1/*
2 * Copyright © 2017 Google, Inc.
3 *
4 * This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Google Author(s): Behdad Esfahbod
25 */
26
27#ifndef HB_KERN_HH
28#define HB_KERN_HH
29
30#include "hb-open-type.hh"
31#include "hb-aat-layout-common.hh"
32#include "hb-ot-layout-gpos-table.hh"
33
34
35namespace OT {
36
37
38template <typename Driver>
39struct hb_kern_machine_t
40{
41 hb_kern_machine_t (const Driver &driver_,
42 bool crossStream_ = false) :
43 driver (driver_),
44 crossStream (crossStream_) {}
45
46 HB_NO_SANITIZE_SIGNED_INTEGER_OVERFLOW
47 void kern (hb_font_t *font,
48 hb_buffer_t *buffer,
49 hb_mask_t kern_mask,
50 bool scale = true) const
51 {
52 OT::hb_ot_apply_context_t c (1, font, buffer);
53 c.set_lookup_mask (kern_mask);
54 c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
55 OT::hb_ot_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;
56 skippy_iter.init (&c);
57
58 bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
59 unsigned int count = buffer->len;
60 hb_glyph_info_t *info = buffer->info;
61 hb_glyph_position_t *pos = buffer->pos;
62 for (unsigned int idx = 0; idx < count;)
63 {
64 if (!(info[idx].mask & kern_mask))
65 {
66 idx++;
67 continue;
68 }
69
70 skippy_iter.reset (idx, 1);
71 if (!skippy_iter.next ())
72 {
73 idx++;
74 continue;
75 }
76
77 unsigned int i = idx;
78 unsigned int j = skippy_iter.idx;
79
80 hb_position_t kern = driver.get_kerning (info[i].codepoint,
81 info[j].codepoint);
82
83
84 if (likely (!kern))
85 goto skip;
86
87 if (horizontal)
88 {
89 if (scale)
90 kern = font->em_scale_x (kern);
91 if (crossStream)
92 {
93 pos[j].y_offset = kern;
94 buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
95 }
96 else
97 {
98 hb_position_t kern1 = kern >> 1;
99 hb_position_t kern2 = kern - kern1;
100 pos[i].x_advance += kern1;
101 pos[j].x_advance += kern2;
102 pos[j].x_offset += kern2;
103 }
104 }
105 else
106 {
107 if (scale)
108 kern = font->em_scale_y (kern);
109 if (crossStream)
110 {
111 pos[j].x_offset = kern;
112 buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
113 }
114 else
115 {
116 hb_position_t kern1 = kern >> 1;
117 hb_position_t kern2 = kern - kern1;
118 pos[i].y_advance += kern1;
119 pos[j].y_advance += kern2;
120 pos[j].y_offset += kern2;
121 }
122 }
123
124 buffer->unsafe_to_break (i, j + 1);
125
126 skip:
127 idx = skippy_iter.idx;
128 }
129 }
130
131 const Driver &driver;
132 bool crossStream;
133};
134
135
136} /* namespace OT */
137
138
139#endif /* HB_KERN_HH */
140