juce_graphics/fonts/juce_Typeface.cpp

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

   This file is part of the JUCE library.
   Copyright (c) 2020 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 6 End-User License
   Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).

   End User License Agreement: www.juce.com/juce-6-licence
   Privacy Policy: www.juce.com/juce-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

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

namespace juce
{

struct FontStyleHelpers
{
    static const char* getStyleName (const bool bold,
                                     const bool italic) noexcept
    {
        if (bold && italic) return "Bold Italic";
        if (bold)           return "Bold";
        if (italic)         return "Italic";
        return "Regular";
    }

    static const char* getStyleName (const int styleFlags) noexcept
    {
        return getStyleName ((styleFlags & Font::bold) != 0,
                             (styleFlags & Font::italic) != 0);
    }

    static bool isBold (const String& style) noexcept
    {
        return style.containsWholeWordIgnoreCase ("Bold");
    }

    static bool isItalic (const String& style) noexcept
    {
        return style.containsWholeWordIgnoreCase ("Italic")
            || style.containsWholeWordIgnoreCase ("Oblique");
    }

    static bool isPlaceholderFamilyName (const String& family)
    {
        return family == Font::getDefaultSansSerifFontName()
            || family == Font::getDefaultSerifFontName()
            || family == Font::getDefaultMonospacedFontName();
    }

    struct ConcreteFamilyNames
    {
        ConcreteFamilyNames()
            : sans  (findName (Font::getDefaultSansSerifFontName())),
              serif (findName (Font::getDefaultSerifFontName())),
              mono  (findName (Font::getDefaultMonospacedFontName()))
        {
        }

        String lookUp (const String& placeholder)
        {
            if (placeholder == Font::getDefaultSansSerifFontName())  return sans;
            if (placeholder == Font::getDefaultSerifFontName())      return serif;
            if (placeholder == Font::getDefaultMonospacedFontName()) return mono;

            return findName (placeholder);
        }

    private:
        static String findName (const String& placeholder)
        {
            const Font f (placeholder, Font::getDefaultStyle(), 15.0f);
            return Font::getDefaultTypefaceForFont (f)->getName();
        }

        String sans, serif, mono;
    };

    static String getConcreteFamilyNameFromPlaceholder (const String& placeholder)
    {
        static ConcreteFamilyNames names;
        return names.lookUp (placeholder);
    }

    static String getConcreteFamilyName (const Font& font)
    {
        const String& family = font.getTypefaceName();

        return isPlaceholderFamilyName (family) ? getConcreteFamilyNameFromPlaceholder (family)
                                                : family;
    }
};

//==============================================================================
Typeface::Typeface (const String& faceName, const String& styleName) noexcept
    : name (faceName), style (styleName)
{
}

Typeface::~Typeface()
{
}

Typeface::Ptr Typeface::getFallbackTypeface()
{
    const Font fallbackFont (Font::getFallbackFontName(), Font::getFallbackFontStyle(), 10.0f);
    return Typeface::Ptr (fallbackFont.getTypeface());
}

EdgeTable* Typeface::getEdgeTableForGlyph (int glyphNumber, const AffineTransform& transform, float fontHeight)
{
    Path path;

    if (getOutlineForGlyph (glyphNumber, path) && ! path.isEmpty())
    {
        applyVerticalHintingTransform (fontHeight, path);

        return new EdgeTable (path.getBoundsTransformed (transform).getSmallestIntegerContainer().expanded (1, 0),
                              path, transform);
    }

    return nullptr;
}

//==============================================================================
struct Typeface::HintingParams
{
    HintingParams (Typeface& t)
    {
        Font font (t);
        font = font.withHeight ((float) standardHeight);

        top = getAverageY (font, "BDEFPRTZOQ", true);
        middle = getAverageY (font, "acegmnopqrsuvwxy", true);
        bottom = getAverageY (font, "BDELZOC", false);
    }

    void applyVerticalHintingTransform (float fontSize, Path& path)
    {
        if (cachedSize != fontSize)
        {
            cachedSize = fontSize;
            cachedScale = Scaling (top, middle, bottom, fontSize);
        }

        if (bottom < top + 3.0f / fontSize)
            return;

        Path result;

        for (Path::Iterator i (path); i.next();)
        {
            switch (i.elementType)
            {
                case Path::Iterator::startNewSubPath:  result.startNewSubPath (i.x1, cachedScale.apply (i.y1)); break;
                case Path::Iterator::lineTo:           result.lineTo (i.x1, cachedScale.apply (i.y1)); break;
                case Path::Iterator::quadraticTo:      result.quadraticTo (i.x1, cachedScale.apply (i.y1),
                                                                           i.x2, cachedScale.apply (i.y2)); break;
                case Path::Iterator::cubicTo:          result.cubicTo (i.x1, cachedScale.apply (i.y1),
                                                                       i.x2, cachedScale.apply (i.y2),
                                                                       i.x3, cachedScale.apply (i.y3)); break;
                case Path::Iterator::closePath:        result.closeSubPath(); break;
                default:                               jassertfalse; break;
            }
        }

        result.swapWithPath (path);
    }

private:
    struct Scaling
    {
        Scaling() noexcept : middle(), upperScale(), upperOffset(), lowerScale(), lowerOffset() {}

        Scaling (float t, float m, float b, float fontSize) noexcept  : middle (m)
        {
            const float newT = std::floor (fontSize * t + 0.5f) / fontSize;
            const float newB = std::floor (fontSize * b + 0.5f) / fontSize;
            const float newM = std::floor (fontSize * m + 0.3f) / fontSize; // this is slightly biased so that lower-case letters
                                                                            // are more likely to become taller than shorter.
            upperScale  = jlimit (0.9f, 1.1f, (newM - newT) / (m - t));
            lowerScale  = jlimit (0.9f, 1.1f, (newB - newM) / (b - m));

            upperOffset = newM - m * upperScale;
            lowerOffset = newB - b * lowerScale;
        }

        float apply (float y) const noexcept
        {
            return y < middle ? (y * upperScale + upperOffset)
                              : (y * lowerScale + lowerOffset);
        }

        float middle, upperScale, upperOffset, lowerScale, lowerOffset;
    };

    float cachedSize = 0;
    Scaling cachedScale;

    static float getAverageY (const Font& font, const char* chars, bool getTop)
    {
        GlyphArrangement ga;
        ga.addLineOfText (font, chars, 0, 0);

        Array<float> yValues;

        for (auto& glyph : ga)
        {
            Path p;
            glyph.createPath (p);
            auto bounds = p.getBounds();

            if (! p.isEmpty())
                yValues.add (getTop ? bounds.getY() : bounds.getBottom());
        }

        std::sort (yValues.begin(), yValues.end());

        auto median = yValues[yValues.size() / 2];
        float total = 0;
        int num = 0;

        for (auto y : yValues)
        {
            if (std::abs (median - y) < 0.05f * (float) standardHeight)
            {
                total += y;
                ++num;
            }
        }

        return num < 4 ? 0.0f : total / ((float) num * (float) standardHeight);
    }

    enum { standardHeight = 100 };
    float top = 0, middle = 0, bottom = 0;
};

void Typeface::applyVerticalHintingTransform (float fontSize, Path& path)
{
    if (fontSize > 3.0f && fontSize < 25.0f)
    {
        ScopedLock sl (hintingLock);

        if (hintingParams == nullptr)
            hintingParams.reset (new HintingParams (*this));

        return hintingParams->applyVerticalHintingTransform (fontSize, path);
    }
}

} // namespace juce