1/*
2 * Copyright (C) 2017 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 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "FontSelectionAlgorithm.h"
28
29namespace WebCore {
30
31FontSelectionAlgorithm::FontSelectionAlgorithm(FontSelectionRequest request, const Vector<Capabilities>& capabilities, Optional<Capabilities> bounds)
32 : m_request(request)
33 , m_capabilities(capabilities)
34{
35 ASSERT(!m_capabilities.isEmpty());
36 if (bounds)
37 m_capabilitiesBounds = bounds.value();
38 else {
39 for (auto& capabilities : m_capabilities)
40 m_capabilitiesBounds.expand(capabilities);
41 }
42}
43
44auto FontSelectionAlgorithm::stretchDistance(Capabilities capabilities) const -> DistanceResult
45{
46 auto width = capabilities.width;
47 ASSERT(width.isValid());
48 if (width.includes(m_request.width))
49 return { FontSelectionValue(), m_request.width };
50
51 if (m_request.width > normalStretchValue()) {
52 if (width.minimum > m_request.width)
53 return { width.minimum - m_request.width, width.minimum };
54 ASSERT(width.maximum < m_request.width);
55 auto threshold = std::max(m_request.width, m_capabilitiesBounds.width.maximum);
56 return { threshold - width.maximum, width.maximum };
57 }
58
59 if (width.maximum < m_request.width)
60 return { m_request.width - width.maximum, width.maximum };
61 ASSERT(width.minimum > m_request.width);
62 auto threshold = std::min(m_request.width, m_capabilitiesBounds.width.minimum);
63 return { width.minimum - threshold, width.minimum };
64}
65
66auto FontSelectionAlgorithm::styleDistance(Capabilities capabilities) const -> DistanceResult
67{
68 auto slope = capabilities.slope;
69 auto requestSlope = m_request.slope.valueOr(normalItalicValue());
70 ASSERT(slope.isValid());
71 if (slope.includes(requestSlope))
72 return { FontSelectionValue(), requestSlope };
73
74 if (requestSlope >= italicThreshold()) {
75 if (slope.minimum > requestSlope)
76 return { slope.minimum - requestSlope, slope.minimum };
77 ASSERT(requestSlope > slope.maximum);
78 auto threshold = std::max(requestSlope, m_capabilitiesBounds.slope.maximum);
79 return { threshold - slope.maximum, slope.maximum };
80 }
81
82 if (requestSlope >= FontSelectionValue()) {
83 if (slope.maximum >= FontSelectionValue() && slope.maximum < requestSlope)
84 return { requestSlope - slope.maximum, slope.maximum };
85 if (slope.minimum > requestSlope)
86 return { slope.minimum, slope.minimum };
87 ASSERT(slope.maximum < FontSelectionValue());
88 auto threshold = std::max(requestSlope, m_capabilitiesBounds.slope.maximum);
89 return { threshold - slope.maximum, slope.maximum };
90 }
91
92 if (requestSlope > -italicThreshold()) {
93 if (slope.minimum > requestSlope && slope.minimum <= FontSelectionValue())
94 return { slope.minimum - requestSlope, slope.minimum };
95 if (slope.maximum < requestSlope)
96 return { -slope.maximum, slope.maximum };
97 ASSERT(slope.minimum > FontSelectionValue());
98 auto threshold = std::min(requestSlope, m_capabilitiesBounds.slope.minimum);
99 return { slope.minimum - threshold, slope.minimum };
100 }
101
102 if (slope.maximum < requestSlope)
103 return { requestSlope - slope.maximum, slope.maximum };
104 ASSERT(slope.minimum > requestSlope);
105 auto threshold = std::min(requestSlope, m_capabilitiesBounds.slope.minimum);
106 return { slope.minimum - threshold, slope.minimum };
107}
108
109auto FontSelectionAlgorithm::weightDistance(Capabilities capabilities) const -> DistanceResult
110{
111 auto weight = capabilities.weight;
112 ASSERT(weight.isValid());
113 if (weight.includes(m_request.weight))
114 return { FontSelectionValue(), m_request.weight };
115
116 if (m_request.weight >= lowerWeightSearchThreshold() && m_request.weight <= upperWeightSearchThreshold()) {
117 if (weight.minimum > m_request.weight && weight.minimum <= upperWeightSearchThreshold())
118 return { weight.minimum - m_request.weight, weight.minimum };
119 if (weight.maximum < m_request.weight)
120 return { upperWeightSearchThreshold() - weight.maximum, weight.maximum };
121 ASSERT(weight.minimum > upperWeightSearchThreshold());
122 auto threshold = std::min(m_request.weight, m_capabilitiesBounds.weight.minimum);
123 return { weight.minimum - threshold, weight.minimum };
124 }
125 if (m_request.weight < lowerWeightSearchThreshold()) {
126 if (weight.maximum < m_request.weight)
127 return { m_request.weight - weight.maximum, weight.maximum };
128 ASSERT(weight.minimum > m_request.weight);
129 auto threshold = std::min(m_request.weight, m_capabilitiesBounds.weight.minimum);
130 return { weight.minimum - threshold, weight.minimum };
131 }
132 ASSERT(m_request.weight >= upperWeightSearchThreshold());
133 if (weight.minimum > m_request.weight)
134 return { weight.minimum - m_request.weight, weight.minimum };
135 ASSERT(weight.maximum < m_request.weight);
136 auto threshold = std::max(m_request.weight, m_capabilitiesBounds.weight.maximum);
137 return { threshold - weight.maximum, weight.maximum };
138}
139
140FontSelectionValue FontSelectionAlgorithm::bestValue(const bool eliminated[], DistanceFunction computeDistance) const
141{
142 Optional<DistanceResult> smallestDistance;
143 for (size_t i = 0, size = m_capabilities.size(); i < size; ++i) {
144 if (eliminated[i])
145 continue;
146 auto distanceResult = (this->*computeDistance)(m_capabilities[i]);
147 if (!smallestDistance || distanceResult.distance < smallestDistance.value().distance)
148 smallestDistance = distanceResult;
149 }
150 return smallestDistance.value().value;
151}
152
153void FontSelectionAlgorithm::filterCapability(bool eliminated[], DistanceFunction computeDistance, CapabilitiesRange inclusionRange)
154{
155 auto value = bestValue(eliminated, computeDistance);
156 for (size_t i = 0, size = m_capabilities.size(); i < size; ++i) {
157 eliminated[i] = eliminated[i]
158 || !(m_capabilities[i].*inclusionRange).includes(value);
159 }
160}
161
162size_t FontSelectionAlgorithm::indexOfBestCapabilities()
163{
164 Vector<bool, 256> eliminated(m_capabilities.size(), false);
165 filterCapability(eliminated.data(), &FontSelectionAlgorithm::stretchDistance, &Capabilities::width);
166 filterCapability(eliminated.data(), &FontSelectionAlgorithm::styleDistance, &Capabilities::slope);
167 filterCapability(eliminated.data(), &FontSelectionAlgorithm::weightDistance, &Capabilities::weight);
168 return eliminated.find(false);
169}
170
171}
172