FontCollection.cpp revision 3dd8757fcf48976295bac566277b6da1046e8362 
1/*
2 * Copyright (C) 2013 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 VERBOSE_DEBUG
18
19#define LOG_TAG "Minikin"
20#include <cutils/log.h>
21
22#include "unicode/unistr.h"
23#include "unicode/unorm2.h"
24
25#include "MinikinInternal.h"
26#include <minikin/FontCollection.h>
27
28using std::vector;
29
30namespace android {
31
32template <typename T>
33static inline T max(T a, T b) {
34    return a>b ? a : b;
35}
36
37uint32_t FontCollection::sNextId = 0;
38
39FontCollection::FontCollection(const vector<FontFamily*>& typefaces) :
40    mMaxChar(0) {
41    AutoMutex _l(gMinikinLock);
42    mId = sNextId++;
43    vector<uint32_t> lastChar;
44    size_t nTypefaces = typefaces.size();
45#ifdef VERBOSE_DEBUG
46    ALOGD("nTypefaces = %zd\n", nTypefaces);
47#endif
48    const FontStyle defaultStyle;
49    for (size_t i = 0; i < nTypefaces; i++) {
50        FontFamily* family = typefaces[i];
51        MinikinFont* typeface = family->getClosestMatch(defaultStyle).font;
52        if (typeface == NULL) {
53            continue;
54        }
55        family->RefLocked();
56        const SparseBitSet* coverage = family->getCoverage();
57        if (coverage == nullptr) {
58            family->UnrefLocked();
59            continue;
60        }
61        mFamilies.push_back(family);  // emplace_back would be better
62        mMaxChar = max(mMaxChar, coverage->length());
63        lastChar.push_back(coverage->nextSetBit(0));
64    }
65    nTypefaces = mFamilies.size();
66    LOG_ALWAYS_FATAL_IF(nTypefaces == 0,
67        "Font collection must have at least one valid typeface");
68    size_t nPages = (mMaxChar + kPageMask) >> kLogCharsPerPage;
69    size_t offset = 0;
70    for (size_t i = 0; i < nPages; i++) {
71        Range dummy;
72        mRanges.push_back(dummy);
73        Range* range = &mRanges.back();
74#ifdef VERBOSE_DEBUG
75        ALOGD("i=%zd: range start = %zd\n", i, offset);
76#endif
77        range->start = offset;
78        for (size_t j = 0; j < nTypefaces; j++) {
79            if (lastChar[j] < (i + 1) << kLogCharsPerPage) {
80                FontFamily* family = mFamilies[j];
81                mFamilyVec.push_back(family);
82                offset++;
83                uint32_t nextChar = family->getCoverage()->nextSetBit((i + 1) << kLogCharsPerPage);
84#ifdef VERBOSE_DEBUG
85                ALOGD("nextChar = %d (j = %zd)\n", nextChar, j);
86#endif
87                lastChar[j] = nextChar;
88            }
89        }
90        range->end = offset;
91    }
92}
93
94FontCollection::~FontCollection() {
95    for (size_t i = 0; i < mFamilies.size(); i++) {
96        mFamilies[i]->UnrefLocked();
97    }
98}
99
100// Implement heuristic for choosing best-match font. Here are the rules:
101// 1. If first font in the collection has the character, it wins.
102// 2. If a font matches both language and script, it gets a score of 4.
103// 3. If a font matches just language, it gets a score of 2.
104// 4. Matching the "compact" or "elegant" variant adds one to the score.
105// 5. Highest score wins, with ties resolved to the first font.
106FontFamily* FontCollection::getFamilyForChar(uint32_t ch, uint32_t vs,
107            FontLanguage lang, int variant) const {
108    if (ch >= mMaxChar) {
109        return NULL;
110    }
111    const Range& range = mRanges[ch >> kLogCharsPerPage];
112#ifdef VERBOSE_DEBUG
113    ALOGD("querying range %zd:%zd\n", range.start, range.end);
114#endif
115    FontFamily* bestFamily = nullptr;
116    int bestScore = -1;
117    for (size_t i = range.start; i < range.end; i++) {
118        FontFamily* family = mFamilyVec[i];
119        if (vs == 0 ? family->getCoverage()->get(ch) : family->hasVariationSelector(ch, vs)) {
120            // First font family in collection always matches
121            if (mFamilies[0] == family) {
122                return family;
123            }
124            int score = lang.match(family->lang()) * 2;
125            if (family->variant() == 0 || family->variant() == variant) {
126                score++;
127            }
128            if (score > bestScore) {
129                bestScore = score;
130                bestFamily = family;
131            }
132        }
133    }
134    if (bestFamily == nullptr && vs != 0) {
135        // If no fonts support the codepoint and variation selector pair,
136        // fallback to select a font family that supports just the base
137        // character, ignoring the variation selector.
138        return getFamilyForChar(ch, 0, lang, variant);
139    }
140    if (bestFamily == nullptr && !mFamilyVec.empty()) {
141        UErrorCode errorCode = U_ZERO_ERROR;
142        const UNormalizer2* normalizer = unorm2_getNFDInstance(&errorCode);
143        if (U_SUCCESS(errorCode)) {
144            UChar decomposed[4];
145            int len = unorm2_getRawDecomposition(normalizer, ch, decomposed, 4, &errorCode);
146            if (U_SUCCESS(errorCode) && len > 0) {
147                int off = 0;
148                U16_NEXT_UNSAFE(decomposed, off, ch);
149                return getFamilyForChar(ch, vs, lang, variant);
150            }
151        }
152        bestFamily = mFamilies[0];
153    }
154    return bestFamily;
155}
156
157const uint32_t NBSP = 0xa0;
158const uint32_t ZWJ = 0x200c;
159const uint32_t ZWNJ = 0x200d;
160const uint32_t KEYCAP = 0x20e3;
161const uint32_t HYPHEN = 0x2010;
162const uint32_t NB_HYPHEN = 0x2011;
163
164// Characters where we want to continue using existing font run instead of
165// recomputing the best match in the fallback list.
166static const uint32_t stickyWhitelist[] = { '!', ',', '-', '.', ':', ';', '?', NBSP, ZWJ, ZWNJ,
167        KEYCAP, HYPHEN, NB_HYPHEN };
168
169static bool isStickyWhitelisted(uint32_t c) {
170    for (size_t i = 0; i < sizeof(stickyWhitelist) / sizeof(stickyWhitelist[0]); i++) {
171        if (stickyWhitelist[i] == c) return true;
172    }
173    return false;
174}
175
176static bool isVariationSelector(uint32_t c) {
177    return (0xFE00 <= c && c <= 0xFE0F) || (0xE0100 <= c && c <= 0xE01EF);
178}
179
180void FontCollection::itemize(const uint16_t *string, size_t string_size, FontStyle style,
181        vector<Run>* result) const {
182    FontLanguage lang = style.getLanguage();
183    int variant = style.getVariant();
184    FontFamily* lastFamily = NULL;
185    Run* run = NULL;
186
187    if (string_size == 0) {
188        return;
189    }
190
191    const uint32_t kEndOfString = 0xFFFFFFFF;
192
193    uint32_t nextCh = 0;
194    uint32_t prevCh = 0;
195    size_t nextUtf16Pos = 0;
196    size_t readLength = 0;
197    U16_NEXT(string, readLength, string_size, nextCh);
198
199    do {
200        const uint32_t ch = nextCh;
201        const size_t utf16Pos = nextUtf16Pos;
202        nextUtf16Pos = readLength;
203        if (readLength < string_size) {
204            U16_NEXT(string, readLength, string_size, nextCh);
205        } else {
206            nextCh = kEndOfString;
207        }
208
209        bool shouldContinueRun = false;
210        if (lastFamily != nullptr) {
211            if (isStickyWhitelisted(ch)) {
212                // Continue using existing font as long as it has coverage and is whitelisted
213                shouldContinueRun = lastFamily->getCoverage()->get(ch);
214            } else if (isVariationSelector(ch)) {
215                // Always continue if the character is a variation selector.
216                shouldContinueRun = true;
217            }
218        }
219
220        if (!shouldContinueRun) {
221            FontFamily* family =
222                    getFamilyForChar(ch, isVariationSelector(nextCh) ? nextCh : 0, lang, variant);
223            if (utf16Pos == 0 || family != lastFamily) {
224                size_t start = utf16Pos;
225                // Workaround for Emoji keycap until we implement per-cluster font
226                // selection: if keycap is found in a different font that also
227                // supports previous char, attach previous char to the new run.
228                // Bug 7557244.
229                if (ch == KEYCAP && utf16Pos != 0 && family && family->getCoverage()->get(prevCh)) {
230                    const size_t prevChLength = U16_LENGTH(prevCh);
231                    run->end -= prevChLength;
232                    if (run->start == run->end) {
233                        result->pop_back();
234                    }
235                    start -= prevChLength;
236                }
237                Run dummy;
238                result->push_back(dummy);
239                run = &result->back();
240                if (family == NULL) {
241                    run->fakedFont.font = NULL;
242                } else {
243                    run->fakedFont = family->getClosestMatch(style);
244                }
245                lastFamily = family;
246                run->start = start;
247            }
248        }
249        prevCh = ch;
250        run->end = nextUtf16Pos;  // exclusive
251    } while (nextCh != kEndOfString);
252}
253
254MinikinFont* FontCollection::baseFont(FontStyle style) {
255    return baseFontFaked(style).font;
256}
257
258FakedFont FontCollection::baseFontFaked(FontStyle style) {
259    if (mFamilies.empty()) {
260        return FakedFont();
261    }
262    return mFamilies[0]->getClosestMatch(style);
263}
264
265uint32_t FontCollection::getId() const {
266    return mId;
267}
268
269void FontCollection::purgeFontFamilyHbFontCache() const {
270    assertMinikinLocked();
271    for (size_t i = 0; i < mFamilies.size(); ++i) {
272        mFamilies[i]->purgeHbFontCache();
273    }
274}
275
276}  // namespace android
277