Source/WebCore/rendering/mathml/RenderMathMLRoot.cpp - external/WebKit_submodule - Git at Google

 /*
  * Copyright (C) 2009 Alex Milowski (alex@milowski.com). All rights reserved.
  * Copyright (C) 2010 François Sausset (sausset@gmail.com). All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"

 #if ENABLE(MATHML)

 #include "RenderMathMLRoot.h"

 #include "GraphicsContext.h"
 #include "PaintInfo.h"
 #include "RenderMathMLRow.h"

 using namespace std;

 namespace WebCore {

 // FIXME: This whole file should be changed to work with various writing modes. See https://bugs.webkit.org/show_bug.cgi?id=48951.

 // Threshold above which the radical shape is modified to look nice with big bases (em)
 const float gThresholdBaseHeightEms = 1.5f;
 // Normal width of the front of the radical sign, before the base & overbar (em)
 const float gFrontWidthEms = 0.75f;
 // Gap between the base and overbar (em)
 const float gSpaceAboveEms = 0.2f;
 // Horizontal position of the bottom point of the radical (* frontWidth)
 const float gRadicalBottomPointXFront = 0.5f;
 // Lower the radical sign's bottom point (px)
 const int gRadicalBottomPointLower = 3;
 // Horizontal position of the top left point of the radical "dip" (* frontWidth)
 const float gRadicalDipLeftPointXFront = 0.8f;
 // Vertical position of the top left point of a sqrt radical "dip" (* baseHeight)
 const float gSqrtRadicalDipLeftPointYPos = 0.5f;
 // Vertical position of the top left point of an nth root radical "dip" (* baseHeight)
 const float gRootRadicalDipLeftPointYPos = 0.625f;
 // Vertical shift of the left end point of the radical (em)
 const float gRadicalLeftEndYShiftEms = 0.05f;
 // Additional bottom root padding if baseHeight > threshold (em)
 const float gBigRootBottomPaddingEms = 0.2f;

 // Radical line thickness (em)
 const float gRadicalLineThicknessEms = 0.02f;
 // Radical thick line thickness (em)
 const float gRadicalThickLineThicknessEms = 0.1f;

 RenderMathMLRoot::RenderMathMLRoot(Element* element)
     : RenderMathMLBlock(element)
 {
 }

 void RenderMathMLRoot::addChild(RenderObject* newChild, RenderObject* beforeChild)
 {
     // Insert an implicit <mrow> for <mroot> as well as <msqrt>, to ensure firstChild() will have a box
     // to measure and store a glyph-based height for preferredLogicalHeightAfterSizing.
     if (!firstChild())
         RenderMathMLBlock::addChild(RenderMathMLRow::createAnonymousWithParentRenderer(this));

     // An <mroot>'s index has { position: absolute }.
     if (newChild->style()->position() == AbsolutePosition)
         RenderMathMLBlock::addChild(newChild);
     else
         firstChild()->addChild(newChild, beforeChild && beforeChild->style()->position() != AbsolutePosition ? beforeChild : 0);
 }

 RenderBoxModelObject* RenderMathMLRoot::index() const
 {
     if (!firstChild())
         return 0;
     RenderObject* index = firstChild()->nextSibling();
     if (!index || !index->isBoxModelObject())
         return 0;
     return toRenderBoxModelObject(index);
 }

 void RenderMathMLRoot::computePreferredLogicalWidths()
 {
     ASSERT(preferredLogicalWidthsDirty() && needsLayout());

     computeChildrenPreferredLogicalHeights();

     int baseHeight = firstChild() ? roundToInt(preferredLogicalHeightAfterSizing(firstChild())) : style()->fontSize();

     int frontWidth = lroundf(gFrontWidthEms * style()->fontSize());

     // Base height above which the shape of the root changes
     float thresholdHeight = gThresholdBaseHeightEms * style()->fontSize();
     if (baseHeight > thresholdHeight && thresholdHeight) {
         float shift = min<float>((baseHeight - thresholdHeight) / thresholdHeight, 1.0f);
         m_overbarLeftPointShift = static_cast<int>(shift * gRadicalBottomPointXFront * frontWidth);
         m_intrinsicPaddingAfter = lroundf(gBigRootBottomPaddingEms * style()->fontSize());
     } else {
         m_overbarLeftPointShift = 0;
         m_intrinsicPaddingAfter = 0;
     }

     int rootPad = lroundf(gSpaceAboveEms * style()->fontSize());
     m_intrinsicPaddingBefore = rootPad;
     m_indexTop = 0;
     if (RenderBoxModelObject* index = this->index()) {
         m_intrinsicPaddingStart = roundToInt(index->maxPreferredLogicalWidth()) + m_overbarLeftPointShift;

         int indexHeight = roundToInt(preferredLogicalHeightAfterSizing(index));
         int partDipHeight = lroundf((1 - gRootRadicalDipLeftPointYPos) * baseHeight);
         int rootExtraTop = partDipHeight + indexHeight - (baseHeight + rootPad);
         if (rootExtraTop > 0)
             m_intrinsicPaddingBefore += rootExtraTop;
         else
             m_indexTop = - rootExtraTop;
     } else
         m_intrinsicPaddingStart = frontWidth;

     RenderMathMLBlock::computePreferredLogicalWidths();

     // Shrink our logical width to its probable value now without triggering unnecessary relayout of our children.
     ASSERT(needsLayout() && logicalWidth() >= maxPreferredLogicalWidth());
     setLogicalWidth(maxPreferredLogicalWidth());
 }

 void RenderMathMLRoot::layout()
 {
     // Our computePreferredLogicalWidths() may change our logical width and then layout our children, which
     // RenderBlock::layout()'s relayoutChildren logic isn't expecting.
     if (preferredLogicalWidthsDirty())
         computePreferredLogicalWidths();

     RenderMathMLBlock::layout();

     RenderBoxModelObject* index = this->index();
     // If |index|, it should be a RenderBlock here, unless the user has overriden its { position: absolute }.
     if (index && index->isBox())
         toRenderBox(index)->setLogicalTop(m_indexTop);
 }

 void RenderMathMLRoot::paint(PaintInfo& info, const LayoutPoint& paintOffset)
 {
     RenderMathMLBlock::paint(info, paintOffset);

     if (info.context->paintingDisabled())
         return;

     IntPoint adjustedPaintOffset = roundedIntPoint(paintOffset + location() + contentBoxRect().location());

     int startX = adjustedPaintOffset.x();
     int frontWidth = lroundf(gFrontWidthEms * style()->fontSize());
     int overbarWidth = roundToInt(contentLogicalWidth()) + m_overbarLeftPointShift;

     int baseHeight = roundToInt(contentLogicalHeight());
     int rootPad = lroundf(gSpaceAboveEms * style()->fontSize());
     adjustedPaintOffset.setY(adjustedPaintOffset.y() - rootPad);

     float radicalDipLeftPointYPos = (index() ? gRootRadicalDipLeftPointYPos : gSqrtRadicalDipLeftPointYPos) * baseHeight;

     FloatPoint overbarLeftPoint(startX - m_overbarLeftPointShift, adjustedPaintOffset.y());
     FloatPoint bottomPoint(startX - gRadicalBottomPointXFront * frontWidth, adjustedPaintOffset.y() + baseHeight + gRadicalBottomPointLower);
     FloatPoint dipLeftPoint(startX - gRadicalDipLeftPointXFront * frontWidth, adjustedPaintOffset.y() + radicalDipLeftPointYPos);
     FloatPoint leftEnd(startX - frontWidth, dipLeftPoint.y() + gRadicalLeftEndYShiftEms * style()->fontSize());

     GraphicsContextStateSaver stateSaver(*info.context);

     info.context->setStrokeThickness(gRadicalLineThicknessEms * style()->fontSize());
     info.context->setStrokeStyle(SolidStroke);
     info.context->setStrokeColor(style()->visitedDependentColor(CSSPropertyColor), ColorSpaceDeviceRGB);
     info.context->setLineJoin(MiterJoin);
     info.context->setMiterLimit(style()->fontSize());

     Path root;

     root.moveTo(FloatPoint(overbarLeftPoint.x() + overbarWidth, adjustedPaintOffset.y()));
     // draw top
     root.addLineTo(overbarLeftPoint);
     // draw from top left corner to bottom point of radical
     root.addLineTo(bottomPoint);
     // draw from bottom point to top of left part of radical base "dip"
     root.addLineTo(dipLeftPoint);
     // draw to end
     root.addLineTo(leftEnd);

     info.context->strokePath(root);

     GraphicsContextStateSaver maskStateSaver(*info.context);

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

     mask.moveTo(overbarLeftPoint);
     mask.addLineTo(bottomPoint);
     mask.addLineTo(dipLeftPoint);
     mask.addLineTo(FloatPoint(2 * dipLeftPoint.x() - leftEnd.x(), 2 * dipLeftPoint.y() - leftEnd.y()));

     info.context->clip(mask);

     // Draw the thick part of the root.
     info.context->setStrokeThickness(gRadicalThickLineThicknessEms * style()->fontSize());
     info.context->setLineCap(SquareCap);

     Path line;
     line.moveTo(bottomPoint);
     line.addLineTo(dipLeftPoint);

     info.context->strokePath(line);
 }

 }

 #endif // ENABLE(MATHML)
	/*
	* Copyright (C) 2009 Alex Milowski (alex@milowski.com). All rights reserved.
	* Copyright (C) 2010 François Sausset (sausset@gmail.com). All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"

	#if ENABLE(MATHML)

	#include "RenderMathMLRoot.h"

	#include "GraphicsContext.h"
	#include "PaintInfo.h"
	#include "RenderMathMLRow.h"

	using namespace std;

	namespace WebCore {

	// FIXME: This whole file should be changed to work with various writing modes. See https://bugs.webkit.org/show_bug.cgi?id=48951.

	// Threshold above which the radical shape is modified to look nice with big bases (em)
	const float gThresholdBaseHeightEms = 1.5f;
	// Normal width of the front of the radical sign, before the base & overbar (em)
	const float gFrontWidthEms = 0.75f;
	// Gap between the base and overbar (em)
	const float gSpaceAboveEms = 0.2f;
	// Horizontal position of the bottom point of the radical (* frontWidth)
	const float gRadicalBottomPointXFront = 0.5f;
	// Lower the radical sign's bottom point (px)
	const int gRadicalBottomPointLower = 3;
	// Horizontal position of the top left point of the radical "dip" (* frontWidth)
	const float gRadicalDipLeftPointXFront = 0.8f;
	// Vertical position of the top left point of a sqrt radical "dip" (* baseHeight)
	const float gSqrtRadicalDipLeftPointYPos = 0.5f;
	// Vertical position of the top left point of an nth root radical "dip" (* baseHeight)
	const float gRootRadicalDipLeftPointYPos = 0.625f;
	// Vertical shift of the left end point of the radical (em)
	const float gRadicalLeftEndYShiftEms = 0.05f;
	// Additional bottom root padding if baseHeight > threshold (em)
	const float gBigRootBottomPaddingEms = 0.2f;

	// Radical line thickness (em)
	const float gRadicalLineThicknessEms = 0.02f;
	// Radical thick line thickness (em)
	const float gRadicalThickLineThicknessEms = 0.1f;

	RenderMathMLRoot::RenderMathMLRoot(Element* element)
	: RenderMathMLBlock(element)
	{
	}

	void RenderMathMLRoot::addChild(RenderObject* newChild, RenderObject* beforeChild)
	{
	// Insert an implicit <mrow> for <mroot> as well as <msqrt>, to ensure firstChild() will have a box
	// to measure and store a glyph-based height for preferredLogicalHeightAfterSizing.
	if (!firstChild())
	RenderMathMLBlock::addChild(RenderMathMLRow::createAnonymousWithParentRenderer(this));

	// An <mroot>'s index has { position: absolute }.
	if (newChild->style()->position() == AbsolutePosition)
	RenderMathMLBlock::addChild(newChild);
	else
	firstChild()->addChild(newChild, beforeChild && beforeChild->style()->position() != AbsolutePosition ? beforeChild : 0);
	}

	RenderBoxModelObject* RenderMathMLRoot::index() const
	{
	if (!firstChild())
	return 0;
	RenderObject* index = firstChild()->nextSibling();
	if (!index \|\| !index->isBoxModelObject())
	return 0;
	return toRenderBoxModelObject(index);
	}

	void RenderMathMLRoot::computePreferredLogicalWidths()
	{
	ASSERT(preferredLogicalWidthsDirty() && needsLayout());

	computeChildrenPreferredLogicalHeights();

	int baseHeight = firstChild() ? roundToInt(preferredLogicalHeightAfterSizing(firstChild())) : style()->fontSize();

	int frontWidth = lroundf(gFrontWidthEms * style()->fontSize());

	// Base height above which the shape of the root changes
	float thresholdHeight = gThresholdBaseHeightEms * style()->fontSize();
	if (baseHeight > thresholdHeight && thresholdHeight) {
	float shift = min<float>((baseHeight - thresholdHeight) / thresholdHeight, 1.0f);
	m_overbarLeftPointShift = static_cast<int>(shift * gRadicalBottomPointXFront * frontWidth);
	m_intrinsicPaddingAfter = lroundf(gBigRootBottomPaddingEms * style()->fontSize());
	} else {
	m_overbarLeftPointShift = 0;
	m_intrinsicPaddingAfter = 0;
	}

	int rootPad = lroundf(gSpaceAboveEms * style()->fontSize());
	m_intrinsicPaddingBefore = rootPad;
	m_indexTop = 0;
	if (RenderBoxModelObject* index = this->index()) {
	m_intrinsicPaddingStart = roundToInt(index->maxPreferredLogicalWidth()) + m_overbarLeftPointShift;

	int indexHeight = roundToInt(preferredLogicalHeightAfterSizing(index));
	int partDipHeight = lroundf((1 - gRootRadicalDipLeftPointYPos) * baseHeight);
	int rootExtraTop = partDipHeight + indexHeight - (baseHeight + rootPad);
	if (rootExtraTop > 0)
	m_intrinsicPaddingBefore += rootExtraTop;
	else
	m_indexTop = - rootExtraTop;
	} else
	m_intrinsicPaddingStart = frontWidth;

	RenderMathMLBlock::computePreferredLogicalWidths();

	// Shrink our logical width to its probable value now without triggering unnecessary relayout of our children.
	ASSERT(needsLayout() && logicalWidth() >= maxPreferredLogicalWidth());
	setLogicalWidth(maxPreferredLogicalWidth());
	}

	void RenderMathMLRoot::layout()
	{
	// Our computePreferredLogicalWidths() may change our logical width and then layout our children, which
	// RenderBlock::layout()'s relayoutChildren logic isn't expecting.
	if (preferredLogicalWidthsDirty())
	computePreferredLogicalWidths();

	RenderMathMLBlock::layout();

	RenderBoxModelObject* index = this->index();
	// If \|index\|, it should be a RenderBlock here, unless the user has overriden its { position: absolute }.
	if (index && index->isBox())
	toRenderBox(index)->setLogicalTop(m_indexTop);
	}

	void RenderMathMLRoot::paint(PaintInfo& info, const LayoutPoint& paintOffset)
	{
	RenderMathMLBlock::paint(info, paintOffset);

	if (info.context->paintingDisabled())
	return;

	IntPoint adjustedPaintOffset = roundedIntPoint(paintOffset + location() + contentBoxRect().location());

	int startX = adjustedPaintOffset.x();
	int frontWidth = lroundf(gFrontWidthEms * style()->fontSize());
	int overbarWidth = roundToInt(contentLogicalWidth()) + m_overbarLeftPointShift;

	int baseHeight = roundToInt(contentLogicalHeight());
	int rootPad = lroundf(gSpaceAboveEms * style()->fontSize());
	adjustedPaintOffset.setY(adjustedPaintOffset.y() - rootPad);

	float radicalDipLeftPointYPos = (index() ? gRootRadicalDipLeftPointYPos : gSqrtRadicalDipLeftPointYPos) * baseHeight;

	FloatPoint overbarLeftPoint(startX - m_overbarLeftPointShift, adjustedPaintOffset.y());
	FloatPoint bottomPoint(startX - gRadicalBottomPointXFront * frontWidth, adjustedPaintOffset.y() + baseHeight + gRadicalBottomPointLower);
	FloatPoint dipLeftPoint(startX - gRadicalDipLeftPointXFront * frontWidth, adjustedPaintOffset.y() + radicalDipLeftPointYPos);
	FloatPoint leftEnd(startX - frontWidth, dipLeftPoint.y() + gRadicalLeftEndYShiftEms * style()->fontSize());

	GraphicsContextStateSaver stateSaver(*info.context);

	info.context->setStrokeThickness(gRadicalLineThicknessEms * style()->fontSize());
	info.context->setStrokeStyle(SolidStroke);
	info.context->setStrokeColor(style()->visitedDependentColor(CSSPropertyColor), ColorSpaceDeviceRGB);
	info.context->setLineJoin(MiterJoin);
	info.context->setMiterLimit(style()->fontSize());

	Path root;

	root.moveTo(FloatPoint(overbarLeftPoint.x() + overbarWidth, adjustedPaintOffset.y()));
	// draw top
	root.addLineTo(overbarLeftPoint);
	// draw from top left corner to bottom point of radical
	root.addLineTo(bottomPoint);
	// draw from bottom point to top of left part of radical base "dip"
	root.addLineTo(dipLeftPoint);
	// draw to end
	root.addLineTo(leftEnd);

	info.context->strokePath(root);

	GraphicsContextStateSaver maskStateSaver(*info.context);

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

	mask.moveTo(overbarLeftPoint);
	mask.addLineTo(bottomPoint);
	mask.addLineTo(dipLeftPoint);
	mask.addLineTo(FloatPoint(2 * dipLeftPoint.x() - leftEnd.x(), 2 * dipLeftPoint.y() - leftEnd.y()));

	info.context->clip(mask);

	// Draw the thick part of the root.
	info.context->setStrokeThickness(gRadicalThickLineThicknessEms * style()->fontSize());
	info.context->setLineCap(SquareCap);

	Path line;
	line.moveTo(bottomPoint);
	line.addLineTo(dipLeftPoint);

	info.context->strokePath(line);
	}

	}

	#endif // ENABLE(MATHML)