layout/mathml/nsMathMLmfracFrame.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   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"),
  29  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  30  * in which case the provisions of the GPL or the LGPL are applicable instead
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  36  * the provisions above, a recipient may use your version of this file under
  37  * the terms of any one of the MPL, the GPL or the LGPL.
  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   NS_DECL_FRAMEARENA_HELPERS
  90
  91   friend nsIFrame* NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
  92
  93   virtual void
  94   SetAdditionalStyleContext(PRInt32          aIndex,
  95                             nsStyleContext*  aStyleContext);
  96   virtual nsStyleContext*
  97   GetAdditionalStyleContext(PRInt32 aIndex) const;
  98
  99   virtual eMathMLFrameType GetMathMLFrameType();
 100
 101   NS_IMETHOD
 102   AttributeChanged(PRInt32         aNameSpaceID,
 103                    nsIAtom*        aAttribute,
 104                    PRInt32         aModType);
 105
 106   NS_IMETHOD
 107   Init(nsIContent*      aContent,
 108        nsIFrame*        aParent,
 109        nsIFrame*        aPrevInFlow);
 110
 111   NS_IMETHOD
 112   Reflow(nsPresContext*          aPresContext,
 113          nsHTMLReflowMetrics&     aDesiredSize,
 114          const nsHTMLReflowState& aReflowState,
 115          nsReflowStatus&          aStatus);
 116
 117   virtual nscoord
 118   GetIntrinsicWidth(nsIRenderingContext* aRenderingContext);
 119
 120   virtual nsresult
 121   Place(nsIRenderingContext& aRenderingContext,
 122         PRBool               aPlaceOrigin,
 123         nsHTMLReflowMetrics& aDesiredSize);
 124
 125   NS_IMETHOD BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 126                               const nsRect&           aDirtyRect,
 127                               const nsDisplayListSet& aLists);
 128
 129   NS_IMETHOD
 130   TransmitAutomaticData();
 131
 132   NS_IMETHOD
 133   UpdatePresentationDataFromChildAt(PRInt32         aFirstIndex,
 134                                     PRInt32         aLastIndex,
 135                                     PRUint32        aFlagsValues,
 136                                     PRUint32        aFlagsToUpdate);
 137
 138   // override the base method so that we can deal with the fraction line
 139   virtual nscoord
 140   FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize);
 141
 142   // helper to translate the thickness attribute into a usable form
 143   static nscoord
 144   CalcLineThickness(nsPresContext*  aPresContext,
 145                     nsStyleContext*  aStyleContext,
 146                     nsString&        aThicknessAttribute,
 147                     nscoord          onePixel,
 148                     nscoord          aDefaultRuleThickness);
 149
 150 protected:
 151   nsMathMLmfracFrame(nsStyleContext* aContext) : nsMathMLContainerFrame(aContext) {}
 152   virtual ~nsMathMLmfracFrame();
 153
 154   virtual PRIntn GetSkipSides() const { return 0; }
 155
 156   PRBool
 157   IsBevelled();
 158
 159   nsRect  mLineRect;
 160   nsMathMLChar* mSlashChar;
 161 };
 162
 163 #endif /* nsMathMLmfracFrame_h___ */