FontFamily.h revision 43bb9743ca91a761b9723674ac862660dd2be834 
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#ifndef MINIKIN_FONT_FAMILY_H
18#define MINIKIN_FONT_FAMILY_H
19
20#include <vector>
21#include <string>
22#include <hb.h>
23
24#include <utils/TypeHelpers.h>
25
26#include <minikin/MinikinRefCounted.h>
27#include <minikin/SparseBitSet.h>
28
29namespace android {
30
31class MinikinFont;
32
33// FontLanguage is a compact representation of a bcp-47 language tag. It
34// does not capture all possible information, only what directly affects
35// font rendering.
36class FontLanguage {
37    friend class FontStyle;
38    friend class FontLanguages;
39public:
40    FontLanguage() : mBits(0) { }
41
42    // Parse from string
43    FontLanguage(const char* buf, size_t size);
44
45    bool operator==(const FontLanguage other) const {
46        return mBits != kUnsupportedLanguage && mBits == other.mBits;
47    }
48    operator bool() const { return mBits != 0; }
49
50    bool isUnsupported() const { return mBits == kUnsupportedLanguage; }
51    bool hasEmojiFlag() const { return isUnsupported() ? false : (mBits & kEmojiFlag); }
52
53    std::string getString() const;
54
55    // 0 = no match, 1 = language matches
56    int match(const FontLanguage other) const;
57
58private:
59    explicit FontLanguage(uint32_t bits) : mBits(bits) { }
60
61    uint32_t bits() const { return mBits; }
62
63    static const uint32_t kUnsupportedLanguage = 0xFFFFFFFFu;
64    static const uint32_t kBaseLangMask = 0xFFFFFFu;
65    static const uint32_t kHansFlag = 1u << 24;
66    static const uint32_t kHantFlag = 1u << 25;
67    static const uint32_t kEmojiFlag = 1u << 26;
68    static const uint32_t kScriptMask = kHansFlag | kHantFlag | kEmojiFlag;
69    uint32_t mBits;
70};
71
72// A list of zero or more instances of FontLanguage, in the order of
73// preference. Used for further resolution of rendering results.
74class FontLanguages {
75public:
76    FontLanguages() { mLangs.clear(); }
77
78    // Parse from string, which is a comma-separated list of languages
79    FontLanguages(const char* buf, size_t size);
80
81    const FontLanguage& operator[](size_t index) const { return mLangs.at(index); }
82
83    size_t size() const { return mLangs.size(); }
84
85private:
86    std::vector<FontLanguage> mLangs;
87};
88
89// FontStyle represents all style information needed to select an actual font
90// from a collection. The implementation is packed into two 32-bit words
91// so it can be efficiently copied, embedded in other objects, etc.
92class FontStyle {
93public:
94    FontStyle() : FontStyle(0 /* variant */, 4 /* weight */, false /* italic */) {}
95    FontStyle(int weight, bool italic) : FontStyle(0 /* variant */, weight, italic) {}
96    FontStyle(uint32_t langListId)
97            : FontStyle(langListId, 0 /* variant */, 4 /* weight */, false /* italic */) {}
98
99    FontStyle(int variant, int weight, bool italic);
100    FontStyle(uint32_t langListId, int variant, int weight, bool italic);
101
102    int getWeight() const { return bits & kWeightMask; }
103    bool getItalic() const { return (bits & kItalicMask) != 0; }
104    int getVariant() const { return (bits >> kVariantShift) & kVariantMask; }
105    uint32_t getLanguageListId() const { return mLanguageListId; }
106
107    bool operator==(const FontStyle other) const {
108          return bits == other.bits && mLanguageListId == other.mLanguageListId;
109    }
110
111    hash_t hash() const;
112
113    // Looks up a language list from an internal cache and returns its ID.
114    // If the passed language list is not in the cache, registers it and returns newly assigned ID.
115    static uint32_t registerLanguageList(const std::string& languages);
116private:
117    static const uint32_t kWeightMask = (1 << 4) - 1;
118    static const uint32_t kItalicMask = 1 << 4;
119    static const int kVariantShift = 5;
120    static const uint32_t kVariantMask = (1 << 2) - 1;
121
122    static uint32_t pack(int variant, int weight, bool italic);
123
124    uint32_t bits;
125    uint32_t mLanguageListId;
126};
127
128enum FontVariant {
129    VARIANT_DEFAULT = 0,
130    VARIANT_COMPACT = 1,
131    VARIANT_ELEGANT = 2,
132};
133
134inline hash_t hash_type(const FontStyle &style) {
135    return style.hash();
136}
137
138// attributes representing transforms (fake bold, fake italic) to match styles
139class FontFakery {
140public:
141    FontFakery() : mFakeBold(false), mFakeItalic(false) { }
142    FontFakery(bool fakeBold, bool fakeItalic) : mFakeBold(fakeBold), mFakeItalic(fakeItalic) { }
143    // TODO: want to support graded fake bolding
144    bool isFakeBold() { return mFakeBold; }
145    bool isFakeItalic() { return mFakeItalic; }
146private:
147    bool mFakeBold;
148    bool mFakeItalic;
149};
150
151struct FakedFont {
152    // ownership is the enclosing FontCollection
153    MinikinFont* font;
154    FontFakery fakery;
155};
156
157class FontFamily : public MinikinRefCounted {
158public:
159    FontFamily() : mHbFont(nullptr) { }
160
161    FontFamily(FontLanguage lang, int variant) : mLang(lang), mVariant(variant), mHbFont(nullptr) {
162    }
163
164    ~FontFamily();
165
166    // Add font to family, extracting style information from the font
167    bool addFont(MinikinFont* typeface);
168
169    void addFont(MinikinFont* typeface, FontStyle style);
170    FakedFont getClosestMatch(FontStyle style) const;
171
172    FontLanguage lang() const { return mLang; }
173    int variant() const { return mVariant; }
174
175    // API's for enumerating the fonts in a family. These don't guarantee any particular order
176    size_t getNumFonts() const;
177    MinikinFont* getFont(size_t index) const;
178    FontStyle getStyle(size_t index) const;
179
180    // Get Unicode coverage. Lifetime of returned bitset is same as receiver. May return nullptr on
181    // error.
182    const SparseBitSet* getCoverage();
183
184    // Returns true if the font has a glyph for the code point and variation selector pair.
185    // Caller should acquire a lock before calling the method.
186    bool hasVariationSelector(uint32_t codepoint, uint32_t variationSelector);
187
188    // Purges cached mHbFont.
189    // hb_font_t keeps a reference to hb_face_t which is managed by HbFaceCache. Thus,
190    // it is good to purge hb_font_t once it is no longer necessary.
191    // Caller should acquire a lock before calling the method.
192    void purgeHbFontCache();
193private:
194    void addFontLocked(MinikinFont* typeface, FontStyle style);
195
196    class Font {
197    public:
198        Font(MinikinFont* typeface, FontStyle style) :
199            typeface(typeface), style(style) { }
200        MinikinFont* typeface;
201        FontStyle style;
202    };
203    FontLanguage mLang;
204    int mVariant;
205    std::vector<Font> mFonts;
206
207    SparseBitSet mCoverage;
208    bool mCoverageValid;
209
210    hb_font_t* mHbFont;
211};
212
213}  // namespace android
214
215#endif  // MINIKIN_FONT_FAMILY_H
216