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.

   By downloading, installing, or using the JUCE framework, or combining the
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   framework to you, and you must discontinue the installation or download
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   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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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
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

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

namespace juce
{

static String substring (const String& text, Range<int> range)
{
    return text.substring (range.getStart(), range.getEnd());
}

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;

    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);

            for (auto& glyph : run->glyphs)
                context.drawGlyph (glyph.glyphCode, AffineTransform::translation (lineOrigin.x + glyph.anchor.x,
                                                                                  lineOrigin.y + glyph.anchor.y));

            if (run->font.isUnderlined())
            {
                auto runExtent = run->getRunBoundsX();
                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);
}

//==============================================================================
namespace TextLayoutHelpers
{
    struct Token
    {
        Token (const String& t, const Font& f, Colour c, bool whitespace)
            : text (t), font (f), colour (c),
              area (font.getStringWidthFloat (t), f.getHeight()),
              isWhitespace (whitespace),
              isNewLine (t.containsChar ('\n') || t.containsChar ('\r'))
        {}

        const String text;
        const Font font;
        const Colour colour;
        Rectangle<float> area;
        int line;
        float lineHeight;
        const bool isWhitespace, isNewLine;

        Token& operator= (const Token&) = delete;
    };

    struct TokenList
    {
        TokenList() noexcept {}

        void createLayout (const AttributedString& text, TextLayout& layout)
        {
            layout.ensureStorageAllocated (totalLines);

            addTextRuns (text);
            layoutRuns (layout.getWidth(), text.getLineSpacing(), text.getWordWrap());

            int charPosition = 0;
            int lineStartPosition = 0;
            int runStartPosition = 0;

            std::unique_ptr<TextLayout::Line> currentLine;
            std::unique_ptr<TextLayout::Run> currentRun;

            bool needToSetLineOrigin = true;

            for (int i = 0; i < tokens.size(); ++i)
            {
                auto& t = *tokens.getUnchecked (i);

                Array<int> newGlyphs;
                Array<float> xOffsets;
                t.font.getGlyphPositions (getTrimmedEndIfNotAllWhitespace (t.text), newGlyphs, xOffsets);

                if (currentRun == nullptr)  currentRun  = std::make_unique<TextLayout::Run>();
                if (currentLine == nullptr) currentLine = std::make_unique<TextLayout::Line>();

                const auto numGlyphs = newGlyphs.size();
                charPosition += numGlyphs;

                if (numGlyphs > 0
                    && (! (t.isWhitespace || t.isNewLine) || needToSetLineOrigin))
                {
                    currentRun->glyphs.ensureStorageAllocated (currentRun->glyphs.size() + newGlyphs.size());
                    auto tokenOrigin = t.area.getPosition().translated (0, t.font.getAscent());

                    if (needToSetLineOrigin)
                    {
                        needToSetLineOrigin = false;
                        currentLine->lineOrigin = tokenOrigin;
                    }

                    auto glyphOffset = tokenOrigin - currentLine->lineOrigin;

                    for (int j = 0; j < newGlyphs.size(); ++j)
                    {
                        auto x = xOffsets.getUnchecked (j);
                        currentRun->glyphs.add (TextLayout::Glyph (newGlyphs.getUnchecked (j),
                                                                   glyphOffset.translated (x, 0),
                                                                   xOffsets.getUnchecked (j + 1) - x));
                    }
                }

                if (auto* nextToken = tokens[i + 1])
                {
                    if (t.font != nextToken->font || t.colour != nextToken->colour)
                    {
                        addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                        runStartPosition = charPosition;
                    }

                    if (t.line != nextToken->line)
                    {
                        if (currentRun == nullptr)
                            currentRun = std::make_unique<TextLayout::Run>();

                        addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                        currentLine->stringRange = { lineStartPosition, charPosition };

                        if (! needToSetLineOrigin)
                            layout.addLine (std::move (currentLine));

                        runStartPosition = charPosition;
                        lineStartPosition = charPosition;
                        needToSetLineOrigin = true;
                    }
                }
                else
                {
                    addRun (*currentLine, currentRun.release(), t, runStartPosition, charPosition);
                    currentLine->stringRange = { lineStartPosition, charPosition };

                    if (! needToSetLineOrigin)
                        layout.addLine (std::move (currentLine));

                    needToSetLineOrigin = true;
                }
            }

            if ((text.getJustification().getFlags() & (Justification::right | Justification::horizontallyCentred)) != 0)
            {
                auto totalW = layout.getWidth();
                bool isCentred = (text.getJustification().getFlags() & Justification::horizontallyCentred) != 0;

                for (auto& line : layout)
                {
                    auto dx = totalW - line.getLineBoundsX().getLength();

                    if (isCentred)
                        dx /= 2.0f;

                    line.lineOrigin.x += dx;
                }
            }
        }

    private:
        static void addRun (TextLayout::Line& glyphLine, TextLayout::Run* glyphRun,
                            const Token& t, int start, int end)
        {
            glyphRun->stringRange = { start, end };
            glyphRun->font = t.font;
            glyphRun->colour = t.colour;
            glyphLine.ascent  = jmax (glyphLine.ascent,  t.font.getAscent());
            glyphLine.descent = jmax (glyphLine.descent, t.font.getDescent());
            glyphLine.runs.add (glyphRun);
        }

        static int getCharacterType (juce_wchar c) noexcept
        {
            if (c == '\r' || c == '\n')
                return 0;

            return CharacterFunctions::isWhitespace (c) ? 2 : 1;
        }

        void appendText (const String& stringText, const Font& font, Colour colour)
        {
            auto t = stringText.getCharPointer();
            String currentString;
            int lastCharType = 0;

            for (;;)
            {
                auto c = t.getAndAdvance();

                if (c == 0)
                    break;

                auto charType = getCharacterType (c);

                if (charType == 0 || charType != lastCharType)
                {
                    if (currentString.isNotEmpty())
                        tokens.add (new Token (currentString, font, colour,
                                               lastCharType == 2 || lastCharType == 0));

                    currentString = String::charToString (c);

                    if (c == '\r' && *t == '\n')
                        currentString += t.getAndAdvance();
                }
                else
                {
                    currentString += c;
                }

                lastCharType = charType;
            }

            if (currentString.isNotEmpty())
                tokens.add (new Token (currentString, font, colour, lastCharType == 2));
        }

        void layoutRuns (float maxWidth, float extraLineSpacing, AttributedString::WordWrap wordWrap)
        {
            float x = 0, y = 0, h = 0;
            int i;

            for (i = 0; i < tokens.size(); ++i)
            {
                auto& t = *tokens.getUnchecked (i);
                t.area.setPosition (x, y);
                t.line = totalLines;
                x += t.area.getWidth();
                h = jmax (h, t.area.getHeight() + extraLineSpacing);

                auto* nextTok = tokens[i + 1];

                if (nextTok == nullptr)
                    break;

                bool tokenTooLarge = (x + nextTok->area.getWidth() > maxWidth);

                if (t.isNewLine || ((! nextTok->isWhitespace) && (tokenTooLarge && wordWrap != AttributedString::none)))
                {
                    setLastLineHeight (i + 1, h);
                    x = 0;
                    y += h;
                    h = 0;
                    ++totalLines;
                }
            }

            setLastLineHeight (jmin (i + 1, tokens.size()), h);
            ++totalLines;
        }

        void setLastLineHeight (int i, float height) noexcept
        {
            while (--i >= 0)
            {
                auto& tok = *tokens.getUnchecked (i);

                if (tok.line == totalLines)
                    tok.lineHeight = height;
                else
                    break;
            }
        }

        void addTextRuns (const AttributedString& text)
        {
            auto numAttributes = text.getNumAttributes();
            tokens.ensureStorageAllocated (jmax (64, numAttributes));

            for (int i = 0; i < numAttributes; ++i)
            {
                auto& attr = text.getAttribute (i);

                appendText (substring (text.getText(), attr.range),
                            attr.font, attr.colour);
            }
        }

        static String getTrimmedEndIfNotAllWhitespace (const String& s)
        {
            auto trimmed = s.trimEnd();

            if (trimmed.isEmpty() && s.isNotEmpty())
                trimmed = s.replaceCharacters ("\r\n\t", "   ");

            return trimmed;
        }

        OwnedArray<Token> tokens;
        int totalLines = 0;

        JUCE_DECLARE_NON_COPYABLE (TokenList)
    };
}

//==============================================================================
void TextLayout::createStandardLayout (const AttributedString& text)
{
    TextLayoutHelpers::TokenList l;
    l.createLayout (text, *this);
}

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