gecko-dev/layout/generic/nsGridContainerFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code is subject to the terms of the Mozilla Public License
 * version 2.0 (the "License"). You can obtain a copy of the License at
 * http://mozilla.org/MPL/2.0/. */

/* rendering object for CSS "display: grid | inline-grid" */

#include "nsGridContainerFrame.h"

#include "nsCSSAnonBoxes.h"
#include "nsPresContext.h"
#include "nsReadableUtils.h"
#include "nsStyleContext.h"

using namespace mozilla;

/**
 * Search for the aNth occurrence of aName in aNameList (forward), starting at
 * the zero-based aFromIndex, and return the 1-based index (line number).
 * Also take into account there is an unconditional match at aImplicitLine
 * unless it's zero.
 * Return the last match if aNth occurrences can't be found, or zero if no
 * occurrence can be found.
 */
static uint32_t
FindLine(const nsString& aName, uint32_t aNth,
         uint32_t aFromIndex, uint32_t aImplicitLine,
         const nsTArray<nsTArray<nsString>>& aNameList)
{
  MOZ_ASSERT(aNth != 0);
  const uint32_t len = aNameList.Length();
  uint32_t lastFound = 0;
  uint32_t line;
  uint32_t i = aFromIndex;
  for (; i < len; i = line) {
    line = i + 1;
    if (line == aImplicitLine || aNameList[i].Contains(aName)) {
      lastFound = line;
      if (--aNth == 0) {
        return lastFound;
      }
    }
  }
  if (aImplicitLine > i) {
    // aImplicitLine is after the lines we searched above so it's last.
    // (grid-template-areas has more tracks than grid-template-[rows|columns])
    lastFound = aImplicitLine;
  }
  return lastFound;
}

/**
 * @see FindLine, this function does the same but searches in reverse.
 */
static uint32_t
RFindLine(const nsString& aName, uint32_t aNth,
          uint32_t aFromIndex, uint32_t aImplicitLine,
          const nsTArray<nsTArray<nsString>>& aNameList)
{
  MOZ_ASSERT(aNth != 0);
  const uint32_t len = aNameList.Length();
  uint32_t lastFound = 0;
  // The implicit line may be beyond the length of aNameList so we match this
  // line first if it's within the 0..aFromIndex range.
  if (aImplicitLine > len && aImplicitLine < aFromIndex) {
    lastFound = aImplicitLine;
    if (--aNth == 0) {
      return lastFound;
    }
  }
  uint32_t i = aFromIndex == 0 ? len : std::min(aFromIndex, len);
  for (; i; --i) {
    if (i == aImplicitLine || aNameList[i - 1].Contains(aName)) {
      lastFound = i;
      if (--aNth == 0) {
        break;
      }
    }
  }
  return lastFound;
}

static uint32_t
FindNamedLine(const nsString& aName, int32_t aNth,
              uint32_t aFromIndex, uint32_t aImplicitLine,
              const nsTArray<nsTArray<nsString>>& aNameList)
{
  MOZ_ASSERT(aNth != 0);
  if (aNth > 0) {
    return ::FindLine(aName, aNth, aFromIndex, aImplicitLine, aNameList);
  }
  return ::RFindLine(aName, -aNth, aFromIndex, aImplicitLine, aNameList);
}

/**
 * A convenience method to lookup a name in 'grid-template-areas'.
 * @param aStyle the StylePosition() for the grid container
 * @return null if not found
 */
static const css::GridNamedArea*
FindNamedArea(const nsSubstring& aName, const nsStylePosition* aStyle)
{
  if (!aStyle->mGridTemplateAreas) {
    return nullptr;
  }
  const nsTArray<css::GridNamedArea>& areas =
    aStyle->mGridTemplateAreas->mNamedAreas;
  size_t len = areas.Length();
  for (size_t i = 0; i < len; ++i) {
    const css::GridNamedArea& area = areas[i];
    if (area.mName == aName) {
      return &area;
    }
  }
  return nullptr;
}

// Return true if aString ends in aSuffix and has at least one character before
// the suffix. Assign aIndex to where the suffix starts.
static bool
IsNameWithSuffix(const nsString& aString, const nsString& aSuffix,
                 uint32_t* aIndex)
{
  if (StringEndsWith(aString, aSuffix)) {
    *aIndex = aString.Length() - aSuffix.Length();
    return *aIndex != 0;
  }
  return false;
}

static bool
IsNameWithEndSuffix(const nsString& aString, uint32_t* aIndex)
{
  return IsNameWithSuffix(aString, NS_LITERAL_STRING("-end"), aIndex);
}

static bool
IsNameWithStartSuffix(const nsString& aString, uint32_t* aIndex)
{
  return IsNameWithSuffix(aString, NS_LITERAL_STRING("-start"), aIndex);
}

//----------------------------------------------------------------------

// Frame class boilerplate
// =======================

NS_QUERYFRAME_HEAD(nsGridContainerFrame)
  NS_QUERYFRAME_ENTRY(nsGridContainerFrame)
NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)

NS_IMPL_FRAMEARENA_HELPERS(nsGridContainerFrame)

nsContainerFrame*
NS_NewGridContainerFrame(nsIPresShell* aPresShell,
                         nsStyleContext* aContext)
{
  return new (aPresShell) nsGridContainerFrame(aContext);
}


//----------------------------------------------------------------------

// nsGridContainerFrame Method Implementations
// ===========================================

void
nsGridContainerFrame::AddImplicitNamedAreas(
  const nsTArray<nsTArray<nsString>>& aLineNameLists)
{
  // http://dev.w3.org/csswg/css-grid/#implicit-named-areas
  // XXX this just checks x-start .. x-end in one dimension and there's
  // no other error checking.  A few wrong cases (maybe):
  // (x-start x-end)
  // (x-start) 0 (x-start) 0 (x-end)
  // (x-end) 0 (x-start) 0 (x-end)
  // (x-start) 0 (x-end) 0 (x-start) 0 (x-end)
  const uint32_t len = aLineNameLists.Length();
  nsTHashtable<nsStringHashKey> currentStarts;
  ImplicitNamedAreas* areas = GetImplicitNamedAreas();
  for (uint32_t i = 0; i < len; ++i) {
    const nsTArray<nsString>& names(aLineNameLists[i]);
    const uint32_t jLen = names.Length();
    for (uint32_t j = 0; j < jLen; ++j) {
      const nsString& name = names[j];
      uint32_t index;
      if (::IsNameWithStartSuffix(name, &index)) {
        currentStarts.PutEntry(nsDependentSubstring(name, 0, index));
      } else if (::IsNameWithEndSuffix(name, &index)) {
        nsDependentSubstring area(name, 0, index);
        if (currentStarts.Contains(area)) {
          if (!areas) {
            areas = new ImplicitNamedAreas;
            Properties().Set(ImplicitNamedAreasProperty(), areas);
          }
          areas->PutEntry(area);
        }
      }
    }
  }
}

void
nsGridContainerFrame::InitImplicitNamedAreas(const nsStylePosition* aStyle)
{
  ImplicitNamedAreas* areas = GetImplicitNamedAreas();
  if (areas) {
    // Clear it, but reuse the hashtable itself for now.  We'll remove it
    // below if it isn't needed anymore.
    areas->Clear();
  }
  AddImplicitNamedAreas(aStyle->mGridTemplateColumns.mLineNameLists);
  AddImplicitNamedAreas(aStyle->mGridTemplateRows.mLineNameLists);
  if (areas && areas->Count() == 0) {
    Properties().Delete(ImplicitNamedAreasProperty());
  }
}

uint32_t
nsGridContainerFrame::ResolveLine(
  const nsStyleGridLine& aLine,
  int32_t aNth,
  uint32_t aFromIndex,
  const nsTArray<nsTArray<nsString>>& aLineNameList,
  uint32_t GridNamedArea::* aAreaStart,
  uint32_t GridNamedArea::* aAreaEnd,
  uint32_t aExplicitGridEnd,
  LineRangeSide aSide,
  const nsStylePosition* aStyle)
{
  MOZ_ASSERT(!aLine.IsAuto());
  uint32_t line = 0;
  if (aLine.mLineName.IsEmpty()) {
    MOZ_ASSERT(aNth != 0, "css-grid 9.2: <integer> must not be zero.");
    line = std::max(int32_t(aFromIndex) + aNth, 1);
  } else {
    if (aNth == 0) {
      // <integer> was omitted; treat it as 1.
      aNth = 1;
    }
    bool isNameOnly = !aLine.mHasSpan && aLine.mInteger == 0;
    if (isNameOnly) {
      const GridNamedArea* area = ::FindNamedArea(aLine.mLineName, aStyle);
      if (area || HasImplicitNamedArea(aLine.mLineName)) {
        // The given name is a named area - look for explicit lines named
        // <name>-start/-end depending on which side we're resolving.
        // http://dev.w3.org/csswg/css-grid/#grid-placement-slot
        uint32_t implicitLine = 0;
        nsAutoString lineName(aLine.mLineName);
        if (aSide == eLineRangeSideStart) {
          lineName.AppendLiteral("-start");
          implicitLine = area ? area->*aAreaStart : 0;
        } else {
          lineName.AppendLiteral("-end");
          implicitLine = area ? area->*aAreaEnd : 0;
        }
        // XXX must Implicit Named Areas have all four lines?
        // http://dev.w3.org/csswg/css-grid/#implicit-named-areas
        line = ::FindNamedLine(lineName, aNth, aFromIndex, implicitLine,
                               aLineNameList);
      }
    }

    if (line == 0) {
      // If mLineName ends in -start/-end, try the prefix as a named area.
      uint32_t implicitLine = 0;
      uint32_t index;
      auto GridNamedArea::* areaEdge = aAreaStart;
      bool found = ::IsNameWithStartSuffix(aLine.mLineName, &index);
      if (!found) {
        found = ::IsNameWithEndSuffix(aLine.mLineName, &index);
        areaEdge = aAreaEnd;
      }
      if (found) {
        const GridNamedArea* area =
          ::FindNamedArea(nsDependentSubstring(aLine.mLineName, 0, index),
                          aStyle);
        if (area) {
          implicitLine = area->*areaEdge;
        }
      }
      line = ::FindNamedLine(aLine.mLineName, aNth, aFromIndex, implicitLine,
                             aLineNameList);
    }

    if (line == 0) {
      // No line matching <custom-ident> exists.
      if (aLine.mHasSpan) {
        // http://dev.w3.org/csswg/css-grid/#grid-placement-span-int
        // Treat 'span <custom-ident> N' as 'span N'.
        line = std::max(int32_t(aFromIndex) + aNth, 1);
      } else {
        // http://dev.w3.org/csswg/css-grid/#grid-placement-int
        // Treat '<custom-ident> N' as first/last line depending on N's sign.
        // XXX this is wrong due to a spec change, see bug 1009776 comment 17.
        // XXX we want to possibly expand the implicit grid here.
        line = aNth >= 0 ? 1 : aExplicitGridEnd;
      }
    }
  }
  // The only case which can result in "auto" (line == 0) is a plain
  // <custom-ident> (without <integer> or 'span') which wasn't found.
  MOZ_ASSERT(line != 0 || (!aLine.mHasSpan && aLine.mInteger == 0),
             "Given a <integer> or 'span' the result should never be auto");
  return line;
}

nsGridContainerFrame::LinePair
nsGridContainerFrame::ResolveLineRangeHelper(
  const nsStyleGridLine& aStart,
  const nsStyleGridLine& aEnd,
  const nsTArray<nsTArray<nsString>>& aLineNameList,
  uint32_t GridNamedArea::* aAreaStart,
  uint32_t GridNamedArea::* aAreaEnd,
  uint32_t aExplicitGridEnd,
  const nsStylePosition* aStyle)
{
  if (aStart.mHasSpan) {
    if (aEnd.mHasSpan || aEnd.IsAuto()) {
      // http://dev.w3.org/csswg/css-grid/#grid-placement-errors
      if (aStart.mLineName.IsEmpty()) {
        // span <integer> / span *
        // span <integer> / auto
        return LinePair(0, aStart.mInteger);
      }
      // span <custom-ident> / span *
      // span <custom-ident> / auto
      return LinePair(0, 1); // XXX subgrid explicit size instead of 1?
    }

    auto end = ResolveLine(aEnd, aEnd.mInteger, 0, aLineNameList, aAreaStart,
                           aAreaEnd, aExplicitGridEnd, eLineRangeSideEnd,
                           aStyle);
    if (end == 0) {
      // span * / <custom-ident> that can't be found
      return LinePair(0, aStart.mInteger);
    }
    int32_t span = aStart.mInteger == 0 ? 1 : aStart.mInteger;
    auto start = ResolveLine(aStart, -span, end, aLineNameList, aAreaStart,
                             aAreaEnd, aExplicitGridEnd, eLineRangeSideStart,
                             aStyle);
    MOZ_ASSERT(start > 0, "A start span can never resolve to 'auto'");
    return LinePair(start, end);
  }

  uint32_t start = 0;
  if (!aStart.IsAuto()) {
    start = ResolveLine(aStart, aStart.mInteger, 0, aLineNameList, aAreaStart,
                        aAreaEnd, aExplicitGridEnd, eLineRangeSideStart,
                        aStyle);
  }
  if (aEnd.IsAuto()) {
    // * (except span) / auto
    return LinePair(start, 1); // XXX subgrid explicit size instead of 1?
  }
  if (start == 0 && aEnd.mHasSpan) {
    if (aEnd.mLineName.IsEmpty()) {
      // auto (or not found <custom-ident>) / span <integer>
      MOZ_ASSERT(aEnd.mInteger != 0);
      return LinePair(0, aEnd.mInteger);
    }
    // http://dev.w3.org/csswg/css-grid/#grid-placement-errors
    // auto (or not found <custom-ident>) / span <custom-ident>
    return LinePair(0, 1); // XXX subgrid explicit size instead of 1?
  }

  uint32_t from = aEnd.mHasSpan ? start : 0;
  auto end = ResolveLine(aEnd, aEnd.mInteger, from, aLineNameList, aAreaStart,
                         aAreaEnd, aExplicitGridEnd, eLineRangeSideEnd, aStyle);
  if (end == 0) {
    // * (except span) / not found <custom-ident>
    end = 1; // XXX subgrid explicit size instead of 1?
  } else if (start == 0) {
    // auto (or not found <custom-ident>) / definite line
    start = std::max(1U, end - 1);
  }
  return LinePair(start, end);
}

nsGridContainerFrame::LineRange
nsGridContainerFrame::ResolveLineRange(
  const nsStyleGridLine& aStart,
  const nsStyleGridLine& aEnd,
  const nsTArray<nsTArray<nsString>>& aLineNameList,
  uint32_t GridNamedArea::* aAreaStart,
  uint32_t GridNamedArea::* aAreaEnd,
  uint32_t aExplicitGridEnd,
  const nsStylePosition* aStyle)
{
  LinePair r = ResolveLineRangeHelper(aStart, aEnd, aLineNameList, aAreaStart,
                                      aAreaEnd, aExplicitGridEnd, aStyle);
  MOZ_ASSERT(r.second != 0);

  // http://dev.w3.org/csswg/css-grid/#grid-placement-errors
  if (r.second <= r.first) {
    r.second = r.first + 1;
  }
  return LineRange(r.first, r.second);
}

nsGridContainerFrame::GridArea
nsGridContainerFrame::PlaceDefinite(nsIFrame* aChild,
                                    const nsStylePosition* aStyle)
{
  const nsStylePosition* itemStyle = aChild->StylePosition();
  return GridArea(
    ResolveLineRange(itemStyle->mGridColumnStart, itemStyle->mGridColumnEnd,
                     aStyle->mGridTemplateColumns.mLineNameLists,
                     &GridNamedArea::mColumnStart, &GridNamedArea::mColumnEnd,
                     mExplicitGridColEnd, aStyle),
    ResolveLineRange(itemStyle->mGridRowStart, itemStyle->mGridRowEnd,
                     aStyle->mGridTemplateRows.mLineNameLists,
                     &GridNamedArea::mRowStart, &GridNamedArea::mRowEnd,
                     mExplicitGridRowEnd, aStyle));
}

void
nsGridContainerFrame::InitializeGridBounds(const nsStylePosition* aStyle)
{
  // http://dev.w3.org/csswg/css-grid/#grid-definition
  uint32_t colEnd = aStyle->mGridTemplateColumns.mLineNameLists.Length();
  uint32_t rowEnd = aStyle->mGridTemplateRows.mLineNameLists.Length();
  auto areas = aStyle->mGridTemplateAreas.get();
  mExplicitGridColEnd = std::max(colEnd, areas ? areas->mNColumns + 1 : 1);
  mExplicitGridRowEnd = std::max(rowEnd, areas ? areas->NRows() + 1 : 1);
  mGridColEnd = mExplicitGridColEnd;
  mGridRowEnd = mExplicitGridRowEnd;
}

void
nsGridContainerFrame::PlaceGridItems(const nsStylePosition* aStyle)
{
  mCellMap.ClearOccupied();
  InitializeGridBounds(aStyle);

  // http://dev.w3.org/csswg/css-grid/#line-placement
  // Resolve definite positions per spec chap 9.2.
  for (nsFrameList::Enumerator e(PrincipalChildList()); !e.AtEnd(); e.Next()) {
    nsIFrame* child = e.get();
    const GridArea& area = PlaceDefinite(child, aStyle);
    GridArea* prop = GetGridAreaForChild(child);
    if (prop) {
      *prop = area;
    } else {
      child->Properties().Set(GridAreaProperty(), new GridArea(area));
    }
    if (area.IsDefinite()) {
      mCellMap.Fill(area);
      InflateGridFor(area);
    }
  }
}

void
nsGridContainerFrame::Reflow(nsPresContext*           aPresContext,
                             nsHTMLReflowMetrics&     aDesiredSize,
                             const nsHTMLReflowState& aReflowState,
                             nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("nsGridContainerFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);

  if (IsFrameTreeTooDeep(aReflowState, aDesiredSize, aStatus)) {
    return;
  }

#ifdef DEBUG
  SanityCheckAnonymousGridItems();
#endif // DEBUG

  LogicalMargin bp = aReflowState.ComputedLogicalBorderPadding();
  bp.ApplySkipSides(GetLogicalSkipSides());
  nscoord contentBSize = GetEffectiveComputedBSize(aReflowState);
  if (contentBSize == NS_AUTOHEIGHT) {
    contentBSize = 0;
  }
  WritingMode wm = aReflowState.GetWritingMode();
  LogicalSize finalSize(wm,
                        aReflowState.ComputedISize() + bp.IStartEnd(wm),
                        contentBSize + bp.BStartEnd(wm));
  aDesiredSize.SetSize(wm, finalSize);
  aDesiredSize.SetOverflowAreasToDesiredBounds();

  const nsStylePosition* stylePos = aReflowState.mStylePosition;
  InitImplicitNamedAreas(stylePos);
  PlaceGridItems(stylePos);

  aStatus = NS_FRAME_COMPLETE;
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
}

nsIAtom*
nsGridContainerFrame::GetType() const
{
  return nsGkAtoms::gridContainerFrame;
}

#ifdef DEBUG_FRAME_DUMP
nsresult
nsGridContainerFrame::GetFrameName(nsAString& aResult) const
{
  return MakeFrameName(NS_LITERAL_STRING("GridContainer"), aResult);
}
#endif

void
nsGridContainerFrame::CellMap::Fill(const GridArea& aGridArea)
{
  MOZ_ASSERT(aGridArea.IsDefinite());
  MOZ_ASSERT(aGridArea.mRows.mStart < aGridArea.mRows.mEnd);
  MOZ_ASSERT(aGridArea.mRows.mStart > 0);
  MOZ_ASSERT(aGridArea.mCols.mStart < aGridArea.mCols.mEnd);
  MOZ_ASSERT(aGridArea.mCols.mStart > 0);
  // Line numbers are 1-based so convert them to a zero-based index.
  const auto numRows = aGridArea.mRows.mEnd - 1;
  const auto numCols = aGridArea.mCols.mEnd - 1;
  mCells.EnsureLengthAtLeast(numRows);
  for (auto i = aGridArea.mRows.mStart - 1; i < numRows; ++i) {
    nsTArray<Cell>& cellsInRow = mCells[i];
    cellsInRow.EnsureLengthAtLeast(numCols);
    for (auto j = aGridArea.mCols.mStart - 1; j < numCols; ++j) {
      cellsInRow[j].mIsOccupied = true;
    }
  }
}

void
nsGridContainerFrame::CellMap::ClearOccupied()
{
  const size_t numRows = mCells.Length();
  for (size_t i = 0; i < numRows; ++i) {
    nsTArray<Cell>& cellsInRow = mCells[i];
    const size_t numCols = cellsInRow.Length();
    for (size_t j = 0; j < numCols; ++j) {
      cellsInRow[j].mIsOccupied = false;
    }
  }
}

#ifdef DEBUG
void
nsGridContainerFrame::CellMap::Dump() const
{
  const size_t numRows = mCells.Length();
  for (size_t i = 0; i < numRows; ++i) {
    const nsTArray<Cell>& cellsInRow = mCells[i];
    const size_t numCols = cellsInRow.Length();
    printf("%lu:\t", (unsigned long)i + 1);
    for (size_t j = 0; j < numCols; ++j) {
      printf(cellsInRow[j].mIsOccupied ? "X " : ". ");
    }
    printf("\n");
  }
}

static bool
FrameWantsToBeInAnonymousGridItem(nsIFrame* aFrame)
{
  // Note: This needs to match the logic in
  // nsCSSFrameConstructor::FrameConstructionItem::NeedsAnonFlexOrGridItem()
  return (aFrame->IsFrameOfType(nsIFrame::eLineParticipant) ||
          nsGkAtoms::placeholderFrame == aFrame->GetType());
}

// Debugging method, to let us assert that our anonymous grid items are
// set up correctly -- in particular, we assert:
//  (1) we don't have any inline non-replaced children
//  (2) we don't have any consecutive anonymous grid items
//  (3) we don't have any empty anonymous grid items
//  (4) all children are on the expected child lists
void
nsGridContainerFrame::SanityCheckAnonymousGridItems() const
{
  // XXX handle kOverflowContainersList / kExcessOverflowContainersList
  // when we implement fragmentation?
  ChildListIDs noCheckLists = kAbsoluteList | kFixedList;
  ChildListIDs checkLists = kPrincipalList | kOverflowList;
  for (nsIFrame::ChildListIterator childLists(this);
       !childLists.IsDone(); childLists.Next()) {
    if (!checkLists.Contains(childLists.CurrentID())) {
      MOZ_ASSERT(noCheckLists.Contains(childLists.CurrentID()),
                 "unexpected non-empty child list");
      continue;
    }

    bool prevChildWasAnonGridItem = false;
    nsFrameList children = childLists.CurrentList();
    for (nsFrameList::Enumerator e(children); !e.AtEnd(); e.Next()) {
      nsIFrame* child = e.get();
      MOZ_ASSERT(!FrameWantsToBeInAnonymousGridItem(child),
                 "frame wants to be inside an anonymous grid item, "
                 "but it isn't");
      if (child->StyleContext()->GetPseudo() ==
            nsCSSAnonBoxes::anonymousGridItem) {
/*
  XXX haven't decided yet whether to reorder children or not.
  XXX If we do, we want this assertion instead of the one below.
        MOZ_ASSERT(!prevChildWasAnonGridItem ||
                   HasAnyStateBits(NS_STATE_GRID_CHILDREN_REORDERED),
                   "two anon grid items in a row (shouldn't happen, unless our "
                   "children have been reordered with the 'order' property)");
*/
        MOZ_ASSERT(!prevChildWasAnonGridItem, "two anon grid items in a row");
        nsIFrame* firstWrappedChild = child->GetFirstPrincipalChild();
        MOZ_ASSERT(firstWrappedChild,
                   "anonymous grid item is empty (shouldn't happen)");
        prevChildWasAnonGridItem = true;
      } else {
        prevChildWasAnonGridItem = false;
      }
    }
  }
}
#endif // DEBUG