1 /* 2 * Copyright (C) 2017 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 #include "LineBreakerUtil.h" 18 19 namespace minikin { 20 21 // Very long words trigger O(n^2) behavior in hyphenation, so we disable hyphenation for 22 // unreasonably long words. This is somewhat of a heuristic because extremely long words are 23 // possible in some languages. This does mean that very long real words can get broken by 24 // desperate breaks, with no hyphens. 25 constexpr size_t LONGEST_HYPHENATED_WORD = 45; 26 27 // Hyphenates a string potentially containing non-breaking spaces. 28 std::vector<HyphenationType> hyphenate(const U16StringPiece& str, const Hyphenator& hyphenator) { 29 std::vector<HyphenationType> out; 30 const size_t len = str.size(); 31 out.resize(len); 32 33 // A word here is any consecutive string of non-NBSP characters. 34 bool inWord = false; 35 size_t wordStart = 0; // The initial value will never be accessed, but just in case. 36 for (size_t i = 0; i <= len; i++) { 37 if (i == len || str[i] == CHAR_NBSP) { 38 if (inWord) { 39 // A word just ended. Hyphenate it. 40 const U16StringPiece word = str.substr(Range(wordStart, i)); 41 if (word.size() <= LONGEST_HYPHENATED_WORD) { 42 hyphenator.hyphenate(word, out.data() + wordStart); 43 } else { // Word is too long. Inefficient to hyphenate. 44 out.insert(out.end(), word.size(), HyphenationType::DONT_BREAK); 45 } 46 inWord = false; 47 } 48 if (i < len) { 49 // Insert one DONT_BREAK for the NBSP. 50 out.push_back(HyphenationType::DONT_BREAK); 51 } 52 } else if (!inWord) { 53 inWord = true; 54 wordStart = i; 55 } 56 } 57 return out; 58 } 59 60 } // namespace minikin 61
