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f09cf789ef
This CL does: 1. Move the getNextWordBreak/getPrevWordBreak function to a separate source file. 2. Adding "ForCache" suffix for function name for making clear these function is for layout cache. 3. Introduce unit tests for them. Bug: 11256006 Change-Id: I4138751a4570915f1a0d6c8921f89700f8ec7f35
77 lines
2.3 KiB
C++
77 lines
2.3 KiB
C++
/*
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* Copyright (C) 2015 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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#define LOG_TAG "Minikin"
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#include "LayoutUtils.h"
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/**
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* For the purpose of layout, a word break is a boundary with no
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* kerning or complex script processing. This is necessarily a
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* heuristic, but should be accurate most of the time.
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*/
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static bool isWordBreakAfter(int c) {
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if (c == ' ' || (c >= 0x2000 && c <= 0x200a) || c == 0x3000) {
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// spaces
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return true;
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}
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// Note: kana is not included, as sophisticated fonts may kern kana
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return false;
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}
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static bool isWordBreakBefore(int c) {
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// CJK ideographs (and yijing hexagram symbols)
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return isWordBreakAfter(c) || (c >= 0x3400 && c <= 0x9fff);
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}
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/**
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* Return offset of previous word break. It is either < offset or == 0.
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*/
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size_t getPrevWordBreakForCache(
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const uint16_t* chars, size_t offset, size_t len) {
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if (offset == 0) return 0;
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if (offset > len) offset = len;
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if (isWordBreakBefore(chars[offset - 1])) {
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return offset - 1;
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}
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for (size_t i = offset - 1; i > 0; i--) {
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if (isWordBreakBefore(chars[i]) || isWordBreakAfter(chars[i - 1])) {
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return i;
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}
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}
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return 0;
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}
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/**
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* Return offset of next word break. It is either > offset or == len.
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*/
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size_t getNextWordBreakForCache(
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const uint16_t* chars, size_t offset, size_t len) {
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if (offset >= len) return len;
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if (isWordBreakAfter(chars[offset])) {
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return offset + 1;
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}
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for (size_t i = offset + 1; i < len; i++) {
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// No need to check isWordBreakAfter(chars[i - 1]) since it is checked
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// in previous iteration. Note that isWordBreakBefore returns true
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// whenever isWordBreakAfter returns true.
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if (isWordBreakBefore(chars[i])) {
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return i;
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}
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}
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return len;
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}
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