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Previously, we stayed on the conservative side and disallowed any grapheme breaks (and thus cursoring) where a virama was followed by a letter, since we did not know if the virama would be forming a cluster with the letter or not. This created problems with Indic languages with infrequent conjuncts, such as Tamil. Now we use the information in calculated advances to find if a cluster is formed. If there is no cluster, we break the grapheme and allow cursoring after the virama. Test: Unit tests added to GraphemeBreakTests and MeasurementTests. Test: Also manually tested Tamil sequences. Bug: 35721792 Change-Id: Ib159edb94b3ad6f693f0d3dad016b332b2cef447
48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
/*
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* Copyright (C) 2014 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_GRAPHEME_BREAK_H
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#define MINIKIN_GRAPHEME_BREAK_H
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namespace minikin {
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class GraphemeBreak {
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public:
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// These values must be kept in sync with CURSOR_AFTER etc in Paint.java
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enum MoveOpt {
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AFTER = 0,
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AT_OR_AFTER = 1,
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BEFORE = 2,
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AT_OR_BEFORE = 3,
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AT = 4
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};
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// Determine whether the given offset is a grapheme break.
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// This implementation generally follows Unicode's UTR #29 extended
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// grapheme break, with various tweaks.
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static bool isGraphemeBreak(const float* advances, const uint16_t* buf, size_t start,
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size_t count, size_t offset);
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// Matches Android's Java API. Note, return (size_t)-1 for AT to
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// signal non-break because unsigned return type.
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static size_t getTextRunCursor(const float* advances, const uint16_t* buf, size_t start,
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size_t count, size_t offset, MoveOpt opt);
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};
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} // namespace minikin
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#endif // MINIKIN_GRAPHEME_BREAK_H
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