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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_COLLECTION_H
18 #define MINIKIN_FONT_COLLECTION_H
19 
20 #include <memory>
21 #include <unordered_set>
22 #include <vector>
23 
24 #include <minikin/MinikinFont.h>
25 #include <minikin/FontFamily.h>
26 
27 namespace minikin {
28 
29 class FontCollection {
30 public:
31     explicit FontCollection(const std::vector<std::shared_ptr<FontFamily>>& typefaces);
32     explicit FontCollection(std::shared_ptr<FontFamily>&& typeface);
33 
34     struct Run {
35         FakedFont fakedFont;
36         int start;
37         int end;
38     };
39 
40     void itemize(const uint16_t *string, size_t string_length, FontStyle style,
41             std::vector<Run>* result) const;
42 
43     // Returns true if there is a glyph for the code point and variation selector pair.
44     // Returns false if no fonts have a glyph for the code point and variation
45     // selector pair, or invalid variation selector is passed.
46     bool hasVariationSelector(uint32_t baseCodepoint, uint32_t variationSelector) const;
47 
48     // Get base font with fakery information (fake bold could affect metrics)
49     FakedFont baseFontFaked(FontStyle style);
50 
51     // Creates new FontCollection based on this collection while applying font variations. Returns
52     // nullptr if none of variations apply to this collection.
53     std::shared_ptr<FontCollection>
54             createCollectionWithVariation(const std::vector<FontVariation>& variations);
55 
getSupportedTags()56     const std::unordered_set<AxisTag>& getSupportedTags() const {
57         return mSupportedAxes;
58     }
59 
60     uint32_t getId() const;
61 
62 private:
63     static const int kLogCharsPerPage = 8;
64     static const int kPageMask = (1 << kLogCharsPerPage) - 1;
65 
66     // mFamilyVec holds the indices of the mFamilies and mRanges holds the range of indices of
67     // mFamilyVec. The maximum number of pages is 0x10FF (U+10FFFF >> 8). The maximum number of
68     // the fonts is 0xFF. Thus, technically the maximum length of mFamilyVec is 0x10EE01
69     // (0x10FF * 0xFF). However, in practice, 16-bit integers are enough since most fonts supports
70     // only limited range of code points.
71     struct Range {
72         uint16_t start;
73         uint16_t end;
74     };
75 
76     // Initialize the FontCollection.
77     void init(const std::vector<std::shared_ptr<FontFamily>>& typefaces);
78 
79     const std::shared_ptr<FontFamily>& getFamilyForChar(uint32_t ch, uint32_t vs,
80             uint32_t langListId, int variant) const;
81 
82     uint32_t calcFamilyScore(uint32_t ch, uint32_t vs, int variant, uint32_t langListId,
83             const std::shared_ptr<FontFamily>& fontFamily) const;
84 
85     uint32_t calcCoverageScore(uint32_t ch, uint32_t vs,
86             const std::shared_ptr<FontFamily>& fontFamily) const;
87 
88     static uint32_t calcLanguageMatchingScore(uint32_t userLangListId,
89                                               const FontFamily& fontFamily);
90 
91     static uint32_t calcVariantMatchingScore(int variant, const FontFamily& fontFamily);
92 
93     // static for allocating unique id's
94     static uint32_t sNextId;
95 
96     // unique id for this font collection (suitable for cache key)
97     uint32_t mId;
98 
99     // Highest UTF-32 code point that can be mapped
100     uint32_t mMaxChar;
101 
102     // This vector has pointers to the all font family instances in this collection.
103     // This vector can't be empty.
104     std::vector<std::shared_ptr<FontFamily>> mFamilies;
105 
106     // Following two vectors are pre-calculated tables for resolving coverage faster.
107     // For example, to iterate over all fonts which support Unicode code point U+XXYYZZ,
108     // iterate font families index from mFamilyVec[mRanges[0xXXYY].start] to
109     // mFamilyVec[mRange[0xXXYY].end] instead of whole mFamilies.
110     // This vector contains indices into mFamilies.
111     // This vector can't be empty.
112     std::vector<Range> mRanges;
113     std::vector<uint8_t> mFamilyVec;
114 
115     // This vector has pointers to the font family instances which have cmap 14 subtables.
116     std::vector<std::shared_ptr<FontFamily>> mVSFamilyVec;
117 
118     // Set of supported axes in this collection.
119     std::unordered_set<AxisTag> mSupportedAxes;
120 };
121 
122 }  // namespace minikin
123 
124 #endif  // MINIKIN_FONT_COLLECTION_H
125