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diff --git a/layout/mathml/nsMathMLFrame.h b/layout/mathml/nsMathMLFrame.h
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+++ b/layout/mathml/nsMathMLFrame.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsMathMLFrame_h___
+#define nsMathMLFrame_h___
+
+#include "mozilla/Attributes.h"
+#include "nsFontMetrics.h"
+#include "nsMathMLOperators.h"
+#include "nsIMathMLFrame.h"
+#include "nsBoundingMetrics.h"
+#include "nsIFrame.h"
+
+class nsMathMLChar;
+class nsCSSValue;
+class nsDisplayListSet;
+
+// Concrete base class with default methods that derived MathML frames can
+// override
+class nsMathMLFrame : public nsIMathMLFrame {
+ public:
+  // nsIMathMLFrame ---
+
+  virtual bool IsSpaceLike() override {
+    return NS_MATHML_IS_SPACE_LIKE(mPresentationData.flags);
+  }
+
+  NS_IMETHOD
+  GetBoundingMetrics(nsBoundingMetrics& aBoundingMetrics) override {
+    aBoundingMetrics = mBoundingMetrics;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  SetBoundingMetrics(const nsBoundingMetrics& aBoundingMetrics) override {
+    mBoundingMetrics = aBoundingMetrics;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  SetReference(const nsPoint& aReference) override {
+    mReference = aReference;
+    return NS_OK;
+  }
+
+  virtual eMathMLFrameType GetMathMLFrameType() override;
+
+  NS_IMETHOD
+  Stretch(mozilla::gfx::DrawTarget* aDrawTarget,
+          nsStretchDirection aStretchDirection,
+          nsBoundingMetrics& aContainerSize,
+          mozilla::ReflowOutput& aDesiredStretchSize) override {
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  GetEmbellishData(nsEmbellishData& aEmbellishData) override {
+    aEmbellishData = mEmbellishData;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  GetPresentationData(nsPresentationData& aPresentationData) override {
+    aPresentationData = mPresentationData;
+    return NS_OK;
+  }
+
+  NS_IMETHOD
+  InheritAutomaticData(nsIFrame* aParent) override;
+
+  NS_IMETHOD
+  TransmitAutomaticData() override { return NS_OK; }
+
+  NS_IMETHOD
+  UpdatePresentationData(uint32_t aFlagsValues,
+                         uint32_t aFlagsToUpdate) override;
+
+  NS_IMETHOD
+  UpdatePresentationDataFromChildAt(int32_t aFirstIndex, int32_t aLastIndex,
+                                    uint32_t aFlagsValues,
+                                    uint32_t aFlagsToUpdate) override {
+    return NS_OK;
+  }
+
+  uint8_t ScriptIncrement(nsIFrame* aFrame) override { return 0; }
+
+  bool IsMrowLike() override { return false; }
+
+  // helper to get the mEmbellishData of a frame
+  // The MathML REC precisely defines an "embellished operator" as:
+  // - an <mo> element;
+  // - or one of the elements <msub>, <msup>, <msubsup>, <munder>, <mover>,
+  //   <munderover>, <mmultiscripts>, <mfrac>, or <semantics>, whose first
+  //   argument exists and is an embellished operator;
+  //- or one of the elements <mstyle>, <mphantom>, or <mpadded>, such that
+  //   an <mrow> containing the same arguments would be an embellished
+  //   operator;
+  // - or an <maction> element whose selected subexpression exists and is an
+  //   embellished operator;
+  // - or an <mrow> whose arguments consist (in any order) of one embellished
+  //   operator and zero or more spacelike elements.
+  static void GetEmbellishDataFrom(nsIFrame* aFrame,
+                                   nsEmbellishData& aEmbellishData);
+
+  // helper to get the presentation data of a frame. If aClimbTree is
+  // set to true and the frame happens to be surrounded by non-MathML
+  // helper frames needed for its support, we walk up the frame hierarchy
+  // until we reach a MathML ancestor or the <root> math element.
+  static void GetPresentationDataFrom(nsIFrame* aFrame,
+                                      nsPresentationData& aPresentationData,
+                                      bool aClimbTree = true);
+
+  // utilities to parse and retrieve numeric values in CSS units
+  // All values are stored in twips.
+  // @pre  aLengthValue is the default length value of the attribute.
+  // @post aLengthValue is the length value computed from the attribute.
+  static void ParseNumericValue(const nsString& aString, nscoord* aLengthValue,
+                                uint32_t aFlags, nsPresContext* aPresContext,
+                                mozilla::ComputedStyle* aComputedStyle,
+                                float aFontSizeInflation);
+
+  static nscoord CalcLength(nsPresContext* aPresContext,
+                            mozilla::ComputedStyle* aComputedStyle,
+                            const nsCSSValue& aCSSValue,
+                            float aFontSizeInflation);
+
+  static eMathMLFrameType GetMathMLFrameTypeFor(nsIFrame* aFrame) {
+    if (aFrame->IsFrameOfType(nsIFrame::eMathML)) {
+      nsIMathMLFrame* mathMLFrame = do_QueryFrame(aFrame);
+      if (mathMLFrame) return mathMLFrame->GetMathMLFrameType();
+    }
+    return eMathMLFrameType_UNKNOWN;
+  }
+
+  // estimate of the italic correction
+  static void GetItalicCorrection(nsBoundingMetrics& aBoundingMetrics,
+                                  nscoord& aItalicCorrection) {
+    aItalicCorrection = aBoundingMetrics.rightBearing - aBoundingMetrics.width;
+    if (0 > aItalicCorrection) {
+      aItalicCorrection = 0;
+    }
+  }
+
+  static void GetItalicCorrection(nsBoundingMetrics& aBoundingMetrics,
+                                  nscoord& aLeftItalicCorrection,
+                                  nscoord& aRightItalicCorrection) {
+    aRightItalicCorrection =
+        aBoundingMetrics.rightBearing - aBoundingMetrics.width;
+    if (0 > aRightItalicCorrection) {
+      aRightItalicCorrection = 0;
+    }
+    aLeftItalicCorrection = -aBoundingMetrics.leftBearing;
+    if (0 > aLeftItalicCorrection) {
+      aLeftItalicCorrection = 0;
+    }
+  }
+
+  // helper methods for getting sup/subdrop's from a child
+  static void GetSubDropFromChild(nsIFrame* aChild, nscoord& aSubDrop,
+                                  float aFontSizeInflation);
+
+  static void GetSupDropFromChild(nsIFrame* aChild, nscoord& aSupDrop,
+                                  float aFontSizeInflation);
+
+  static void GetSkewCorrectionFromChild(nsIFrame* aChild,
+                                         nscoord& aSkewCorrection) {
+    // default is 0
+    // individual classes should over-ride this method if necessary
+    aSkewCorrection = 0;
+  }
+
+  // 2 levels of subscript shifts
+  static void GetSubScriptShifts(nsFontMetrics* fm, nscoord& aSubScriptShift1,
+                                 nscoord& aSubScriptShift2) {
+    nscoord xHeight = fm->XHeight();
+    aSubScriptShift1 = NSToCoordRound(150.000f / 430.556f * xHeight);
+    aSubScriptShift2 = NSToCoordRound(247.217f / 430.556f * xHeight);
+  }
+
+  // 3 levels of superscript shifts
+  static void GetSupScriptShifts(nsFontMetrics* fm, nscoord& aSupScriptShift1,
+                                 nscoord& aSupScriptShift2,
+                                 nscoord& aSupScriptShift3) {
+    nscoord xHeight = fm->XHeight();
+    aSupScriptShift1 = NSToCoordRound(412.892f / 430.556f * xHeight);
+    aSupScriptShift2 = NSToCoordRound(362.892f / 430.556f * xHeight);
+    aSupScriptShift3 = NSToCoordRound(288.889f / 430.556f * xHeight);
+  }
+
+  // these are TeX specific params not found in ordinary fonts
+
+  static void GetSubDrop(nsFontMetrics* fm, nscoord& aSubDrop) {
+    nscoord xHeight = fm->XHeight();
+    aSubDrop = NSToCoordRound(50.000f / 430.556f * xHeight);
+  }
+
+  static void GetSupDrop(nsFontMetrics* fm, nscoord& aSupDrop) {
+    nscoord xHeight = fm->XHeight();
+    aSupDrop = NSToCoordRound(386.108f / 430.556f * xHeight);
+  }
+
+  static void GetNumeratorShifts(nsFontMetrics* fm, nscoord& numShift1,
+                                 nscoord& numShift2, nscoord& numShift3) {
+    nscoord xHeight = fm->XHeight();
+    numShift1 = NSToCoordRound(676.508f / 430.556f * xHeight);
+    numShift2 = NSToCoordRound(393.732f / 430.556f * xHeight);
+    numShift3 = NSToCoordRound(443.731f / 430.556f * xHeight);
+  }
+
+  static void GetDenominatorShifts(nsFontMetrics* fm, nscoord& denShift1,
+                                   nscoord& denShift2) {
+    nscoord xHeight = fm->XHeight();
+    denShift1 = NSToCoordRound(685.951f / 430.556f * xHeight);
+    denShift2 = NSToCoordRound(344.841f / 430.556f * xHeight);
+  }
+
+  static void GetEmHeight(nsFontMetrics* fm, nscoord& emHeight) {
+#if 0
+    // should switch to this API in order to scale with changes of TextZoom
+    emHeight = fm->EmHeight();
+#else
+    emHeight = fm->Font().size.ToAppUnits();
+#endif
+  }
+
+  static void GetAxisHeight(nsFontMetrics* fm, nscoord& axisHeight) {
+    axisHeight = NSToCoordRound(250.000f / 430.556f * fm->XHeight());
+  }
+
+  static void GetBigOpSpacings(nsFontMetrics* fm, nscoord& bigOpSpacing1,
+                               nscoord& bigOpSpacing2, nscoord& bigOpSpacing3,
+                               nscoord& bigOpSpacing4, nscoord& bigOpSpacing5) {
+    nscoord xHeight = fm->XHeight();
+    bigOpSpacing1 = NSToCoordRound(111.111f / 430.556f * xHeight);
+    bigOpSpacing2 = NSToCoordRound(166.667f / 430.556f * xHeight);
+    bigOpSpacing3 = NSToCoordRound(200.000f / 430.556f * xHeight);
+    bigOpSpacing4 = NSToCoordRound(600.000f / 430.556f * xHeight);
+    bigOpSpacing5 = NSToCoordRound(100.000f / 430.556f * xHeight);
+  }
+
+  static void GetRuleThickness(nsFontMetrics* fm, nscoord& ruleThickness) {
+    nscoord xHeight = fm->XHeight();
+    ruleThickness = NSToCoordRound(40.000f / 430.556f * xHeight);
+  }
+
+  // Some parameters are not accurately obtained using the x-height.
+  // Here are some slower variants to obtain the desired metrics
+  // by actually measuring some characters
+  static void GetRuleThickness(mozilla::gfx::DrawTarget* aDrawTarget,
+                               nsFontMetrics* aFontMetrics,
+                               nscoord& aRuleThickness);
+
+  static void GetAxisHeight(mozilla::gfx::DrawTarget* aDrawTarget,
+                            nsFontMetrics* aFontMetrics, nscoord& aAxisHeight);
+
+  static void GetRadicalParameters(nsFontMetrics* aFontMetrics,
+                                   bool aDisplayStyle,
+                                   nscoord& aRadicalRuleThickness,
+                                   nscoord& aRadicalExtraAscender,
+                                   nscoord& aRadicalVerticalGap);
+
+ protected:
+#if defined(DEBUG) && defined(SHOW_BOUNDING_BOX)
+  void DisplayBoundingMetrics(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                              const nsPoint& aPt,
+                              const nsBoundingMetrics& aMetrics,
+                              const nsDisplayListSet& aLists);
+#endif
+
+  /**
+   * Display a solid rectangle in the frame's text color. Used for drawing
+   * fraction separators and root/sqrt overbars.
+   */
+  void DisplayBar(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                  const nsRect& aRect, const nsDisplayListSet& aLists,
+                  uint32_t aIndex = 0);
+
+  // information about the presentation policy of the frame
+  nsPresentationData mPresentationData;
+
+  // information about a container that is an embellished operator
+  nsEmbellishData mEmbellishData;
+
+  // Metrics that _exactly_ enclose the text of the frame
+  nsBoundingMetrics mBoundingMetrics;
+
+  // Reference point of the frame: mReference.y is the baseline
+  nsPoint mReference;
+};
+
+#endif /* nsMathMLFrame_h___ */