tor-browser

The Tor Browser
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ScrollSnapInfo.cpp (3643B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #include "ScrollSnapInfo.h"
      8 
      9 #include "mozilla/WritingModes.h"
     10 #include "nsPoint.h"
     11 #include "nsRect.h"
     12 #include "nsStyleStruct.h"
     13 
     14 namespace mozilla {
     15 
     16 ScrollSnapInfo::ScrollSnapInfo()
     17    : mScrollSnapStrictnessX(StyleScrollSnapStrictness::None),
     18      mScrollSnapStrictnessY(StyleScrollSnapStrictness::None) {}
     19 
     20 bool ScrollSnapInfo::HasScrollSnapping() const {
     21  return mScrollSnapStrictnessY != StyleScrollSnapStrictness::None ||
     22         mScrollSnapStrictnessX != StyleScrollSnapStrictness::None;
     23 }
     24 
     25 bool ScrollSnapInfo::HasSnapPositions() const {
     26  if (!HasScrollSnapping()) {
     27    return false;
     28  }
     29 
     30  for (const auto& target : mSnapTargets) {
     31    if ((target.mSnapPoint.mX &&
     32         mScrollSnapStrictnessX != StyleScrollSnapStrictness::None) ||
     33        (target.mSnapPoint.mY &&
     34         mScrollSnapStrictnessY != StyleScrollSnapStrictness::None)) {
     35      return true;
     36    }
     37  }
     38  return false;
     39 }
     40 
     41 void ScrollSnapInfo::InitializeScrollSnapStrictness(
     42    WritingMode aWritingMode, const nsStyleDisplay* aDisplay) {
     43  if (aDisplay->mScrollSnapType.strictness == StyleScrollSnapStrictness::None) {
     44    return;
     45  }
     46 
     47  mScrollSnapStrictnessX = StyleScrollSnapStrictness::None;
     48  mScrollSnapStrictnessY = StyleScrollSnapStrictness::None;
     49 
     50  switch (aDisplay->mScrollSnapType.axis) {
     51    case StyleScrollSnapAxis::X:
     52      mScrollSnapStrictnessX = aDisplay->mScrollSnapType.strictness;
     53      break;
     54    case StyleScrollSnapAxis::Y:
     55      mScrollSnapStrictnessY = aDisplay->mScrollSnapType.strictness;
     56      break;
     57    case StyleScrollSnapAxis::Block:
     58      if (aWritingMode.IsVertical()) {
     59        mScrollSnapStrictnessX = aDisplay->mScrollSnapType.strictness;
     60      } else {
     61        mScrollSnapStrictnessY = aDisplay->mScrollSnapType.strictness;
     62      }
     63      break;
     64    case StyleScrollSnapAxis::Inline:
     65      if (aWritingMode.IsVertical()) {
     66        mScrollSnapStrictnessY = aDisplay->mScrollSnapType.strictness;
     67      } else {
     68        mScrollSnapStrictnessX = aDisplay->mScrollSnapType.strictness;
     69      }
     70      break;
     71    case StyleScrollSnapAxis::Both:
     72      mScrollSnapStrictnessX = aDisplay->mScrollSnapType.strictness;
     73      mScrollSnapStrictnessY = aDisplay->mScrollSnapType.strictness;
     74      break;
     75  }
     76 }
     77 
     78 void ScrollSnapInfo::ForEachValidTargetFor(
     79    const nsPoint& aDestination,
     80    const std::function<bool(const SnapTarget&)>& aFunc) const {
     81  for (const auto& target : mSnapTargets) {
     82    nsPoint snapPoint(
     83        mScrollSnapStrictnessX != StyleScrollSnapStrictness::None &&
     84                target.mSnapPoint.mX
     85            ? *target.mSnapPoint.mX
     86            : aDestination.x,
     87        mScrollSnapStrictnessY != StyleScrollSnapStrictness::None &&
     88                target.mSnapPoint.mY
     89            ? *target.mSnapPoint.mY
     90            : aDestination.y);
     91    nsRect snappedPort = nsRect(snapPoint, mSnapportSize);
     92    // Ignore snap points if snapping to the point would leave the snap area
     93    // outside of the snapport.
     94    // https://drafts.csswg.org/css-scroll-snap-1/#snap-scope
     95    //
     96    // NOTE: We don't use BaseRect::Intersects() here since the function returns
     97    // false in cases where the given rectangle is empty.
     98    if (!snappedPort.EdgeInclusiveIntersection(target.mSnapArea)) {
     99      continue;
    100    }
    101 
    102    if (!aFunc(target)) {
    103      break;
    104    }
    105  }
    106 }
    107 
    108 }  // namespace mozilla