forked from mirrors/gecko-dev
a25126cd0d
Differential Revision: https://phabricator.services.mozilla.com/D60857 --HG-- extra : moz-landing-system : lando
116 lines
4.3 KiB
C++
116 lines
4.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsMathMLmfracFrame_h___
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#define nsMathMLmfracFrame_h___
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#include "mozilla/Attributes.h"
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#include "nsMathMLContainerFrame.h"
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namespace mozilla {
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class PresShell;
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} // namespace mozilla
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//
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// <mfrac> -- form a fraction from two subexpressions
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//
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/*
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The MathML REC describes:
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The <mfrac> element is used for fractions. It can also be used to mark up
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fraction-like objects such as binomial coefficients and Legendre symbols.
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The syntax for <mfrac> is:
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<mfrac> numerator denominator </mfrac>
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Attributes of <mfrac>:
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Name values default
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linethickness number [ v-unit ] | thin | medium | thick 1
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E.g.,
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linethickness=2 actually means that linethickness=2*DEFAULT_THICKNESS
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(DEFAULT_THICKNESS is not specified by MathML, see below.)
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The linethickness attribute indicates the thickness of the horizontal
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"fraction bar", or "rule", typically used to render fractions. A fraction
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with linethickness="0" renders without the bar, and might be used within
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binomial coefficients. A linethickness greater than one might be used with
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nested fractions.
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In general, the value of linethickness can be a number, as a multiplier
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of the default thickness of the fraction bar (the default thickness is
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not specified by MathML), or a number with a unit of vertical length (see
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Section 2.3.3), or one of the keywords medium (same as 1), thin (thinner
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than 1, otherwise up to the renderer), or thick (thicker than 1, otherwise
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up to the renderer).
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The <mfrac> element sets displaystyle to "false", or if it was already
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false increments scriptlevel by 1, within numerator and denominator.
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These attributes are inherited by every element from its rendering
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environment, but can be set explicitly only on the <mstyle>
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element.
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*/
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class nsMathMLmfracFrame final : public nsMathMLContainerFrame {
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public:
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NS_DECL_FRAMEARENA_HELPERS(nsMathMLmfracFrame)
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friend nsIFrame* NS_NewMathMLmfracFrame(mozilla::PresShell* aPresShell,
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ComputedStyle* aStyle);
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virtual eMathMLFrameType GetMathMLFrameType() override;
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virtual nsresult MeasureForWidth(DrawTarget* aDrawTarget,
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ReflowOutput& aDesiredSize) override;
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virtual nsresult Place(DrawTarget* aDrawTarget, bool aPlaceOrigin,
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ReflowOutput& aDesiredSize) override;
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virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsDisplayListSet& aLists) override;
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virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
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int32_t aModType) override;
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NS_IMETHOD
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TransmitAutomaticData() override;
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// override the base method so that we can deal with the fraction line
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virtual nscoord FixInterFrameSpacing(ReflowOutput& aDesiredSize) override;
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// helper to translate the thickness attribute into a usable form
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nscoord CalcLineThickness(nsPresContext* aPresContext,
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ComputedStyle* aComputedStyle,
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nsString& aThicknessAttribute, nscoord onePixel,
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nscoord aDefaultRuleThickness,
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float aFontSizeInflation);
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uint8_t ScriptIncrement(nsIFrame* aFrame) override;
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protected:
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explicit nsMathMLmfracFrame(ComputedStyle* aStyle,
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nsPresContext* aPresContext)
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: nsMathMLContainerFrame(aStyle, aPresContext, kClassID),
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mLineRect(),
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mSlashChar(nullptr),
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mLineThickness(0),
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mIsBevelled(false) {}
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virtual ~nsMathMLmfracFrame();
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nsresult PlaceInternal(DrawTarget* aDrawTarget, bool aPlaceOrigin,
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ReflowOutput& aDesiredSize, bool aWidthOnly);
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// Display a slash
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void DisplaySlash(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
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nscoord aThickness, const nsDisplayListSet& aLists);
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nsRect mLineRect;
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nsMathMLChar* mSlashChar;
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nscoord mLineThickness;
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bool mIsBevelled;
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};
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#endif /* nsMathMLmfracFrame_h___ */
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