summaryrefslogtreecommitdiff
path: root/Build/source/libs/harfbuzz/harfbuzz-src/src/OT/glyf/SimpleGlyph.hh
blob: 6df978cf13e18a2e8d235862ac4afa8ed5f2a09d (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
#ifndef OT_GLYF_SIMPLEGLYPH_HH
#define OT_GLYF_SIMPLEGLYPH_HH


#include "../../hb-open-type.hh"


namespace OT {
namespace glyf_impl {


struct SimpleGlyph
{
  enum simple_glyph_flag_t
  {
    FLAG_ON_CURVE       = 0x01,
    FLAG_X_SHORT        = 0x02,
    FLAG_Y_SHORT        = 0x04,
    FLAG_REPEAT         = 0x08,
    FLAG_X_SAME         = 0x10,
    FLAG_Y_SAME         = 0x20,
    FLAG_OVERLAP_SIMPLE = 0x40,
    FLAG_RESERVED2      = 0x80
  };

  const GlyphHeader &header;
  hb_bytes_t bytes;
  SimpleGlyph (const GlyphHeader &header_, hb_bytes_t bytes_) :
    header (header_), bytes (bytes_) {}

  unsigned int instruction_len_offset () const
  { return GlyphHeader::static_size + 2 * header.numberOfContours; }

  unsigned int length (unsigned int instruction_len) const
  { return instruction_len_offset () + 2 + instruction_len; }

  unsigned int instructions_length () const
  {
    unsigned int instruction_length_offset = instruction_len_offset ();
    if (unlikely (instruction_length_offset + 2 > bytes.length)) return 0;

    const HBUINT16 &instructionLength = StructAtOffset<HBUINT16> (&bytes, instruction_length_offset);
    /* Out of bounds of the current glyph */
    if (unlikely (length (instructionLength) > bytes.length)) return 0;
    return instructionLength;
  }

  const hb_bytes_t trim_padding () const
  {
    /* based on FontTools _g_l_y_f.py::trim */
    const uint8_t *glyph = (uint8_t*) bytes.arrayZ;
    const uint8_t *glyph_end = glyph + bytes.length;
    /* simple glyph w/contours, possibly trimmable */
    glyph += instruction_len_offset ();

    if (unlikely (glyph + 2 >= glyph_end)) return hb_bytes_t ();
    unsigned int num_coordinates = StructAtOffset<HBUINT16> (glyph - 2, 0) + 1;
    unsigned int num_instructions = StructAtOffset<HBUINT16> (glyph, 0);

    glyph += 2 + num_instructions;

    unsigned int coord_bytes = 0;
    unsigned int coords_with_flags = 0;
    while (glyph < glyph_end)
    {
      uint8_t flag = *glyph;
      glyph++;

      unsigned int repeat = 1;
      if (flag & FLAG_REPEAT)
      {
	if (unlikely (glyph >= glyph_end)) return hb_bytes_t ();
	repeat = *glyph + 1;
	glyph++;
      }

      unsigned int xBytes, yBytes;
      xBytes = yBytes = 0;
      if (flag & FLAG_X_SHORT) xBytes = 1;
      else if ((flag & FLAG_X_SAME) == 0) xBytes = 2;

      if (flag & FLAG_Y_SHORT) yBytes = 1;
      else if ((flag & FLAG_Y_SAME) == 0) yBytes = 2;

      coord_bytes += (xBytes + yBytes) * repeat;
      coords_with_flags += repeat;
      if (coords_with_flags >= num_coordinates) break;
    }

    if (unlikely (coords_with_flags != num_coordinates)) return hb_bytes_t ();
    return bytes.sub_array (0, bytes.length + coord_bytes - (glyph_end - glyph));
  }

  /* zero instruction length */
  void drop_hints ()
  {
    GlyphHeader &glyph_header = const_cast<GlyphHeader &> (header);
    (HBUINT16 &) StructAtOffset<HBUINT16> (&glyph_header, instruction_len_offset ()) = 0;
  }

  void drop_hints_bytes (hb_bytes_t &dest_start, hb_bytes_t &dest_end) const
  {
    unsigned int instructions_len = instructions_length ();
    unsigned int glyph_length = length (instructions_len);
    dest_start = bytes.sub_array (0, glyph_length - instructions_len);
    dest_end = bytes.sub_array (glyph_length, bytes.length - glyph_length);
  }

  void set_overlaps_flag ()
  {
    if (unlikely (!header.numberOfContours)) return;

    unsigned flags_offset = length (instructions_length ());
    if (unlikely (flags_offset + 1 > bytes.length)) return;

    HBUINT8 &first_flag = (HBUINT8 &) StructAtOffset<HBUINT16> (&bytes, flags_offset);
    first_flag = (uint8_t) first_flag | FLAG_OVERLAP_SIMPLE;
  }

  static bool read_flags (const HBUINT8 *&p /* IN/OUT */,
			  contour_point_vector_t &points_ /* IN/OUT */,
			  const HBUINT8 *end)
  {
    unsigned count = points_.length;
    for (unsigned int i = 0; i < count;)
    {
      if (unlikely (p + 1 > end)) return false;
      uint8_t flag = *p++;
      points_.arrayZ[i++].flag = flag;
      if (flag & FLAG_REPEAT)
      {
	if (unlikely (p + 1 > end)) return false;
	unsigned int repeat_count = *p++;
	unsigned stop = hb_min (i + repeat_count, count);
	for (; i < stop;)
	  points_.arrayZ[i++].flag = flag;
      }
    }
    return true;
  }

  static bool read_points (const HBUINT8 *&p /* IN/OUT */,
			   contour_point_vector_t &points_ /* IN/OUT */,
			   const HBUINT8 *end,
			   float contour_point_t::*m,
			   const simple_glyph_flag_t short_flag,
			   const simple_glyph_flag_t same_flag)
  {
    int v = 0;

    unsigned count = points_.length;
    for (unsigned i = 0; i < count; i++)
    {
      unsigned flag = points_[i].flag;
      if (flag & short_flag)
      {
	if (unlikely (p + 1 > end)) return false;
	if (flag & same_flag)
	  v += *p++;
	else
	  v -= *p++;
      }
      else
      {
	if (!(flag & same_flag))
	{
	  if (unlikely (p + HBINT16::static_size > end)) return false;
	  v += *(const HBINT16 *) p;
	  p += HBINT16::static_size;
	}
      }
      points_.arrayZ[i].*m = v;
    }
    return true;
  }

  bool get_contour_points (contour_point_vector_t &points_ /* OUT */,
			   bool phantom_only = false) const
  {
    const HBUINT16 *endPtsOfContours = &StructAfter<HBUINT16> (header);
    int num_contours = header.numberOfContours;
    assert (num_contours);
    /* One extra item at the end, for the instruction-count below. */
    if (unlikely (!bytes.check_range (&endPtsOfContours[num_contours]))) return false;
    unsigned int num_points = endPtsOfContours[num_contours - 1] + 1;

    points_.alloc (num_points + 4); // Allocate for phantom points, to avoid a possible copy
    if (!points_.resize (num_points)) return false;
    if (phantom_only) return true;

    for (int i = 0; i < num_contours; i++)
      points_[endPtsOfContours[i]].is_end_point = true;

    /* Skip instructions */
    const HBUINT8 *p = &StructAtOffset<HBUINT8> (&endPtsOfContours[num_contours + 1],
						 endPtsOfContours[num_contours]);

    if (unlikely ((const char *) p < bytes.arrayZ)) return false; /* Unlikely overflow */
    const HBUINT8 *end = (const HBUINT8 *) (bytes.arrayZ + bytes.length);
    if (unlikely (p >= end)) return false;

    /* Read x & y coordinates */
    return read_flags (p, points_, end)
        && read_points (p, points_, end, &contour_point_t::x,
			FLAG_X_SHORT, FLAG_X_SAME)
	&& read_points (p, points_, end, &contour_point_t::y,
			FLAG_Y_SHORT, FLAG_Y_SAME);
  }
};


} /* namespace glyf_impl */
} /* namespace OT */


#endif /* OT_GLYF_SIMPLEGLYPH_HH */