1/* 2 * Copyright (C) 2005, 2006, 2007 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of 14 * its contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29#include "config.h" 30#include "StringTruncator.h" 31 32#include "Font.h" 33#include "TextBreakIterator.h" 34#include "TextRun.h" 35#include <wtf/Assertions.h> 36#include <wtf/Vector.h> 37#include <wtf/unicode/CharacterNames.h> 38 39namespace WebCore { 40 41#define STRING_BUFFER_SIZE 2048 42 43typedef unsigned TruncationFunction(const String&, unsigned length, unsigned keepCount, UChar* buffer); 44 45static inline int textBreakAtOrPreceding(TextBreakIterator* it, int offset) 46{ 47 if (isTextBreak(it, offset)) 48 return offset; 49 50 int result = textBreakPreceding(it, offset); 51 return result == TextBreakDone ? 0 : result; 52} 53 54static inline int boundedTextBreakFollowing(TextBreakIterator* it, int offset, int length) 55{ 56 int result = textBreakFollowing(it, offset); 57 return result == TextBreakDone ? length : result; 58} 59 60static unsigned centerTruncateToBuffer(const String& string, unsigned length, unsigned keepCount, UChar* buffer) 61{ 62 ASSERT(keepCount < length); 63 ASSERT(keepCount < STRING_BUFFER_SIZE); 64 65 unsigned omitStart = (keepCount + 1) / 2; 66 NonSharedCharacterBreakIterator it(string.characters(), length); 67 unsigned omitEnd = boundedTextBreakFollowing(it, omitStart + (length - keepCount) - 1, length); 68 omitStart = textBreakAtOrPreceding(it, omitStart); 69 70 unsigned truncatedLength = omitStart + 1 + (length - omitEnd); 71 ASSERT(truncatedLength <= length); 72 73 memcpy(buffer, string.characters(), sizeof(UChar) * omitStart); 74 buffer[omitStart] = horizontalEllipsis; 75 memcpy(&buffer[omitStart + 1], &string.characters()[omitEnd], sizeof(UChar) * (length - omitEnd)); 76 77 return truncatedLength; 78} 79 80static unsigned rightTruncateToBuffer(const String& string, unsigned length, unsigned keepCount, UChar* buffer) 81{ 82 ASSERT(keepCount < length); 83 ASSERT(keepCount < STRING_BUFFER_SIZE); 84 85 NonSharedCharacterBreakIterator it(string.characters(), length); 86 unsigned keepLength = textBreakAtOrPreceding(it, keepCount); 87 unsigned truncatedLength = keepLength + 1; 88 89 memcpy(buffer, string.characters(), sizeof(UChar) * keepLength); 90 buffer[keepLength] = horizontalEllipsis; 91 92 return truncatedLength; 93} 94 95static float stringWidth(const Font& renderer, const UChar* characters, unsigned length, bool disableRoundingHacks) 96{ 97 TextRun run(characters, length); 98 if (disableRoundingHacks) 99 run.disableRoundingHacks(); 100 return renderer.width(run); 101} 102 103static String truncateString(const String& string, float maxWidth, const Font& font, TruncationFunction truncateToBuffer, bool disableRoundingHacks) 104{ 105 if (string.isEmpty()) 106 return string; 107 108 ASSERT(maxWidth >= 0); 109 110 float currentEllipsisWidth = stringWidth(font, &horizontalEllipsis, 1, disableRoundingHacks); 111 112 UChar stringBuffer[STRING_BUFFER_SIZE]; 113 unsigned truncatedLength; 114 unsigned keepCount; 115 unsigned length = string.length(); 116 117 if (length > STRING_BUFFER_SIZE) { 118 keepCount = STRING_BUFFER_SIZE - 1; // need 1 character for the ellipsis 119 truncatedLength = centerTruncateToBuffer(string, length, keepCount, stringBuffer); 120 } else { 121 keepCount = length; 122 memcpy(stringBuffer, string.characters(), sizeof(UChar) * length); 123 truncatedLength = length; 124 } 125 126 float width = stringWidth(font, stringBuffer, truncatedLength, disableRoundingHacks); 127 if (width <= maxWidth) 128 return string; 129 130 unsigned keepCountForLargestKnownToFit = 0; 131 float widthForLargestKnownToFit = currentEllipsisWidth; 132 133 unsigned keepCountForSmallestKnownToNotFit = keepCount; 134 float widthForSmallestKnownToNotFit = width; 135 136 if (currentEllipsisWidth >= maxWidth) { 137 keepCountForLargestKnownToFit = 1; 138 keepCountForSmallestKnownToNotFit = 2; 139 } 140 141 while (keepCountForLargestKnownToFit + 1 < keepCountForSmallestKnownToNotFit) { 142 ASSERT(widthForLargestKnownToFit <= maxWidth); 143 ASSERT(widthForSmallestKnownToNotFit > maxWidth); 144 145 float ratio = (keepCountForSmallestKnownToNotFit - keepCountForLargestKnownToFit) 146 / (widthForSmallestKnownToNotFit - widthForLargestKnownToFit); 147 keepCount = static_cast<unsigned>(maxWidth * ratio); 148 149 if (keepCount <= keepCountForLargestKnownToFit) { 150 keepCount = keepCountForLargestKnownToFit + 1; 151 } else if (keepCount >= keepCountForSmallestKnownToNotFit) { 152 keepCount = keepCountForSmallestKnownToNotFit - 1; 153 } 154 155 ASSERT(keepCount < length); 156 ASSERT(keepCount > 0); 157 ASSERT(keepCount < keepCountForSmallestKnownToNotFit); 158 ASSERT(keepCount > keepCountForLargestKnownToFit); 159 160 truncatedLength = truncateToBuffer(string, length, keepCount, stringBuffer); 161 162 width = stringWidth(font, stringBuffer, truncatedLength, disableRoundingHacks); 163 if (width <= maxWidth) { 164 keepCountForLargestKnownToFit = keepCount; 165 widthForLargestKnownToFit = width; 166 } else { 167 keepCountForSmallestKnownToNotFit = keepCount; 168 widthForSmallestKnownToNotFit = width; 169 } 170 } 171 172 if (keepCountForLargestKnownToFit == 0) { 173 keepCountForLargestKnownToFit = 1; 174 } 175 176 if (keepCount != keepCountForLargestKnownToFit) { 177 keepCount = keepCountForLargestKnownToFit; 178 truncatedLength = truncateToBuffer(string, length, keepCount, stringBuffer); 179 } 180 181 return String(stringBuffer, truncatedLength); 182} 183 184String StringTruncator::centerTruncate(const String& string, float maxWidth, const Font& font, EnableRoundingHacksOrNot enableRoundingHacks) 185{ 186 return truncateString(string, maxWidth, font, centerTruncateToBuffer, !enableRoundingHacks); 187} 188 189String StringTruncator::rightTruncate(const String& string, float maxWidth, const Font& font, EnableRoundingHacksOrNot enableRoundingHacks) 190{ 191 return truncateString(string, maxWidth, font, rightTruncateToBuffer, !enableRoundingHacks); 192} 193 194float StringTruncator::width(const String& string, const Font& font, EnableRoundingHacksOrNot enableRoundingHacks) 195{ 196 return stringWidth(font, string.characters(), string.length(), !enableRoundingHacks); 197} 198 199} // namespace WebCore 200