text: /*
   * This program 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; either version 2
   * of the License, or (at your option) any later version.
   *
   * This program 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 this program; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   */
  
  /** \file
   * \ingroup blf
   *
   * Utility function to generate font preview images.
   *
   * Isolate since this needs to be called by #ImBuf code (bad level call).
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include <ft2build.h>
  
  #include FT_FREETYPE_H
  
  #include "BLI_listbase.h"
  #include "BLI_rect.h"
  #include "BLI_threads.h"
  #include "BLI_utildefines.h"
  
  #include "blf_internal.h"
  #include "blf_internal_types.h"
  
  #include "BLF_api.h"
  #include "BLT_translation.h"
  
  #include "BLI_strict_flags.h"
  
  /**
   * This function is used for generating thumbnail previews.
   *
   * \note called from a thread, so it bypasses the normal BLF_* api (which isn't thread-safe).
   */
  void BLF_thumb_preview(const char *filename,
                         const char **draw_str,
                         const char **i18n_draw_str,
                         const unsigned char draw_str_lines,
                         const float font_color[4],
                         const int font_size,
                         unsigned char *buf,
                         int w,
                         int h,
                         int channels)
  {
    const unsigned int dpi = 72;
    const int font_size_min = 6;
    int font_size_curr;
    /* shrink 1/th each line */
    int font_shrink = 4;
  
    FontBLF *font;
    GlyphCacheBLF *gc;
  
    /* Create a new blender font obj and fill it with default values */
    font = blf_font_new("thumb_font", filename);
    if (!font) {
      printf("Info: Can't load font '%s', no preview possible\n", filename);
      return;
    }
  
    /* Would be done via the BLF API, but we're not using a fontid here */
    font->buf_info.cbuf = buf;
    font->buf_info.ch = channels;
    font->buf_info.dims[0] = w;
    font->buf_info.dims[1] = h;
  
    /* Always create the image with a white font,
     * the caller can theme how it likes */
    memcpy(font->buf_info.col_init, font_color, sizeof(font->buf_info.col_init));
    font->pos[1] = (float)h;
  
    font_size_curr = font_size;
  
    blf_draw_buffer__start(font);
  
    for (int i = 0; i < draw_str_lines; i++) {
      const char *draw_str_i18n = i18n_draw_str[i] != NULL ? i18n_draw_str[i] : draw_str[i];
      const size_t draw_str_i18n_len = strlen(draw_str_i18n);
      int draw_str_i18n_nbr = 0;
  
      blf_font_size(font, (unsigned int)MAX2(font_size_min, font_size_curr), dpi);
      gc = blf_glyph_cache_find(font, font->size, font->dpi);
      /* There will be no matching glyph cache if blf_font_size() failed to set font size. */
      if (!gc) {
        break;
      }
  
      /* decrease font size each time */
      font_size_curr -= (font_size_curr / font_shrink);
      font_shrink += 1;
  
      font->pos[1] -= gc->ascender * 1.1f;
  
      /* We fallback to default english strings in case not enough chars are available in current
       * font for given translated string (useful in non-latin i18n context, like Chinese,
       * since many fonts will then show nothing but ugly 'missing char' in their preview).
       * Does not handle all cases, but much better than nothing.
       */
      if (blf_font_count_missing_chars(font, draw_str_i18n, draw_str_i18n_len, &draw_str_i18n_nbr) >
          (draw_str_i18n_nbr / 2)) {
        blf_font_draw_buffer(font, draw_str[i], strlen(draw_str[i]), NULL);
      }
      else {
        blf_font_draw_buffer(font, draw_str_i18n, draw_str_i18n_len, NULL);
      }
    }
  
    blf_draw_buffer__end();
    blf_font_free(font);
  }
  