/* -*- 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 nsMathMLmfracFrame_h___

#define nsMathMLmfracFrame_h___

#include "mozilla/Attributes.h"

#include "nsMathMLContainerFrame.h"

//

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

//

/*

The MathML REC describes:

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

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

The syntax for <mfrac> is:

  <mfrac> numerator denominator </mfrac>

Attributes of <mfrac>:

     Name                      values                     default

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

E.g.,

linethickness=2 actually means that linethickness=2*DEFAULT_THICKNESS

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

The linethickness attribute indicates the thickness of the horizontal

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

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

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

nested fractions.

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

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

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

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

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

up to the renderer).

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

false increments scriptlevel by 1, within numerator and denominator.

These attributes are inherited by every element from its rendering

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

element.

*/

class nsMathMLmfracFrame final : public nsMathMLContainerFrame

{

public:

  NS_DECL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)

  friend nsIFrame* NS_NewMathMLmfracFrame(nsIPresShell* aPresShell, ComputedStyle* aStyle);

  virtual eMathMLFrameType GetMathMLFrameType() override;

  virtual nsresult

  MeasureForWidth(DrawTarget* aDrawTarget,

                  ReflowOutput& aDesiredSize) override;

  virtual nsresult

  Place(DrawTarget*          aDrawTarget,

        bool                 aPlaceOrigin,

        ReflowOutput& aDesiredSize) override;

  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,

                                const nsDisplayListSet& aLists) override;

  virtual nsresult

  AttributeChanged(int32_t  aNameSpaceID,

                   nsAtom* aAttribute,

                   int32_t  aModType) override;

  NS_IMETHOD

  TransmitAutomaticData() override;

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

  virtual nscoord

  FixInterFrameSpacing(ReflowOutput& aDesiredSize) override;

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

  static nscoord

  CalcLineThickness(nsPresContext*  aPresContext,

                    ComputedStyle*  aComputedStyle,

                    nsString&        aThicknessAttribute,

                    nscoord          onePixel,

                    nscoord          aDefaultRuleThickness,

                    float            aFontSizeInflation);

  uint8_t

  ScriptIncrement(nsIFrame* aFrame) override;

protected:

  explicit nsMathMLmfracFrame(ComputedStyle* aStyle)

    : nsMathMLContainerFrame(aStyle, kClassID)

    , mLineRect()

    , mSlashChar(nullptr)

    , mLineThickness(0)

    , mIsBevelled(false)

  {}

  virtual ~nsMathMLmfracFrame();

  nsresult PlaceInternal(DrawTarget*          aDrawTarget,

                         bool                 aPlaceOrigin,

                         ReflowOutput& aDesiredSize,

                         bool                 aWidthOnly);

  // Display a slash

  void DisplaySlash(nsDisplayListBuilder* aBuilder,

                    nsIFrame* aFrame, const nsRect& aRect,

                    nscoord aThickness,

                    const nsDisplayListSet& aLists);

  nsRect        mLineRect;

  nsMathMLChar* mSlashChar;

  nscoord       mLineThickness;

  bool          mIsBevelled;

};

#endif /* nsMathMLmfracFrame_h___ */