mirror of
https://github.com/mozilla/gecko-dev.git
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342 lines
13 KiB
C++
342 lines
13 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsCOMPtr.h"
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#include "nsFrame.h"
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#include "nsPresContext.h"
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#include "nsStyleContext.h"
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#include "nsStyleConsts.h"
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#include "nsRenderingContext.h"
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#include "nsMathMLmsubsupFrame.h"
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//
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// <msubsup> -- attach a subscript-superscript pair to a base - implementation
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//
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nsIFrame*
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NS_NewMathMLmsubsupFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
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{
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return new (aPresShell) nsMathMLmsubsupFrame(aContext);
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}
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NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmsubsupFrame)
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nsMathMLmsubsupFrame::~nsMathMLmsubsupFrame()
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{
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}
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NS_IMETHODIMP
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nsMathMLmsubsupFrame::TransmitAutomaticData()
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{
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// if our base is an embellished operator, let its state bubble to us
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mPresentationData.baseFrame = mFrames.FirstChild();
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GetEmbellishDataFrom(mPresentationData.baseFrame, mEmbellishData);
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// 1. The REC says:
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// The <msubsup> element increments scriptlevel by 1, and sets displaystyle to
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// "false", within subscript and superscript, but leaves both attributes
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// unchanged within base.
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// 2. The TeXbook (Ch 17. p.141) says the superscript inherits the compression
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// while the subscript is compressed
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UpdatePresentationDataFromChildAt(1, -1,
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~NS_MATHML_DISPLAYSTYLE,
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NS_MATHML_DISPLAYSTYLE);
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UpdatePresentationDataFromChildAt(1, 1,
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NS_MATHML_COMPRESSED,
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NS_MATHML_COMPRESSED);
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return NS_OK;
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}
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/* virtual */ nsresult
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nsMathMLmsubsupFrame::Place(nsRenderingContext& aRenderingContext,
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bool aPlaceOrigin,
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nsHTMLReflowMetrics& aDesiredSize)
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{
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// extra spacing between base and sup/subscript
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nscoord scriptSpace = 0;
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// subscriptshift
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//
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// "Specifies the minimum amount to shift the baseline of subscript down; the
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// default is for the rendering agent to use its own positioning rules."
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//
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// values: length
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// default: automatic
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//
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// We use 0 as the default value so unitless values can be ignored.
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// XXXfredw Should we forbid negative values? (bug 411227)
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//
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nsAutoString value;
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nscoord subScriptShift = 0;
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GetAttribute(mContent, mPresentationData.mstyle,
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nsGkAtoms::subscriptshift_, value);
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if (!value.IsEmpty()) {
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ParseNumericValue(value, &subScriptShift,
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nsMathMLElement::PARSE_ALLOW_NEGATIVE,
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PresContext(), mStyleContext);
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}
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// superscriptshift
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//
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// "Specifies the minimum amount to shift the baseline of superscript up; the
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// default is for the rendering agent to use its own positioning rules."
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//
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// values: length
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// default: automatic
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//
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// We use 0 as the default value so unitless values can be ignored.
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// XXXfredw Should we forbid negative values? (bug 411227)
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//
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nscoord supScriptShift = 0;
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GetAttribute(mContent, mPresentationData.mstyle,
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nsGkAtoms::superscriptshift_, value);
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if (!value.IsEmpty()) {
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ParseNumericValue(value, &supScriptShift,
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nsMathMLElement::PARSE_ALLOW_NEGATIVE,
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PresContext(), mStyleContext);
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}
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return nsMathMLmsubsupFrame::PlaceSubSupScript(PresContext(),
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aRenderingContext,
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aPlaceOrigin,
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aDesiredSize,
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this,
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subScriptShift,
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supScriptShift,
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scriptSpace);
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}
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// exported routine that both munderover and msubsup share.
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// munderover uses this when movablelimits is set.
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nsresult
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nsMathMLmsubsupFrame::PlaceSubSupScript(nsPresContext* aPresContext,
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nsRenderingContext& aRenderingContext,
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bool aPlaceOrigin,
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nsHTMLReflowMetrics& aDesiredSize,
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nsMathMLContainerFrame* aFrame,
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nscoord aUserSubScriptShift,
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nscoord aUserSupScriptShift,
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nscoord aScriptSpace)
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{
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// force the scriptSpace to be atleast 1 pixel
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nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
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aScriptSpace = NS_MAX(onePixel, aScriptSpace);
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////////////////////////////////////
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// Get the children's desired sizes
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nsHTMLReflowMetrics baseSize;
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nsHTMLReflowMetrics subScriptSize;
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nsHTMLReflowMetrics supScriptSize;
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nsBoundingMetrics bmBase, bmSubScript, bmSupScript;
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nsIFrame* subScriptFrame = nsnull;
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nsIFrame* supScriptFrame = nsnull;
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nsIFrame* baseFrame = aFrame->GetFirstPrincipalChild();
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if (baseFrame)
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subScriptFrame = baseFrame->GetNextSibling();
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if (subScriptFrame)
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supScriptFrame = subScriptFrame->GetNextSibling();
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if (!baseFrame || !subScriptFrame || !supScriptFrame ||
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supScriptFrame->GetNextSibling()) {
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// report an error, encourage people to get their markups in order
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return aFrame->ReflowError(aRenderingContext, aDesiredSize);
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}
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GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
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GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
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GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);
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// get the subdrop from the subscript font
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nscoord subDrop;
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GetSubDropFromChild(subScriptFrame, subDrop);
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// parameter v, Rule 18a, App. G, TeXbook
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nscoord minSubScriptShift = bmBase.descent + subDrop;
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// get the supdrop from the supscript font
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nscoord supDrop;
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GetSupDropFromChild(supScriptFrame, supDrop);
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// parameter u, Rule 18a, App. G, TeXbook
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nscoord minSupScriptShift = bmBase.ascent - supDrop;
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//////////////////
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// Place Children
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//////////////////
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//////////////////////////////////////////////////
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// Get subscript shift
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// slightly different from nsMathMLmsubFrame.cpp
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//////////////////////////////////////////////////
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// subScriptShift{1,2}
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// = minimum amount to shift the subscript down
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// = sub{1,2} in TeXbook
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// subScriptShift1 = subscriptshift attribute * x-height
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nscoord subScriptShift1, subScriptShift2;
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nsRefPtr<nsFontMetrics> fm;
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nsLayoutUtils::GetFontMetricsForFrame(baseFrame, getter_AddRefs(fm));
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aRenderingContext.SetFont(fm);
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// get x-height (an ex)
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nscoord xHeight = fm->XHeight();
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nscoord ruleSize;
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GetRuleThickness (aRenderingContext, fm, ruleSize);
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// Get subScriptShift{1,2} default from font
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GetSubScriptShifts (fm, subScriptShift1, subScriptShift2);
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if (0 < aUserSubScriptShift) {
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// the user has set the subscriptshift attribute
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float scaler = ((float) subScriptShift2) / subScriptShift1;
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subScriptShift1 = NS_MAX(subScriptShift1, aUserSubScriptShift);
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subScriptShift2 = NSToCoordRound(scaler * subScriptShift1);
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}
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// get a tentative value for subscriptshift
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// Rule 18d, App. G, TeXbook
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nscoord subScriptShift =
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NS_MAX(minSubScriptShift,NS_MAX(subScriptShift1,subScriptShift2));
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//////////////////////////////////////////////////
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// Get supscript shift
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// same code from nsMathMLmsupFrame.cpp
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//////////////////////////////////////////////////
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// get min supscript shift limit from x-height
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// = d(x) + 1/4 * sigma_5, Rule 18c, App. G, TeXbook
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nscoord minShiftFromXHeight = (nscoord)
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(bmSupScript.descent + (1.0f/4.0f) * xHeight);
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// supScriptShift{1,2,3}
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// = minimum amount to shift the supscript up
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// = sup{1,2,3} in TeX
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// supScriptShift1 = superscriptshift attribute * x-height
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// Note that there are THREE values for supscript shifts depending
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// on the current style
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nscoord supScriptShift1, supScriptShift2, supScriptShift3;
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// Set supScriptShift{1,2,3} default from font
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GetSupScriptShifts (fm, supScriptShift1, supScriptShift2, supScriptShift3);
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if (0 < aUserSupScriptShift) {
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// the user has set the superscriptshift attribute
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float scaler2 = ((float) supScriptShift2) / supScriptShift1;
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float scaler3 = ((float) supScriptShift3) / supScriptShift1;
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supScriptShift1 = NS_MAX(supScriptShift1, aUserSupScriptShift);
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supScriptShift2 = NSToCoordRound(scaler2 * supScriptShift1);
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supScriptShift3 = NSToCoordRound(scaler3 * supScriptShift1);
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}
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// get sup script shift depending on current script level and display style
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// Rule 18c, App. G, TeXbook
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nscoord supScriptShift;
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nsPresentationData presentationData;
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aFrame->GetPresentationData(presentationData);
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if ( aFrame->GetStyleFont()->mScriptLevel == 0 &&
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NS_MATHML_IS_DISPLAYSTYLE(presentationData.flags) &&
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!NS_MATHML_IS_COMPRESSED(presentationData.flags)) {
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// Style D in TeXbook
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supScriptShift = supScriptShift1;
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}
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else if (NS_MATHML_IS_COMPRESSED(presentationData.flags)) {
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// Style C' in TeXbook = D',T',S',SS'
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supScriptShift = supScriptShift3;
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}
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else {
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// everything else = T,S,SS
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supScriptShift = supScriptShift2;
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}
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// get tentative value for superscriptshift
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// Rule 18c, App. G, TeXbook
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supScriptShift =
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NS_MAX(minSupScriptShift,NS_MAX(supScriptShift,minShiftFromXHeight));
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//////////////////////////////////////////////////
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// Negotiate between supScriptShift and subScriptShift
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// so that there will be enough gap between them
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// Rule 18e, App. G, TeXbook
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//////////////////////////////////////////////////
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nscoord gap =
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(supScriptShift - bmSupScript.descent) -
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(bmSubScript.ascent - subScriptShift);
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if (gap < 4.0f * ruleSize) {
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// adjust subScriptShift to get a gap of (4.0 * ruleSize)
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subScriptShift += NSToCoordRound ((4.0f * ruleSize) - gap);
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}
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// next we want to ensure that the bottom of the superscript
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// will be > (4/5) * x-height above baseline
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gap = NSToCoordRound ((4.0f/5.0f) * xHeight -
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(supScriptShift - bmSupScript.descent));
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if (gap > 0) {
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supScriptShift += gap;
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subScriptShift -= gap;
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}
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//////////////////////////////////////////////////
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// Do the Placing
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//////////////////////////////////////////////////
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// get bounding box for base + subscript + superscript
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nsBoundingMetrics boundingMetrics;
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boundingMetrics.ascent =
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NS_MAX(bmBase.ascent, (bmSupScript.ascent + supScriptShift));
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boundingMetrics.descent =
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NS_MAX(bmBase.descent, (bmSubScript.descent + subScriptShift));
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// leave aScriptSpace after both super/subscript
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// add italicCorrection between base and superscript
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// add "a little to spare" as well (see TeXbook Ch.11, p.64), as we
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// estimate the italic creation ourselves and it isn't the same as TeX
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nscoord italicCorrection;
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GetItalicCorrection(bmBase, italicCorrection);
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italicCorrection += onePixel;
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boundingMetrics.width = bmBase.width + aScriptSpace +
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NS_MAX((italicCorrection + bmSupScript.width), bmSubScript.width);
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boundingMetrics.leftBearing = bmBase.leftBearing;
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boundingMetrics.rightBearing = bmBase.width +
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NS_MAX((italicCorrection + bmSupScript.rightBearing), bmSubScript.rightBearing);
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aFrame->SetBoundingMetrics(boundingMetrics);
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// reflow metrics
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aDesiredSize.ascent =
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NS_MAX(baseSize.ascent,
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NS_MAX(subScriptSize.ascent - subScriptShift,
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supScriptSize.ascent + supScriptShift));
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aDesiredSize.height = aDesiredSize.ascent +
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NS_MAX(baseSize.height - baseSize.ascent,
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NS_MAX(subScriptSize.height - subScriptSize.ascent + subScriptShift,
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supScriptSize.height - subScriptSize.ascent - supScriptShift));
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aDesiredSize.width = boundingMetrics.width;
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aDesiredSize.mBoundingMetrics = boundingMetrics;
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aFrame->SetReference(nsPoint(0, aDesiredSize.ascent));
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if (aPlaceOrigin) {
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nscoord dx, dy;
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// now place the base ...
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dx = aFrame->MirrorIfRTL(aDesiredSize.width, baseSize.width, 0);
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dy = aDesiredSize.ascent - baseSize.ascent;
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FinishReflowChild(baseFrame, aPresContext, nsnull,
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baseSize, dx, dy, 0);
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// ... and subscript
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dx = aFrame->MirrorIfRTL(aDesiredSize.width, subScriptSize.width,
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bmBase.width);
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dy = aDesiredSize.ascent - (subScriptSize.ascent - subScriptShift);
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FinishReflowChild(subScriptFrame, aPresContext, nsnull,
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subScriptSize, dx, dy, 0);
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// ... and the superscript
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dx = aFrame->MirrorIfRTL(aDesiredSize.width, supScriptSize.width,
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bmBase.width + italicCorrection);
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dy = aDesiredSize.ascent - (supScriptSize.ascent + supScriptShift);
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FinishReflowChild(supScriptFrame, aPresContext, nsnull,
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supScriptSize, dx, dy, 0);
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}
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return NS_OK;
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}
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