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/*
* 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}};
SECURITY_DCHECK(desired.style() < FontStyleItalic + 1);
SECURITY_DCHECK(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());
SECURITY_DCHECK(desiredScoresLookup < scoreLookupSize);
SECURITY_DCHECK(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
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