summaryrefslogtreecommitdiffstats
path: root/modules/woff2/src/glyph.cc
blob: 5b4948679c76c3933e8075ccb37e9c693bbb25cb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
/* Copyright 2013 Google Inc. All Rights Reserved.

   Distributed under MIT license.
   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/

/* Glyph manipulation */

#include "./glyph.h"

#include <stdlib.h>
#include <limits>
#include "./buffer.h"
#include "./store_bytes.h"

namespace woff2 {

static const int32_t kFLAG_ONCURVE = 1;
static const int32_t kFLAG_XSHORT = 1 << 1;
static const int32_t kFLAG_YSHORT = 1 << 2;
static const int32_t kFLAG_REPEAT = 1 << 3;
static const int32_t kFLAG_XREPEATSIGN = 1 << 4;
static const int32_t kFLAG_YREPEATSIGN = 1 << 5;
static const int32_t kFLAG_OVERLAP_SIMPLE = 1 << 6;
static const int32_t kFLAG_ARG_1_AND_2_ARE_WORDS = 1 << 0;
static const int32_t kFLAG_WE_HAVE_A_SCALE = 1 << 3;
static const int32_t kFLAG_MORE_COMPONENTS = 1 << 5;
static const int32_t kFLAG_WE_HAVE_AN_X_AND_Y_SCALE = 1 << 6;
static const int32_t kFLAG_WE_HAVE_A_TWO_BY_TWO = 1 << 7;
static const int32_t kFLAG_WE_HAVE_INSTRUCTIONS = 1 << 8;

bool ReadCompositeGlyphData(Buffer* buffer, Glyph* glyph) {
  glyph->have_instructions = false;
  glyph->composite_data = buffer->buffer() + buffer->offset();
  size_t start_offset = buffer->offset();
  uint16_t flags = kFLAG_MORE_COMPONENTS;
  while (flags & kFLAG_MORE_COMPONENTS) {
    if (!buffer->ReadU16(&flags)) {
      return FONT_COMPRESSION_FAILURE();
    }
    glyph->have_instructions |= (flags & kFLAG_WE_HAVE_INSTRUCTIONS) != 0;
    size_t arg_size = 2;  // glyph index
    if (flags & kFLAG_ARG_1_AND_2_ARE_WORDS) {
      arg_size += 4;
    } else {
      arg_size += 2;
    }
    if (flags & kFLAG_WE_HAVE_A_SCALE) {
      arg_size += 2;
    } else if (flags & kFLAG_WE_HAVE_AN_X_AND_Y_SCALE) {
      arg_size += 4;
    } else if (flags & kFLAG_WE_HAVE_A_TWO_BY_TWO) {
      arg_size += 8;
    }
    if (!buffer->Skip(arg_size)) {
      return FONT_COMPRESSION_FAILURE();
    }
  }
  if (buffer->offset() - start_offset > std::numeric_limits<uint32_t>::max()) {
    return FONT_COMPRESSION_FAILURE();
  }
  glyph->composite_data_size = buffer->offset() - start_offset;
  return true;
}

bool ReadGlyph(const uint8_t* data, size_t len, Glyph* glyph) {
  Buffer buffer(data, len);

  int16_t num_contours;
  if (!buffer.ReadS16(&num_contours)) {
    return FONT_COMPRESSION_FAILURE();
  }

  // Read the bounding box.
  if (!buffer.ReadS16(&glyph->x_min) ||
      !buffer.ReadS16(&glyph->y_min) ||
      !buffer.ReadS16(&glyph->x_max) ||
      !buffer.ReadS16(&glyph->y_max)) {
    return FONT_COMPRESSION_FAILURE();
  }

  if (num_contours == 0) {
    // Empty glyph.
    return true;
  }

  if (num_contours > 0) {
    // Simple glyph.
    glyph->contours.resize(num_contours);

    // Read the number of points per contour.
    uint16_t last_point_index = 0;
    for (int i = 0; i < num_contours; ++i) {
      uint16_t point_index;
      if (!buffer.ReadU16(&point_index)) {
        return FONT_COMPRESSION_FAILURE();
      }
      uint16_t num_points = point_index - last_point_index + (i == 0 ? 1 : 0);
      glyph->contours[i].resize(num_points);
      last_point_index = point_index;
    }

    // Read the instructions.
    if (!buffer.ReadU16(&glyph->instructions_size)) {
      return FONT_COMPRESSION_FAILURE();
    }
    glyph->instructions_data = data + buffer.offset();
    if (!buffer.Skip(glyph->instructions_size)) {
      return FONT_COMPRESSION_FAILURE();
    }

    // Read the run-length coded flags.
    std::vector<std::vector<uint8_t> > flags(num_contours);
    {
      uint8_t flag = 0;
      uint8_t flag_repeat = 0;
      for (int i = 0; i < num_contours; ++i) {
        flags[i].resize(glyph->contours[i].size());
        for (size_t j = 0; j < glyph->contours[i].size(); ++j) {
          if (flag_repeat == 0) {
            if (!buffer.ReadU8(&flag)) {
              return FONT_COMPRESSION_FAILURE();
            }
            if (flag & kFLAG_REPEAT) {
              if (!buffer.ReadU8(&flag_repeat)) {
                return FONT_COMPRESSION_FAILURE();
              }
            }
          } else {
            flag_repeat--;
          }
          flags[i][j] = flag;
          glyph->contours[i][j].on_curve = flag & kFLAG_ONCURVE;
        }
      }
    }

    if (!flags.empty() && !flags[0].empty()) {
      glyph->overlap_simple_flag_set = (flags[0][0] & kFLAG_OVERLAP_SIMPLE);
    }

    // Read the x coordinates.
    int prev_x = 0;
    for (int i = 0; i < num_contours; ++i) {
      for (size_t j = 0; j < glyph->contours[i].size(); ++j) {
        uint8_t flag = flags[i][j];
        if (flag & kFLAG_XSHORT) {
          // single byte x-delta coord value
          uint8_t x_delta;
          if (!buffer.ReadU8(&x_delta)) {
            return FONT_COMPRESSION_FAILURE();
          }
          int sign = (flag & kFLAG_XREPEATSIGN) ? 1 : -1;
          glyph->contours[i][j].x = prev_x + sign * x_delta;
        } else {
          // double byte x-delta coord value
          int16_t x_delta = 0;
          if (!(flag & kFLAG_XREPEATSIGN)) {
            if (!buffer.ReadS16(&x_delta)) {
              return FONT_COMPRESSION_FAILURE();
            }
          }
          glyph->contours[i][j].x = prev_x + x_delta;
        }
        prev_x = glyph->contours[i][j].x;
      }
    }

    // Read the y coordinates.
    int prev_y = 0;
    for (int i = 0; i < num_contours; ++i) {
      for (size_t j = 0; j < glyph->contours[i].size(); ++j) {
        uint8_t flag = flags[i][j];
        if (flag & kFLAG_YSHORT) {
          // single byte y-delta coord value
          uint8_t y_delta;
          if (!buffer.ReadU8(&y_delta)) {
            return FONT_COMPRESSION_FAILURE();
          }
          int sign = (flag & kFLAG_YREPEATSIGN) ? 1 : -1;
          glyph->contours[i][j].y = prev_y + sign * y_delta;
        } else {
          // double byte y-delta coord value
          int16_t y_delta = 0;
          if (!(flag & kFLAG_YREPEATSIGN)) {
            if (!buffer.ReadS16(&y_delta)) {
              return FONT_COMPRESSION_FAILURE();
            }
          }
          glyph->contours[i][j].y = prev_y + y_delta;
        }
        prev_y = glyph->contours[i][j].y;
      }
    }
  } else if (num_contours == -1) {
    // Composite glyph.
    if (!ReadCompositeGlyphData(&buffer, glyph)) {
      return FONT_COMPRESSION_FAILURE();
    }
    // Read the instructions.
    if (glyph->have_instructions) {
      if (!buffer.ReadU16(&glyph->instructions_size)) {
        return FONT_COMPRESSION_FAILURE();
      }
      glyph->instructions_data = data + buffer.offset();
      if (!buffer.Skip(glyph->instructions_size)) {
        return FONT_COMPRESSION_FAILURE();
      }
    } else {
      glyph->instructions_size = 0;
    }
  } else {
    return FONT_COMPRESSION_FAILURE();
  }
  return true;
}

namespace {

void StoreBbox(const Glyph& glyph, size_t* offset, uint8_t* dst) {
  Store16(glyph.x_min, offset, dst);
  Store16(glyph.y_min, offset, dst);
  Store16(glyph.x_max, offset, dst);
  Store16(glyph.y_max, offset, dst);
}

void StoreInstructions(const Glyph& glyph, size_t* offset, uint8_t* dst) {
  Store16(glyph.instructions_size, offset, dst);
  StoreBytes(glyph.instructions_data, glyph.instructions_size, offset, dst);
}

bool StoreEndPtsOfContours(const Glyph& glyph, size_t* offset, uint8_t* dst) {
  int end_point = -1;
  for (const auto& contour : glyph.contours) {
    end_point += contour.size();
    if (contour.size() > std::numeric_limits<uint16_t>::max() ||
        end_point > std::numeric_limits<uint16_t>::max()) {
      return FONT_COMPRESSION_FAILURE();
    }
    Store16(end_point, offset, dst);
  }
  return true;
}

bool StorePoints(const Glyph& glyph, size_t* offset,
                 uint8_t* dst, size_t dst_size) {
  int previous_flag = -1;
  int repeat_count = 0;
  int last_x = 0;
  int last_y = 0;
  size_t x_bytes = 0;
  size_t y_bytes = 0;

  // Store the flags and calculate the total size of the x and y coordinates.
  for (const auto& contour : glyph.contours) {
    for (const auto& point : contour) {
      int flag = point.on_curve ? kFLAG_ONCURVE : 0;
      if (previous_flag == -1 && glyph.overlap_simple_flag_set) {
        // First flag needs to have overlap simple bit set.
        flag = flag | kFLAG_OVERLAP_SIMPLE;
      }
      int dx = point.x - last_x;
      int dy = point.y - last_y;
      if (dx == 0) {
        flag |= kFLAG_XREPEATSIGN;
      } else if (dx > -256 && dx < 256) {
        flag |= kFLAG_XSHORT | (dx > 0 ? kFLAG_XREPEATSIGN : 0);
        x_bytes += 1;
      } else {
        x_bytes += 2;
      }
      if (dy == 0) {
        flag |= kFLAG_YREPEATSIGN;
      } else if (dy > -256 && dy < 256) {
        flag |= kFLAG_YSHORT | (dy > 0 ? kFLAG_YREPEATSIGN : 0);
        y_bytes += 1;
      } else {
        y_bytes += 2;
      }
      if (flag == previous_flag && repeat_count != 255) {
        dst[*offset - 1] |= kFLAG_REPEAT;
        repeat_count++;
      } else {
        if (repeat_count != 0) {
          if (*offset >= dst_size) {
            return FONT_COMPRESSION_FAILURE();
          }
          dst[(*offset)++] = repeat_count;
        }
        if (*offset >= dst_size) {
          return FONT_COMPRESSION_FAILURE();
        }
        dst[(*offset)++] = flag;
        repeat_count = 0;
      }
      last_x = point.x;
      last_y = point.y;
      previous_flag = flag;
    }
  }
  if (repeat_count != 0) {
    if (*offset >= dst_size) {
      return FONT_COMPRESSION_FAILURE();
    }
    dst[(*offset)++] = repeat_count;
  }

  if (*offset + x_bytes + y_bytes > dst_size) {
    return FONT_COMPRESSION_FAILURE();
  }

  // Store the x and y coordinates.
  size_t x_offset = *offset;
  size_t y_offset = *offset + x_bytes;
  last_x = 0;
  last_y = 0;
  for (const auto& contour : glyph.contours) {
    for (const auto& point : contour) {
      int dx = point.x - last_x;
      int dy = point.y - last_y;
      if (dx == 0) {
        // pass
      } else if (dx > -256 && dx < 256) {
        dst[x_offset++] = std::abs(dx);
      } else {
        Store16(dx, &x_offset, dst);
      }
      if (dy == 0) {
        // pass
      } else if (dy > -256 && dy < 256) {
        dst[y_offset++] = std::abs(dy);
      } else {
        Store16(dy, &y_offset, dst);
      }
      last_x += dx;
      last_y += dy;
    }
  }
  *offset = y_offset;
  return true;
}

}  // namespace

bool StoreGlyph(const Glyph& glyph, uint8_t* dst, size_t* dst_size) {
  size_t offset = 0;
  if (glyph.composite_data_size > 0) {
    // Composite glyph.
    if (*dst_size < ((10ULL + glyph.composite_data_size) +
                     ((glyph.have_instructions ? 2ULL : 0) +
                      glyph.instructions_size))) {
      return FONT_COMPRESSION_FAILURE();
    }
    Store16(-1, &offset, dst);
    StoreBbox(glyph, &offset, dst);
    StoreBytes(glyph.composite_data, glyph.composite_data_size, &offset, dst);
    if (glyph.have_instructions) {
      StoreInstructions(glyph, &offset, dst);
    }
  } else if (glyph.contours.size() > 0) {
    // Simple glyph.
    if (glyph.contours.size() > std::numeric_limits<int16_t>::max()) {
      return FONT_COMPRESSION_FAILURE();
    }
    if (*dst_size < ((12ULL + 2 * glyph.contours.size()) +
                     glyph.instructions_size)) {
      return FONT_COMPRESSION_FAILURE();
    }
    Store16(glyph.contours.size(), &offset, dst);
    StoreBbox(glyph, &offset, dst);
    if (!StoreEndPtsOfContours(glyph, &offset, dst)) {
      return FONT_COMPRESSION_FAILURE();
    }
    StoreInstructions(glyph, &offset, dst);
    if (!StorePoints(glyph, &offset, dst, *dst_size)) {
      return FONT_COMPRESSION_FAILURE();
    }
  }
  *dst_size = offset;
  return true;
}

} // namespace woff2