FontCollection.cpp revision fc119c68f5def1e44e65ae4cdd147c01d62c9ad2 
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
112    // Even if the font supports variation sequence, mRanges isn't aware of the base character of
113    // the sequence. Search all FontFamilies if variation sequence is specified.
114    // TODO: Always use mRanges for font search.
115    const std::vector<FontFamily*>& familyVec = (vs == 0) ? mFamilyVec : mFamilies;
116    Range range;
117    if (vs == 0) {
118        range = mRanges[ch >> kLogCharsPerPage];
119    } else {
120        range = { 0, mFamilies.size() };
121    }
122
123#ifdef VERBOSE_DEBUG
124    ALOGD("querying range %zd:%zd\n", range.start, range.end);
125#endif
126    FontFamily* bestFamily = nullptr;
127    int bestScore = -1;
128    for (size_t i = range.start; i < range.end; i++) {
129        FontFamily* family = familyVec[i];
130        if (vs == 0 ? family->getCoverage()->get(ch) : family->hasVariationSelector(ch, vs)) {
131            // First font family in collection always matches
132            if (mFamilies[0] == family) {
133                return family;
134            }
135            int score = lang.match(family->lang()) * 2;
136            if (family->variant() == 0 || family->variant() == variant) {
137                score++;
138            }
139            if (score > bestScore) {
140                bestScore = score;
141                bestFamily = family;
142            }
143        }
144    }
145    if (bestFamily == nullptr && vs != 0) {
146        // If no fonts support the codepoint and variation selector pair,
147        // fallback to select a font family that supports just the base
148        // character, ignoring the variation selector.
149        return getFamilyForChar(ch, 0, lang, variant);
150    }
151    if (bestFamily == nullptr && !mFamilyVec.empty()) {
152        UErrorCode errorCode = U_ZERO_ERROR;
153        const UNormalizer2* normalizer = unorm2_getNFDInstance(&errorCode);
154        if (U_SUCCESS(errorCode)) {
155            UChar decomposed[4];
156            int len = unorm2_getRawDecomposition(normalizer, ch, decomposed, 4, &errorCode);
157            if (U_SUCCESS(errorCode) && len > 0) {
158                int off = 0;
159                U16_NEXT_UNSAFE(decomposed, off, ch);
160                return getFamilyForChar(ch, vs, lang, variant);
161            }
162        }
163        bestFamily = mFamilies[0];
164    }
165    return bestFamily;
166}
167
168const uint32_t NBSP = 0xa0;
169const uint32_t ZWJ = 0x200c;
170const uint32_t ZWNJ = 0x200d;
171const uint32_t KEYCAP = 0x20e3;
172const uint32_t HYPHEN = 0x2010;
173const uint32_t NB_HYPHEN = 0x2011;
174
175// Characters where we want to continue using existing font run instead of
176// recomputing the best match in the fallback list.
177static const uint32_t stickyWhitelist[] = { '!', ',', '-', '.', ':', ';', '?', NBSP, ZWJ, ZWNJ,
178        KEYCAP, HYPHEN, NB_HYPHEN };
179
180static bool isStickyWhitelisted(uint32_t c) {
181    for (size_t i = 0; i < sizeof(stickyWhitelist) / sizeof(stickyWhitelist[0]); i++) {
182        if (stickyWhitelist[i] == c) return true;
183    }
184    return false;
185}
186
187static bool isVariationSelector(uint32_t c) {
188    return (0xFE00 <= c && c <= 0xFE0F) || (0xE0100 <= c && c <= 0xE01EF);
189}
190
191void FontCollection::itemize(const uint16_t *string, size_t string_size, FontStyle style,
192        vector<Run>* result) const {
193    FontLanguage lang = style.getLanguage();
194    int variant = style.getVariant();
195    FontFamily* lastFamily = NULL;
196    Run* run = NULL;
197
198    if (string_size == 0) {
199        return;
200    }
201
202    const uint32_t kEndOfString = 0xFFFFFFFF;
203
204    uint32_t nextCh = 0;
205    uint32_t prevCh = 0;
206    size_t nextUtf16Pos = 0;
207    size_t readLength = 0;
208    U16_NEXT(string, readLength, string_size, nextCh);
209
210    do {
211        const uint32_t ch = nextCh;
212        const size_t utf16Pos = nextUtf16Pos;
213        nextUtf16Pos = readLength;
214        if (readLength < string_size) {
215            U16_NEXT(string, readLength, string_size, nextCh);
216        } else {
217            nextCh = kEndOfString;
218        }
219
220        bool shouldContinueRun = false;
221        if (lastFamily != nullptr) {
222            if (isStickyWhitelisted(ch)) {
223                // Continue using existing font as long as it has coverage and is whitelisted
224                shouldContinueRun = lastFamily->getCoverage()->get(ch);
225            } else if (isVariationSelector(ch)) {
226                // Always continue if the character is a variation selector.
227                shouldContinueRun = true;
228            }
229        }
230
231        if (!shouldContinueRun) {
232            FontFamily* family =
233                    getFamilyForChar(ch, isVariationSelector(nextCh) ? nextCh : 0, lang, variant);
234            if (utf16Pos == 0 || family != lastFamily) {
235                size_t start = utf16Pos;
236                // Workaround for Emoji keycap until we implement per-cluster font
237                // selection: if keycap is found in a different font that also
238                // supports previous char, attach previous char to the new run.
239                // Bug 7557244.
240                if (ch == KEYCAP && utf16Pos != 0 && family && family->getCoverage()->get(prevCh)) {
241                    const size_t prevChLength = U16_LENGTH(prevCh);
242                    run->end -= prevChLength;
243                    if (run->start == run->end) {
244                        result->pop_back();
245                    }
246                    start -= prevChLength;
247                }
248                Run dummy;
249                result->push_back(dummy);
250                run = &result->back();
251                if (family == NULL) {
252                    run->fakedFont.font = NULL;
253                } else {
254                    run->fakedFont = family->getClosestMatch(style);
255                }
256                lastFamily = family;
257                run->start = start;
258            }
259        }
260        prevCh = ch;
261        run->end = nextUtf16Pos;  // exclusive
262    } while (nextCh != kEndOfString);
263}
264
265MinikinFont* FontCollection::baseFont(FontStyle style) {
266    return baseFontFaked(style).font;
267}
268
269FakedFont FontCollection::baseFontFaked(FontStyle style) {
270    if (mFamilies.empty()) {
271        return FakedFont();
272    }
273    return mFamilies[0]->getClosestMatch(style);
274}
275
276uint32_t FontCollection::getId() const {
277    return mId;
278}
279
280void FontCollection::purgeFontFamilyHbFontCache() const {
281    assertMinikinLocked();
282    for (size_t i = 0; i < mFamilies.size(); ++i) {
283        mFamilies[i]->purgeHbFontCache();
284    }
285}
286
287}  // namespace android
288