зеркало из https://github.com/mozilla/pjs.git
455 строки
16 KiB
C++
455 строки
16 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 "nsMathMLmmultiscriptsFrame.h"
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//
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// <mmultiscripts> -- attach prescripts and tensor indices to a base - implementation
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//
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nsIFrame*
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NS_NewMathMLmmultiscriptsFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
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{
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return new (aPresShell) nsMathMLmmultiscriptsFrame(aContext);
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}
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NS_IMPL_FRAMEARENA_HELPERS(nsMathMLmmultiscriptsFrame)
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nsMathMLmmultiscriptsFrame::~nsMathMLmmultiscriptsFrame()
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{
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}
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NS_IMETHODIMP
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nsMathMLmmultiscriptsFrame::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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// The REC says:
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// The <mmultiscripts> element increments scriptlevel by 1, and sets
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// displaystyle to "false", within each of its arguments except base
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UpdatePresentationDataFromChildAt(1, -1,
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~NS_MATHML_DISPLAYSTYLE, NS_MATHML_DISPLAYSTYLE);
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// The TeXbook (Ch 17. p.141) says the superscript inherits the compression
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// while the subscript is compressed. So here we collect subscripts and set
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// the compression flag in them.
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PRInt32 count = 0;
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bool isSubScript = false;
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nsAutoTArray<nsIFrame*, 8> subScriptFrames;
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nsIFrame* childFrame = mFrames.FirstChild();
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while (childFrame) {
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if (childFrame->GetContent()->Tag() == nsGkAtoms::mprescripts_) {
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// mprescripts frame
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}
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else if (0 == count) {
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// base frame
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}
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else {
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// super/subscript block
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if (isSubScript) {
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// subscript
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subScriptFrames.AppendElement(childFrame);
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}
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else {
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// superscript
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}
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isSubScript = !isSubScript;
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}
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count++;
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childFrame = childFrame->GetNextSibling();
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}
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for (PRInt32 i = subScriptFrames.Length() - 1; i >= 0; i--) {
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childFrame = subScriptFrames[i];
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PropagatePresentationDataFor(childFrame,
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NS_MATHML_COMPRESSED, NS_MATHML_COMPRESSED);
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}
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return NS_OK;
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}
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void
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nsMathMLmmultiscriptsFrame::ProcessAttributes()
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{
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mSubScriptShift = 0;
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mSupScriptShift = 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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GetAttribute(mContent, mPresentationData.mstyle,
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nsGkAtoms::subscriptshift_, value);
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if (!value.IsEmpty()) {
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ParseNumericValue(value, &mSubScriptShift,
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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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GetAttribute(mContent, mPresentationData.mstyle,
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nsGkAtoms::superscriptshift_, value);
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if (!value.IsEmpty()) {
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ParseNumericValue(value, &mSupScriptShift,
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nsMathMLElement::PARSE_ALLOW_NEGATIVE,
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PresContext(), mStyleContext);
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}
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}
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/* virtual */ nsresult
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nsMathMLmmultiscriptsFrame::Place(nsRenderingContext& aRenderingContext,
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bool aPlaceOrigin,
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nsHTMLReflowMetrics& aDesiredSize)
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{
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////////////////////////////////////
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// Get the children's desired sizes
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nscoord minShiftFromXHeight, subDrop, supDrop;
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////////////////////////////////////////
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// Initialize super/sub shifts that
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// depend only on the current font
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////////////////////////////////////////
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ProcessAttributes();
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// get x-height (an ex)
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const nsStyleFont* font = GetStyleFont();
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nsRefPtr<nsFontMetrics> fm;
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nsLayoutUtils::GetFontMetricsForFrame(this, getter_AddRefs(fm));
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aRenderingContext.SetFont(fm);
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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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// scriptspace from TeX for extra spacing after sup/subscript (0.5pt in plain TeX)
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// forced to be at least 1 pixel here
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nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
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nscoord scriptSpace = NS_MAX(nsPresContext::CSSPointsToAppUnits(0.5f), onePixel);
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/////////////////////////////////////
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// first the shift for the subscript
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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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// Get subScriptShift{1,2} default from font
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GetSubScriptShifts (fm, subScriptShift1, subScriptShift2);
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if (0 < mSubScriptShift) {
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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, mSubScriptShift);
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subScriptShift2 = NSToCoordRound(scaler * subScriptShift1);
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}
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// the font dependent shift
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nscoord subScriptShift = NS_MAX(subScriptShift1,subScriptShift2);
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/////////////////////////////////////
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// next the shift for the superscript
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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 < mSupScriptShift) {
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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, mSupScriptShift);
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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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if ( font->mScriptLevel == 0 &&
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NS_MATHML_IS_DISPLAYSTYLE(mPresentationData.flags) &&
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!NS_MATHML_IS_COMPRESSED(mPresentationData.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(mPresentationData.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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////////////////////////////////////
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// Get the children's sizes
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////////////////////////////////////
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nscoord width = 0, prescriptsWidth = 0, rightBearing = 0;
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nsIFrame* mprescriptsFrame = nsnull; // frame of <mprescripts/>, if there.
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bool isSubScript = false;
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nscoord minSubScriptShift = 0, minSupScriptShift = 0;
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nscoord trySubScriptShift = subScriptShift;
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nscoord trySupScriptShift = supScriptShift;
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nscoord maxSubScriptShift = subScriptShift;
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nscoord maxSupScriptShift = supScriptShift;
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PRInt32 count = 0;
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nsHTMLReflowMetrics baseSize;
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nsHTMLReflowMetrics subScriptSize;
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nsHTMLReflowMetrics supScriptSize;
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nsIFrame* baseFrame = nsnull;
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nsIFrame* subScriptFrame = nsnull;
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nsIFrame* supScriptFrame = nsnull;
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bool firstPrescriptsPair = false;
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nsBoundingMetrics bmBase, bmSubScript, bmSupScript;
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nscoord italicCorrection = 0;
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mBoundingMetrics.width = 0;
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mBoundingMetrics.ascent = mBoundingMetrics.descent = -0x7FFFFFFF;
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nscoord ascent = -0x7FFFFFFF, descent = -0x7FFFFFFF;
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aDesiredSize.width = aDesiredSize.height = 0;
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nsIFrame* childFrame = mFrames.FirstChild();
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while (childFrame) {
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if (childFrame->GetContent()->Tag() == nsGkAtoms::mprescripts_) {
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if (mprescriptsFrame) {
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// duplicate <mprescripts/> found
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// report an error, encourage people to get their markups in order
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return ReflowError(aRenderingContext, aDesiredSize);
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}
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mprescriptsFrame = childFrame;
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firstPrescriptsPair = true;
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}
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else {
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if (0 == count) {
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// base
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baseFrame = childFrame;
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GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
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GetItalicCorrection(bmBase, italicCorrection);
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// for the superscript, we always add "a little to spare"
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italicCorrection += onePixel;
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// we update mBoundingMetrics.{ascent,descent} with that
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// of the baseFrame only after processing all the sup/sub pairs
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// XXX need italic correction only *if* there are postscripts ?
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mBoundingMetrics.width = bmBase.width + italicCorrection;
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mBoundingMetrics.rightBearing = bmBase.rightBearing;
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mBoundingMetrics.leftBearing = bmBase.leftBearing; // until overwritten
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}
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else {
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// super/subscript block
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if (isSubScript) {
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// subscript
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subScriptFrame = childFrame;
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GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
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// get the subdrop from the subscript font
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GetSubDropFromChild (subScriptFrame, subDrop);
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// parameter v, Rule 18a, App. G, TeXbook
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minSubScriptShift = bmBase.descent + subDrop;
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trySubScriptShift = NS_MAX(minSubScriptShift,subScriptShift);
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mBoundingMetrics.descent =
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NS_MAX(mBoundingMetrics.descent,bmSubScript.descent);
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descent = NS_MAX(descent,subScriptSize.height - subScriptSize.ascent);
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width = bmSubScript.width + scriptSpace;
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rightBearing = bmSubScript.rightBearing;
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}
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else {
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// supscript
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supScriptFrame = childFrame;
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GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);
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// get the supdrop from the supscript font
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GetSupDropFromChild (supScriptFrame, supDrop);
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// parameter u, Rule 18a, App. G, TeXbook
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minSupScriptShift = bmBase.ascent - supDrop;
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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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minShiftFromXHeight = NSToCoordRound
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((bmSupScript.descent + (1.0f/4.0f) * xHeight));
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trySupScriptShift =
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NS_MAX(minSupScriptShift,NS_MAX(minShiftFromXHeight,supScriptShift));
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mBoundingMetrics.ascent =
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NS_MAX(mBoundingMetrics.ascent,bmSupScript.ascent);
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ascent = NS_MAX(ascent,supScriptSize.ascent);
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width = NS_MAX(width, bmSupScript.width + scriptSpace);
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rightBearing = NS_MAX(rightBearing, bmSupScript.rightBearing);
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if (!mprescriptsFrame) { // we are still looping over base & postscripts
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mBoundingMetrics.rightBearing = mBoundingMetrics.width + rightBearing;
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mBoundingMetrics.width += width;
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}
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else {
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prescriptsWidth += width;
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if (firstPrescriptsPair) {
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firstPrescriptsPair = false;
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mBoundingMetrics.leftBearing =
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NS_MIN(bmSubScript.leftBearing, bmSupScript.leftBearing);
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}
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}
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width = rightBearing = 0;
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// negotiate between the various shifts so that
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// there is enough gap between the sup and subscripts
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// Rule 18e, App. G, TeXbook
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nscoord gap =
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(trySupScriptShift - bmSupScript.descent) -
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(bmSubScript.ascent - trySubScriptShift);
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if (gap < 4.0f * ruleSize) {
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// adjust trySubScriptShift to get a gap of (4.0 * ruleSize)
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trySubScriptShift += 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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(trySupScriptShift - bmSupScript.descent));
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if (gap > 0.0f) {
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trySupScriptShift += gap;
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trySubScriptShift -= gap;
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}
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maxSubScriptShift = NS_MAX(maxSubScriptShift, trySubScriptShift);
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maxSupScriptShift = NS_MAX(maxSupScriptShift, trySupScriptShift);
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trySubScriptShift = subScriptShift;
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trySupScriptShift = supScriptShift;
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}
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}
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isSubScript = !isSubScript;
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}
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count++;
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childFrame = childFrame->GetNextSibling();
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}
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// note: width=0 if all sup-sub pairs match correctly
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if ((0 != width) || !baseFrame || !subScriptFrame || !supScriptFrame) {
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// report an error, encourage people to get their markups in order
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return ReflowError(aRenderingContext, aDesiredSize);
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}
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// we left out the width of prescripts, so ...
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mBoundingMetrics.rightBearing += prescriptsWidth;
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mBoundingMetrics.width += prescriptsWidth;
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// we left out the base during our bounding box updates, so ...
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mBoundingMetrics.ascent =
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NS_MAX(mBoundingMetrics.ascent+maxSupScriptShift,bmBase.ascent);
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mBoundingMetrics.descent =
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NS_MAX(mBoundingMetrics.descent+maxSubScriptShift,bmBase.descent);
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// get the reflow metrics ...
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aDesiredSize.ascent =
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NS_MAX(ascent+maxSupScriptShift,baseSize.ascent);
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aDesiredSize.height = aDesiredSize.ascent +
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NS_MAX(descent+maxSubScriptShift,baseSize.height - baseSize.ascent);
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aDesiredSize.width = mBoundingMetrics.width;
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aDesiredSize.mBoundingMetrics = mBoundingMetrics;
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mReference.x = 0;
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mReference.y = aDesiredSize.ascent;
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//////////////////
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// Place Children
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// Place prescripts, followed by base, and then postscripts.
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// The list of frames is in the order: {base} {postscripts} {prescripts}
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// We go over the list in a circular manner, starting at <prescripts/>
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if (aPlaceOrigin) {
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nscoord dx = 0, dy = 0;
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count = 0;
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childFrame = mprescriptsFrame;
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do {
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if (!childFrame) { // end of prescripts,
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// place the base ...
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childFrame = baseFrame;
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dy = aDesiredSize.ascent - baseSize.ascent;
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FinishReflowChild (baseFrame, PresContext(), nsnull, baseSize,
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MirrorIfRTL(aDesiredSize.width,
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baseSize.width,
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dx),
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dy, 0);
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dx += bmBase.width + italicCorrection;
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}
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else if (mprescriptsFrame != childFrame) {
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// process each sup/sub pair
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if (0 == count) {
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subScriptFrame = childFrame;
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count = 1;
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}
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else if (1 == count) {
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supScriptFrame = childFrame;
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count = 0;
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// get the ascent/descent of sup/subscripts stored in their rects
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// rect.x = descent, rect.y = ascent
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GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
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GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);
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// center w.r.t. largest width
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width = NS_MAX(subScriptSize.width, supScriptSize.width);
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dy = aDesiredSize.ascent - subScriptSize.ascent +
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maxSubScriptShift;
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FinishReflowChild (subScriptFrame, PresContext(), nsnull,
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subScriptSize,
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MirrorIfRTL(aDesiredSize.width,
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subScriptSize.width,
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dx + (width-subScriptSize.width)/2),
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dy, 0);
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dy = aDesiredSize.ascent - supScriptSize.ascent -
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maxSupScriptShift;
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FinishReflowChild (supScriptFrame, PresContext(), nsnull,
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supScriptSize,
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MirrorIfRTL(aDesiredSize.width,
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supScriptSize.width,
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dx + (width-supScriptSize.width)/2),
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dy, 0);
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dx += width + scriptSpace;
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}
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}
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childFrame = childFrame->GetNextSibling();
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} while (mprescriptsFrame != childFrame);
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}
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return NS_OK;
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}
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