WritingMode.h   [plain text]

/*
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 */

#ifndef WritingMode_h
#define WritingMode_h

namespace WebCore {

enum TextDirection { LTR, RTL };

inline bool isLeftToRightDirection(TextDirection direction)
{
    return direction == LTR;
}

enum WritingMode {
    TopToBottomWritingMode = 0, // horizontal-tb
    BottomToTopWritingMode = 1, // horizontal-bt
    LeftToRightWritingMode = 2, // vertical-lr
    RightToLeftWritingMode = 3, // vertical-rl
};

#define MAKE_TEXT_FLOW(writingMode, direction)  ((writingMode) << 1 | (direction))

// Define the text flow in terms of the writing mode and the text direction. The first
// part is the line growing direction and the second part is the block growing direction.
enum TextFlow {
    InlineEastBlockSouth = MAKE_TEXT_FLOW(TopToBottomWritingMode, LTR),
    InlineWestBlockSouth = MAKE_TEXT_FLOW(TopToBottomWritingMode, RTL),
    InlineEastBlockNorth = MAKE_TEXT_FLOW(BottomToTopWritingMode, LTR),
    InlineWestBlockNorth = MAKE_TEXT_FLOW(BottomToTopWritingMode, RTL),
    InlineSouthBlockEast = MAKE_TEXT_FLOW(LeftToRightWritingMode, LTR),
    InlineSouthBlockWest = MAKE_TEXT_FLOW(LeftToRightWritingMode, RTL),
    InlineNorthBlockEast = MAKE_TEXT_FLOW(RightToLeftWritingMode, LTR),
    InlineNorthBlockWest = MAKE_TEXT_FLOW(RightToLeftWritingMode, RTL)
};

inline TextFlow makeTextFlow(WritingMode writingMode, TextDirection direction)
{
    return static_cast<TextFlow>(MAKE_TEXT_FLOW(writingMode, direction));
}

#undef MAKE_TEXT_FLOW

const unsigned TextFlowReversedMask = 1;
const unsigned TextFlowFlippedMask = 2;
const unsigned TextFlowVerticalMask = 4;

inline bool isReversedTextFlow(TextFlow textflow)
{
    return textflow & TextFlowReversedMask;
}

inline bool isFlippedTextFlow(TextFlow textflow)
{
    return textflow & TextFlowFlippedMask;
}

inline bool isVerticalTextFlow(TextFlow textflow)
{
    return textflow & TextFlowVerticalMask;
}

// Lines have vertical orientation; modes vertical-lr or vertical-rl.
inline bool isVerticalWritingMode(WritingMode writingMode)
{
    return isVerticalTextFlow(makeTextFlow(writingMode, LTR));
}

// Block progression increases in the opposite direction to normal; modes vertical-rl or horizontal-bt.
inline bool isFlippedWritingMode(WritingMode writingMode)
{
    return isFlippedTextFlow(makeTextFlow(writingMode, LTR));
}

// Lines have horizontal orientation; modes horizontal-tb or horizontal-bt.
inline bool isHorizontalWritingMode(WritingMode writingMode)
{
    return !isVerticalWritingMode(writingMode);
}

// Bottom of the line occurs earlier in the block; modes vertical-lr or horizontal-bt.
inline bool isFlippedLinesWritingMode(WritingMode writingMode)
{
    return isVerticalWritingMode(writingMode) != isFlippedWritingMode(writingMode);
}

enum LogicalBoxSide {
    BeforeSide,
    EndSide,
    AfterSide,
    StartSide
};

enum PhysicalBoxSide {
    NilSide = -1,
    TopSide,
    RightSide,
    BottomSide,
    LeftSide
};

inline bool isHorizontalPhysicalSide(PhysicalBoxSide physicalSide)
{
    return physicalSide == LeftSide || physicalSide == RightSide;
}

inline PhysicalBoxSide mirrorPhysicalSide(PhysicalBoxSide physicalSide)
{
    // top <-> bottom and left <-> right conversion
    return static_cast<PhysicalBoxSide>((static_cast<int>(physicalSide) + 2) % 4);
}

inline PhysicalBoxSide rotatePhysicalSide(PhysicalBoxSide physicalSide)
{
    // top <-> left and right <-> bottom conversion
    bool horizontalSide = isHorizontalPhysicalSide(physicalSide);
    return static_cast<PhysicalBoxSide>((static_cast<int>(physicalSide) + (horizontalSide ? 1 : 3)) % 4);
}

inline PhysicalBoxSide mapLogicalSideToPhysicalSide(TextFlow textflow, LogicalBoxSide logicalSide)
{
    PhysicalBoxSide physicalSide = static_cast<PhysicalBoxSide>(logicalSide);
    bool horizontalSide = isHorizontalPhysicalSide(physicalSide);

    if (isVerticalTextFlow(textflow))
        physicalSide = rotatePhysicalSide(physicalSide);

    if ((horizontalSide && isReversedTextFlow(textflow)) || (!horizontalSide && isFlippedTextFlow(textflow)))
        physicalSide = mirrorPhysicalSide(physicalSide);

    return physicalSide;
}

inline PhysicalBoxSide mapLogicalSideToPhysicalSide(WritingMode writingMode, LogicalBoxSide logicalSide)
{
    // Set the direction such that side is mirrored if isFlippedWritingMode() is true
    TextDirection direction = isFlippedWritingMode(writingMode) ? RTL : LTR;
    return mapLogicalSideToPhysicalSide(makeTextFlow(writingMode, direction), logicalSide);
}

} // namespace WebCore

#endif // WritingMode_h