src/third_party/WebKit/Source/core/rendering/style/GridResolvedPosition.cpp

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/rendering/style/GridResolvedPosition.h"
   7
   8 #include "core/rendering/RenderBox.h"
   9 #include "core/rendering/style/GridCoordinate.h"
  10
  11 namespace blink {
  12
  13 static const NamedGridLinesMap& gridLinesForSide(const RenderStyle& style, GridPositionSide side)
  14 {
  15     return (side == ColumnStartSide || side == ColumnEndSide) ? style.namedGridColumnLines() : style.namedGridRowLines();
  16 }
  17
  18 static inline String implicitNamedGridLineForSide(const String& lineName, GridPositionSide side)
  19 {
  20     return lineName + ((side == ColumnStartSide || side == RowStartSide) ? "-start" : "-end");
  21 }
  22
  23 static bool isValidNamedLineOrArea(const String& lineName, const RenderStyle& style, GridPositionSide side)
  24 {
  25     const NamedGridLinesMap& gridLineNames = gridLinesForSide(style, side);
  26
  27     return gridLineNames.contains(implicitNamedGridLineForSide(lineName, side)) || gridLineNames.contains(lineName);
  28 }
  29
  30 static GridPositionSide calculateInitialPositionSide(GridTrackSizingDirection direction)
  31 {
  32     return (direction == ForColumns) ? ColumnStartSide : RowStartSide;
  33 }
  34
  35 static GridPositionSide calculateFinalPositionSide(GridTrackSizingDirection direction)
  36 {
  37     return (direction == ForColumns) ? ColumnEndSide : RowEndSide;
  38 }
  39
  40 void GridResolvedPosition::initialAndFinalPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction, GridPosition& initialPosition, GridPosition& finalPosition)
  41 {
  42     initialPosition = (direction == ForColumns) ? gridItem.style()->gridColumnStart() : gridItem.style()->gridRowStart();
  43     finalPosition = (direction == ForColumns) ? gridItem.style()->gridColumnEnd() : gridItem.style()->gridRowEnd();
  44     GridPositionSide initialPositionSide = calculateInitialPositionSide(direction);
  45     GridPositionSide finalPositionSide = calculateFinalPositionSide(direction);
  46
  47     // We must handle the placement error handling code here instead of in the StyleAdjuster because we don't want to
  48     // overwrite the specified values.
  49     if (initialPosition.isSpan() && finalPosition.isSpan())
  50         finalPosition.setAutoPosition();
  51
  52     // Try to early detect the case of non existing named grid lines. This way we could assume later that
  53     // GridResolvedPosition::resolveGrisPositionFromStyle() always return a valid resolved position.
  54     if (initialPosition.isNamedGridArea() && !isValidNamedLineOrArea(initialPosition.namedGridLine(), gridContainerStyle, initialPositionSide))
  55         initialPosition.setAutoPosition();
  56
  57     if (finalPosition.isNamedGridArea() && !isValidNamedLineOrArea(finalPosition.namedGridLine(), gridContainerStyle, finalPositionSide))
  58         finalPosition.setAutoPosition();
  59
  60     // If the grid item has an automatic position and a grid span for a named line in a given dimension, instead treat the grid span as one.
  61     if (initialPosition.isAuto() && finalPosition.isSpan() && !finalPosition.namedGridLine().isNull())
  62         finalPosition.setSpanPosition(1, String());
  63     if (finalPosition.isAuto() && initialPosition.isSpan() && !initialPosition.namedGridLine().isNull())
  64         initialPosition.setSpanPosition(1, String());
  65 }
  66
  67 GridSpan GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction, const GridResolvedPosition& resolvedInitialPosition)
  68 {
  69     GridPosition initialPosition, finalPosition;
  70     initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
  71
  72     GridPositionSide finalPositionSide = calculateFinalPositionSide(direction);
  73
  74     // This method will only be used when both positions need to be resolved against the opposite one.
  75     ASSERT(initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition());
  76
  77     GridResolvedPosition resolvedFinalPosition = resolvedInitialPosition;
  78
  79     if (initialPosition.isSpan()) {
  80         resolvedFinalPosition = resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, initialPosition, finalPositionSide)->resolvedFinalPosition;
  81     } else if (finalPosition.isSpan()) {
  82         resolvedFinalPosition = resolveGridPositionAgainstOppositePosition(gridContainerStyle, resolvedInitialPosition, finalPosition, finalPositionSide)->resolvedFinalPosition;
  83     }
  84
  85     return GridSpan(resolvedInitialPosition, resolvedFinalPosition);
  86 }
  87
  88 PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction)
  89 {
  90     GridPosition initialPosition, finalPosition;
  91     initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
  92
  93     GridPositionSide initialPositionSide = calculateInitialPositionSide(direction);
  94     GridPositionSide finalPositionSide = calculateFinalPositionSide(direction);
  95
  96     if (initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition()) {
  97         // FIXME: Implement properly "stack" value in auto-placement algorithm.
  98         if (gridContainerStyle.isGridAutoFlowAlgorithmStack())
  99             return adoptPtr(new GridSpan(0, 0));
 100
 101         // We can't get our grid positions without running the auto placement algorithm.
 102         return nullptr;
 103     }
 104
 105     if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
 106         // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
 107         GridResolvedPosition finalResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalPositionSide);
 108         return resolveGridPositionAgainstOppositePosition(gridContainerStyle, finalResolvedPosition, initialPosition, initialPositionSide);
 109     }
 110
 111     if (finalPosition.shouldBeResolvedAgainstOppositePosition()) {
 112         // Infer our position from the initial position ('1 / auto' or '3 / span 2' case).
 113         GridResolvedPosition initialResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialPositionSide);
 114         return resolveGridPositionAgainstOppositePosition(gridContainerStyle, initialResolvedPosition, finalPosition, finalPositionSide);
 115     }
 116
 117     GridResolvedPosition resolvedInitialPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialPositionSide);
 118     GridResolvedPosition resolvedFinalPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalPositionSide);
 119
 120     // If 'grid-after' specifies a line at or before that specified by 'grid-before', it computes to 'span 1'.
 121     if (resolvedFinalPosition < resolvedInitialPosition)
 122         resolvedFinalPosition = resolvedInitialPosition;
 123
 124     return adoptPtr(new GridSpan(resolvedInitialPosition, resolvedFinalPosition));
 125 }
 126
 127 size_t GridResolvedPosition::explicitGridColumnCount(const RenderStyle& gridContainerStyle)
 128 {
 129     return gridContainerStyle.gridTemplateColumns().size();
 130 }
 131
 132 size_t GridResolvedPosition::explicitGridRowCount(const RenderStyle& gridContainerStyle)
 133 {
 134     return gridContainerStyle.gridTemplateRows().size();
 135 }
 136
 137 size_t GridResolvedPosition::explicitGridSizeForSide(const RenderStyle& gridContainerStyle, GridPositionSide side)
 138 {
 139     return (side == ColumnStartSide || side == ColumnEndSide) ? explicitGridColumnCount(gridContainerStyle) : explicitGridRowCount(gridContainerStyle);
 140 }
 141
 142 GridResolvedPosition GridResolvedPosition::resolveNamedGridLinePositionFromStyle(const RenderStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
 143 {
 144     ASSERT(!position.namedGridLine().isNull());
 145
 146     const NamedGridLinesMap& gridLinesNames = gridLinesForSide(gridContainerStyle, side);
 147     NamedGridLinesMap::const_iterator it = gridLinesNames.find(position.namedGridLine());
 148     if (it == gridLinesNames.end()) {
 149         if (position.isPositive())
 150             return GridResolvedPosition(0);
 151         const size_t lastLine = explicitGridSizeForSide(gridContainerStyle, side);
 152         return adjustGridPositionForSide(lastLine, side);
 153     }
 154
 155     size_t namedGridLineIndex;
 156     if (position.isPositive())
 157         namedGridLineIndex = std::min<size_t>(position.integerPosition(), it->value.size()) - 1;
 158     else
 159         namedGridLineIndex = std::max<int>(it->value.size() - abs(position.integerPosition()), 0);
 160     return adjustGridPositionForSide(it->value[namedGridLineIndex], side);
 161 }
 162
 163 GridResolvedPosition GridResolvedPosition::resolveGridPositionFromStyle(const RenderStyle& gridContainerStyle, const GridPosition& position, GridPositionSide side)
 164 {
 165     switch (position.type()) {
 166     case ExplicitPosition: {
 167         ASSERT(position.integerPosition());
 168
 169         if (!position.namedGridLine().isNull())
 170             return resolveNamedGridLinePositionFromStyle(gridContainerStyle, position, side);
 171
 172         // Handle <integer> explicit position.
 173         if (position.isPositive())
 174             return adjustGridPositionForSide(position.integerPosition() - 1, side);
 175
 176         size_t resolvedPosition = abs(position.integerPosition()) - 1;
 177         const size_t endOfTrack = explicitGridSizeForSide(gridContainerStyle, side);
 178
 179         // Per http://lists.w3.org/Archives/Public/www-style/2013Mar/0589.html, we clamp negative value to the first line.
 180         if (endOfTrack < resolvedPosition)
 181             return GridResolvedPosition(0);
 182
 183         return adjustGridPositionForSide(endOfTrack - resolvedPosition, side);
 184     }
 185     case NamedGridAreaPosition:
 186     {
 187         // First attempt to match the grid area’s edge to a named grid area: if there is a named line with the name
 188         // ''<custom-ident>-start (for grid-*-start) / <custom-ident>-end'' (for grid-*-end), contributes the first such
 189         // line to the grid item’s placement.
 190         String namedGridLine = position.namedGridLine();
 191         ASSERT(isValidNamedLineOrArea(namedGridLine, gridContainerStyle, side));
 192
 193         const NamedGridLinesMap& gridLineNames = gridLinesForSide(gridContainerStyle, side);
 194         NamedGridLinesMap::const_iterator implicitLineIter = gridLineNames.find(implicitNamedGridLineForSide(namedGridLine, side));
 195         if (implicitLineIter != gridLineNames.end())
 196             return adjustGridPositionForSide(implicitLineIter->value[0], side);
 197
 198         // Otherwise, if there is a named line with the specified name, contributes the first such line to the grid
 199         // item’s placement.
 200         NamedGridLinesMap::const_iterator explicitLineIter = gridLineNames.find(namedGridLine);
 201         if (explicitLineIter != gridLineNames.end())
 202             return adjustGridPositionForSide(explicitLineIter->value[0], side);
 203
 204         // If none of the above works specs mandate us to treat it as auto BUT we should have detected it before calling
 205         // this function in GridResolvedPosition::resolveGridPositionsFromStyle(). We should be also covered by the
 206         // ASSERT at the beginning of this block.
 207         ASSERT_NOT_REACHED();
 208         return GridResolvedPosition(0);
 209     }
 210     case AutoPosition:
 211     case SpanPosition:
 212         // 'auto' and span depend on the opposite position for resolution (e.g. grid-row: auto / 1 or grid-column: span 3 / "myHeader").
 213         ASSERT_NOT_REACHED();
 214         return GridResolvedPosition(0);
 215     }
 216     ASSERT_NOT_REACHED();
 217     return GridResolvedPosition(0);
 218 }
 219
 220 PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionAgainstOppositePosition(const RenderStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
 221 {
 222     if (position.isAuto())
 223         return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition);
 224
 225     ASSERT(position.isSpan());
 226     ASSERT(position.spanPosition() > 0);
 227
 228     if (!position.namedGridLine().isNull()) {
 229         // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
 230         return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, resolvedOppositePosition, position, side);
 231     }
 232
 233     return GridSpan::createWithSpanAgainstOpposite(resolvedOppositePosition, position, side);
 234 }
 235
 236 PassOwnPtr<GridSpan> GridResolvedPosition::resolveNamedGridLinePositionAgainstOppositePosition(const RenderStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
 237 {
 238     ASSERT(position.isSpan());
 239     ASSERT(!position.namedGridLine().isNull());
 240     // Negative positions are not allowed per the specification and should have been handled during parsing.
 241     ASSERT(position.spanPosition() > 0);
 242
 243     const NamedGridLinesMap& gridLinesNames = gridLinesForSide(gridContainerStyle, side);
 244     NamedGridLinesMap::const_iterator it = gridLinesNames.find(position.namedGridLine());
 245
 246     // If there is no named grid line of that name, we resolve the position to 'auto' (which is equivalent to 'span 1' in this case).
 247     // See http://lists.w3.org/Archives/Public/www-style/2013Jun/0394.html.
 248     if (it == gridLinesNames.end())
 249         return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition);
 250
 251     return GridSpan::createWithNamedSpanAgainstOpposite(resolvedOppositePosition, position, side, it->value);
 252 }
 253
 254 } // namespace blink