1/*
2 * Copyright (C) 2013 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 "TextPaintStyle.h"
28
29#include "Frame.h"
30#include "GraphicsContext.h"
31#include "PaintInfo.h"
32#include "RenderStyle.h"
33#include "RenderText.h"
34#include "RenderView.h"
35#include "Settings.h"
36
37namespace WebCore {
38
39TextPaintStyle::TextPaintStyle(ColorSpace colorSpace)
40    : colorSpace(colorSpace)
41    , strokeWidth(0)
42#if ENABLE(LETTERPRESS)
43    , useLetterpressEffect(false)
44#endif
45{
46}
47
48TextPaintStyle::TextPaintStyle(Color color, ColorSpace colorSpace)
49    : colorSpace(colorSpace)
50    , fillColor(color)
51    , strokeColor(color)
52    , strokeWidth(0)
53#if ENABLE(LETTERPRESS)
54    , useLetterpressEffect(false)
55#endif
56{
57}
58
59static Color adjustColorForVisibilityOnBackground(Color textColor, Color backgroundColor)
60{
61    int d = differenceSquared(textColor, backgroundColor);
62    // Semi-arbitrarily chose 65025 (255^2) value here after a few tests.
63    if (d > 65025)
64        return textColor;
65
66    int distanceFromWhite = differenceSquared(textColor, Color::white);
67    int distanceFromBlack = differenceSquared(textColor, Color::black);
68    if (distanceFromWhite < distanceFromBlack)
69        return textColor.dark();
70
71    return textColor.light();
72}
73
74TextPaintStyle computeTextPaintStyle(const RenderText& renderer, const RenderStyle& lineStyle, const PaintInfo& paintInfo)
75{
76    TextPaintStyle paintStyle(lineStyle.colorSpace());
77
78#if ENABLE(LETTERPRESS)
79    paintStyle.useLetterpressEffect = lineStyle.textDecorationsInEffect() & TextDecorationLetterpress;
80#endif
81    paintStyle.strokeWidth = lineStyle.textStrokeWidth();
82
83    if (paintInfo.forceBlackText()) {
84        paintStyle.fillColor = Color::black;
85        paintStyle.strokeColor = Color::black;
86        paintStyle.emphasisMarkColor = Color::black;
87        return paintStyle;
88    }
89    paintStyle.fillColor = lineStyle.visitedDependentColor(CSSPropertyWebkitTextFillColor);
90
91    bool forceBackgroundToWhite = false;
92    if (renderer.document().printing()) {
93        if (lineStyle.printColorAdjust() == PrintColorAdjustEconomy)
94            forceBackgroundToWhite = true;
95        if (renderer.frame().settings().shouldPrintBackgrounds())
96            forceBackgroundToWhite = false;
97    }
98
99    // Make the text fill color legible against a white background
100    if (forceBackgroundToWhite)
101        paintStyle.fillColor = adjustColorForVisibilityOnBackground(paintStyle.fillColor, Color::white);
102
103    paintStyle.strokeColor = lineStyle.visitedDependentColor(CSSPropertyWebkitTextStrokeColor);
104
105    // Make the text stroke color legible against a white background
106    if (forceBackgroundToWhite)
107        paintStyle.strokeColor = adjustColorForVisibilityOnBackground(paintStyle.strokeColor, Color::white);
108
109    paintStyle.emphasisMarkColor = lineStyle.visitedDependentColor(CSSPropertyWebkitTextEmphasisColor);
110
111    // Make the text stroke color legible against a white background
112    if (forceBackgroundToWhite)
113        paintStyle.emphasisMarkColor = adjustColorForVisibilityOnBackground(paintStyle.emphasisMarkColor, Color::white);
114
115    return paintStyle;
116}
117
118TextPaintStyle computeTextSelectionPaintStyle(const TextPaintStyle& textPaintStyle, const RenderText& renderer, const RenderStyle& lineStyle, const PaintInfo& paintInfo, bool& paintSelectedTextOnly, bool& paintSelectedTextSeparately, const ShadowData*& selectionShadow)
119{
120    paintSelectedTextOnly = (paintInfo.phase == PaintPhaseSelection);
121    paintSelectedTextSeparately = false;
122    selectionShadow = paintInfo.forceBlackText() ? nullptr : lineStyle.textShadow();
123
124    TextPaintStyle selectionPaintStyle = textPaintStyle;
125
126#if ENABLE(TEXT_SELECTION)
127    Color foreground = paintInfo.forceBlackText() ? Color::black : renderer.selectionForegroundColor();
128    if (foreground.isValid() && foreground != selectionPaintStyle.fillColor) {
129        if (!paintSelectedTextOnly)
130            paintSelectedTextSeparately = true;
131        selectionPaintStyle.fillColor = foreground;
132    }
133
134    Color emphasisMarkForeground = paintInfo.forceBlackText() ? Color::black : renderer.selectionEmphasisMarkColor();
135    if (emphasisMarkForeground.isValid() && emphasisMarkForeground != selectionPaintStyle.emphasisMarkColor) {
136        if (!paintSelectedTextOnly)
137            paintSelectedTextSeparately = true;
138        selectionPaintStyle.emphasisMarkColor = emphasisMarkForeground;
139    }
140
141    if (RenderStyle* pseudoStyle = renderer.getCachedPseudoStyle(SELECTION)) {
142        const ShadowData* shadow = paintInfo.forceBlackText() ? 0 : pseudoStyle->textShadow();
143        if (shadow != selectionShadow) {
144            if (!paintSelectedTextOnly)
145                paintSelectedTextSeparately = true;
146            selectionShadow = shadow;
147        }
148
149        float strokeWidth = pseudoStyle->textStrokeWidth();
150        if (strokeWidth != selectionPaintStyle.strokeWidth) {
151            if (!paintSelectedTextOnly)
152                paintSelectedTextSeparately = true;
153            selectionPaintStyle.strokeWidth = strokeWidth;
154        }
155
156        Color stroke = paintInfo.forceBlackText() ? Color::black : pseudoStyle->visitedDependentColor(CSSPropertyWebkitTextStrokeColor);
157        if (stroke != selectionPaintStyle.strokeColor) {
158            if (!paintSelectedTextOnly)
159                paintSelectedTextSeparately = true;
160            selectionPaintStyle.strokeColor = stroke;
161        }
162    }
163#else
164    UNUSED_PARAM(renderer);
165    UNUSED_PARAM(lineStyle);
166    UNUSED_PARAM(paintInfo);
167#endif
168    return selectionPaintStyle;
169}
170
171void updateGraphicsContext(GraphicsContext& context, const TextPaintStyle& paintStyle, FillColorType fillColorType)
172{
173    TextDrawingModeFlags mode = context.textDrawingMode();
174    TextDrawingModeFlags newMode = mode;
175#if ENABLE(LETTERPRESS)
176    if (paintStyle.useLetterpressEffect)
177        newMode |= TextModeLetterpress;
178    else
179        newMode &= ~TextModeLetterpress;
180#endif
181    if (paintStyle.strokeWidth > 0)
182        newMode |= TextModeStroke;
183    if (mode != newMode) {
184        context.setTextDrawingMode(newMode);
185        mode = newMode;
186    }
187
188    Color fillColor = fillColorType == UseEmphasisMarkColor ? paintStyle.emphasisMarkColor : paintStyle.fillColor;
189    if (mode & TextModeFill && (fillColor != context.fillColor() || paintStyle.colorSpace != context.fillColorSpace()))
190        context.setFillColor(fillColor, paintStyle.colorSpace);
191
192    if (mode & TextModeStroke) {
193        if (paintStyle.strokeColor != context.strokeColor())
194            context.setStrokeColor(paintStyle.strokeColor, paintStyle.colorSpace);
195        if (paintStyle.strokeWidth != context.strokeThickness())
196            context.setStrokeThickness(paintStyle.strokeWidth);
197    }
198}
199
200}
201