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Bug 1916988 - Support CSS width/height properties on MathML elements. r=emilio
This patch implements support for the width/height properties on MathML elements [1]. The general algorithm from the spec is as follows: (1) The outcome of the math layout is a "math content box". (2) The content box sets its size from computed width/height values. If auto, it's the one of the "math content box". This patch ignores percentage values for now [2] [3]. (3) math content box is shifted so that its inline-start and top edges aligns with the ones of the content box. There are exceptions elements like mfrac and munder/mover/munderover which instead horizontally center the math content box within the content box. For baseline adjustment, we follow what Chromium does, see [4]. (4) Padding+border are added around the content box. Note that we ignore the box-sizing property for now [5]. The patch essentially tweaks the various MathML layout algorithms to perform steps (3) and (4) before the calls to GetBorderPaddingForPlace and InflateReflowAndBoundingMetrics. [1] https://w3c.github.io/mathml-core/#layout-algorithms [2] w3c/mathml-core#76 [3] w3c/mathml-core#77 [4] w3c/mathml-core#259 [5] w3c/mathml-core#257 Below is more information about test coverage: - width-height-001: Verify that width, height, inline-size and block-size properties sets the size of the content box. This test used to verify they are ignored, this patch fixes the `` tag. It also adds a test for the case the specified size is smaller than the content (we force non empty descendants to make sure this content is large enough) and to verify the width is used for the preferred width. - width-height-002, width-height-003: These are reftests visually checking offsets of the math content box within a larger content box (specified by width/height) for the mtext, mrow, mpadded, mfrac, msqrt, mroot, in LTR/RTL modes. In particular they allow to verify some painted elements like fraction bar and radical symbols. - width-height-004: This test more directly checks that the math content box is horizontally centered within a larger content box for munder, mover, munderover and mfrac. This patch extends the test to cover the case when the math content box is wider (i.e. overflowing outside the content box) and removes unnecessary specified height. - width-height-005: New test for other layout algorithm that don't center the math content box, checking inline-start edges of children when a width is specified. We check both LTR/RTL modes and wider/narrower content boxes. - width-height-006: Same but checking the top edges for larger/smaller height and verifying that baseline is perserved. Differential Revision: https://phabricator.services.mozilla.com/D221436 UltraBlame original commit: dc848382811227e2f040f438794da638b8792f5b
1 parent a94d52b commit 384bff9

24 files changed

+9839
-732
lines changed

‎layout/mathml/nsMathMLContainerFrame.cpp

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‎layout/mathml/nsMathMLContainerFrame.h

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@@ -1353,6 +1353,42 @@ radical
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symbol
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.
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IgnoreBorderPadding
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/
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/
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If
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DoNotAdjustForWidthAndHeight
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is
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set
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the
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function
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will
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complete
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/
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/
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without
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setting
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the
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computed
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width
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and
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height
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after
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the
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math
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layout
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.
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This
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/
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/
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can
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be
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used
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similarly
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to
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IgnoreBorderPadding
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above
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.
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DoNotAdjustForWidthAndHeight
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}
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;
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using
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aFlags
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)
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;
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struct
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WidthAndHeightForPlaceAdjustment
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{
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mozilla
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:
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:
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Maybe
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<
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nscoord
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>
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width
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;
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mozilla
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:
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:
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Maybe
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<
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nscoord
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>
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height
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;
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}
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;
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WidthAndHeightForPlaceAdjustment
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GetWidthAndHeightForPlaceAdjustment
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(
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const
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PlaceFlags
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&
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aFlags
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)
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;
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virtual
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bool
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IsMathContentBoxHorizontallyCentered
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(
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)
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const
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{
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return
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false
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;
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}
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nscoord
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ApplyAdjustmentForWidthAndHeight
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(
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const
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PlaceFlags
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&
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aFlags
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const
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WidthAndHeightForPlaceAdjustment
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&
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aSizes
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ReflowOutput
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&
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aReflowOutput
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nsBoundingMetrics
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&
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aBoundingMetrics
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)
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;
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protected
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:
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/

‎layout/mathml/nsMathMLTokenFrame.cpp

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@@ -1240,6 +1240,36 @@ descent
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;
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/
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/
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Apply
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width
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/
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height
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to
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math
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content
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box
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.
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auto
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sizes
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=
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GetWidthAndHeightForPlaceAdjustment
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(
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aFlags
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)
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;
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auto
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shiftX
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=
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ApplyAdjustmentForWidthAndHeight
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(
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aFlags
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sizes
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aDesiredSize
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mBoundingMetrics
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)
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;
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/
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/
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padding
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+
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.
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left
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;
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dx
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+
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=
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shiftX
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;
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for
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(
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nsIFrame

‎layout/mathml/nsMathMLmencloseFrame.cpp

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@@ -1729,6 +1729,11 @@ PlaceFlag
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:
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:
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IgnoreBorderPadding
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+
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PlaceFlag
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:
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:
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DoNotAdjustForWidthAndHeight
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;
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nsresult
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rv
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;
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/
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/
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Apply
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width
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/
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height
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to
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math
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content
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box
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.
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auto
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sizes
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=
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GetWidthAndHeightForPlaceAdjustment
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(
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aFlags
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)
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;
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dx_left
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+
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=
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ApplyAdjustmentForWidthAndHeight
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(
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aFlags
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sizes
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aDesiredSize
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mBoundingMetrics
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)
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;
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/
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/
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padding
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+

‎layout/mathml/nsMathMLmfracFrame.cpp

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@@ -2458,6 +2458,89 @@ mBoundingMetrics
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;
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/
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/
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Apply
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width
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/
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height
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to
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math
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content
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box
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.
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auto
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sizes
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=
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GetWidthAndHeightForPlaceAdjustment
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(
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aFlags
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)
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;
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auto
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shiftX
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=
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ApplyAdjustmentForWidthAndHeight
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(
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aFlags
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sizes
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aDesiredSize
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mBoundingMetrics
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)
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;
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if
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(
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sizes
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.
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width
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)
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{
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/
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/
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MathML
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Core
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says
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the
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math
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content
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box
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is
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horizontally
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centered
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/
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/
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but
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the
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fraction
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bar
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still
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takes
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the
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full
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width
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of
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the
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content
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box
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.
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dxNum
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+
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=
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shiftX
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;
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dxDen
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+
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=
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shiftX
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;
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width
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=
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*
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sizes
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.
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width
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;
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}
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/
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/
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‎layout/mathml/nsMathMLmfracFrame.h

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(
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)
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;
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bool
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IsMathContentBoxHorizontallyCentered
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(
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)
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const
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final
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{
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return
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true
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;
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}
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/
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/
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Display

‎layout/mathml/nsMathMLmmultiscriptsFrame.cpp

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@@ -4198,6 +4198,39 @@ boundingMetrics
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;
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/
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Apply
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width
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/
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height
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to
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math
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content
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box
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.
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auto
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sizes
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=
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aFrame
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-
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>
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GetWidthAndHeightForPlaceAdjustment
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(
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aFlags
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)
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;
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aFrame
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-
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>
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ApplyAdjustmentForWidthAndHeight
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(
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aFlags
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sizes
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aDesiredSize
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boundingMetrics
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)
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;
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/
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/
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padding
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+

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