1 files changed, 113 insertions, 0 deletions
diff --git a/layout/mathml/nsMathMLmfracFrame.h b/layout/mathml/nsMathMLmfracFrame.h
new file mode 100644
index 0000000000..27f2fa27d2
--- /dev/null
+++ b/layout/mathml/nsMathMLmfracFrame.h
@@ -0,0 +1,113 @@
+/* -*- 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"
+
+namespace mozilla {
+class PresShell;
+}  // namespace mozilla
+
+//
+// <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(mozilla::PresShell* 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
+  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,
+                              nsPresContext* aPresContext)
+      : nsMathMLContainerFrame(aStyle, aPresContext, kClassID),
+        mSlashChar(nullptr),
+        mLineThickness(0) {}
+  virtual ~nsMathMLmfracFrame();
+
+  nsresult PlaceInternal(DrawTarget* aDrawTarget, bool aPlaceOrigin,
+                         ReflowOutput& aDesiredSize, bool aWidthOnly);
+
+  // Display a slash
+  void DisplaySlash(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
+                    nscoord aThickness, const nsDisplayListSet& aLists);
+
+  nsRect mLineRect;
+  nsMathMLChar* mSlashChar;
+  nscoord mLineThickness;
+};
+
+#endif /* nsMathMLmfracFrame_h___ */