| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "LayoutUtils.h" |
| |
| namespace minikin { |
| |
| /* |
| * Determine whether the code unit is a word space for the purposes of justification. |
| * TODO: Support NBSP and other stretchable whitespace (b/34013491 and b/68204709). |
| */ |
| bool isWordSpace(uint16_t code_unit) { |
| return code_unit == ' '; |
| } |
| |
| /** |
| * For the purpose of layout, a word break is a boundary with no |
| * kerning or complex script processing. This is necessarily a |
| * heuristic, but should be accurate most of the time. |
| */ |
| static bool isWordBreakAfter(uint16_t c) { |
| if (c == ' ' || (0x2000 <= c && c <= 0x200A) || c == 0x3000) { |
| // spaces |
| return true; |
| } |
| // Note: kana is not included, as sophisticated fonts may kern kana |
| return false; |
| } |
| |
| static bool isWordBreakBefore(uint16_t c) { |
| // CJK ideographs (and yijing hexagram symbols) |
| return isWordBreakAfter(c) || (0x3400 <= c && c <= 0x9FFF); |
| } |
| |
| /** |
| * Return offset of previous word break. It is either < offset or == 0. |
| */ |
| uint32_t getPrevWordBreakForCache(const U16StringPiece& textBuf, uint32_t offset) { |
| if (offset == 0) return 0; |
| if (offset > textBuf.size()) offset = textBuf.size(); |
| if (isWordBreakBefore(textBuf[offset - 1])) { |
| return offset - 1; |
| } |
| for (uint32_t i = offset - 1; i > 0; i--) { |
| if (isWordBreakBefore(textBuf[i]) || isWordBreakAfter(textBuf[i - 1])) { |
| return i; |
| } |
| } |
| return 0; |
| } |
| |
| /** |
| * Return offset of next word break. It is either > offset or == len. |
| */ |
| uint32_t getNextWordBreakForCache(const U16StringPiece& textBuf, uint32_t offset) { |
| if (offset >= textBuf.size()) return textBuf.size(); |
| if (isWordBreakAfter(textBuf[offset])) { |
| return offset + 1; |
| } |
| for (uint32_t i = offset + 1; i < textBuf.size(); i++) { |
| // No need to check isWordBreakAfter(chars[i - 1]) since it is checked |
| // in previous iteration. Note that isWordBreakBefore returns true |
| // whenever isWordBreakAfter returns true. |
| if (isWordBreakBefore(textBuf[i])) { |
| return i; |
| } |
| } |
| return textBuf.size(); |
| } |
| |
| } // namespace minikin |