it's not clear to us
|
|
// what we should do for now.
|
|
// https://github.com/w3c/csswg-drafts/issues/7438
|
|
const ScrollSnapInfo::SnapTarget* focusedTarget = nullptr;
|
|
Maybe<nscoord> x, y;
|
|
aSnapInfo.ForEachValidTargetFor(
|
|
aCurrentPosition, [&](const auto& aTarget) -> bool {
|
|
if (aTarget.mSnapPoint.mX && aSnapInfo.mScrollSnapStrictnessX !=
|
|
StyleScrollSnapStrictness::None) {
|
|
if (aLastSnapTargetIds->mIdsOnX.Contains(aTarget.mTargetId)) {
|
|
if (targetIdForFocusedContent == aTarget.mTargetId) {
|
|
// If we've already found the candidate on Y axis, but if snapping
|
|
// to the point results this target is scrolled out, we can't use
|
|
// it.
|
|
if ((y && !aTarget.mSnapArea.Intersects(
|
|
nsRect(nsPoint(*aTarget.mSnapPoint.mX, *y),
|
|
aSnapInfo.mSnapportSize)))) {
|
|
y.reset();
|
|
}
|
|
|
|
focusedTarget = &aTarget;
|
|
// If the focused one is valid, then it's the candidate.
|
|
x = aTarget.mSnapPoint.mX;
|
|
}
|
|
|
|
if (!x) {
|
|
// Update the candidate on X axis only if
|
|
// 1) we haven't yet found the candidate on Y axis
|
|
// 2) or if we've found the candiate on Y axis and if snapping to
|
|
// the
|
|
// candidate position result the target element is visible
|
|
// inside the snapport.
|
|
if (!y || (y && aTarget.mSnapArea.Intersects(
|
|
nsRect(nsPoint(*aTarget.mSnapPoint.mX, *y),
|
|
aSnapInfo.mSnapportSize)))) {
|
|
x = aTarget.mSnapPoint.mX;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (aTarget.mSnapPoint.mY && aSnapInfo.mScrollSnapStrictnessY !=
|
|
StyleScrollSnapStrictness::None) {
|
|
if (aLastSnapTargetIds->mIdsOnY.Contains(aTarget.mTargetId)) {
|
|
if (targetIdForFocusedContent == aTarget.mTargetId) {
|
|
NS_ASSERTION(
|
|
!focusedTarget || focusedTarget == &aTarget,
|
|
"If the focused target has been found on X axis, the "
|
|
"target should be same");
|
|
// If we've already found the candidate on X axis other than the
|
|
// focused one, but if snapping to the point results this target
|
|
// is scrolled out, we can't use it.
|
|
if (!focusedTarget &&
|
|
(x && !aTarget.mSnapArea.Intersects(
|
|
nsRect(nsPoint(*x, *aTarget.mSnapPoint.mY),
|
|
aSnapInfo.mSnapportSize)))) {
|
|
x.reset();
|
|
}
|
|
|
|
focusedTarget = &aTarget;
|
|
y = aTarget.mSnapPoint.mY;
|
|
}
|
|
|
|
if (!y) {
|
|
if (!x || (x && aTarget.mSnapArea.Intersects(
|
|
nsRect(nsPoint(*x, *aTarget.mSnapPoint.mY),
|
|
aSnapInfo.mSnapportSize)))) {
|
|
y = aTarget.mSnapPoint.mY;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// If we found candidates on both axes, it's the one we need.
|
|
if (x && y &&
|
|
// If we haven't found the focused target, it's possible that we
|
|
// haven't iterated it, don't break in such case.
|
|
(targetIdForFocusedContent == ScrollSnapTargetId::None ||
|
|
focusedTarget)) {
|
|
return false;
|
|
}
|
|
return true;
|
|
});
|
|
|
|
return {x, y};
|
|
}
|
|
|
|
Maybe<SnapDestination> ScrollSnapUtils::GetSnapPointForResnap(
|
|
const ScrollSnapInfo& aSnapInfo, const nsRect& aScrollRange,
|
|
const nsPoint& aCurrentPosition,
|
|
const UniquePtr<ScrollSnapTargetIds>& aLastSnapTargetIds,
|
|
const nsIContent* aFocusedContent) {
|
|
if (!aLastSnapTargetIds) {
|
|
return GetSnapPointForDestination(aSnapInfo, ScrollUnit::DEVICE_PIXELS,
|
|
ScrollSnapFlags::IntendedEndPosition,
|
|
aScrollRange, aCurrentPosition,
|
|
aCurrentPosition);
|
|
}
|
|
|
|
auto [x, y] = GetCandidateInLastTargets(aSnapInfo, aCurrentPosition,
|
|
aLastSnapTargetIds, aFocusedContent);
|
|
if (!x && !y) {
|
|
// In the worst case there's no longer valid snap points previously snapped,
|
|
// try to find new valid snap points.
|
|
return GetSnapPointForDestination(aSnapInfo, ScrollUnit::DEVICE_PIXELS,
|
|
ScrollSnapFlags::IntendedEndPosition,
|
|
aScrollRange, aCurrentPosition,
|
|
aCurrentPosition);
|
|
}
|
|
|
|
// If there's no candidate on one of the axes in the last snap points, try
|
|
// to find a new candidate.
|
|
if (!x || !y) {
|
|
nsPoint newPosition =
|
|
nsPoint(x ? *x : aCurrentPosition.x, y ? *y : aCurrentPosition.y);
|
|
CalcSnapPoints calcSnapPoints(ScrollUnit::DEVICE_PIXELS,
|
|
ScrollSnapFlags::IntendedEndPosition,
|
|
newPosition, newPosition);
|
|
|
|
aSnapInfo.ForEachValidTargetFor(
|
|
newPosition, [&, &x = x, &y = y](const auto& aTarget) -> bool {
|
|
if (!x && aTarget.mSnapPoint.mX &&
|
|
aSnapInfo.mScrollSnapStrictnessX !=
|
|
StyleScrollSnapStrictness::None) {
|
|
calcSnapPoints.AddVerticalEdge(aTarget);
|
|
}
|
|
if (!y && aTarget.mSnapPoint.mY &&
|
|
aSnapInfo.mScrollSnapStrictnessY !=
|
|
StyleScrollSnapStrictness::None) {
|
|
calcSnapPoints.AddHorizontalEdge(aTarget);
|
|
}
|
|
return true;
|
|
});
|
|
|
|
auto finalPos = calcSnapPoints.GetBestEdge(aSnapInfo.mSnapportSize);
|
|
if (!x) {
|
|
x = Some(finalPos.mPosition.x);
|
|
}
|
|
if (!y) {
|
|
y = Some(finalPos.mPosition.y);
|
|
}
|
|
}
|
|
|
|
SnapDestination snapTarget{nsPoint(*x, *y)};
|
|
// Collect snap points where the position is still same as the new snap
|
|
// position.
|
|
aSnapInfo.ForEachValidTargetFor(
|
|
snapTarget.mPosition, [&, &x = x, &y = y](const auto& aTarget) -> bool {
|
|
if (aTarget.mSnapPoint.mX &&
|
|
aSnapInfo.mScrollSnapStrictnessX !=
|
|
StyleScrollSnapStrictness::None &&
|
|
aTarget.mSnapPoint.mX == x) {
|
|
snapTarget.mTargetIds.mIdsOnX.AppendElement(aTarget.mTargetId);
|
|
}
|
|
|
|
if (aTarget.mSnapPoint.mY &&
|
|
aSnapInfo.mScrollSnapStrictnessY !=
|
|
StyleScrollSnapStrictness::None &&
|
|
aTarget.mSnapPoint.mY == y) {
|
|
snapTarget.mTargetIds.mIdsOnY.AppendElement(aTarget.mTargetId);
|
|
}
|
|
return true;
|
|
});
|
|
return Some(snapTarget);
|
|
}
|
|
|
|
void ScrollSnapUtils::PostPendingResnapIfNeededFor(nsIFrame* aFrame) {
|
|
ScrollSnapTargetId id = GetTargetIdFor(aFrame);
|
|
if (id == ScrollSnapTargetId::None) {
|
|
return;
|
|
}
|
|
|
|
if (ScrollContainerFrame* sf = nsLayoutUtils::GetNearestScrollContainerFrame(
|
|
aFrame, nsLayoutUtils::SCROLLABLE_SAME_DOC |
|
|
nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN)) {
|
|
sf->PostPendingResnapIfNeeded(aFrame);
|
|
}
|
|
}
|
|
|
|
void ScrollSnapUtils::PostPendingResnapFor(nsIFrame* aFrame) {
|
|
if (ScrollContainerFrame* sf = nsLayoutUtils::GetNearestScrollContainerFrame(
|
|
aFrame, nsLayoutUtils::SCROLLABLE_SAME_DOC |
|
|
nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN)) {
|
|
sf->PostPendingResnap();
|
|
}
|
|
}
|
|
|
|
bool ScrollSnapUtils::NeedsToRespectTargetWritingMode(
|
|
const nsSize& aSnapAreaSize, const nsSize& aSnapportSize) {
|
|
// Use the writing-mode on the target element if the snap area is larger than
|
|
// the snapport.
|
|
// https://drafts.csswg.org/css-scroll-snap/#snap-scope
|
|
//
|
|
// It's unclear `larger` means that the size is larger than only on the target
|
|
// axis. If it doesn't, it will pick the same axis in the case where only one
|
|
// axis is larger. For example, if an element size is (200 x 10) and the
|
|
// snapport size is (100 x 100) and if the element's writing mode is different
|
|
// from the scroller's writing mode, then `scroll-snap-align: start start`
|
|
// will be conflict.
|
|
return aSnapAreaSize.width > aSnapportSize.width ||
|
|
aSnapAreaSize.height > aSnapportSize.height;
|
|
}
|
|
|
|
static nsRect InflateByScrollMargin(const nsRect& aTargetRect,
|
|
const nsMargin& aScrollMargin,
|
|
const nsRect& aScrolledRect) {
|
|
// Inflate the rect by scroll-margin.
|
|
nsRect result = aTargetRect;
|
|
result.Inflate(aScrollMargin);
|
|
|
|
// But don't be beyond the limit boundary.
|
|
return result.Intersect(aScrolledRect);
|
|
}
|
|
|
|
nsRect ScrollSnapUtils::GetSnapAreaFor(const nsIFrame* aFrame,
|
|
const nsIFrame* aScrolledFrame,
|
|
const nsRect& aScrolledRect) {
|
|
nsRect targetRect = nsLayoutUtils::TransformFrameRectToAncestor(
|
|
aFrame, aFrame->GetRectRelativeToSelf(), aScrolledFrame);
|
|
|
|
// The snap area contains scroll-margin values.
|
|
// https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-area
|
|
nsMargin scrollMargin = aFrame->StyleMargin()->GetScrollMargin();
|
|
return InflateByScrollMargin(targetRect, scrollMargin, aScrolledRect);
|
|
}
|
|
|
|
} // namespace mozilla
|