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/*
* 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.
*/
#define LOG_TAG "Minikin"
#include "LayoutUtils.h"
/**
* 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(int c) {
if (c == ' ' || (c >= 0x2000 && c <= 0x200a) || c == 0x3000) {
// spaces
return true;
}
// Note: kana is not included, as sophisticated fonts may kern kana
return false;
}
static bool isWordBreakBefore(int c) {
// CJK ideographs (and yijing hexagram symbols)
return isWordBreakAfter(c) || (c >= 0x3400 && c <= 0x9fff);
}
/**
* Return offset of previous word break. It is either < offset or == 0.
*/
size_t getPrevWordBreakForCache(
const uint16_t* chars, size_t offset, size_t len) {
if (offset == 0) return 0;
if (offset > len) offset = len;
if (isWordBreakBefore(chars[offset - 1])) {
return offset - 1;
}
for (size_t i = offset - 1; i > 0; i--) {
if (isWordBreakBefore(chars[i]) || isWordBreakAfter(chars[i - 1])) {
return i;
}
}
return 0;
}
/**
* Return offset of next word break. It is either > offset or == len.
*/
size_t getNextWordBreakForCache(
const uint16_t* chars, size_t offset, size_t len) {
if (offset >= len) return len;
if (isWordBreakAfter(chars[offset])) {
return offset + 1;
}
for (size_t i = offset + 1; i < len; 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(chars[i])) {
return i;
}
}
return len;
}
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