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f3afe92def
Some fonts support multiple scripts, for example, some fonts for Korean supports not only "Kore" but also "Jamo". To select fonts based on their multiple languages, this CL introduces the following changes: - Compares all languages of the font family and use the maximum score for font selection. - Even if each language of the font family doesn't support the requested language, the font get score of 2 if the requested font is covered by all of the languages of the font family. For example, the font for "ko-Hang,ko-Hani" gets score of 2 for the requested language "ko-Kore". Bug: 26687969 Change-Id: I7f13b51464c9b01982bb573251d77052b9ddbd70
127 lines
4.5 KiB
C++
127 lines
4.5 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MINIKIN_FONT_LANGUAGE_H
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#define MINIKIN_FONT_LANGUAGE_H
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#include <string>
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#include <vector>
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#include <hb.h>
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namespace android {
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// Due to the limits in font fallback score calculation, we can't use anything more than 17
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// languages.
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const size_t FONT_LANGUAGES_LIMIT = 17;
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class FontLanguages;
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// FontLanguage is a compact representation of a BCP 47 language tag. It
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// does not capture all possible information, only what directly affects
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// font rendering.
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struct FontLanguage {
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public:
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// Default constructor creates the unsupported language.
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FontLanguage() : mScript(0ul), mLanguage(0ul), mSubScriptBits(0ul) {}
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// Parse from string
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FontLanguage(const char* buf, size_t length);
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bool operator==(const FontLanguage other) const {
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return !isUnsupported() && isEqualScript(other) && mLanguage == other.mLanguage;
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}
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bool operator!=(const FontLanguage other) const {
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return !(*this == other);
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}
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bool isUnsupported() const { return mLanguage == 0ul; }
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bool hasEmojiFlag() const { return mSubScriptBits & kEmojiFlag; }
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bool isEqualScript(const FontLanguage& other) const;
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// Returns true if this script supports the given script. For example, ja-Jpan supports Hira,
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// ja-Hira doesn't support Jpan.
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bool supportsHbScript(hb_script_t script) const;
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std::string getString() const;
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// Calculates a matching score. This score represents how well the input languages cover this
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// language. The maximum score in the language list is returned.
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// 0 = no match, 1 = script match, 2 = script and primary language match.
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int calcScoreFor(const FontLanguages& supported) const;
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uint64_t getIdentifier() const { return (uint64_t)mScript << 32 | (uint64_t)mLanguage; }
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private:
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friend class FontLanguages; // for FontLanguages constructor
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// ISO 15924 compliant script code. The 4 chars script code are packed into a 32 bit integer.
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uint32_t mScript;
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// ISO 639-1 or ISO 639-2 compliant language code.
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// The two or three letter language code is packed into 32 bit integer.
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// mLanguage = 0 means the FontLanguage is unsupported.
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uint32_t mLanguage;
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// For faster comparing, use 8 bits for specific scripts.
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static const uint8_t kBopomofoFlag = 1u;
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static const uint8_t kEmojiFlag = 1u << 1;
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static const uint8_t kHanFlag = 1u << 2;
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static const uint8_t kHangulFlag = 1u << 3;
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static const uint8_t kHiraganaFlag = 1u << 4;
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static const uint8_t kKatakanaFlag = 1u << 5;
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static const uint8_t kSimplifiedChineseFlag = 1u << 6;
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static const uint8_t kTraditionalChineseFlag = 1u << 7;
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uint8_t mSubScriptBits;
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static uint8_t scriptToSubScriptBits(uint32_t script);
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// Returns true if the provide subscript bits has the requested subscript bits.
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// Note that this function returns false if the requested subscript bits are empty.
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static bool supportsScript(uint8_t providedBits, uint8_t requestedBits);
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};
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// An immutable list of languages.
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class FontLanguages {
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public:
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FontLanguages(std::vector<FontLanguage>&& languages);
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FontLanguages() : mUnionOfSubScriptBits(0), mIsAllTheSameLanguage(false) {}
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FontLanguages(FontLanguages&&) = default;
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size_t size() const { return mLanguages.size(); }
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bool empty() const { return mLanguages.empty(); }
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const FontLanguage& operator[] (size_t n) const { return mLanguages[n]; }
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private:
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friend struct FontLanguage; // for calcScoreFor
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std::vector<FontLanguage> mLanguages;
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uint8_t mUnionOfSubScriptBits;
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bool mIsAllTheSameLanguage;
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uint8_t getUnionOfSubScriptBits() const { return mUnionOfSubScriptBits; }
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bool isAllTheSameLanguage() const { return mIsAllTheSameLanguage; }
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// Do not copy and assign.
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FontLanguages(const FontLanguages&) = delete;
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void operator=(const FontLanguages&) = delete;
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};
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} // namespace android
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#endif // MINIKIN_FONT_LANGUAGE_H
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