tor-browser

GridLines.cpp (14816B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "GridLines.h"

#include "GridDimension.h"
#include "GridLine.h"
#include "mozilla/dom/GridArea.h"
#include "mozilla/dom/GridBinding.h"
#include "nsGridContainerFrame.h"

namespace mozilla::dom {

NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridLines, mParent, mLines)
NS_IMPL_CYCLE_COLLECTING_ADDREF(GridLines)
NS_IMPL_CYCLE_COLLECTING_RELEASE(GridLines)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridLines)
 NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
 NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

GridLines::GridLines(GridDimension* aParent) : mParent(aParent) {
 MOZ_ASSERT(aParent, "Should never be instantiated with a null GridDimension");
}

GridLines::~GridLines() = default;

JSObject* GridLines::WrapObject(JSContext* aCx,
                               JS::Handle<JSObject*> aGivenProto) {
 return GridLines_Binding::Wrap(aCx, this, aGivenProto);
}

uint32_t GridLines::Length() const { return mLines.Length(); }

GridLine* GridLines::Item(uint32_t aIndex) {
 return mLines.SafeElementAt(aIndex);
}

GridLine* GridLines::IndexedGetter(uint32_t aIndex, bool& aFound) {
 aFound = aIndex < mLines.Length();
 if (!aFound) {
   return nullptr;
 }
 return mLines[aIndex];
}

static void AddLineNameIfNotPresent(nsTArray<RefPtr<nsAtom>>& aLineNames,
                                   nsAtom* aName) {
 if (!aLineNames.Contains(aName)) {
   aLineNames.AppendElement(aName);
 }
}

static void AddLineNamesIfNotPresent(nsTArray<RefPtr<nsAtom>>& aLineNames,
                                    const nsTArray<RefPtr<nsAtom>>& aNames) {
 for (const auto& name : aNames) {
   AddLineNameIfNotPresent(aLineNames, name);
 }
}

void GridLines::SetLineInfo(const ComputedGridTrackInfo* aTrackInfo,
                           const ComputedGridLineInfo* aLineInfo,
                           const nsTArray<RefPtr<GridArea>>& aAreas,
                           bool aIsRow) {
 MOZ_ASSERT(aLineInfo);
 mLines.Clear();

 if (!aTrackInfo) {
   return;
 }

 uint32_t lineCount =
     aTrackInfo->mEndFragmentTrack - aTrackInfo->mStartFragmentTrack + 1;

 // If there is at least one track, line count is one more
 // than the number of tracks.
 if (lineCount > 0) {
   nscoord lastTrackEdge = 0;
   nscoord startOfNextTrack;
   uint32_t repeatIndex = 0;
   uint32_t numRepeatTracks = aTrackInfo->mRemovedRepeatTracks.Length();
   uint32_t numAddedLines = 0;

   // For the calculation of negative line numbers, we need to know
   // the total number of leading implicit and explicit tracks.
   // This might be different from the number of tracks sizes in
   // aTrackInfo, because some of those tracks may be auto-fits that
   // have been removed.
   uint32_t leadingTrackCount =
       aTrackInfo->mNumLeadingImplicitTracks + aTrackInfo->mNumExplicitTracks;
   if (numRepeatTracks > 0) {
     for (auto& removedTrack : aTrackInfo->mRemovedRepeatTracks) {
       if (removedTrack) {
         ++leadingTrackCount;
       }
     }
   }

   for (uint32_t i = aTrackInfo->mStartFragmentTrack;
        i < aTrackInfo->mEndFragmentTrack + 1; i++) {
     // Since line indexes are 1-based, calculate a 1-based value
     // for this track to simplify some calculations.
     const uint32_t line1Index = i + 1;

     startOfNextTrack = (i < aTrackInfo->mEndFragmentTrack)
                            ? aTrackInfo->mPositions[i]
                            : lastTrackEdge;

     // Get the line names for the current line. aLineInfo->mNames
     // may contain duplicate names. This is intentional, since grid
     // layout works fine with duplicate names, and we don't want to
     // detect and remove duplicates in layout since it is an O(n^2)
     // problem. We do the work here since this is only run when
     // requested by devtools, and slowness here will not affect
     // normal browsing.
     nsTArray<RefPtr<nsAtom>> empty{};
     const nsTArray<RefPtr<nsAtom>>& possiblyDuplicateLineNames(
         aLineInfo->mNames.SafeElementAt(i, empty));

     nsTArray<RefPtr<nsAtom>> lineNames;
     AddLineNamesIfNotPresent(lineNames, possiblyDuplicateLineNames);

     // Add in names from grid areas where this line is used as a boundary.
     for (auto area : aAreas) {
       // We specifically ignore line names from implicitly named areas,
       // because it can be confusing for designers who might naturally use
       // a named line of "-start" or "-end" and create an implicit named
       // area without meaning to.
       if (area->Type() == GridDeclaration::Implicit) {
         continue;
       }

       bool haveNameToAdd = false;
       nsAutoString nameToAdd;
       area->GetName(nameToAdd);
       if (aIsRow) {
         if (area->RowStart() == line1Index) {
           haveNameToAdd = true;
           nameToAdd.AppendLiteral("-start");
         } else if (area->RowEnd() == line1Index) {
           haveNameToAdd = true;
           nameToAdd.AppendLiteral("-end");
         }
       } else {
         if (area->ColumnStart() == line1Index) {
           haveNameToAdd = true;
           nameToAdd.AppendLiteral("-start");
         } else if (area->ColumnEnd() == line1Index) {
           haveNameToAdd = true;
           nameToAdd.AppendLiteral("-end");
         }
       }

       if (haveNameToAdd) {
         RefPtr<nsAtom> name = NS_Atomize(nameToAdd);
         AddLineNameIfNotPresent(lineNames, name);
       }
     }

     if (i >= (aTrackInfo->mRepeatFirstTrack +
               aTrackInfo->mNumLeadingImplicitTracks) &&
         repeatIndex < numRepeatTracks) {
       numAddedLines += AppendRemovedAutoFits(
           aTrackInfo, aLineInfo, lastTrackEdge, repeatIndex, numRepeatTracks,
           leadingTrackCount, lineNames);
     }

     // If this line is the one that ends a repeat, then add
     // in the mNamesFollowingRepeat names from aLineInfo.
     if (numRepeatTracks > 0 && i == (aTrackInfo->mRepeatFirstTrack +
                                      aTrackInfo->mNumLeadingImplicitTracks +
                                      numRepeatTracks - numAddedLines)) {
       AddLineNamesIfNotPresent(lineNames, aLineInfo->mNamesFollowingRepeat);
     }

     RefPtr<GridLine> line = new GridLine(this);
     mLines.AppendElement(line);
     MOZ_ASSERT(line1Index > 0, "line1Index must be positive.");
     bool isBeforeFirstExplicit =
         (line1Index <= aTrackInfo->mNumLeadingImplicitTracks);
     bool isAfterLastExplicit = line1Index > (leadingTrackCount + 1);
     // Calculate an actionable line number for this line, that could be used
     // in a css grid property to align a grid item or area at that line.
     // For implicit lines that appear before line 1, report a number of 0.
     // We can't report negative indexes, because those have a different
     // meaning in the css grid spec (negative indexes are negative-1-based
     // from the end of the grid decreasing towards the front).
     uint32_t lineNumber = isBeforeFirstExplicit
                               ? 0
                               : (line1Index + numAddedLines -
                                  aTrackInfo->mNumLeadingImplicitTracks);

     // The negativeNumber is counted back from the leadingTrackCount.
     int32_t lineNegativeNumber =
         isAfterLastExplicit
             ? 0
             : (line1Index + numAddedLines - (leadingTrackCount + 2));
     GridDeclaration lineType = (isBeforeFirstExplicit || isAfterLastExplicit)
                                    ? GridDeclaration::Implicit
                                    : GridDeclaration::Explicit;
     line->SetLineValues(
         lineNames, nsPresContext::AppUnitsToDoubleCSSPixels(lastTrackEdge),
         nsPresContext::AppUnitsToDoubleCSSPixels(startOfNextTrack -
                                                  lastTrackEdge),
         lineNumber, lineNegativeNumber, lineType);

     if (i < aTrackInfo->mEndFragmentTrack) {
       lastTrackEdge = aTrackInfo->mPositions[i] + aTrackInfo->mSizes[i];
     }
   }

   // Define a function that gets the mLines index for a given line number.
   // This is necessary since it's possible for a line number to not be
   // represented in mLines. If this is the case, then return  -1.
   const int32_t lineCount = mLines.Length();
   const uint32_t lastLineNumber = mLines[lineCount - 1]->Number();
   auto IndexForLineNumber =
       [lineCount, lastLineNumber](uint32_t aLineNumber) -> int32_t {
     if (lastLineNumber == 0) {
       // None of the lines have addressable numbers, so none of them can have
       // aLineNumber
       return -1;
     }

     int32_t possibleIndex = (int32_t)aLineNumber - 1;
     if (possibleIndex < 0 || possibleIndex > lineCount - 1) {
       // aLineNumber is not represented in mLines.
       return -1;
     }

     return possibleIndex;
   };

   // Post-processing loop for implicit grid areas.
   for (const auto& area : aAreas) {
     if (area->Type() == GridDeclaration::Implicit) {
       // Get the appropriate indexes for the area's start and end lines as
       // they are represented in mLines.
       int32_t startIndex =
           IndexForLineNumber(aIsRow ? area->RowStart() : area->ColumnStart());
       int32_t endIndex =
           IndexForLineNumber(aIsRow ? area->RowEnd() : area->ColumnEnd());

       // If both start and end indexes are -1, then stop here since we cannot
       // reason about the naming for either lines.
       if (startIndex < 0 && endIndex < 0) {
         break;
       }

       // Get the "-start" and "-end" line names of the grid area.
       nsAutoString startLineName;
       area->GetName(startLineName);
       startLineName.AppendLiteral("-start");
       nsAutoString endLineName;
       area->GetName(endLineName);
       endLineName.AppendLiteral("-end");

       // Get the list of existing line names for the start and end of the grid
       // area. In the case where one of the start or end indexes are -1, use a
       // dummy line as a substitute for the start/end line.
       RefPtr<GridLine> dummyLine = new GridLine(this);
       RefPtr<GridLine> areaStartLine =
           startIndex > -1 ? mLines[startIndex] : dummyLine;
       nsTArray<RefPtr<nsAtom>> startLineNames(areaStartLine->Names().Clone());

       RefPtr<GridLine> areaEndLine =
           endIndex > -1 ? mLines[endIndex] : dummyLine;
       nsTArray<RefPtr<nsAtom>> endLineNames(areaEndLine->Names().Clone());

       RefPtr<nsAtom> start = NS_Atomize(startLineName);
       RefPtr<nsAtom> end = NS_Atomize(endLineName);
       if (startLineNames.Contains(end) || endLineNames.Contains(start)) {
         // Add the reversed line names.
         AddLineNameIfNotPresent(startLineNames, end);
         AddLineNameIfNotPresent(endLineNames, start);
       } else {
         // Add the normal line names.
         AddLineNameIfNotPresent(startLineNames, start);
         AddLineNameIfNotPresent(endLineNames, end);
       }

       areaStartLine->SetLineNames(startLineNames);
       areaEndLine->SetLineNames(endLineNames);
     }
   }
 }
}

uint32_t GridLines::AppendRemovedAutoFits(
   const ComputedGridTrackInfo* aTrackInfo,
   const ComputedGridLineInfo* aLineInfo, nscoord aLastTrackEdge,
   uint32_t& aRepeatIndex, uint32_t aNumRepeatTracks,
   uint32_t aNumLeadingTracks, nsTArray<RefPtr<nsAtom>>& aLineNames) {
 bool extractedExplicitLineNames = false;
 nsTArray<RefPtr<nsAtom>> explicitLineNames;
 uint32_t linesAdded = 0;
 while (aRepeatIndex < aNumRepeatTracks &&
        aTrackInfo->mRemovedRepeatTracks[aRepeatIndex]) {
   // If this is not the very first call to this function, and if we
   // haven't already added a line this call, pull all the explicit
   // names to pass along to the next line that will be added after
   // this function completes.
   if (aRepeatIndex > 0 && linesAdded == 0) {
     // Find the names that didn't match the before or after names,
     // and extract them.
     for (const auto& name : aLineNames) {
       if (!aLineInfo->mNamesBefore.Contains(name) &&
           !aLineInfo->mNamesAfter.Contains(name)) {
         explicitLineNames.AppendElement(name);
       }
     }
     for (const auto& extractedName : explicitLineNames) {
       aLineNames.RemoveElement(extractedName);
     }
     extractedExplicitLineNames = true;
   }

   AddLineNamesIfNotPresent(aLineNames, aLineInfo->mNamesBefore);

   RefPtr<GridLine> line = new GridLine(this);
   mLines.AppendElement(line);

   // Time to calculate the line numbers. For the positive numbers
   // we count with a 1-based index from mRepeatFirstTrack. Although
   // this number is the index of the first repeat track AFTER all
   // the leading implicit tracks, that's still what we want since
   // all those leading implicit tracks have line number 0.
   uint32_t lineNumber = aTrackInfo->mRepeatFirstTrack + aRepeatIndex + 1;

   // The negative number does have to account for the leading
   // implicit tracks. We've been passed aNumLeadingTracks which is
   // the total of the leading implicit tracks plus the explicit
   // tracks. So all we have to do is subtract that number plus one
   // from the 0-based index of this track.
   int32_t lineNegativeNumber =
       (aTrackInfo->mNumLeadingImplicitTracks + aTrackInfo->mRepeatFirstTrack +
        aRepeatIndex) -
       (aNumLeadingTracks + 1);
   line->SetLineValues(
       aLineNames, nsPresContext::AppUnitsToDoubleCSSPixels(aLastTrackEdge),
       nsPresContext::AppUnitsToDoubleCSSPixels(0), lineNumber,
       lineNegativeNumber, GridDeclaration::Explicit);

   // No matter what, the next line should have the after names associated
   // with it. If we go through the loop again, the before names will also
   // be added.
   aLineNames = aLineInfo->mNamesAfter.Clone();
   aRepeatIndex++;

   linesAdded++;
 }

 aRepeatIndex++;

 if (extractedExplicitLineNames) {
   // Pass on the explicit names we saved to the next explicit line.
   AddLineNamesIfNotPresent(aLineNames, explicitLineNames);
 }

 // If we haven't finished adding auto-repeated tracks, then we need to put
 // back the before names, in case we cleared them above.
 if (aRepeatIndex < aNumRepeatTracks) {
   AddLineNamesIfNotPresent(aLineNames, aLineInfo->mNamesBefore);
 }

 return linesAdded;
}

}  // namespace mozilla::dom