third_party/harfbuzz/contrib/harfbuzz-freetype.c

   1 #include <stdint.h>
   2
   3 #include <ft2build.h>
   4 #include FT_FREETYPE_H
   5 #include FT_TRUETYPE_TABLES_H
   6
   7 #if 0
   8 #include <freetype/freetype.h>
   9 #include <freetype/tttables.h>
  10 #endif
  11
  12 #include <harfbuzz-shaper.h>
  13 #include "harfbuzz-unicode.h"
  14
  15 static HB_Bool
  16 hb_freetype_string_to_glyphs(HB_Font font,
  17                              const HB_UChar16 *chars, hb_uint32 len,
  18                              HB_Glyph *glyphs, hb_uint32 *numGlyphs,
  19                              HB_Bool is_rtl) {
  20   FT_Face face = (FT_Face) font->userData;
  21   if (len > *numGlyphs)
  22     return 0;
  23
  24   ssize_t i = 0;
  25   hb_uint32 j = 0;
  26   while (i < len) {
  27     const uint32_t cp = utf16_to_code_point(chars, len, &i);
  28     glyphs[j++] = FT_Get_Char_Index(face, cp);
  29   }
  30
  31   *numGlyphs = j;
  32
  33   return 1;
  34 }
  35
  36 static void
  37 hb_freetype_advances_get(HB_Font font, const HB_Glyph *glyphs, hb_uint32 len,
  38                          HB_Fixed *advances, int flags) {
  39   FT_Face face = (FT_Face) font->userData;
  40
  41   hb_uint32 i;
  42   for (i = 0; i < len; ++i) {
  43     const FT_Error error = FT_Load_Glyph(face, glyphs[i], FT_LOAD_DEFAULT);
  44     if (error) {
  45       advances[i] = 0;
  46       continue;
  47     }
  48
  49     advances[i] = face->glyph->advance.x;
  50   }
  51 }
  52
  53 static HB_Bool
  54 hb_freetype_can_render(HB_Font font, const HB_UChar16 *chars, hb_uint32 len) {
  55   FT_Face face = (FT_Face)font->userData;
  56
  57   ssize_t i = 0;
  58   while (i < len) {
  59     const uint32_t cp = utf16_to_code_point(chars, len, &i);
  60     if (FT_Get_Char_Index(face, cp) == 0)
  61       return 0;
  62   }
  63
  64   return 1;
  65 }
  66
  67 static HB_Error
  68 hb_freetype_outline_point_get(HB_Font font, HB_Glyph glyph, int flags,
  69                               hb_uint32 point, HB_Fixed *xpos, HB_Fixed *ypos,
  70                               hb_uint32 *n_points) {
  71   HB_Error error = HB_Err_Ok;
  72   FT_Face face = (FT_Face) font->userData;
  73
  74   int load_flags = (flags & HB_ShaperFlag_UseDesignMetrics) ? FT_LOAD_NO_HINTING : FT_LOAD_DEFAULT;
  75
  76   if ((error = (HB_Error) FT_Load_Glyph(face, glyph, load_flags)))
  77     return error;
  78
  79   if (face->glyph->format != ft_glyph_format_outline)
  80     return (HB_Error)HB_Err_Invalid_SubTable;
  81
  82   *n_points = face->glyph->outline.n_points;
  83   if (!(*n_points))
  84     return HB_Err_Ok;
  85
  86   if (point > *n_points)
  87     return (HB_Error)HB_Err_Invalid_SubTable;
  88
  89   *xpos = face->glyph->outline.points[point].x;
  90   *ypos = face->glyph->outline.points[point].y;
  91
  92   return HB_Err_Ok;
  93 }
  94
  95 static void
  96 hb_freetype_glyph_metrics_get(HB_Font font, HB_Glyph glyph,
  97                               HB_GlyphMetrics *metrics) {
  98   FT_Face face = (FT_Face) font->userData;
  99
 100   const FT_Error error = FT_Load_Glyph(face, glyph, FT_LOAD_DEFAULT);
 101   if (error) {
 102     metrics->x = metrics->y = metrics->width = metrics->height = 0;
 103     metrics->xOffset = metrics->yOffset = 0;
 104     return;
 105   }
 106
 107   const FT_Glyph_Metrics *ftmetrics = &face->glyph->metrics;
 108   metrics->width = ftmetrics->width;
 109   metrics->height = ftmetrics->height;
 110   metrics->x = ftmetrics->horiAdvance;
 111   metrics->y = 0;  // unclear what this is
 112   metrics->xOffset = ftmetrics->horiBearingX;
 113   metrics->yOffset = ftmetrics->horiBearingY;
 114 }
 115
 116 static HB_Fixed
 117 hb_freetype_font_metric_get(HB_Font font, HB_FontMetric metric) {
 118   FT_Face face = (FT_Face) font->userData;
 119
 120   switch (metric) {
 121   case HB_FontAscent:
 122     // Note that we aren't scanning the VDMX table which we probably would in
 123     // an ideal world.
 124     return face->ascender;
 125   default:
 126     return 0;
 127   }
 128 }
 129
 130 const HB_FontClass hb_freetype_class = {
 131   hb_freetype_string_to_glyphs,
 132   hb_freetype_advances_get,
 133   hb_freetype_can_render,
 134   hb_freetype_outline_point_get,
 135   hb_freetype_glyph_metrics_get,
 136   hb_freetype_font_metric_get,
 137 };
 138
 139 HB_Error
 140 hb_freetype_table_sfnt_get(void *voidface, const HB_Tag tag, HB_Byte *buffer, HB_UInt *len) {
 141   FT_Face face = (FT_Face) voidface;
 142   FT_ULong ftlen = *len;
 143
 144   if (!FT_IS_SFNT(face))
 145     return HB_Err_Invalid_Argument;
 146
 147   const FT_Error error = FT_Load_Sfnt_Table(face, tag, 0, buffer, &ftlen);
 148   *len = ftlen;
 149   return (HB_Error) error;
 150 }