Accessibility/TextInterface.Next

IA2/ATK Text Interface. Next

Problems of exiting approach

• (#1) Embedded objects concepts adds complexity which potentially affects on performance
• (#2) Hard to figure what the word is. Example

  <p>a<a>b</a><c></p>

  p is one word 'abc'

Use cases

• Move by unit and get the text
• Get selection
• Get/set caret

Text Range API

Advantages:

• solves both #1 and #2
• nice concept in replace to embed characters and text offsets concepts
• doesn't have text offsets restrictions like one text offsets may describe two text points (for example, caret right before a link and inside the link
• close to UIA which is good in terms of portability
• more steady to bugs since wrong move in text is better than wrong offsets because wrong move allows to traverse the whole text while wrong offsets usually don't

Disadvantages:

• can be complex for implementation

types:
TextRange
Accessible
TextEndPoint: EP_start, EP_end
TextEndPoints: EPS_startToStart, EPS_startToEnd, EPS_endToStart, EPS_endToEnd
TextUnit: UNIT_PARAGRAPH, UNIT_LINE, UNIT_WORD, UNIT_CHARACTER
TextPosition: POS_FIRST, POS_LAST, POS_ALL, POS_CARET, POS_SELECTION
TextAttributes
Rect

TextRange:
void compareEndPoints(TextRange other, TextEndPoints which)
void setEndPoint(TextRange other, TextEndPoints which)
void expand(TextUnit unit)
void move(TextUnit unit, long direction, TextEndPoint endPoint)
TextRange copy()
void updateCaret()
void updateSelection()
optional: isCollapsed, collapse
TextRange[] childRanges()
TextAttributes attributes()
Accessible enclosingAccessible()
Rect screenLocation()

TextProvider:
TextRange rangeForAccessible(Accessible accessible)
TextRange rangeForPosition(TextPosition position)
TextRange rangeForScreenLocation(Rect location)

No embed objects for inlines

Advantages:

• a relatively small changes, totally goes with IA2 and ATK specifications
• solves words navigation problem (#2)

Disadvantages:

• not backward compatible since AT might have dependencies on exiting implementation, AT sniffing can be a requirement
• doesn't solve complexity problem (#1)

Text Interface Extension

Advantages:

• relatively small change
• supposed to solve navigation problem (#2)
• partially solves problem (#1) since it lets words, line navigation with no embedded characters (reading the selection spanned through paragraphs is still complex)

Disadvantages:

• doesn't solve perf problem (#1) in general

getUnitBoundaries(Accessible accessible, long offset, Unit unit, Accessible* startAccessible, long* startOffset, Accessible* endAccessible, long* endOffset)
findNextChange(Accessible startAccessible, long startOffset, Accessible endAccessible, long endOffset, Accessible* changeAccessible, long* changeOffset)