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| 1 /* |
| 2 * Copyright (C) 2013 Google 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 are |
| 6 * met: |
| 7 * |
| 8 * * Redistributions of source code must retain the above copyright |
| 9 * notice, this list of conditions and the following disclaimer. |
| 10 * * Redistributions in binary form must reproduce the above |
| 11 * copyright notice, this list of conditions and the following disclaimer |
| 12 * in the documentation and/or other materials provided with the |
| 13 * distribution. |
| 14 * * Neither the name of Google Inc. nor the names of its |
| 15 * contributors may be used to endorse or promote products derived from |
| 16 * this software without specific prior written permission. |
| 17 * |
| 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 29 */ |
| 30 |
| 31 #include "config.h" |
| 32 #include "core/html/parser/HTMLSrcsetParser.h" |
| 33 |
| 34 #include "core/html/parser/HTMLParserIdioms.h" |
| 35 #include "core/platform/ParsingUtilities.h" |
| 36 |
| 37 namespace WebCore { |
| 38 |
| 39 static bool compareByScaleFactor(const ImageCandidate& first, const ImageCandida
te& second) |
| 40 { |
| 41 return first.scaleFactor() < second.scaleFactor(); |
| 42 } |
| 43 |
| 44 // http://www.whatwg.org/specs/web-apps/current-work/multipage/embedded-content-
1.html#processing-the-image-candidates |
| 45 template<typename CharType> |
| 46 static void parseImageCandidatesFromSrcsetAttribute(const String& attribute, con
st CharType* attributeStart, unsigned length, Vector<ImageCandidate>& imageCandi
dates) |
| 47 { |
| 48 const CharType* position = attributeStart; |
| 49 const CharType* attributeEnd = position + length; |
| 50 |
| 51 while (position < attributeEnd) { |
| 52 float imgScaleFactor = 1.0; |
| 53 // 4. Splitting loop: Skip whitespace. |
| 54 skipWhile<CharType, isHTMLSpace<CharType> >(position, attributeEnd); |
| 55 if (position == attributeEnd) |
| 56 break; |
| 57 const CharType* imageURLStart = position; |
| 58 |
| 59 // If The current candidate is either totally empty or only contains spa
ce, skipping. |
| 60 if (*position == ',') { |
| 61 ++position; |
| 62 continue; |
| 63 } |
| 64 // 5. Collect a sequence of characters that are not space characters, an
d let that be url. |
| 65 ++position; |
| 66 skipUntil<CharType, isHTMLSpace<CharType> >(position, attributeEnd); |
| 67 const CharType* imageURLEnd = position; |
| 68 |
| 69 if (position != attributeEnd && *(position - 1) == ',') { |
| 70 --imageURLEnd; |
| 71 } else { |
| 72 // 7. Collect a sequence of characters that are not "," (U+002C) cha
racters, and let that be descriptors. |
| 73 skipWhile<CharType, isHTMLSpace<CharType> >(position, attributeEnd); |
| 74 const CharType* qualifierStart = position; |
| 75 if (position != attributeEnd && *position != ',') { |
| 76 // This part differs from the spec as the current implementation
only supports pixel density descriptors for now. |
| 77 skipUntil<CharType, isHTMLSpaceOrComma<CharType> >(position, att
ributeEnd); |
| 78 const CharType* qualifierEnd = position; |
| 79 ASSERT(qualifierEnd > qualifierStart); |
| 80 // Make sure there are no other descriptors |
| 81 skipWhile<CharType, isHTMLSpace<CharType> >(position, attributeE
nd); |
| 82 // If the first non-html-space character after the scale modifie
r is not a comma, |
| 83 // the current candidate is an invalid input. |
| 84 if (position != attributeEnd && *position != ',') { |
| 85 skipUntil<CharType>(position, attributeEnd, ','); |
| 86 ++position; |
| 87 continue; |
| 88 } |
| 89 // If the current qualifier is not an 'x', the resource is ignor
ed |
| 90 if (*(qualifierEnd - 1) != 'x') |
| 91 continue; |
| 92 |
| 93 bool validScaleFactor = false; |
| 94 unsigned scaleFactorLengthWithoutUnit = qualifierEnd - qualifier
Start - 1; |
| 95 imgScaleFactor = charactersToFloat(qualifierStart, scaleFactorLe
ngthWithoutUnit, &validScaleFactor); |
| 96 |
| 97 if (!validScaleFactor) |
| 98 continue; |
| 99 } |
| 100 } |
| 101 |
| 102 imageCandidates.append(ImageCandidate(attribute, imageURLStart - attribu
teStart, imageURLEnd - imageURLStart, imgScaleFactor)); |
| 103 // 11. Return to the step labeled splitting loop. |
| 104 } |
| 105 } |
| 106 |
| 107 static void parseImageCandidatesFromSrcsetAttribute(const String& attribute, Vec
tor<ImageCandidate>& imageCandidates) |
| 108 { |
| 109 if (attribute.isNull()) |
| 110 return; |
| 111 |
| 112 if (attribute.is8Bit()) |
| 113 parseImageCandidatesFromSrcsetAttribute<LChar>(attribute, attribute.char
acters8(), attribute.length(), imageCandidates); |
| 114 else |
| 115 parseImageCandidatesFromSrcsetAttribute<UChar>(attribute, attribute.char
acters16(), attribute.length(), imageCandidates); |
| 116 } |
| 117 |
| 118 static ImageCandidate pickBestImageCandidate(float deviceScaleFactor, Vector<Ima
geCandidate>& imageCandidates) |
| 119 { |
| 120 if (imageCandidates.isEmpty()) |
| 121 return ImageCandidate(); |
| 122 |
| 123 std::stable_sort(imageCandidates.begin(), imageCandidates.end(), compareBySc
aleFactor); |
| 124 |
| 125 unsigned i; |
| 126 for (i = 0; i < imageCandidates.size() - 1; ++i) { |
| 127 if (imageCandidates[i].scaleFactor() >= deviceScaleFactor) |
| 128 break; |
| 129 } |
| 130 return imageCandidates[i]; |
| 131 } |
| 132 |
| 133 ImageCandidate bestFitSourceForSrcsetAttribute(float deviceScaleFactor, const St
ring& srcsetAttribute) |
| 134 { |
| 135 Vector<ImageCandidate> imageCandidates; |
| 136 |
| 137 parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates); |
| 138 |
| 139 return pickBestImageCandidate(deviceScaleFactor, imageCandidates); |
| 140 } |
| 141 |
| 142 String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& sr
cAttribute, const String& srcsetAttribute) |
| 143 { |
| 144 if (srcsetAttribute.isNull()) |
| 145 return srcAttribute; |
| 146 |
| 147 Vector<ImageCandidate> imageCandidates; |
| 148 |
| 149 parseImageCandidatesFromSrcsetAttribute(srcsetAttribute, imageCandidates); |
| 150 |
| 151 if (!srcAttribute.isEmpty()) |
| 152 imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.leng
th(), 1.0)); |
| 153 |
| 154 return pickBestImageCandidate(deviceScaleFactor, imageCandidates).toString()
; |
| 155 } |
| 156 |
| 157 String bestFitSourceForImageAttributes(float deviceScaleFactor, const String& sr
cAttribute, ImageCandidate& srcsetImageCandidate) |
| 158 { |
| 159 if (srcsetImageCandidate.isEmpty()) |
| 160 return srcAttribute; |
| 161 |
| 162 Vector<ImageCandidate> imageCandidates; |
| 163 imageCandidates.append(srcsetImageCandidate); |
| 164 |
| 165 if (!srcAttribute.isEmpty()) |
| 166 imageCandidates.append(ImageCandidate(srcAttribute, 0, srcAttribute.leng
th(), 1.0)); |
| 167 |
| 168 return pickBestImageCandidate(deviceScaleFactor, imageCandidates).toString()
; |
| 169 } |
| 170 |
| 171 } |
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