The Tor Browser: layout/mathml/nsMathMLmfracFrame.h@8bccb770b82d

     1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* This Source Code Form is subject to the terms of the Mozilla Public

     3  * License, v. 2.0. If a copy of the MPL was not distributed with this

     4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     6 #ifndef nsMathMLmfracFrame_h___

     7 #define nsMathMLmfracFrame_h___

     9 #include "mozilla/Attributes.h"

    10 #include "nsMathMLContainerFrame.h"

    12 //

    13 // <mfrac> -- form a fraction from two subexpressions

    14 //

    16 /*

    17 The MathML REC describes:

    19 The <mfrac> element is used for fractions. It can also be used to mark up

    20 fraction-like objects such as binomial coefficients and Legendre symbols.

    21 The syntax for <mfrac> is:

    22   <mfrac> numerator denominator </mfrac>

    24 Attributes of <mfrac>:

    25      Name                      values                     default

    26   linethickness  number [ v-unit ] | thin | medium | thick  1

    28 E.g.,

    29 linethickness=2 actually means that linethickness=2*DEFAULT_THICKNESS

    30 (DEFAULT_THICKNESS is not specified by MathML, see below.)

    32 The linethickness attribute indicates the thickness of the horizontal

    33 "fraction bar", or "rule", typically used to render fractions. A fraction

    34 with linethickness="0" renders without the bar, and might be used within

    35 binomial coefficients. A linethickness greater than one might be used with

    36 nested fractions.

    38 In general, the value of linethickness can be a number, as a multiplier

    39 of the default thickness of the fraction bar (the default thickness is

    40 not specified by MathML), or a number with a unit of vertical length (see

    41 Section 2.3.3), or one of the keywords medium (same as 1), thin (thinner

    42 than 1, otherwise up to the renderer), or thick (thicker than 1, otherwise

    43 up to the renderer).

    45 The <mfrac> element sets displaystyle to "false", or if it was already

    46 false increments scriptlevel by 1, within numerator and denominator.

    47 These attributes are inherited by every element from its rendering

    48 environment, but can be set explicitly only on the <mstyle>

    49 element.

    50 */

    52 class nsMathMLmfracFrame : public nsMathMLContainerFrame {

    53 public:

    54   NS_DECL_FRAMEARENA_HELPERS

    56   friend nsIFrame* NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);

    58   virtual eMathMLFrameType GetMathMLFrameType() MOZ_OVERRIDE;

    60   virtual nsresult

    61   MeasureForWidth(nsRenderingContext& aRenderingContext,

    62                   nsHTMLReflowMetrics& aDesiredSize) MOZ_OVERRIDE;

    64   virtual nsresult

    65   Place(nsRenderingContext& aRenderingContext,

    66         bool                 aPlaceOrigin,

    67         nsHTMLReflowMetrics& aDesiredSize) MOZ_OVERRIDE;

    69   virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,

    70                                 const nsRect&           aDirtyRect,

    71                                 const nsDisplayListSet& aLists) MOZ_OVERRIDE;

    73   NS_IMETHOD

    74   TransmitAutomaticData() MOZ_OVERRIDE;

    76   // override the base method so that we can deal with the fraction line

    77   virtual nscoord

    78   FixInterFrameSpacing(nsHTMLReflowMetrics& aDesiredSize) MOZ_OVERRIDE;

    80   // helper to translate the thickness attribute into a usable form

    81   static nscoord

    82   CalcLineThickness(nsPresContext*  aPresContext,

    83                     nsStyleContext*  aStyleContext,

    84                     nsString&        aThicknessAttribute,

    85                     nscoord          onePixel,

    86                     nscoord          aDefaultRuleThickness);

    88   uint8_t

    89   ScriptIncrement(nsIFrame* aFrame) MOZ_OVERRIDE;

    91 protected:

    92   nsMathMLmfracFrame(nsStyleContext* aContext) : nsMathMLContainerFrame(aContext) {}

    93   virtual ~nsMathMLmfracFrame();

    95   nsresult PlaceInternal(nsRenderingContext& aRenderingContext,

    96                          bool                 aPlaceOrigin,

    97                          nsHTMLReflowMetrics& aDesiredSize,

    98                          bool                 aWidthOnly);

   100   // Display a slash

   101   void DisplaySlash(nsDisplayListBuilder* aBuilder,

   102                     nsIFrame* aFrame, const nsRect& aRect,

   103                     nscoord aThickness,

   104                     const nsDisplayListSet& aLists);

   106   nsRect        mLineRect;

   107   nsMathMLChar* mSlashChar;

   108   nscoord       mLineThickness;

   109   bool          mIsBevelled;

   110 };

   112 #endif /* nsMathMLmfracFrame_h___ */

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