polybar/include/cairo/font.hpp

#pragma once

#include <cairo/cairo-ft.h>

#include "cairo/types.hpp"
#include "cairo/utils.hpp"
#include "common.hpp"
#include "components/logger.hpp"
#include "errors.hpp"
#include "settings.hpp"
#include "utils/math.hpp"
#include "utils/scope.hpp"
#include "utils/string.hpp"

POLYBAR_NS

namespace cairo {
/**
 * @brief Global pointer to the Freetype library handler
 */
static FT_Library g_ftlib;

/**
 * @brief Abstract font face
 */
class font {
 public:
  explicit font(cairo_t* cairo, double offset) : m_cairo(cairo), m_offset(offset) {}
  virtual ~font(){};

  virtual string name() const = 0;
  virtual string file() const = 0;
  virtual double offset() const = 0;
  virtual double size(double dpi) const = 0;

  virtual cairo_font_extents_t extents() = 0;

  virtual void use() {
    cairo_set_font_face(m_cairo, cairo_font_face_reference(m_font_face));
  }

  virtual size_t match(string_util::unicode_character& character) = 0;
  virtual size_t match(string_util::unicode_charlist& charlist) = 0;
  virtual size_t render(const string& text, double x = 0.0, double y = 0.0) = 0;
  virtual void textwidth(const string& text, cairo_text_extents_t* extents) = 0;

 protected:
  cairo_t* m_cairo;
  cairo_font_face_t* m_font_face{nullptr};
  cairo_font_extents_t m_extents{};
  double m_offset{0.0};
};

/**
 * @brief Font based on fontconfig/freetype
 */
class font_fc : public font {
 public:
  explicit font_fc(cairo_t* cairo, FcPattern* pattern, double offset, double dpi_x, double dpi_y)
      : font(cairo, offset), m_pattern(pattern) {
    cairo_matrix_t fm;
    cairo_matrix_t ctm;
    cairo_matrix_init_scale(&fm, size(dpi_x), size(dpi_y));
    cairo_get_matrix(m_cairo, &ctm);

    auto fontface = cairo_ft_font_face_create_for_pattern(m_pattern);
    auto opts = cairo_font_options_create();
    m_scaled = cairo_scaled_font_create(fontface, &fm, &ctm, opts);
    cairo_font_options_destroy(opts);
    cairo_font_face_destroy(fontface);

    auto status = cairo_scaled_font_status(m_scaled);
    if (status != CAIRO_STATUS_SUCCESS) {
      throw application_error(sstream() << "cairo_scaled_font_create(): " << cairo_status_to_string(status));
    }

    auto lock = make_unique<utils::ft_face_lock>(m_scaled);
    auto face = static_cast<FT_Face>(*lock);

    if (FT_Select_Charmap(face, FT_ENCODING_UNICODE) == FT_Err_Ok) {
      return;
    } else if (FT_Select_Charmap(face, FT_ENCODING_BIG5) == FT_Err_Ok) {
      return;
    } else if (FT_Select_Charmap(face, FT_ENCODING_SJIS) == FT_Err_Ok) {
      return;
    }

    lock.reset();
  }

  ~font_fc() override {
    if (m_scaled != nullptr) {
      cairo_scaled_font_destroy(m_scaled);
    }
    if (m_pattern != nullptr) {
      FcPatternDestroy(m_pattern);
    }
  }

  cairo_font_extents_t extents() override {
    cairo_scaled_font_extents(m_scaled, &m_extents);
    return m_extents;
  }

  string name() const override {
    return property("family");
  }

  string file() const override {
    return property("file");
  }

  double offset() const override {
    return m_offset;
  }

  /**
   * Calculates the font size in pixels for the given dpi
   *
   * We use the two font properties size and pixelsize. size is in points and
   * needs to be scaled with the given dpi. pixelsize is not scaled.
   *
   * If both size properties are 0, we fall back to a default value of 10
   * points for scalable fonts or 10 pixel for non-scalable ones. This should
   * only happen if both properties are purposefully set to 0
   *
   * For scalable fonts we try to use the size property scaled according to
   * the dpi.
   * For non-scalable fonts we try to use the pixelsize property as-is
   */
  double size(double dpi) const override {
    bool scalable;
    double fc_pixelsize = 0, fc_size = 0;

    property(FC_SCALABLE, &scalable);

    // Size in points
    property(FC_SIZE, &fc_size);

    // Size in pixels
    property(FC_PIXEL_SIZE, &fc_pixelsize);

    // Fall back to a default value if the size is 0
    double pixelsize = fc_pixelsize == 0 ? 10 : fc_pixelsize;
    double size = fc_size == 0 ? 10 : fc_size;

    // Font size in pixels if we use the pixelsize property
    int px_pixelsize = pixelsize + 0.5;

    /*
     * Font size in pixels if we use the size property. Since the size
     * specifies the font size in points, this is converted to pixels
     * according to the dpi given.
     * One point is 1/72 inches, thus this gives us the number of 'dots'
     * (or pixels) for this font
     */
    int px_size = size / 72.0 * dpi + 0.5;

    if (fc_size == 0 && fc_pixelsize == 0) {
      return scalable ? px_size : px_pixelsize;
    }

    if (scalable) {
      /*
       * Use the point size if it's not 0. The pixelsize is only used if the
       * size property is 0 and pixelsize is not
       */
      if (fc_size != 0) {
        return px_size;
      } else {
        return px_pixelsize;
      }
    } else {
      /*
       * Non-scalable fonts do it the other way around, here the size
       * property is only used if pixelsize is 0 and size is not
       */
      if (fc_pixelsize != 0) {
        return px_pixelsize;
      } else {
        return px_size;
      }
    }
  }

  void use() override {
    cairo_set_scaled_font(m_cairo, m_scaled);
  }

  size_t match(string_util::unicode_character& character) override {
    auto lock = make_unique<utils::ft_face_lock>(m_scaled);
    auto face = static_cast<FT_Face>(*lock);
    return FT_Get_Char_Index(face, character.codepoint) ? 1 : 0;
  }

  size_t match(string_util::unicode_charlist& charlist) override {
    auto lock = make_unique<utils::ft_face_lock>(m_scaled);
    auto face = static_cast<FT_Face>(*lock);
    size_t available_chars = 0;
    for (auto&& c : charlist) {
      if (FT_Get_Char_Index(face, c.codepoint)) {
        available_chars++;
      } else {
        break;
      }
    }

    return available_chars;
  }

  size_t render(const string& text, double x = 0.0, double y = 0.0) override {
    cairo_glyph_t* glyphs{nullptr};
    cairo_text_cluster_t* clusters{nullptr};
    cairo_text_cluster_flags_t cf{};
    int nglyphs = 0;
    int nclusters = 0;

    string utf8 = string(text);
    auto status = cairo_scaled_font_text_to_glyphs(
        m_scaled, x, y, utf8.c_str(), utf8.size(), &glyphs, &nglyphs, &clusters, &nclusters, &cf);

    if (status != CAIRO_STATUS_SUCCESS) {
      throw application_error(sstream() << "cairo_scaled_font_text_to_glyphs() " << cairo_status_to_string(status));
    }

    size_t bytes = 0;
    for (int g = 0; g < nglyphs; g++) {
      if (glyphs[g].index) {
        bytes += clusters[g].num_bytes;
      } else {
        break;
      }
    }

    if (bytes && bytes < text.size()) {
      cairo_glyph_free(glyphs);
      cairo_text_cluster_free(clusters);

      utf8 = text.substr(0, bytes);
      auto status = cairo_scaled_font_text_to_glyphs(
          m_scaled, x, y, utf8.c_str(), utf8.size(), &glyphs, &nglyphs, &clusters, &nclusters, &cf);

      if (status != CAIRO_STATUS_SUCCESS) {
        throw application_error(sstream() << "cairo_scaled_font_text_to_glyphs() " << cairo_status_to_string(status));
      }
    }

    if (bytes) {
      // auto lock = make_unique<utils::device_lock>(cairo_surface_get_device(cairo_get_target(m_cairo)));
      // if (lock.get()) {
      //   cairo_glyph_path(m_cairo, glyphs, nglyphs);
      // }

      cairo_text_extents_t extents{};
      cairo_scaled_font_glyph_extents(m_scaled, glyphs, nglyphs, &extents);
      cairo_show_text_glyphs(m_cairo, utf8.c_str(), utf8.size(), glyphs, nglyphs, clusters, nclusters, cf);
      cairo_fill(m_cairo);
      cairo_move_to(m_cairo, x + extents.x_advance, 0.0);
    }

    cairo_glyph_free(glyphs);
    cairo_text_cluster_free(clusters);

    return bytes;
  }

  void textwidth(const string& text, cairo_text_extents_t* extents) override {
    cairo_scaled_font_text_extents(m_scaled, text.c_str(), extents);
  }

 protected:
  string property(string&& property) const {
    FcChar8* file;
    if (FcPatternGetString(m_pattern, property.c_str(), 0, &file) == FcResultMatch) {
      return string(reinterpret_cast<char*>(file));
    } else {
      return "";
    }
  }

  void property(string&& property, bool* dst) const {
    FcBool b;
    FcPatternGetBool(m_pattern, property.c_str(), 0, &b);
    *dst = b;
  }

  void property(string&& property, double* dst) const {
    FcPatternGetDouble(m_pattern, property.c_str(), 0, dst);
  }

  void property(string&& property, int* dst) const {
    FcPatternGetInteger(m_pattern, property.c_str(), 0, dst);
  }

 private:
  cairo_scaled_font_t* m_scaled{nullptr};
  FcPattern* m_pattern{nullptr};
};

/**
 * Match and create font from given fontconfig pattern
 */
inline decltype(auto) make_font(cairo_t* cairo, string&& fontname, double offset, double dpi_x, double dpi_y) {
  static bool fc_init{false};
  if (!fc_init && !(fc_init = FcInit())) {
    throw application_error("Could not load fontconfig");
  } else if (FT_Init_FreeType(&g_ftlib) != FT_Err_Ok) {
    throw application_error("Could not load FreeType");
  }

  static scope_util::on_exit fc_cleanup([] {
    FT_Done_FreeType(g_ftlib);
    FcFini();
  });

  auto pattern = FcNameParse((FcChar8*)fontname.c_str());

  if (!pattern) {
    logger::make().err("Could not parse font \"%s\"", fontname);
    throw application_error("Could not parse font \"" + fontname + "\"");
  }

  FcDefaultSubstitute(pattern);
  FcConfigSubstitute(nullptr, pattern, FcMatchPattern);

  FcResult result;
  FcPattern* match = FcFontMatch(nullptr, pattern, &result);
  FcPatternDestroy(pattern);

  if (match == nullptr) {
    throw application_error("Could not load font \"" + fontname + "\"");
  }

#ifdef DEBUG_FONTCONFIG
  FcPatternPrint(match);
#endif

  return make_shared<font_fc>(cairo, match, offset, dpi_x, dpi_y);
}
} // namespace cairo

POLYBAR_NS_END