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1 /*
2  * Copyright (C) 2009 Alex Milowski (alex@milowski.com). All rights reserved.
3  * Copyright (C) 2010 François Sausset (sausset@gmail.com). All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
15  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
16  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
17  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
18  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
19  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
20  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include "config.h"
28 
29 #if ENABLE(MATHML)
30 
31 #include "RenderMathMLSquareRoot.h"
32 
33 #include "GraphicsContext.h"
34 #include "MathMLNames.h"
35 #include "PaintInfo.h"
36 #include "Path.h"
37 
38 namespace WebCore {
39 
40 using namespace MathMLNames;
41 
42 // Bottom padding of the radical (px)
43 const int gRadicalBasePad = 3;
44 // Threshold above which the radical shape is modified to look nice with big bases (%)
45 const float gThresholdBaseHeight = 1.5f;
46 // Radical width (%)
47 const float gRadicalWidth = 0.75f;
48 // Horizontal position of the bottom point of the radical (%)
49 const float gRadicalBottomPointXPos= 0.5f;
50 // Horizontal position of the top left point of the radical (%)
51 const float gRadicalTopLeftPointXPos = 0.2f;
52 // Vertical position of the top left point of the radical (%)
53 const float gRadicalTopLeftPointYPos = 0.5f;
54 // Vertical shift of the left end point of the radical (%)
55 const float gRadicalLeftEndYShift = 0.05f;
56 // Additional bottom root padding (%)
57 const float gRootBottomPadding = 0.2f;
58 
59 // Radical line thickness (%)
60 const float gRadicalLineThickness = 0.02f;
61 // Radical thick line thickness (%)
62 const float gRadicalThickLineThickness = 0.1f;
63 
RenderMathMLSquareRoot(Node * expression)64 RenderMathMLSquareRoot::RenderMathMLSquareRoot(Node *expression)
65     : RenderMathMLBlock(expression)
66 {
67 }
68 
paint(PaintInfo & info,int tx,int ty)69 void RenderMathMLSquareRoot::paint(PaintInfo& info, int tx, int ty)
70 {
71     RenderMathMLBlock::paint(info, tx, ty);
72 
73     if (info.context->paintingDisabled())
74         return;
75 
76     tx += x();
77     ty += y();
78 
79     int maxHeight = 0;
80     int width = 0;
81     RenderObject* current = firstChild();
82     while (current) {
83         if (current->isBoxModelObject()) {
84 
85             RenderBoxModelObject* box = toRenderBoxModelObject(current);
86 
87             // Check to see if this box has a larger height
88             if (box->offsetHeight() > maxHeight)
89                 maxHeight = box->offsetHeight();
90             width += box->offsetWidth();
91         }
92         current = current->nextSibling();
93     }
94     // default to the font size in pixels if we're empty
95     if (!maxHeight)
96         maxHeight = style()->fontSize();
97 
98     int frontWidth = static_cast<int>(style()->fontSize() * gRadicalWidth);
99     int topStartShift = 0;
100     // Base height above which the shape of the root changes
101     int thresholdHeight = static_cast<int>(gThresholdBaseHeight * style()->fontSize());
102 
103     if (maxHeight > thresholdHeight && thresholdHeight) {
104         float shift = (maxHeight - thresholdHeight) / static_cast<float>(thresholdHeight);
105         if (shift > 1.)
106             shift = 1.0f;
107         topStartShift = static_cast<int>(gRadicalBottomPointXPos * frontWidth * shift);
108     }
109 
110     width += topStartShift;
111 
112     FloatPoint topStart(tx + frontWidth - topStartShift, ty);
113     FloatPoint bottomLeft(tx + frontWidth * gRadicalBottomPointXPos , ty + maxHeight + gRadicalBasePad);
114     FloatPoint topLeft(tx + frontWidth * gRadicalTopLeftPointXPos , ty + gRadicalTopLeftPointYPos * maxHeight);
115     FloatPoint leftEnd(tx , topLeft.y() + gRadicalLeftEndYShift * style()->fontSize());
116 
117     info.context->save();
118 
119     info.context->setStrokeThickness(gRadicalLineThickness * style()->fontSize());
120     info.context->setStrokeStyle(SolidStroke);
121     info.context->setStrokeColor(style()->visitedDependentColor(CSSPropertyColor), ColorSpaceDeviceRGB);
122     info.context->setLineJoin(MiterJoin);
123     info.context->setMiterLimit(style()->fontSize());
124 
125     Path root;
126 
127     root.moveTo(FloatPoint(topStart.x() + width , ty));
128     // draw top
129     root.addLineTo(topStart);
130     // draw from top left corner to bottom point of radical
131     root.addLineTo(bottomLeft);
132     // draw from bottom point to top of left part of radical base "pocket"
133     root.addLineTo(topLeft);
134     // draw to end
135     root.addLineTo(leftEnd);
136 
137     info.context->strokePath(root);
138 
139     info.context->save();
140 
141     // Build a mask to draw the thick part of the root.
142     Path mask;
143 
144     mask.moveTo(topStart);
145     mask.addLineTo(bottomLeft);
146     mask.addLineTo(topLeft);
147     mask.addLineTo(FloatPoint(2 * topLeft.x() - leftEnd.x(), 2 * topLeft.y() - leftEnd.y()));
148 
149     info.context->clip(mask);
150 
151     // Draw the thick part of the root.
152     info.context->setStrokeThickness(gRadicalThickLineThickness * style()->fontSize());
153     info.context->setLineCap(SquareCap);
154 
155     Path line;
156     line.moveTo(bottomLeft);
157     line.addLineTo(topLeft);
158 
159     info.context->strokePath(line);
160 
161     info.context->restore();
162 
163     info.context->restore();
164 }
165 
layout()166 void RenderMathMLSquareRoot::layout()
167 {
168     int maxHeight = 0;
169 
170     RenderObject* current = firstChild();
171     while (current) {
172         if (current->isBoxModelObject()) {
173             RenderBoxModelObject* box = toRenderBoxModelObject(current);
174 
175             if (box->offsetHeight() > maxHeight)
176                 maxHeight = box->offsetHeight();
177 
178             box->style()->setVerticalAlign(BASELINE);
179         }
180         current = current->nextSibling();
181     }
182 
183     if (!maxHeight)
184         maxHeight = style()->fontSize();
185 
186 
187     if (maxHeight > static_cast<int>(gThresholdBaseHeight * style()->fontSize()))
188         style()->setPaddingBottom(Length(static_cast<int>(gRootBottomPadding * style()->fontSize()), Fixed));
189 
190 
191     RenderBlock::layout();
192 }
193 
194 }
195 
196 #endif // ENABLE(MATHML)
197 
198 
199