gecko-dev/layout/mathml/nsMathMLmsubFrame.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla MathML Project.
*
* The Initial Developer of the Original Code is
* The University Of Queensland.
* Portions created by the Initial Developer are Copyright (C) 1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Roger B. Sidje <rbs@maths.uq.edu.au>
* David J. Fiddes <D.J.Fiddes@hw.ac.uk>
* Shyjan Mahamud <mahamud@cs.cmu.edu> (added TeX rendering rules)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "nsCOMPtr.h"
#include "nsFrame.h"
#include "nsPresContext.h"
#include "nsStyleContext.h"
#include "nsStyleConsts.h"
#include "nsMathMLmsubFrame.h"
//
// <msub> -- attach a subscript to a base - implementation
//
nsIFrame*
NS_NewMathMLmsubFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsMathMLmsubFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmsubFrame)
nsMathMLmsubFrame::~nsMathMLmsubFrame()
{
}
NS_IMETHODIMP
nsMathMLmsubFrame::TransmitAutomaticData()
{
// if our base is an embellished operator, let its state bubble to us
mPresentationData.baseFrame = mFrames.FirstChild();
GetEmbellishDataFrom(mPresentationData.baseFrame, mEmbellishData);
// 1. The REC says:
// The <msub> element increments scriptlevel by 1, and sets displaystyle to
// "false", within subscript, but leaves both attributes unchanged within base.
// 2. The TeXbook (Ch 17. p.141) says the subscript is compressed
UpdatePresentationDataFromChildAt(1, -1,
~NS_MATHML_DISPLAYSTYLE | NS_MATHML_COMPRESSED,
NS_MATHML_DISPLAYSTYLE | NS_MATHML_COMPRESSED);
return NS_OK;
}
/* virtual */ nsresult
nsMathMLmsubFrame::Place (nsRenderingContext& aRenderingContext,
bool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize)
{
// extra spacing after sup/subscript
nscoord scriptSpace = nsPresContext::CSSPointsToAppUnits(0.5f); // 0.5pt as in plain TeX
// check if the subscriptshift attribute is there
nscoord subScriptShift = 0;
nsAutoString value;
GetAttribute(mContent, mPresentationData.mstyle,
nsGkAtoms::subscriptshift_, value);
if (!value.IsEmpty()) {
nsCSSValue cssValue;
if (ParseNumericValue(value, cssValue) && cssValue.IsLengthUnit()) {
subScriptShift = CalcLength(PresContext(), mStyleContext, cssValue);
}
}
return nsMathMLmsubFrame::PlaceSubScript(PresContext(),
aRenderingContext,
aPlaceOrigin,
aDesiredSize,
this,
subScriptShift,
scriptSpace);
}
// exported routine that both munder and msub share.
// munder uses this when movablelimits is set.
nsresult
nsMathMLmsubFrame::PlaceSubScript (nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
bool aPlaceOrigin,
nsHTMLReflowMetrics& aDesiredSize,
nsMathMLContainerFrame* aFrame,
nscoord aUserSubScriptShift,
nscoord aScriptSpace)
{
// force the scriptSpace to be atleast 1 pixel
aScriptSpace = NS_MAX(nsPresContext::CSSPixelsToAppUnits(1), aScriptSpace);
////////////////////////////////////
// Get the children's desired sizes
nsBoundingMetrics bmBase, bmSubScript;
nsHTMLReflowMetrics baseSize;
nsHTMLReflowMetrics subScriptSize;
nsIFrame* baseFrame = aFrame->GetFirstPrincipalChild();
nsIFrame* subScriptFrame = nsnull;
if (baseFrame)
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subScriptFrame = baseFrame->GetNextSibling();
if (!baseFrame || !subScriptFrame || subScriptFrame->GetNextSibling()) {
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// report an error, encourage people to get their markups in order
return aFrame->ReflowError(aRenderingContext, aDesiredSize);
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}
GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
// get the subdrop from the subscript font
nscoord subDrop;
GetSubDropFromChild(subScriptFrame, subDrop);
// parameter v, Rule 18a, App. G, TeXbook
nscoord minSubScriptShift = bmBase.descent + subDrop;
//////////////////
// Place Children
// get min subscript shift limit from x-height
// = h(x) - 4/5 * sigma_5, Rule 18b, App. G, TeXbook
nscoord xHeight = 0;
nsRefPtr<nsFontMetrics> fm;
nsLayoutUtils::GetFontMetricsForFrame(baseFrame, getter_AddRefs(fm));
xHeight = fm->XHeight();
nscoord minShiftFromXHeight = (nscoord)
(bmSubScript.ascent - (4.0f/5.0f) * xHeight);
// subScriptShift
// = minimum amount to shift the subscript down set by user or from the font
// = sub1 in TeX
// = subscriptshift attribute * x-height
nscoord subScriptShift, dummy;
// get subScriptShift default from font
GetSubScriptShifts (fm, subScriptShift, dummy);
subScriptShift =
NS_MAX(subScriptShift, aUserSubScriptShift);
// get actual subscriptshift to be used
// Rule 18b, App. G, TeXbook
nscoord actualSubScriptShift =
NS_MAX(minSubScriptShift,NS_MAX(subScriptShift,minShiftFromXHeight));
// get bounding box for base + subscript
nsBoundingMetrics boundingMetrics;
boundingMetrics.ascent =
NS_MAX(bmBase.ascent, bmSubScript.ascent - actualSubScriptShift);
boundingMetrics.descent =
NS_MAX(bmBase.descent, bmSubScript.descent + actualSubScriptShift);
// add aScriptSpace to the subscript's width
boundingMetrics.width = bmBase.width + bmSubScript.width + aScriptSpace;
boundingMetrics.leftBearing = bmBase.leftBearing;
boundingMetrics.rightBearing = NS_MAX(bmBase.rightBearing, bmBase.width +
NS_MAX(bmSubScript.width + aScriptSpace, bmSubScript.rightBearing));
aFrame->SetBoundingMetrics (boundingMetrics);
// reflow metrics
aDesiredSize.ascent =
NS_MAX(baseSize.ascent, subScriptSize.ascent - actualSubScriptShift);
aDesiredSize.height = aDesiredSize.ascent +
NS_MAX(baseSize.height - baseSize.ascent,
subScriptSize.height - subScriptSize.ascent + actualSubScriptShift);
aDesiredSize.width = boundingMetrics.width;
aDesiredSize.mBoundingMetrics = boundingMetrics;
aFrame->SetReference(nsPoint(0, aDesiredSize.ascent));
if (aPlaceOrigin) {
nscoord dx, dy;
// now place the base ...
dx = 0; dy = aDesiredSize.ascent - baseSize.ascent;
FinishReflowChild (baseFrame, aPresContext, nsnull, baseSize, dx, dy, 0);
// ... and subscript
dx = bmBase.width;
dy = aDesiredSize.ascent - (subScriptSize.ascent - actualSubScriptShift);
FinishReflowChild (subScriptFrame, aPresContext, nsnull, subScriptSize, dx, dy, 0);
}
return NS_OK;
}