FontLanguage.cpp revision 5e995fb850c2b32631914c3815dfb421855fba9b 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "Minikin"
18
19#include "FontLanguage.h"
20
21#include <hb.h>
22#include <unicode/uloc.h>
23
24namespace android {
25
26#define SCRIPT_TAG(c1, c2, c3, c4) \
27        ((uint32_t)(c1)) << 24 | ((uint32_t)(c2)) << 16 | ((uint32_t)(c3)) <<  8 | ((uint32_t)(c4))
28
29// Parse BCP 47 language identifier into internal structure
30FontLanguage::FontLanguage(const char* buf, size_t length) : FontLanguage() {
31    size_t i;
32    for (i = 0; i < length; i++) {
33        char c = buf[i];
34        if (c == '-' || c == '_') break;
35    }
36    if (i == 2 || i == 3) {  // only accept two or three letter language code.
37        mLanguage = buf[0] | (buf[1] << 8) | ((i == 3) ? (buf[2] << 16) : 0);
38    } else {
39        // We don't understand anything other than two-letter or three-letter
40        // language codes, so we skip parsing the rest of the string.
41        mLanguage = 0ul;
42        return;
43    }
44
45    size_t next;
46    for (i++; i < length; i = next + 1) {
47        for (next = i; next < length; next++) {
48            char c = buf[next];
49            if (c == '-' || c == '_') break;
50        }
51        if (next - i == 4 && 'A' <= buf[i] && buf[i] <= 'Z') {
52            mScript = SCRIPT_TAG(buf[i], buf[i + 1], buf[i + 2], buf[i + 3]);
53        }
54    }
55
56    mSubScriptBits = scriptToSubScriptBits(mScript);
57}
58
59//static
60uint8_t FontLanguage::scriptToSubScriptBits(uint32_t script) {
61    uint8_t subScriptBits = 0u;
62    switch (script) {
63        case SCRIPT_TAG('H', 'a', 'n', 'g'):
64            subScriptBits = kHangulFlag;
65            break;
66        case SCRIPT_TAG('H', 'a', 'n', 'i'):
67            subScriptBits = kHanFlag;
68            break;
69        case SCRIPT_TAG('H', 'a', 'n', 's'):
70            subScriptBits = kHanFlag | kSimplifiedChineseFlag;
71            break;
72        case SCRIPT_TAG('H', 'a', 'n', 't'):
73            subScriptBits = kHanFlag | kTraditionalChineseFlag;
74            break;
75        case SCRIPT_TAG('H', 'i', 'r', 'a'):
76            subScriptBits = kHiraganaFlag;
77            break;
78        case SCRIPT_TAG('H', 'r', 'k', 't'):
79            subScriptBits = kKatakanaFlag | kHiraganaFlag;
80            break;
81        case SCRIPT_TAG('J', 'p', 'a', 'n'):
82            subScriptBits = kHanFlag | kKatakanaFlag | kHiraganaFlag;
83            break;
84        case SCRIPT_TAG('K', 'a', 'n', 'a'):
85            subScriptBits = kKatakanaFlag;
86            break;
87        case SCRIPT_TAG('K', 'o', 'r', 'e'):
88            subScriptBits = kHanFlag | kHangulFlag;
89            break;
90        case SCRIPT_TAG('Q', 'a', 'a', 'e'):
91            subScriptBits = kEmojiFlag;
92            break;
93    }
94    return subScriptBits;
95}
96
97std::string FontLanguage::getString() const {
98    if (mLanguage == 0ul) {
99        return "und";
100    }
101    char buf[16];
102    size_t i = 0;
103    buf[i++] = mLanguage & 0xFF ;
104    buf[i++] = (mLanguage >> 8) & 0xFF;
105    char third_letter = (mLanguage >> 16) & 0xFF;
106    if (third_letter != 0) buf[i++] = third_letter;
107    if (mScript != 0) {
108      buf[i++] = '-';
109      buf[i++] = (mScript >> 24) & 0xFFu;
110      buf[i++] = (mScript >> 16) & 0xFFu;
111      buf[i++] = (mScript >> 8) & 0xFFu;
112      buf[i++] = mScript & 0xFFu;
113    }
114    return std::string(buf, i);
115}
116
117bool FontLanguage::isEqualScript(const FontLanguage other) const {
118    return other.mScript == mScript;
119}
120
121bool FontLanguage::supportsHbScript(hb_script_t script) const {
122    static_assert(SCRIPT_TAG('J', 'p', 'a', 'n') == HB_TAG('J', 'p', 'a', 'n'),
123                  "The Minikin script and HarfBuzz hb_script_t have different encodings.");
124    if (script == mScript) return true;
125    uint8_t requestedBits = scriptToSubScriptBits(script);
126    return requestedBits != 0 && (mSubScriptBits & requestedBits) == requestedBits;
127}
128
129int FontLanguage::match(const FontLanguage other) const {
130    // TODO: Use script for matching.
131    return *this == other;
132}
133
134#undef SCRIPT_TAG
135}  // namespace android
136