1/*
2 * Copyright (C) 2014 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. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "InlineTextBoxStyle.h"
28
29#include "FontCascade.h"
30#include "InlineTextBox.h"
31#include "RootInlineBox.h"
32#include "TextUnderlineOffset.h"
33
34namespace WebCore {
35
36float computeUnderlineOffset(TextUnderlinePosition underlinePosition, TextUnderlineOffset underlineOffset, const FontMetrics& fontMetrics, const InlineTextBox* inlineTextBox, float defaultGap)
37{
38 // This represents the gap between the baseline and the closest edge of the underline.
39 float gap = std::max<int>(1, std::ceil(defaultGap / 2.0f));
40
41 // FIXME: The code for visual overflow detection passes in a null inline text box. This means it is now
42 // broken for the case where auto needs to behave like "under".
43
44 // According to the specification TextUnderlinePosition::Auto should avoid drawing through glyphs in
45 // scripts where it would not be appropriate (e.g., ideographs).
46 // Strictly speaking this can occur whenever the line contains ideographs
47 // even if it is horizontal, but detecting this has performance implications. For now we only work with
48 // vertical text, since we already determined the baseline type to be ideographic in that
49 // case.
50
51 auto resolvedUnderlinePosition = underlinePosition;
52 if (resolvedUnderlinePosition == TextUnderlinePosition::Auto && underlineOffset.isAuto()) {
53 if (inlineTextBox)
54 resolvedUnderlinePosition = inlineTextBox->root().baselineType() == IdeographicBaseline ? TextUnderlinePosition::Under : TextUnderlinePosition::Auto;
55 else
56 resolvedUnderlinePosition = TextUnderlinePosition::Auto;
57 }
58
59 switch (resolvedUnderlinePosition) {
60 case TextUnderlinePosition::Auto:
61 if (underlineOffset.isAuto())
62 return fontMetrics.ascent() + gap;
63 return fontMetrics.ascent() + std::max(0.0f, underlineOffset.lengthValue());
64 case TextUnderlinePosition::FromFont:
65 return fontMetrics.ascent() + std::max(0.0f, fontMetrics.underlinePosition() + underlineOffset.lengthOr(0));
66 case TextUnderlinePosition::Under: {
67 ASSERT(inlineTextBox);
68 // Position underline relative to the bottom edge of the lowest element's content box.
69 const RootInlineBox& rootBox = inlineTextBox->root();
70 const RenderElement* decorationRenderer = inlineTextBox->parent()->renderer().enclosingRendererWithTextDecoration(TextDecoration::Underline, inlineTextBox->isFirstLine());
71
72 float offset;
73 if (inlineTextBox->renderer().style().isFlippedLinesWritingMode()) {
74 offset = inlineTextBox->logicalTop();
75 rootBox.minLogicalTopForTextDecorationLine(offset, decorationRenderer, TextDecoration::Underline);
76 offset = inlineTextBox->logicalTop() - offset;
77 } else {
78 offset = inlineTextBox->logicalBottom();
79 rootBox.maxLogicalBottomForTextDecorationLine(offset, decorationRenderer, TextDecoration::Underline);
80 offset -= inlineTextBox->logicalBottom();
81 }
82 auto desiredOffset = inlineTextBox->logicalHeight() + gap + std::max(offset, 0.0f) + underlineOffset.lengthOr(0);
83 return std::max<float>(desiredOffset, fontMetrics.ascent());
84 }
85 }
86
87 ASSERT_NOT_REACHED();
88 return fontMetrics.ascent() + gap;
89}
90
91WavyStrokeParameters getWavyStrokeParameters(float fontSize)
92{
93 WavyStrokeParameters result;
94 // More information is in the WavyStrokeParameters definition.
95 result.controlPointDistance = fontSize * 1.5 / 16;
96 result.step = fontSize / 4.5;
97 return result;
98}
99
100static inline void extendIntToFloat(int& extendMe, float extendTo)
101{
102 extendMe = std::max(extendMe, static_cast<int>(ceilf(extendTo)));
103}
104
105GlyphOverflow visualOverflowForDecorations(const RenderStyle& lineStyle, const InlineTextBox* inlineTextBox)
106{
107 ASSERT(!inlineTextBox || inlineTextBox->lineStyle() == lineStyle);
108
109 auto decoration = lineStyle.textDecorationsInEffect();
110 if (decoration.isEmpty())
111 return GlyphOverflow();
112
113 float strokeThickness = lineStyle.textDecorationThickness().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
114 WavyStrokeParameters wavyStrokeParameters;
115 float wavyOffset = 0;
116
117 TextDecorationStyle decorationStyle = lineStyle.textDecorationStyle();
118 float height = lineStyle.fontCascade().fontMetrics().floatHeight();
119 GlyphOverflow overflowResult;
120
121 if (decorationStyle == TextDecorationStyle::Wavy) {
122 wavyStrokeParameters = getWavyStrokeParameters(lineStyle.computedFontPixelSize());
123 wavyOffset = wavyOffsetFromDecoration();
124 overflowResult.left = strokeThickness;
125 overflowResult.right = strokeThickness;
126 }
127
128 // These metrics must match where underlines get drawn.
129 // FIXME: Share the code in TextDecorationPainter::paintTextDecoration() so we can just query it for the painted geometry.
130 if (decoration & TextDecoration::Underline) {
131 // Compensate for the integral ceiling in GraphicsContext::computeLineBoundsAndAntialiasingModeForText()
132 int underlineOffset = 1;
133 float textDecorationBaseFontSize = 16;
134 auto defaultGap = lineStyle.computedFontSize() / textDecorationBaseFontSize;
135 underlineOffset += computeUnderlineOffset(lineStyle.textUnderlinePosition(), lineStyle.textUnderlineOffset(), lineStyle.fontMetrics(), inlineTextBox, defaultGap);
136 if (decorationStyle == TextDecorationStyle::Wavy) {
137 extendIntToFloat(overflowResult.bottom, underlineOffset + wavyOffset + wavyStrokeParameters.controlPointDistance + strokeThickness - height);
138 extendIntToFloat(overflowResult.top, -(underlineOffset + wavyOffset - wavyStrokeParameters.controlPointDistance - strokeThickness));
139 } else {
140 extendIntToFloat(overflowResult.bottom, underlineOffset + strokeThickness - height);
141 extendIntToFloat(overflowResult.top, -underlineOffset);
142 }
143 }
144 if (decoration & TextDecoration::Overline) {
145 FloatRect rect(FloatPoint(), FloatSize(1, strokeThickness));
146 float autoTextDecorationThickness = TextDecorationThickness::createWithAuto().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
147 rect.move(0, autoTextDecorationThickness - strokeThickness - wavyOffset);
148 if (decorationStyle == TextDecorationStyle::Wavy) {
149 FloatBoxExtent wavyExpansion;
150 wavyExpansion.setTop(wavyStrokeParameters.controlPointDistance);
151 wavyExpansion.setBottom(wavyStrokeParameters.controlPointDistance);
152 rect.expand(wavyExpansion);
153 }
154 extendIntToFloat(overflowResult.top, -rect.y());
155 extendIntToFloat(overflowResult.bottom, rect.maxY() - height);
156 }
157 if (decoration & TextDecoration::LineThrough) {
158 FloatRect rect(FloatPoint(), FloatSize(1, strokeThickness));
159 float autoTextDecorationThickness = TextDecorationThickness::createWithAuto().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
160 auto center = 2 * lineStyle.fontMetrics().floatAscent() / 3 + autoTextDecorationThickness / 2;
161 rect.move(0, center - strokeThickness / 2);
162 if (decorationStyle == TextDecorationStyle::Wavy) {
163 FloatBoxExtent wavyExpansion;
164 wavyExpansion.setTop(wavyStrokeParameters.controlPointDistance);
165 wavyExpansion.setBottom(wavyStrokeParameters.controlPointDistance);
166 rect.expand(wavyExpansion);
167 }
168 extendIntToFloat(overflowResult.top, -rect.y());
169 extendIntToFloat(overflowResult.bottom, rect.maxY() - height);
170 }
171 return overflowResult;
172}
173
174}
175