C++ GridPosition::isSpan方法代码示例

void GridResolvedPosition::initialAndFinalPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction, GridPosition& initialPosition, GridPosition& finalPosition)
{
    initialPosition = (direction == ForColumns) ? gridItem.style()->gridColumnStart() : gridItem.style()->gridRowStart();
    finalPosition = (direction == ForColumns) ? gridItem.style()->gridColumnEnd() : gridItem.style()->gridRowEnd();
    GridPositionSide initialPositionSide = calculateInitialPositionSide(direction);
    GridPositionSide finalPositionSide = calculateFinalPositionSide(direction);

    // We must handle the placement error handling code here instead of in the StyleAdjuster because we don't want to
    // overwrite the specified values.
    if (initialPosition.isSpan() && finalPosition.isSpan())
        finalPosition.setAutoPosition();

    // Try to early detect the case of non existing named grid lines. This way we could assume later that
    // GridResolvedPosition::resolveGrisPositionFromStyle() always return a valid resolved position.
    if (initialPosition.isNamedGridArea() && !isValidNamedLineOrArea(initialPosition.namedGridLine(), gridContainerStyle, initialPositionSide))
        initialPosition.setAutoPosition();

    if (finalPosition.isNamedGridArea() && !isValidNamedLineOrArea(finalPosition.namedGridLine(), gridContainerStyle, finalPositionSide))
        finalPosition.setAutoPosition();

    // 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.
    if (initialPosition.isAuto() && finalPosition.isSpan() && !finalPosition.namedGridLine().isNull())
        finalPosition.setSpanPosition(1, String());
    if (finalPosition.isAuto() && initialPosition.isSpan() && !initialPosition.namedGridLine().isNull())
        initialPosition.setSpanPosition(1, String());
}

static void adjustGridPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction, GridPosition& initialPosition, GridPosition& finalPosition)
{
    bool isForColumns = direction == ForColumns;
    initialPosition = isForColumns ? gridItem.style().gridItemColumnStart() : gridItem.style().gridItemRowStart();
    finalPosition = isForColumns ? gridItem.style().gridItemColumnEnd() : gridItem.style().gridItemRowEnd();

    // We must handle the placement error handling code here instead of in the StyleAdjuster because we don't want to
    // overwrite the specified values.
    if (initialPosition.isSpan() && finalPosition.isSpan())
        finalPosition.setAutoPosition();

    if (gridItem.isOutOfFlowPositioned()) {
        // Early detect the case of non existing named grid lines for positioned items.
        if (initialPosition.isNamedGridArea() && !NamedLineCollection::isValidNamedLineOrArea(initialPosition.namedGridLine(), gridContainerStyle, initialPositionSide(direction)))
            initialPosition.setAutoPosition();

        if (finalPosition.isNamedGridArea() && !NamedLineCollection::isValidNamedLineOrArea(finalPosition.namedGridLine(), gridContainerStyle, finalPositionSide(direction)))
            finalPosition.setAutoPosition();
    }

    // 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.
    if (initialPosition.isAuto() && finalPosition.isSpan() && !finalPosition.namedGridLine().isNull())
        finalPosition.setSpanPosition(1, String());
    if (finalPosition.isAuto() && initialPosition.isSpan() && !initialPosition.namedGridLine().isNull())
        initialPosition.setSpanPosition(1, String());
}

PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction)
{
    GridPosition initialPosition = (direction == ForColumns) ? gridItem.style()->gridColumnStart() : gridItem.style()->gridRowStart();
    const GridPositionSide initialPositionSide = (direction == ForColumns) ? ColumnStartSide : RowStartSide;
    GridPosition finalPosition = (direction == ForColumns) ? gridItem.style()->gridColumnEnd() : gridItem.style()->gridRowEnd();
    const GridPositionSide finalPositionSide = (direction == ForColumns) ? ColumnEndSide : RowEndSide;

    // We must handle the placement error handling code here instead of in the StyleAdjuster because we don't want to
    // overwrite the specified values.
    if (initialPosition.isSpan() && finalPosition.isSpan())
        finalPosition.setAutoPosition();

    if (initialPosition.isNamedGridArea() && !gridContainerStyle.namedGridArea().contains(initialPosition.namedGridLine()))
        initialPosition.setAutoPosition();

    if (finalPosition.isNamedGridArea() && !gridContainerStyle.namedGridArea().contains(finalPosition.namedGridLine()))
        finalPosition.setAutoPosition();

    if (initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition()) {
        if (gridContainerStyle.gridAutoFlow() == AutoFlowNone)
            return adoptPtr(new GridSpan(0, 0));

        // We can't get our grid positions without running the auto placement algorithm.
        return nullptr;
    }

    if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
        // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
        GridResolvedPosition finalResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalPositionSide);
        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, finalResolvedPosition, initialPosition, initialPositionSide);
    }

    if (finalPosition.shouldBeResolvedAgainstOppositePosition()) {
        // Infer our position from the initial position ('1 / auto' or '3 / span 2' case).
        GridResolvedPosition initialResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialPositionSide);
        return resolveGridPositionAgainstOppositePosition(gridContainerStyle, initialResolvedPosition, finalPosition, finalPositionSide);
    }

    GridResolvedPosition resolvedInitialPosition = resolveGridPositionFromStyle(gridContainerStyle, initialPosition, initialPositionSide);
    GridResolvedPosition resolvedFinalPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalPositionSide);

    // If 'grid-after' specifies a line at or before that specified by 'grid-before', it computes to 'span 1'.
    if (resolvedFinalPosition < resolvedInitialPosition)
        resolvedFinalPosition = resolvedInitialPosition;

    return adoptPtr(new GridSpan(resolvedInitialPosition, resolvedFinalPosition));
}

static GridSpan resolveNamedGridLinePositionAgainstOppositePosition(const RenderStyle& gridContainerStyle, int oppositeLine, const GridPosition& position, GridPositionSide side, unsigned autoRepeatTracksCount)
{
    ASSERT(position.isSpan());
    ASSERT(!position.namedGridLine().isNull());
    // Negative positions are not allowed per the specification and should have been handled during parsing.
    ASSERT(position.spanPosition() > 0);

    unsigned lastLine = explicitGridSizeForSide(gridContainerStyle, side, autoRepeatTracksCount);
    NamedLineCollection linesCollection(gridContainerStyle, position.namedGridLine(), directionFromSide(side), lastLine, autoRepeatTracksCount);
    return definiteGridSpanWithNamedLineSpanAgainstOpposite(oppositeLine, position, side, lastLine, linesCollection);
}

PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionAgainstOppositePosition(const RenderStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
{
    if (position.isAuto())
        return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition);

    ASSERT(position.isSpan());
    ASSERT(position.spanPosition() > 0);

    if (!position.namedGridLine().isNull()) {
        // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
        return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, resolvedOppositePosition, position, side);
    }

    return GridSpan::createWithSpanAgainstOpposite(resolvedOppositePosition, position, side);
}

unsigned GridPositionsResolver::spanSizeForAutoPlacedItem(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction)
{
    GridPosition initialPosition, finalPosition;
    adjustGridPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);

    // This method will only be used when both positions need to be resolved against the opposite one.
    ASSERT(initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition());

    if (initialPosition.isAuto() && finalPosition.isAuto())
        return 1;

    GridPosition position = initialPosition.isSpan() ? initialPosition : finalPosition;
    ASSERT(position.isSpan());

    ASSERT(position.spanPosition());
    return position.spanPosition();
}

GridSpan GridResolvedPosition::resolveGridPositionAgainstOppositePosition(const ComputedStyle& gridContainerStyle, const GridResolvedPosition& resolvedOppositePosition, const GridPosition& position, GridPositionSide side)
{
    if (position.isAuto()) {
        if ((side == ColumnStartSide || side == RowStartSide) && resolvedOppositePosition.toInt())
            return GridSpan::definiteGridSpan(resolvedOppositePosition.prev(), resolvedOppositePosition);
        return GridSpan::definiteGridSpan(resolvedOppositePosition, resolvedOppositePosition.next());
    }

    ASSERT(position.isSpan());
    ASSERT(position.spanPosition() > 0);

    if (!position.namedGridLine().isNull()) {
        // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
        return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, resolvedOppositePosition, position, side);
    }

    return GridSpan::definiteGridSpanWithSpanAgainstOpposite(resolvedOppositePosition, position, side);
}

static GridSpan resolveGridPositionAgainstOppositePosition(const RenderStyle& gridContainerStyle, int oppositeLine, const GridPosition& position, GridPositionSide side, unsigned autoRepeatTracksCount)
{
    if (position.isAuto()) {
        if (isStartSide(side))
            return GridSpan::untranslatedDefiniteGridSpan(oppositeLine - 1, oppositeLine);
        return GridSpan::untranslatedDefiniteGridSpan(oppositeLine, oppositeLine + 1);
    }

    ASSERT(position.isSpan());
    ASSERT(position.spanPosition() > 0);

    if (!position.namedGridLine().isNull()) {
        // span 2 'c' -> we need to find the appropriate grid line before / after our opposite position.
        return resolveNamedGridLinePositionAgainstOppositePosition(gridContainerStyle, oppositeLine, position, side, autoRepeatTracksCount);
    }

    // 'span 1' is contained inside a single grid track regardless of the direction.
    // That's why the CSS span value is one more than the offset we apply.
    unsigned positionOffset = position.spanPosition();
    if (isStartSide(side))
        return GridSpan::untranslatedDefiniteGridSpan(oppositeLine - positionOffset, oppositeLine);

    return GridSpan::untranslatedDefiniteGridSpan(oppositeLine, oppositeLine + positionOffset);
}