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
38namespace WebCore {
39
40using namespace MathMLNames;
41
42// Bottom padding of the radical (px)
43const int gRadicalBasePad = 3;
44// Threshold above which the radical shape is modified to look nice with big bases (%)
45const float gThresholdBaseHeight = 1.5f;
46// Radical width (%)
47const float gRadicalWidth = 0.75f;
48// Horizontal position of the bottom point of the radical (%)
49const float gRadicalBottomPointXPos= 0.5f;
50// Horizontal position of the top left point of the radical (%)
51const float gRadicalTopLeftPointXPos = 0.2f;
52// Vertical position of the top left point of the radical (%)
53const float gRadicalTopLeftPointYPos = 0.5f;
54// Vertical shift of the left end point of the radical (%)
55const float gRadicalLeftEndYShift = 0.05f;
56// Additional bottom root padding (%)
57const float gRootBottomPadding = 0.2f;
58
59// Radical line thickness (%)
60const float gRadicalLineThickness = 0.02f;
61// Radical thick line thickness (%)
62const float gRadicalThickLineThickness = 0.1f;
63
64RenderMathMLSquareRoot::RenderMathMLSquareRoot(Node *expression)
65    : RenderMathMLBlock(expression)
66{
67}
68
69void 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
166void 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