JUCE/modules/juce_graphics/fonts/juce_TextLayout.cpp

/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

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   Or:

   You may also use this code under the terms of the AGPLv3:
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   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
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   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

TextLayout::Glyph::Glyph (int glyph, Point<float> anch, float w) noexcept
    : glyphCode (glyph), anchor (anch), width (w)
{
}

//==============================================================================
TextLayout::Run::Run (Range<int> range, int numGlyphsToPreallocate)
    : stringRange (range)
{
    glyphs.ensureStorageAllocated (numGlyphsToPreallocate);
}

Range<float> TextLayout::Run::getRunBoundsX() const noexcept
{
    Range<float> range;
    bool isFirst = true;

    for (auto& glyph : glyphs)
    {
        Range<float> r (glyph.anchor.x, glyph.anchor.x + glyph.width);

        if (isFirst)
        {
            isFirst = false;
            range = r;
        }
        else
        {
            range = range.getUnionWith (r);
        }
    }

    return range;
}

//==============================================================================
TextLayout::Line::Line (Range<int> range, Point<float> o, float asc, float desc,
                        float lead, int numRunsToPreallocate)
    : stringRange (range), lineOrigin (o),
      ascent (asc), descent (desc), leading (lead)
{
    runs.ensureStorageAllocated (numRunsToPreallocate);
}

TextLayout::Line::Line (const Line& other)
    : stringRange (other.stringRange), lineOrigin (other.lineOrigin),
      ascent (other.ascent), descent (other.descent), leading (other.leading)
{
    runs.addCopiesOf (other.runs);
}

TextLayout::Line& TextLayout::Line::operator= (const Line& other)
{
    auto copy = other;
    swap (copy);
    return *this;
}

Range<float> TextLayout::Line::getLineBoundsX() const noexcept
{
    Range<float> range;
    bool isFirst = true;

    for (auto* run : runs)
    {
        auto runRange = run->getRunBoundsX();

        if (isFirst)
        {
            isFirst = false;
            range = runRange;
        }
        else
        {
            range = range.getUnionWith (runRange);
        }
    }

    return range + lineOrigin.x;
}

Range<float> TextLayout::Line::getLineBoundsY() const noexcept
{
    return { lineOrigin.y - ascent,
             lineOrigin.y + descent };
}

Rectangle<float> TextLayout::Line::getLineBounds() const noexcept
{
    auto x = getLineBoundsX();
    auto y = getLineBoundsY();

    return { x.getStart(), y.getStart(), x.getLength(), y.getLength() };
}

void TextLayout::Line::swap (Line& other) noexcept
{
    std::swap (other.runs,          runs);
    std::swap (other.stringRange,   stringRange);
    std::swap (other.lineOrigin,    lineOrigin);
    std::swap (other.ascent,        ascent);
    std::swap (other.descent,       descent);
    std::swap (other.leading,       leading);
}

//==============================================================================
TextLayout::TextLayout()
    : width (0), height (0), justification (Justification::topLeft)
{
}

TextLayout::TextLayout (const TextLayout& other)
    : width (other.width), height (other.height),
      justification (other.justification)
{
    lines.addCopiesOf (other.lines);
}

TextLayout::TextLayout (TextLayout&& other) noexcept
    : lines (std::move (other.lines)),
      width (other.width), height (other.height),
      justification (other.justification)
{
}

TextLayout& TextLayout::operator= (TextLayout&& other) noexcept
{
    lines = std::move (other.lines);
    width = other.width;
    height = other.height;
    justification = other.justification;
    return *this;
}

TextLayout& TextLayout::operator= (const TextLayout& other)
{
    width = other.width;
    height = other.height;
    justification = other.justification;
    lines.clear();
    lines.addCopiesOf (other.lines);
    return *this;
}

TextLayout::~TextLayout()
{
}

TextLayout::Line& TextLayout::getLine (int index) const noexcept
{
    return *lines.getUnchecked (index);
}

void TextLayout::ensureStorageAllocated (int numLinesNeeded)
{
    lines.ensureStorageAllocated (numLinesNeeded);
}

void TextLayout::addLine (std::unique_ptr<Line> line)
{
    lines.add (line.release());
}

void TextLayout::draw (Graphics& g, Rectangle<float> area) const
{
    auto origin = justification.appliedToRectangle (Rectangle<float> (width, getHeight()), area).getPosition();

    auto& context   = g.getInternalContext();
    context.saveState();

    auto clip       = context.getClipBounds();
    auto clipTop    = (float) clip.getY()      - origin.y;
    auto clipBottom = (float) clip.getBottom() - origin.y;

    std::vector<uint16_t> glyphNumbers;
    std::vector<Point<float>> positions;

    for (auto& line : *this)
    {
        auto lineRangeY = line.getLineBoundsY();

        if (lineRangeY.getEnd() < clipTop)
            continue;

        if (lineRangeY.getStart() > clipBottom)
            break;

        auto lineOrigin = origin + line.lineOrigin;

        for (auto* run : line.runs)
        {
            context.setFont (run->font);
            context.setFill (run->colour);

            const auto& glyphs = run->glyphs;

            glyphNumbers.resize ((size_t) glyphs.size());
            std::transform (glyphs.begin(), glyphs.end(), glyphNumbers.begin(), [&] (const Glyph& x)
            {
                return (uint16_t) x.glyphCode;
            });

            positions.resize ((size_t) glyphs.size());
            std::transform (glyphs.begin(), glyphs.end(), positions.begin(), [&] (const Glyph& x)
            {
                return x.anchor;
            });

            context.drawGlyphs (glyphNumbers, positions, AffineTransform::translation (lineOrigin));

            if (run->font.isUnderlined())
            {
                const auto runExtent = run->getRunBoundsX();
                const auto lineThickness = run->font.getDescent() * 0.3f;

                context.fillRect ({ runExtent.getStart() + lineOrigin.x,
                                    lineOrigin.y + lineThickness * 2.0f,
                                    runExtent.getLength(),
                                    lineThickness });
            }
        }
    }

    context.restoreState();
}

void TextLayout::createLayout (const AttributedString& text, float maxWidth)
{
    createLayout (text, maxWidth, 1.0e7f);
}

void TextLayout::createLayout (const AttributedString& text, float maxWidth, float maxHeight)
{
    lines.clear();
    width = maxWidth;
    height = maxHeight;
    justification = text.getJustification();

    if (! createNativeLayout (text))
        createStandardLayout (text);

    recalculateSize();
}

void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text, float maxWidth)
{
    createLayoutWithBalancedLineLengths (text, maxWidth, 1.0e7f);
}

void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text, float maxWidth, float maxHeight)
{
    auto minimumWidth = maxWidth / 2.0f;
    auto bestWidth = maxWidth;
    float bestLineProportion = 0.0f;

    while (maxWidth > minimumWidth)
    {
        createLayout (text, maxWidth, maxHeight);

        if (getNumLines() < 2)
            return;

        auto line1 = lines.getUnchecked (lines.size() - 1)->getLineBoundsX().getLength();
        auto line2 = lines.getUnchecked (lines.size() - 2)->getLineBoundsX().getLength();
        auto shortest = jmin (line1, line2);
        auto longest  = jmax (line1, line2);
        auto prop = shortest > 0 ? longest / shortest : 1.0f;

        if (prop > 0.9f && prop < 1.1f)
            return;

        if (prop > bestLineProportion)
        {
            bestLineProportion = prop;
            bestWidth = maxWidth;
        }

        maxWidth -= 10.0f;
    }

    if (! approximatelyEqual (bestWidth, maxWidth))
        createLayout (text, bestWidth, maxHeight);
}

//==============================================================================
template <typename T, typename U>
static auto castTo (const Range<U>& r)
{
    return Range<T> (static_cast<T> (r.getStart()), static_cast<T> (r.getEnd()));
}

static auto getFontsForRange (const detail::RangedValues<Font>& fonts)
{
    std::vector<FontForRange> result;
    result.reserve (fonts.size());

    std::transform (fonts.begin(),
                    fonts.end(),
                    std::back_inserter (result),
                    [] (auto entry) {
                        return FontForRange { entry.range, entry.value };
                    });

    return result;
}

static Range<int64> getInputRange (const ShapedText& st, Range<int64> glyphRange)
{
    if (glyphRange.isEmpty())
    {
        jassertfalse;
        return {};
    }

    const auto startInputRange = st.getTextRange (glyphRange.getStart());
    const auto endInputRange   = st.getTextRange (glyphRange.getEnd() - 1);

    // The glyphRange is always in visual order and could have an opposite direction to the text
    return { std::min (startInputRange.getStart(), endInputRange.getStart()),
             std::max (startInputRange.getEnd(), endInputRange.getEnd()) };
}

static Range<int64> getLineInputRange (const ShapedText& st, int64 lineNumber)
{
    return getInputRange (st, ShapedText::Detail { &st }.getSimpleShapedText()
                                                        .getLineNumbers()
                                                        .getItem ((size_t) lineNumber).range);
}

struct MaxFontAscentAndDescent
{
    float ascent{}, descent{};
};

static MaxFontAscentAndDescent getMaxFontAscentAndDescentInEnclosingLine (const ShapedText& st,
                                                                          Range<int64> lineChunkRange)
{
    const auto sst = ShapedText::Detail { &st }.getSimpleShapedText();

    const auto lineRange = sst.getLineNumbers()
                              .getItemWithEnclosingRange (lineChunkRange.getStart())->range;

    const auto fonts = sst.getResolvedFonts().getIntersectionsWith (lineRange);

    MaxFontAscentAndDescent result;

    for (const auto& [r, font] : fonts)
    {
        result.ascent = std::max (result.ascent, font.getAscent());
        result.descent = std::max (result.descent, font.getDescent());
    }

    return result;
}

static std::optional<TextDirection> getTextDirection (const AttributedString& text)
{
    using ReadingDirection = AttributedString::ReadingDirection;

    const auto dir = text.getReadingDirection();

    if (dir == ReadingDirection::leftToRight)
        return TextDirection::ltr;

    if (dir == ReadingDirection::rightToLeft)
        return TextDirection::rtl;

    return std::nullopt;
}

void TextLayout::createStandardLayout (const AttributedString& text)
{
    detail::RangedValues<Font> fonts;
    detail::RangedValues<Colour> colours;

    for (auto i = 0, iMax = text.getNumAttributes(); i < iMax; ++i)
    {
        const auto& attribute = text.getAttribute (i);
        const auto range = castTo<int64> (attribute.range);
        fonts.set (range, attribute.font);
        colours.set (range, attribute.colour);
    }

    ShapedText shapedText { text.getText(), ShapedTextOptions{}.withFontsForRange (getFontsForRange (fonts))
                                                               .withMaxWidth (width)
                                                               .withLanguage (SystemStats::getUserLanguage())
                                                               .withTrailingWhitespacesShouldFit (false)
                                                               .withJustification (justification)
                                                               .withReadingDirection (getTextDirection (text)) };

    std::optional<int64> lastLineNumber;
    std::unique_ptr<Line> line;

    auto& jt = ShapedText::Detail { &shapedText }.getJustifiedText();
    jt.accessTogetherWith ([&] (Span<const ShapedGlyph> glyphs,
                                Span<Point<float>> positions,
                                Font font,
                                Range<int64> glyphRange,
                                int64 lineNumber,
                                Colour colour)
                           {
                               if (std::exchange (lastLineNumber, lineNumber) != lineNumber)
                               {
                                   if (line != nullptr)
                                       addLine (std::move (line));

                                   const auto ascentAndDescent = getMaxFontAscentAndDescentInEnclosingLine (shapedText,
                                                                                                            glyphRange);

                                   line = std::make_unique<Line> (castTo<int> (getLineInputRange (shapedText, lineNumber)),
                                                                  positions[0],
                                                                  ascentAndDescent.ascent,
                                                                  ascentAndDescent.descent,
                                                                  0.0f,
                                                                  0);
                               }

                               auto run = std::make_unique<Run> (castTo<int> (getInputRange (shapedText, glyphRange)), 0);

                               run->font = font;
                               run->colour = colour;

                               for (decltype (glyphs.size()) i = 0, iMax = glyphs.size(); i < iMax; ++i)
                               {
                                   if (glyphs[i].whitespace)
                                       continue;

                                   run->glyphs.add ({ (int) glyphs[i].glyphId, positions[i] - line->lineOrigin, glyphs[i].advance.x });
                               }

                               line->runs.add (std::move (run));
                           },
                           colours);

    if (line != nullptr)
        addLine (std::move (line));
}

void TextLayout::recalculateSize()
{
    if (! lines.isEmpty())
    {
        auto bounds = lines.getFirst()->getLineBounds();

        for (auto* line : lines)
            bounds = bounds.getUnion (line->getLineBounds());

        for (auto* line : lines)
            line->lineOrigin.x -= bounds.getX();

        width  = bounds.getWidth();
        height = bounds.getHeight();
    }
    else
    {
        width = 0;
        height = 0;
    }
}

} // namespace juce