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
|
/*
* Copyright © 2018 Ebrahim Byagowi
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#ifndef HB_OT_COLOR_SBIX_TABLE_HH
#define HB_OT_COLOR_SBIX_TABLE_HH
#include "hb-open-type.hh"
/*
* sbix -- Standard Bitmap Graphics
* https://docs.microsoft.com/en-us/typography/opentype/spec/sbix
* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6sbix.html
*/
#define HB_OT_TAG_sbix HB_TAG('s','b','i','x')
namespace OT {
struct SBIXGlyph
{
HBINT16 xOffset; /* The horizontal (x-axis) offset from the left
* edge of the graphic to the glyph’s origin.
* That is, the x-coordinate of the point on the
* baseline at the left edge of the glyph. */
HBINT16 yOffset; /* The vertical (y-axis) offset from the bottom
* edge of the graphic to the glyph’s origin.
* That is, the y-coordinate of the point on the
* baseline at the left edge of the glyph. */
Tag graphicType; /* Indicates the format of the embedded graphic
* data: one of 'jpg ', 'png ' or 'tiff', or the
* special format 'dupe'. */
UnsizedArrayOf<HBUINT8>
data; /* The actual embedded graphic data. The total
* length is inferred from sequential entries in
* the glyphDataOffsets array and the fixed size
* (8 bytes) of the preceding fields. */
public:
DEFINE_SIZE_ARRAY (8, data);
};
struct SBIXStrike
{
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
imageOffsetsZ.sanitize_shallow (c, c->get_num_glyphs () + 1));
}
hb_blob_t *get_glyph_blob (unsigned int glyph_id,
hb_blob_t *sbix_blob,
hb_tag_t file_type,
int *x_offset,
int *y_offset,
unsigned int num_glyphs,
unsigned int *strike_ppem) const
{
if (unlikely (!ppem)) return hb_blob_get_empty (); /* To get Null() object out of the way. */
unsigned int retry_count = 8;
unsigned int sbix_len = sbix_blob->length;
unsigned int strike_offset = (const char *) this - (const char *) sbix_blob->data;
assert (strike_offset < sbix_len);
retry:
if (unlikely (glyph_id >= num_glyphs ||
imageOffsetsZ[glyph_id + 1] <= imageOffsetsZ[glyph_id] ||
imageOffsetsZ[glyph_id + 1] - imageOffsetsZ[glyph_id] <= SBIXGlyph::min_size ||
(unsigned int) imageOffsetsZ[glyph_id + 1] > sbix_len - strike_offset))
return hb_blob_get_empty ();
unsigned int glyph_offset = strike_offset + (unsigned int) imageOffsetsZ[glyph_id] + SBIXGlyph::min_size;
unsigned int glyph_length = imageOffsetsZ[glyph_id + 1] - imageOffsetsZ[glyph_id] - SBIXGlyph::min_size;
const SBIXGlyph *glyph = &(this+imageOffsetsZ[glyph_id]);
if (glyph->graphicType == HB_TAG ('d','u','p','e'))
{
if (glyph_length >= 2)
{
glyph_id = *((HBUINT16 *) &glyph->data);
if (retry_count--)
goto retry;
}
return hb_blob_get_empty ();
}
if (unlikely (file_type != glyph->graphicType))
return hb_blob_get_empty ();
if (strike_ppem) *strike_ppem = ppem;
if (x_offset) *x_offset = glyph->xOffset;
if (y_offset) *y_offset = glyph->yOffset;
return hb_blob_create_sub_blob (sbix_blob, glyph_offset, glyph_length);
}
public:
HBUINT16 ppem; /* The PPEM size for which this strike was designed. */
HBUINT16 resolution; /* The device pixel density (in PPI) for which this
* strike was designed. (E.g., 96 PPI, 192 PPI.) */
protected:
UnsizedArrayOf<LOffsetTo<SBIXGlyph>>
imageOffsetsZ; /* Offset from the beginning of the strike data header
* to bitmap data for an individual glyph ID. */
public:
DEFINE_SIZE_STATIC (8);
};
struct sbix
{
static constexpr hb_tag_t tableTag = HB_OT_TAG_sbix;
bool has_data () const { return version; }
const SBIXStrike &get_strike (unsigned int i) const { return this+strikes[i]; }
struct accelerator_t
{
void init (hb_face_t *face)
{
table = hb_sanitize_context_t().reference_table<sbix> (face);
num_glyphs = face->get_num_glyphs ();
}
void fini () { table.destroy (); }
bool has_data () const { return table->has_data (); }
bool get_extents (hb_font_t *font,
hb_codepoint_t glyph,
hb_glyph_extents_t *extents) const
{
/* We only support PNG right now, and following function checks type. */
return get_png_extents (font, glyph, extents);
}
hb_blob_t *reference_png (hb_font_t *font,
hb_codepoint_t glyph_id,
int *x_offset,
int *y_offset,
unsigned int *available_ppem) const
{
return choose_strike (font).get_glyph_blob (glyph_id, table.get_blob (),
HB_TAG ('p','n','g',' '),
x_offset, y_offset,
num_glyphs, available_ppem);
}
private:
const SBIXStrike &choose_strike (hb_font_t *font) const
{
unsigned count = table->strikes.len;
if (unlikely (!count))
return Null(SBIXStrike);
unsigned int requested_ppem = hb_max (font->x_ppem, font->y_ppem);
if (!requested_ppem)
requested_ppem = 1<<30; /* Choose largest strike. */
/* TODO Add DPI sensitivity as well? */
unsigned int best_i = 0;
unsigned int best_ppem = table->get_strike (0).ppem;
for (unsigned int i = 1; i < count; i++)
{
unsigned int ppem = (table->get_strike (i)).ppem;
if ((requested_ppem <= ppem && ppem < best_ppem) ||
(requested_ppem > best_ppem && ppem > best_ppem))
{
best_i = i;
best_ppem = ppem;
}
}
return table->get_strike (best_i);
}
struct PNGHeader
{
HBUINT8 signature[8];
struct
{
struct
{
HBUINT32 length;
Tag type;
} header;
HBUINT32 width;
HBUINT32 height;
HBUINT8 bitDepth;
HBUINT8 colorType;
HBUINT8 compressionMethod;
HBUINT8 filterMethod;
HBUINT8 interlaceMethod;
} IHDR;
public:
DEFINE_SIZE_STATIC (29);
};
bool get_png_extents (hb_font_t *font,
hb_codepoint_t glyph,
hb_glyph_extents_t *extents) const
{
/* Following code is safe to call even without data.
* But faster to short-circuit. */
if (!has_data ())
return false;
int x_offset = 0, y_offset = 0;
unsigned int strike_ppem = 0;
hb_blob_t *blob = reference_png (font, glyph, &x_offset, &y_offset, &strike_ppem);
const PNGHeader &png = *blob->as<PNGHeader>();
extents->x_bearing = x_offset;
extents->y_bearing = y_offset;
extents->width = png.IHDR.width;
extents->height = png.IHDR.height;
/* Convert to font units. */
if (strike_ppem)
{
float scale = font->face->get_upem () / (float) strike_ppem;
extents->x_bearing = roundf (extents->x_bearing * scale);
extents->y_bearing = roundf (extents->y_bearing * scale);
extents->width = roundf (extents->width * scale);
extents->height = roundf (extents->height * scale);
}
hb_blob_destroy (blob);
return strike_ppem;
}
private:
hb_blob_ptr_t<sbix> table;
unsigned int num_glyphs;
};
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (likely (c->check_struct (this) &&
version >= 1 &&
strikes.sanitize (c, this)));
}
protected:
HBUINT16 version; /* Table version number — set to 1 */
HBUINT16 flags; /* Bit 0: Set to 1. Bit 1: Draw outlines.
* Bits 2 to 15: reserved (set to 0). */
LOffsetLArrayOf<SBIXStrike>
strikes; /* Offsets from the beginning of the 'sbix'
* table to data for each individual bitmap strike. */
public:
DEFINE_SIZE_ARRAY (8, strikes);
};
struct sbix_accelerator_t : sbix::accelerator_t {};
} /* namespace OT */
#endif /* HB_OT_COLOR_SBIX_TABLE_HH */
|