| /* |
| * 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 "platform/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(kFontStyleNormal == 0 && kFontStyleItalic == 2, |
| "Enumeration values need to match lookup table."); |
| unsigned style_score_lookup_table[][kFontStyleItalic + 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}}; |
| |
| SECURITY_DCHECK(desired.Style() < kFontStyleItalic + 1); |
| SECURITY_DCHECK(candidate.Style() < kFontStyleItalic + 1); |
| |
| return style_score_lookup_table[desired.Style()][candidate.Style()]; |
| } |
| |
| static inline unsigned WeightScore(FontTraits desired, FontTraits candidate) { |
| static_assert(kFontWeight100 == 0 && kFontWeight900 - kFontWeight100 == 8, |
| "Enumeration values need to match lookup table."); |
| static const unsigned kScoreLookupSize = kFontWeight900 + 1; |
| // https://drafts.csswg.org/css-fonts/#font-style-matching |
| // "..if the desired weight is available that face matches. " |
| static const unsigned kWeightScoreLookup[kScoreLookupSize][kScoreLookupSize] = |
| { |
| // "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 desired_scores_lookup = static_cast<unsigned>(desired.Weight()); |
| unsigned candidate_score_lookup = static_cast<unsigned>(candidate.Weight()); |
| SECURITY_DCHECK(desired_scores_lookup < kScoreLookupSize); |
| SECURITY_DCHECK(candidate_score_lookup < kScoreLookupSize); |
| |
| return kWeightScoreLookup[desired_scores_lookup][candidate_score_lookup]; |
| } |
| |
| bool FontStyleMatcher::IsCandidateBetter(CSSSegmentedFontFace* candidate, |
| CSSSegmentedFontFace* current) { |
| const FontTraits& candidate_traits = candidate->Traits(); |
| const FontTraits& current_traits = 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 stretch_comparison = 0, style_comparison = 0, weight_comparison = 0; |
| |
| stretch_comparison = |
| StretchDistanceToDesired(font_traits_, candidate_traits) - |
| StretchDistanceToDesired(font_traits_, current_traits); |
| |
| if (stretch_comparison > 0) |
| return false; |
| if (stretch_comparison < 0) |
| return true; |
| |
| style_comparison = StyleScore(font_traits_, candidate_traits) - |
| StyleScore(font_traits_, current_traits); |
| |
| if (style_comparison > 0) |
| return true; |
| if (style_comparison < 0) |
| return false; |
| |
| weight_comparison = WeightScore(font_traits_, candidate_traits) - |
| WeightScore(font_traits_, current_traits); |
| |
| if (weight_comparison > 0) |
| return true; |
| |
| return false; |
| } |
| |
| } // namespace blink |
