layout/mathml/base/src/nsMathMLmfracFrame.h

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   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is Mozilla MathML Project.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * The University Of Queensland.
  19  * Portions created by the Initial Developer are Copyright (C) 1999
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Roger B. Sidje <rbs@maths.uq.edu.au>
  24  *   David J. Fiddes <D.J.Fiddes@hw.ac.uk>
  25  *   Shyjan Mahamud <mahamud@cs.cmu.edu>
  26  *
  27  * Alternatively, the contents of this file may be used under the terms of
  28  * either of the GNU General Public License Version 2 or later (the "GPL"),
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  36  * the provisions above, a recipient may use your version of this file under
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  38  *
  39  * ***** END LICENSE BLOCK ***** */
  40
  41 #ifndef nsMathMLmfracFrame_h___
  42 #define nsMathMLmfracFrame_h___
  43
  44 #include "nsCOMPtr.h"
  45 #include "nsMathMLContainerFrame.h"
  46
  47 //
  48 // <mfrac> -- form a fraction from two subexpressions
  49 //
  50
  51 /*
  52 The MathML REC describes:
  53
  54 The <mfrac> element is used for fractions. It can also be used to mark up
  55 fraction-like objects such as binomial coefficients and Legendre symbols.
  56 The syntax for <mfrac> is:
  57   <mfrac> numerator denominator </mfrac>
  58
  59 Attributes of <mfrac>:
  60      Name                      values                     default
  61   linethickness  number [ v-unit ] | thin | medium | thick  1
  62
  63 E.g.,
  64 linethickness=2 actually means that linethickness=2*DEFAULT_THICKNESS
  65 (DEFAULT_THICKNESS is not specified by MathML, see below.)
  66
  67 The linethickness attribute indicates the thickness of the horizontal
  68 "fraction bar", or "rule", typically used to render fractions. A fraction
  69 with linethickness="0" renders without the bar, and might be used within
  70 binomial coefficients. A linethickness greater than one might be used with
  71 nested fractions.
  72
  73 In general, the value of linethickness can be a number, as a multiplier
  74 of the default thickness of the fraction bar (the default thickness is
  75 not specified by MathML), or a number with a unit of vertical length (see
  76 Section 2.3.3), or one of the keywords medium (same as 1), thin (thinner
  77 than 1, otherwise up to the renderer), or thick (thicker than 1, otherwise
  78 up to the renderer).
  79
  80 The <mfrac> element sets displaystyle to "false", or if it was already
  81 false increments scriptlevel by 1, within numerator and denominator.
  82 These attributes are inherited by every element from its rendering
  83 environment, but can be set explicitly only on the <mstyle>
  84 element.
  85 */
  86
  87 class nsMathMLmfracFrame : public nsMathMLContainerFrame {
  88 public:
  89   friend nsIFrame* NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
  90
  91   virtual void
  92   SetAdditionalStyleContext(PRInt32          aIndex,
  93                             nsStyleContext*  aStyleContext);
  94   virtual nsStyleContext*
  95   GetAdditionalStyleContext(PRInt32 aIndex) const;
  96
  97   virtual eMathMLFrameType GetMathMLFrameType();
  98
  99   NS_IMETHOD
 100   AttributeChanged(PRInt32         aNameSpaceID,
 101                    nsIAtom*        aAttribute,
 102                    PRInt32         aModType);
 103
 104   NS_IMETHOD
 105   Init(nsIContent*      aContent,
 106        nsIFrame*        aParent,
 107        nsIFrame*        aPrevInFlow);
 108
 109   NS_IMETHOD
 110   Reflow(nsPresContext*          aPresContext,
 111          nsHTMLReflowMetrics&     aDesiredSize,
 112          const nsHTMLReflowState& aReflowState,
 113          nsReflowStatus&          aStatus);
 114
 115   virtual nscoord
 116   GetIntrinsicWidth(nsIRenderingContext* aRenderingContext);
 117
 118   virtual nsresult
 119   Place(nsIRenderingContext& aRenderingContext,
 120         PRBool               aPlaceOrigin,
 121         nsHTMLReflowMetrics& aDesiredSize);
 122
 123   NS_IMETHOD BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 124                               const nsRect&           aDirtyRect,
 125                               const nsDisplayListSet& aLists);
 126
 127   NS_IMETHOD
 128   TransmitAutomaticData();
 129
 130   NS_IMETHOD
 131   UpdatePresentationDataFromChildAt(PRInt32         aFirstIndex,
 132                                     PRInt32         aLastIndex,
 133                                     PRUint32        aFlagsValues,
 134                                     PRUint32        aFlagsToUpdate);
 135
 136   // override the base method so that we can deal with the fraction line
 137   virtual nscoord
 138   FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize);
 139
 140   // helper to translate the thickness attribute into a usable form
 141   static nscoord
 142   CalcLineThickness(nsPresContext*  aPresContext,
 143                     nsStyleContext*  aStyleContext,
 144                     nsString&        aThicknessAttribute,
 145                     nscoord          onePixel,
 146                     nscoord          aDefaultRuleThickness);
 147
 148 protected:
 149   nsMathMLmfracFrame(nsStyleContext* aContext) : nsMathMLContainerFrame(aContext) {}
 150   virtual ~nsMathMLmfracFrame();
 151
 152   virtual PRIntn GetSkipSides() const { return 0; }
 153
 154   PRBool
 155   IsBevelled();
 156
 157   nsRect  mLineRect;
 158   nsMathMLChar* mSlashChar;
 159 };
 160
 161 #endif /* nsMathMLmfracFrame_h___ */