font_unix.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "../../stdafx.h"
#include "../../debug.h"
#include "../../fontdetection.h"
#include "../../string_func.h"
#include "../../strings_func.h"
 
#include <fontconfig/fontconfig.h>
 
#include "safeguards.h"
 
#include <ft2build.h>
#include FT_FREETYPE_H
 
extern FT_Library _library;
 
static std::tuple<std::string, std::string> SplitFontFamilyAndStyle(std::string_view font_name)
{
  auto separator = font_name.find(',');
  if (separator == std::string_view::npos) return { std::string(font_name), std::string() };
 
  auto begin = font_name.find_first_not_of("\t ", separator + 1);
  if (begin == std::string_view::npos) return { std::string(font_name.substr(0, separator)), std::string() };
 
  return { std::string(font_name.substr(0, separator)), std::string(font_name.substr(begin)) };
}
 
FT_Error GetFontByFaceName(const char *font_name, FT_Face *face)
{
  FT_Error err = FT_Err_Cannot_Open_Resource;
 
  if (!FcInit()) {
    ShowInfo("Unable to load font configuration");
    return err;
  }
 
  auto fc_instance = FcConfigReference(nullptr);
  assert(fc_instance != nullptr);
 
  /* Split & strip the font's style */
  auto [font_family, font_style] = SplitFontFamilyAndStyle(font_name);
 
  /* Resolve the name and populate the information structure */
  FcPattern *pat = FcPatternCreate();
  if (!font_family.empty()) FcPatternAddString(pat, FC_FAMILY, reinterpret_cast<const FcChar8 *>(font_family.c_str()));
  if (!font_style.empty()) FcPatternAddString(pat, FC_STYLE, reinterpret_cast<const FcChar8 *>(font_style.c_str()));
  FcConfigSubstitute(nullptr, pat, FcMatchPattern);
  FcDefaultSubstitute(pat);
  FcFontSet *fs = FcFontSetCreate();
  FcResult  result;
  FcPattern *match = FcFontMatch(nullptr, pat, &result);
 
  if (fs != nullptr && match != nullptr) {
    FcChar8 *family;
    FcChar8 *style;
    FcChar8 *file;
    int32_t index;
    FcFontSetAdd(fs, match);
 
    for (int i = 0; err != FT_Err_Ok && i < fs->nfont; i++) {
      /* Try the new filename */
      if (FcPatternGetString(fs->fonts[i], FC_FILE, 0, &file) == FcResultMatch &&
        FcPatternGetString(fs->fonts[i], FC_FAMILY, 0, &family) == FcResultMatch &&
        FcPatternGetString(fs->fonts[i], FC_STYLE, 0, &style) == FcResultMatch &&
        FcPatternGetInteger(fs->fonts[i], FC_INDEX, 0, &index) == FcResultMatch) {
 
        /* The correct style? */
        if (!font_style.empty() && !StrEqualsIgnoreCase(font_style, (char *)style)) continue;
 
        /* Font config takes the best shot, which, if the family name is spelled
         * wrongly a 'random' font, so check whether the family name is the
         * same as the supplied name */
        if (StrEqualsIgnoreCase(font_family, (char *)family)) {
          err = FT_New_Face(_library, (char *)file, index, face);
        }
      }
    }
  }
 
  FcPatternDestroy(pat);
  FcFontSetDestroy(fs);
  FcConfigDestroy(fc_instance);
 
  return err;
}
 
bool SetFallbackFont(FontCacheSettings *settings, const std::string &language_isocode, int, MissingGlyphSearcher *callback)
{
  bool ret = false;
 
  if (!FcInit()) return ret;
 
  auto fc_instance = FcConfigReference(nullptr);
  assert(fc_instance != nullptr);
 
  /* Fontconfig doesn't handle full language isocodes, only the part
   * before the _ of e.g. en_GB is used, so "remove" everything after
   * the _. */
  std::string lang = fmt::format(":lang={}", language_isocode.substr(0, language_isocode.find('_')));
 
  /* First create a pattern to match the wanted language. */
  FcPattern *pat = FcNameParse((const FcChar8 *)lang.c_str());
  /* We only want to know these attributes. */
  FcObjectSet *os = FcObjectSetBuild(FC_FILE, FC_INDEX, FC_SPACING, FC_SLANT, FC_WEIGHT, nullptr);
  /* Get the list of filenames matching the wanted language. */
  FcFontSet *fs = FcFontList(nullptr, pat, os);
 
  /* We don't need these anymore. */
  FcObjectSetDestroy(os);
  FcPatternDestroy(pat);
 
  if (fs != nullptr) {
    int best_weight = -1;
    const char *best_font = nullptr;
    int best_index = 0;
 
    for (int i = 0; i < fs->nfont; i++) {
      FcPattern *font = fs->fonts[i];
 
      FcChar8 *file = nullptr;
      FcResult res = FcPatternGetString(font, FC_FILE, 0, &file);
      if (res != FcResultMatch || file == nullptr) {
        continue;
      }
 
      /* Get a font with the right spacing .*/
      int value = 0;
      FcPatternGetInteger(font, FC_SPACING, 0, &value);
      if (callback->Monospace() != (value == FC_MONO) && value != FC_DUAL) continue;
 
      /* Do not use those that explicitly say they're slanted. */
      FcPatternGetInteger(font, FC_SLANT, 0, &value);
      if (value != 0) continue;
 
      /* We want the fatter font as they look better at small sizes. */
      FcPatternGetInteger(font, FC_WEIGHT, 0, &value);
      if (value <= best_weight) continue;
 
      /* Possible match based on attributes, get index. */
      int32_t index;
      res = FcPatternGetInteger(font, FC_INDEX, 0, &index);
      if (res != FcResultMatch) continue;
 
      callback->SetFontNames(settings, (const char *)file, &index);
 
      bool missing = callback->FindMissingGlyphs();
      Debug(fontcache, 1, "Font \"{}\" misses{} glyphs", (char *)file, missing ? "" : " no");
 
      if (!missing) {
        best_weight = value;
        best_font = (const char *)file;
        best_index = index;
      }
    }
 
    if (best_font != nullptr) {
      ret = true;
      callback->SetFontNames(settings, best_font, &best_index);
      InitFontCache(callback->Monospace());
    }
 
    /* Clean up the list of filenames. */
    FcFontSetDestroy(fs);
  }
 
  FcConfigDestroy(fc_instance);
  return ret;
}