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fc5a16c571
This reuses the SVG machinery for calculating unit lengths and leaves vi and vb unimplemented. These units need special handling since they depend on the writing mode, but MathML does not support non-horizontal writing modes yet. See https://bugzilla.mozilla.org/show_bug.cgi?id=1935717. Differential Revision: https://phabricator.services.mozilla.com/D230738
107 lines
3.8 KiB
C++
107 lines
3.8 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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eMathMLFrameType GetMathMLFrameType() override;
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nsresult Place(DrawTarget* aDrawTarget, const PlaceFlags& aFlags,
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ReflowOutput& aDesiredSize) override;
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void BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsDisplayListSet& aLists) override;
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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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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(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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mSlashChar(nullptr),
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mLineThickness(0) {}
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virtual ~nsMathMLmfracFrame();
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bool IsMathContentBoxHorizontallyCentered() const final { return true; }
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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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};
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#endif /* nsMathMLmfracFrame_h___ */
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