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 "RenderMathMLRoot.h"

    32 

    33 #include "GraphicsContext.h"

    34 #include "MathMLNames.h"

    35 

    36 namespace WebCore {

    37     

    38 using namespace MathMLNames;

    39 

    40 // Left margin of the radical (px)

    41 const int gRadicalLeftMargin = 3;

    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 = 1.5;

    46 // Radical width (%)

    47 const float gRadicalWidth = 0.75;

    48 // Horizontal position of the bottom point of the radical (%)

    49 const float gRadicalBottomPointXPos= 0.5;

    50 // Horizontal position of the top left point of the radical (%)

    51 const float gRadicalTopLeftPointXPos = 0.8;

    52 // Vertical position of the top left point of the radical (%)

    53 const float gRadicalTopLeftPointYPos = 0.625; 

    54 // Vertical shift of the left end point of the radical (%)

    55 const float gRadicalLeftEndYShift = 0.05;

    56 // Root padding around the base (%)

    57 const float gRootPadding = 0.2;

    58 // Additional bottom root padding (%)

    59 const float gRootBottomPadding = 0.2;

    60     

    61 // Radical line thickness (%)

    62 const float gRadicalLineThickness = 0.02;

    63 // Radical thick line thickness (%)

    64 const float gRadicalThickLineThickness = 0.1;

    65     

    66 RenderMathMLRoot::RenderMathMLRoot(Node *expression) 

    67 : RenderMathMLBlock(expression) 

    68 {

    69 }

    70 

    71 void RenderMathMLRoot::addChild(RenderObject* child, RenderObject* )

    72 {

    73     if (isEmpty()) {

    74         // Add a block for the index

    75         RenderBlock* block = new (renderArena()) RenderBlock(node());

    76         RefPtr<RenderStyle> indexStyle = makeBlockStyle();

    77         indexStyle->setDisplay(INLINE_BLOCK);

    78         block->setStyle(indexStyle.release());

    79         RenderBlock::addChild(block);

    80         

    81         // FIXME: the wrapping does not seem to be needed anymore.

    82         // this is the base, so wrap it so we can pad it

    83         block = new (renderArena()) RenderBlock(node());

    84         RefPtr<RenderStyle> baseStyle = makeBlockStyle();

    85         baseStyle->setDisplay(INLINE_BLOCK);

    86         baseStyle->setPaddingLeft(Length(5 * gRadicalWidth , Percent));

    87         block->setStyle(baseStyle.release());

    88         RenderBlock::addChild(block);

    89         block->addChild(child);

    90     } else {

    91         // always add to the index

    92         firstChild()->addChild(child);

    93     }

    94 }

    95     

    96 void RenderMathMLRoot::paint(PaintInfo& info, int tx, int ty)

    97 {

    98     RenderMathMLBlock::paint(info , tx , ty);

    99     

   100     if (info.context->paintingDisabled())

   101         return;

   102     

   103     tx += x();

   104     ty += y();

   105     

   106     RenderBoxModelObject* indexBox = toRenderBoxModelObject(lastChild());

   107     

   108     int maxHeight = indexBox->offsetHeight();

   109     // default to the font size in pixels if we're empty

   110     if (!maxHeight)

   111         maxHeight = style()->fontSize();

   112     int width = indexBox->offsetWidth();

   113     

   114     int indexWidth = 0;

   115     RenderObject* current = firstChild();

   116     while (current != lastChild()) {

   117         if (current->isBoxModelObject()) {

   118             RenderBoxModelObject* box = toRenderBoxModelObject(current);

   119             indexWidth += box->offsetWidth();

   120         }

   121         current = current->nextSibling();

   122     }

   123     

   124     int frontWidth = static_cast<int>(style()->fontSize() * gRadicalWidth);

   125     int topStartShift = 0;

   126     // Base height above which the shape of the root changes

   127     int thresholdHeight = static_cast<int>(gThresholdBaseHeight * style()->fontSize());

   128     

   129     if (maxHeight > thresholdHeight && thresholdHeight) {

   130         float shift = (maxHeight - thresholdHeight) / static_cast<float>(thresholdHeight);

   131         if (shift > 1.)

   132             shift = 1.;

   133         topStartShift = static_cast<int>(gRadicalBottomPointXPos * frontWidth * shift);

   134     }

   135     

   136     width += topStartShift;

   137     

   138     int rootPad = static_cast<int>(gRootPadding * style()->fontSize());

   139     int start = tx + indexWidth + gRadicalLeftMargin + style()->paddingLeft().value() - rootPad;

   140     ty += style()->paddingTop().value() - rootPad;

   141     

   142     FloatPoint topStart(start - topStartShift, ty);

   143     FloatPoint bottomLeft(start - gRadicalBottomPointXPos * frontWidth , ty + maxHeight + gRadicalBasePad);

   144     FloatPoint topLeft(start - gRadicalTopLeftPointXPos * frontWidth , ty + gRadicalTopLeftPointYPos * maxHeight);

   145     FloatPoint leftEnd(start - frontWidth , topLeft.y() + gRadicalLeftEndYShift * style()->fontSize());

   146     

   147     info.context->save();

   148     

   149     info.context->setStrokeThickness(gRadicalLineThickness * style()->fontSize());

   150     info.context->setStrokeStyle(SolidStroke);

   151     info.context->setStrokeColor(style()->visitedDependentColor(CSSPropertyColor), sRGBColorSpace);

   152     info.context->setLineJoin(MiterJoin);

   153     info.context->setMiterLimit(style()->fontSize());

   154     

   155     Path root;

   156     

   157     root.moveTo(FloatPoint(topStart.x() + width, ty));

   158     // draw top

   159     root.addLineTo(topStart);

   160     // draw from top left corner to bottom point of radical

   161     root.addLineTo(bottomLeft);

   162     // draw from bottom point to top of left part of radical base "pocket"

   163     root.addLineTo(topLeft);

   164     // draw to end

   165     root.addLineTo(leftEnd);

   166     

   167     info.context->beginPath();

   168     info.context->addPath(root);

   169     info.context->strokePath();

   170     

   171     info.context->save();

   172     

   173     // Build a mask to draw the thick part of the root.

   174     Path mask;

   175     

   176     mask.moveTo(topStart);

   177     mask.addLineTo(bottomLeft);

   178     mask.addLineTo(topLeft);

   179     mask.addLineTo(FloatPoint(2 * topLeft.x() - leftEnd.x(), 2 * topLeft.y() - leftEnd.y()));

   180     

   181     info.context->beginPath();

   182     info.context->addPath(mask);

   183     info.context->clip(mask);

   184     

   185     // Draw the thick part of the root.

   186     info.context->setStrokeThickness(gRadicalThickLineThickness * style()->fontSize());

   187     info.context->setLineCap(SquareCap);

   188     

   189     Path line;

   190     

   191     line = line.createLine(bottomLeft, topLeft);

   192     

   193     info.context->beginPath();

   194     info.context->addPath(line);

   195     info.context->strokePath();

   196     

   197     info.context->restore();

   198     

   199     info.context->restore();

   200 

   201 }

   202 

   203 void RenderMathMLRoot::layout()

   204 {

   205     RenderBlock::layout();

   206     

   207     int maxHeight = toRenderBoxModelObject(lastChild())->offsetHeight();

   208     

   209     RenderObject* current = lastChild()->firstChild();

   210     current->style()->setVerticalAlign(BASELINE);

   211     

   212     if (!maxHeight)

   213         maxHeight = style()->fontSize();

   214     

   215     // Base height above which the shape of the root changes

   216     int thresholdHeight = static_cast<int>(gThresholdBaseHeight * style()->fontSize());

   217     int topStartShift = 0;

   218     

   219     if (maxHeight > thresholdHeight && thresholdHeight) {

   220         float shift = (maxHeight - thresholdHeight) / static_cast<float>(thresholdHeight);

   221         if (shift > 1.)

   222             shift = 1.;

   223         int frontWidth = static_cast<int>(style()->fontSize() * gRadicalWidth);

   224         topStartShift = static_cast<int>(gRadicalBottomPointXPos * frontWidth * shift);

   225         

   226         style()->setPaddingBottom(Length(static_cast<int>(gRootBottomPadding * style()->fontSize()), Fixed));

   227     }

   228     

   229     // Positioning of the index

   230     RenderBoxModelObject* indexBox = toRenderBoxModelObject(firstChild()->firstChild());

   231     

   232     int indexShift = indexBox->offsetWidth() + topStartShift;

   233     int radicalHeight = static_cast<int>((1 - gRadicalTopLeftPointYPos) * maxHeight);

   234     int rootMarginTop = radicalHeight + style()->paddingBottom().value() + indexBox->offsetHeight() - (maxHeight + static_cast<int>(gRootPadding * style()->fontSize()));

   235     

   236     style()->setPaddingLeft(Length(indexShift, Fixed));

   237     if (rootMarginTop > 0)

   238         style()->setPaddingTop(Length(rootMarginTop + static_cast<int>(gRootPadding * style()->fontSize()), Fixed));

   239     

   240     setNeedsLayoutAndPrefWidthsRecalc();

   241     markContainingBlocksForLayout();

   242     RenderBlock::layout();

   243 

   244     indexBox->style()->setBottom(Length(radicalHeight + style()->paddingBottom().value(), Fixed));

   245 

   246     // Now that we've potentially changed its position, we need layout the index again.

   247     indexBox->setNeedsLayoutAndPrefWidthsRecalc();

   248     indexBox->layout();

   249 }

   250     

   251 }

   252 

   253 #endif // ENABLE(MATHML)

   254 

   255