| /* |
| * Copyright (C) 2007, 2008, 2011 Apple Inc. All rights reserved. |
| * Copyright (C) 2015 Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "core/css/FontStyleMatcher.h" |
| |
| #include "core/css/CSSSegmentedFontFace.h" |
| #include "wtf/Assertions.h" |
| |
| #include <stdlib.h> |
| |
| namespace blink { |
| |
| static inline unsigned stretchDistanceToDesired(FontTraits desired, |
| FontTraits candidate) { |
| return abs(static_cast<int>(desired.stretch() - candidate.stretch())); |
| } |
| |
| static inline unsigned styleScore(FontTraits desired, FontTraits candidate) { |
| static_assert(FontStyleNormal == 0 && FontStyleItalic == 2, |
| "Enumeration values need to match lookup table."); |
| unsigned styleScoreLookupTable[][FontStyleItalic + 1] = { |
| // "If the value is normal, normal faces are checked first, then oblique |
| // faces, then italic faces." |
| // i.e. normal has the highest score, then oblique, then italic. |
| {2, 1, 0}, |
| // "If the value is oblique, oblique faces are checked first, then italic |
| // faces and then normal faces." |
| // i.e. normal gets the lowest score, oblique gets the highest, italic |
| // second best. |
| {0, 2, 1}, |
| // "If the value of font-style is italic, italic faces are checked first, |
| // then oblique, then normal faces" |
| // i.e. normal gets the lowest score, oblique is second best, italic |
| // highest. |
| {0, 1, 2}}; |
| |
| ASSERT_WITH_SECURITY_IMPLICATION(desired.style() < FontStyleItalic + 1); |
| ASSERT_WITH_SECURITY_IMPLICATION(candidate.style() < FontStyleItalic + 1); |
| |
| return styleScoreLookupTable[desired.style()][candidate.style()]; |
| } |
| |
| static inline unsigned weightScore(FontTraits desired, FontTraits candidate) { |
| static_assert(FontWeight100 == 0 && FontWeight900 - FontWeight100 == 8, |
| "Enumeration values need to match lookup table."); |
| static const unsigned scoreLookupSize = FontWeight900 + 1; |
| // https://drafts.csswg.org/css-fonts/#font-style-matching |
| // "..if the desired weight is available that face matches. " |
| static const unsigned weightScoreLookup[scoreLookupSize][scoreLookupSize] = { |
| // "If the desired weight is less than 400, weights below the desired |
| // weight are checked in descending order followed by weights above the |
| // desired weight in ascending order until a match is found." |
| {9, 8, 7, 6, 5, 4, 3, 2, 1}, // FontWeight100 desired |
| {8, 9, 7, 6, 5, 4, 3, 2, 1}, // FontWeight200 desired |
| {7, 8, 9, 6, 5, 4, 3, 2, 1}, // FontWeight300 desired |
| |
| // "If the desired weight is 400, 500 is checked first and then the rule |
| // for desired weights less than 400 is used." |
| {5, 6, 7, 9, 8, 4, 3, 2, 1}, // FontWeight400 desired |
| |
| // "If the desired weight is 500, 400 is checked first and then the rule |
| // for desired weights less than 400 is used." |
| {5, 6, 7, 8, 9, 4, 3, 2, 1}, // FontWeight500 desired |
| |
| // "If the desired weight is greater than 500, weights above the desired |
| // weight are checked in ascending order followed by weights below the |
| // desired weight in descending order until a match is found." |
| {1, 2, 3, 4, 5, 9, 8, 7, 6}, // FontWeight600 desired |
| {1, 2, 3, 4, 5, 6, 9, 8, 7}, // FontWeight700 desired |
| {1, 2, 3, 4, 5, 6, 7, 9, 8}, // FontWeight800 desired |
| {1, 2, 3, 4, 5, 6, 7, 8, 9} // FontWeight900 desired |
| }; |
| |
| unsigned desiredScoresLookup = static_cast<unsigned>(desired.weight()); |
| unsigned candidateScoreLookup = static_cast<unsigned>(candidate.weight()); |
| ASSERT_WITH_SECURITY_IMPLICATION(desiredScoresLookup < scoreLookupSize); |
| ASSERT_WITH_SECURITY_IMPLICATION(candidateScoreLookup < scoreLookupSize); |
| |
| return weightScoreLookup[desiredScoresLookup][candidateScoreLookup]; |
| } |
| |
| bool FontStyleMatcher::isCandidateBetter(CSSSegmentedFontFace* candidate, |
| CSSSegmentedFontFace* current) { |
| const FontTraits& candidateTraits = candidate->traits(); |
| const FontTraits& currentTraits = current->traits(); |
| |
| // According to CSS3 Fonts Font Style matching, there is a precedence for |
| // matching: |
| // A better stretch match wins over a better style match, a better style match |
| // wins over a better weight match, where "better" means closer to the desired |
| // traits. |
| int stretchComparison = 0, styleComparison = 0, weightComparison = 0; |
| |
| stretchComparison = stretchDistanceToDesired(m_fontTraits, candidateTraits) - |
| stretchDistanceToDesired(m_fontTraits, currentTraits); |
| |
| if (stretchComparison > 0) |
| return false; |
| if (stretchComparison < 0) |
| return true; |
| |
| styleComparison = styleScore(m_fontTraits, candidateTraits) - |
| styleScore(m_fontTraits, currentTraits); |
| |
| if (styleComparison > 0) |
| return true; |
| if (styleComparison < 0) |
| return false; |
| |
| weightComparison = weightScore(m_fontTraits, candidateTraits) - |
| weightScore(m_fontTraits, currentTraits); |
| |
| if (weightComparison > 0) |
| return true; |
| |
| return false; |
| } |
| |
| } // namespace blink |