Accessibility/MathML

Summary

This page describes a draft of changes to be made to add MathML accessibility to Gecko.

Interface

nsIAccessibleMathML

Inherit from nsISupports.

readonly attribute AString tokenValue;
// Get token value for token MathML elements (mi, mo, mn, mtext, mspace, ms,
// mglyph).  Returns empty string if not a token element.

readonly attribute boolean isToken;
// Check if this element is a token MathML element.

readonly attribute nsIPersistentProperties attributes;
// Get attributes specific to the MathML element.

Two options for describing relations between MathML elements:

Option 1: Explicit readonly attributes (accessors) for going from parent elements to children and vice versa. e.g.

readonly attribute nsIAccessibleMathML radicand;
readonly attribute nsIAccessibleMathML rootIndex;
readonly attribute nsIAccessibleMathML under;
...
readonly attribute nsIAccessibleMathML parent;

Returns nullptr if the related accessible doesn't exist.

Option 2: Relations linking accessibles based on role, so we won't have attributes/functions in the interface. An example would be for a fraction structure, as follows.

<math>
  <mfrac>
    <mi>a</mi>
    <mn>2</mn>
  </mfrac>
</math>

mfrac would have RELATION_NUMERATOR_IS -> mi and RELATION_DENOMINATOR_IS -> mn or similar. mi would have RELATION_NUMERATOR_FOR -> mfrac and mn would have RELATION_DENOMINATOR_FOR -> mfrac.

MathMLAccessible

Inherit from AccessibleWrap, and implements nsIAccessibleMathML.

• NativeAttributes - Override Accessible, and append MathML specific attributes if the element accepts them.
• GetTokenValue - Sets token value string if applicable.
• GetIsToken - Returns true if element is a token element.

Roles

One role for each of the following constructs (41 of them):

Tokens

• mi
• mn
• mo
• mtext
• mspace
• ms
• mglyph

Layout (semantic meaning)

• mrow
• mfrac
• msqrt
• mroot
• mfenced
• menclose

Layout (formatting)

• mstyle
• mpadded
• mphantom

Layout (elementary math)

• mstack
• mlongdiv
• msgroup
• msrow
• mscarries
• mscarry
• msline

Script/limits

• msub
• msup
• msubsup
• munder
• mover
• munderover
• mmultiscripts

Tables/matrices

• mtable
• mlabeledtr
• mtr
• mtd

Table formatting

• maligngroup
• malignmark

Semantics annotation

• semantics
• annotation
• annotation-xml

Other

• maction
• merror

Sample Gecko roles

• MATHML_IDENTIFIER
• MATHML_NUMBER
• MATHML_OPERATOR
• MATHML_TEXT
• MATHML_SPACE
• MATHML_STRING_LITERAL
• MATHML_GLYPH
• MATHML_ROW
• MATHML_FRACTION
• MATHML_SQUARE_ROOT
• MATHML_ROOT
• MATHML_FENCED
• MATHML_ENCLOSED
• MATHML_STYLE
• MATHML_PADDED
• MATHML_PHANTOM
• MATHML_SUB
• MATHML_SUP
• MATHML_SUB_SUP
• MATHML_UNDER
• MATHML_OVER
• MATHML_UNDER_OVER
• MATHML_MULTISCRIPTS
• MATHML_TABLE
• MATHML_LABELED_ROW
• MATHML_TABLE_ROW
• MATHML_CELL
• MATHML_ALIGNMENT_GROUP
• MATHML_ALIGNMENT_MARK
• MATHML_ACTION
• MATHML_ERROR
• MATHML_SEMANTICS
• MATHML_ANNOTATION
• MATHML_XML_ANNOTATION
• MATHML_STACK
• MATHML_LONG_DIVISION
• MATHML_STACK_GROUP
• MATHML_STACK_ROW
• MATHML_STACK_CARRIES
• MATHML_STACK_CARRY
• MATHML_STACK_LINE