1 /* 2 * Copyright (C) 2015 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 #define LOG_TAG "Minikin" 18 19 #include "LayoutUtils.h" 20 21 /** 22 * For the purpose of layout, a word break is a boundary with no 23 * kerning or complex script processing. This is necessarily a 24 * heuristic, but should be accurate most of the time. 25 */ 26 static bool isWordBreakAfter(int c) { 27 if (c == ' ' || (c >= 0x2000 && c <= 0x200a) || c == 0x3000) { 28 // spaces 29 return true; 30 } 31 // Note: kana is not included, as sophisticated fonts may kern kana 32 return false; 33 } 34 35 static bool isWordBreakBefore(int c) { 36 // CJK ideographs (and yijing hexagram symbols) 37 return isWordBreakAfter(c) || (c >= 0x3400 && c <= 0x9fff); 38 } 39 40 /** 41 * Return offset of previous word break. It is either < offset or == 0. 42 */ 43 size_t getPrevWordBreakForCache( 44 const uint16_t* chars, size_t offset, size_t len) { 45 if (offset == 0) return 0; 46 if (offset > len) offset = len; 47 if (isWordBreakBefore(chars[offset - 1])) { 48 return offset - 1; 49 } 50 for (size_t i = offset - 1; i > 0; i--) { 51 if (isWordBreakBefore(chars[i]) || isWordBreakAfter(chars[i - 1])) { 52 return i; 53 } 54 } 55 return 0; 56 } 57 58 /** 59 * Return offset of next word break. It is either > offset or == len. 60 */ 61 size_t getNextWordBreakForCache( 62 const uint16_t* chars, size_t offset, size_t len) { 63 if (offset >= len) return len; 64 if (isWordBreakAfter(chars[offset])) { 65 return offset + 1; 66 } 67 for (size_t i = offset + 1; i < len; i++) { 68 // No need to check isWordBreakAfter(chars[i - 1]) since it is checked 69 // in previous iteration. Note that isWordBreakBefore returns true 70 // whenever isWordBreakAfter returns true. 71 if (isWordBreakBefore(chars[i])) { 72 return i; 73 } 74 } 75 return len; 76 } 77
