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  *   Frederic Wang <fred.wang@free.fr>
  27  *
  28  * Alternatively, the contents of this file may be used under the terms of
  29  * either of the GNU General Public License Version 2 or later (the "GPL"),
  30  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  31  * in which case the provisions of the GPL or the LGPL are applicable instead
  32  * of those above. If you wish to allow use of your version of this file only
  33  * under the terms of either the GPL or the LGPL, and not to allow others to
  34  * use your version of this file under the terms of the MPL, indicate your
  35  * decision by deleting the provisions above and replace them with the notice
  36  * and other provisions required by the GPL or the LGPL. If you do not delete
  37  * the provisions above, a recipient may use your version of this file under
  38  * the terms of any one of the MPL, the GPL or the LGPL.
  39  *
  40  * ***** END LICENSE BLOCK ***** */
  41
  42 #ifndef nsMathMLmfracFrame_h___
  43 #define nsMathMLmfracFrame_h___
  44
  45 #include "nsCOMPtr.h"
  46 #include "nsMathMLContainerFrame.h"
  47
  48 //
  49 // <mfrac> -- form a fraction from two subexpressions
  50 //
  51
  52 /*
  53 The MathML REC describes:
  54
  55 The <mfrac> element is used for fractions. It can also be used to mark up
  56 fraction-like objects such as binomial coefficients and Legendre symbols.
  57 The syntax for <mfrac> is:
  58   <mfrac> numerator denominator </mfrac>
  59
  60 Attributes of <mfrac>:
  61      Name                      values                     default
  62   linethickness  number [ v-unit ] | thin | medium | thick  1
  63
  64 E.g.,
  65 linethickness=2 actually means that linethickness=2*DEFAULT_THICKNESS
  66 (DEFAULT_THICKNESS is not specified by MathML, see below.)
  67
  68 The linethickness attribute indicates the thickness of the horizontal
  69 "fraction bar", or "rule", typically used to render fractions. A fraction
  70 with linethickness="0" renders without the bar, and might be used within
  71 binomial coefficients. A linethickness greater than one might be used with
  72 nested fractions.
  73
  74 In general, the value of linethickness can be a number, as a multiplier
  75 of the default thickness of the fraction bar (the default thickness is
  76 not specified by MathML), or a number with a unit of vertical length (see
  77 Section 2.3.3), or one of the keywords medium (same as 1), thin (thinner
  78 than 1, otherwise up to the renderer), or thick (thicker than 1, otherwise
  79 up to the renderer).
  80
  81 The <mfrac> element sets displaystyle to "false", or if it was already
  82 false increments scriptlevel by 1, within numerator and denominator.
  83 These attributes are inherited by every element from its rendering
  84 environment, but can be set explicitly only on the <mstyle>
  85 element.
  86 */
  87
  88 class nsMathMLmfracFrame : public nsMathMLContainerFrame {
  89 public:
  90   NS_DECL_FRAMEARENA_HELPERS
  91
  92   friend nsIFrame* NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
  93
  94   virtual eMathMLFrameType GetMathMLFrameType();
  95
  96   NS_IMETHOD
  97   AttributeChanged(PRInt32         aNameSpaceID,
  98                    nsIAtom*        aAttribute,
  99                    PRInt32         aModType);
 100
 101   NS_IMETHOD
 102   Init(nsIContent*      aContent,
 103        nsIFrame*        aParent,
 104        nsIFrame*        aPrevInFlow);
 105
 106   virtual nsresult
 107   MeasureForWidth(nsIRenderingContext& aRenderingContext,
 108                   nsHTMLReflowMetrics& aDesiredSize);
 109
 110   virtual nsresult
 111   Place(nsIRenderingContext& aRenderingContext,
 112         PRBool               aPlaceOrigin,
 113         nsHTMLReflowMetrics& aDesiredSize);
 114
 115   NS_IMETHOD BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 116                               const nsRect&           aDirtyRect,
 117                               const nsDisplayListSet& aLists);
 118
 119   NS_IMETHOD
 120   TransmitAutomaticData();
 121
 122   NS_IMETHOD
 123   UpdatePresentationDataFromChildAt(PRInt32         aFirstIndex,
 124                                     PRInt32         aLastIndex,
 125                                     PRUint32        aFlagsValues,
 126                                     PRUint32        aFlagsToUpdate);
 127
 128   // override the base method so that we can deal with the fraction line
 129   virtual nscoord
 130   FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize);
 131
 132   // helper to translate the thickness attribute into a usable form
 133   static nscoord
 134   CalcLineThickness(nsPresContext*  aPresContext,
 135                     nsStyleContext*  aStyleContext,
 136                     nsString&        aThicknessAttribute,
 137                     nscoord          onePixel,
 138                     nscoord          aDefaultRuleThickness);
 139
 140 protected:
 141   nsMathMLmfracFrame(nsStyleContext* aContext) : nsMathMLContainerFrame(aContext) {}
 142   virtual ~nsMathMLmfracFrame();
 143
 144   virtual PRIntn GetSkipSides() const { return 0; }
 145
 146   PRBool
 147   IsBevelled();
 148
 149   nsresult PlaceInternal(nsIRenderingContext& aRenderingContext,
 150                          PRBool               aPlaceOrigin,
 151                          nsHTMLReflowMetrics& aDesiredSize,
 152                          PRBool               aWidthOnly);
 153
 154   // Display a slash
 155   nsresult DisplaySlash(nsDisplayListBuilder* aBuilder,
 156                         nsIFrame* aFrame, const nsRect& aRect,
 157                         nscoord aThickness,
 158                         const nsDisplayListSet& aLists);
 159
 160   nsRect        mLineRect;
 161   nsMathMLChar* mSlashChar;
 162   nscoord       mLineThickness;
 163   PRPackedBool  mIsBevelled;
 164 };
 165
 166 #endif /* nsMathMLmfracFrame_h___ */