at-spi-idl: Accessibility::Text Interface Reference

# Accessibility::Text Interface Reference

`import "Accessibility_Text.idl";`

Inheritance diagram for Accessibility::Text:

## Data Structures
struct | Range
## Public Types
typedef sequence< Range > | RangeList
## Public Member Functions
string | getText (in long startOffset, in long endOffset)
boolean | setCaretOffset (in long offset)
string | getTextBeforeOffset (in long offset, in TEXT_BOUNDARY_TYPE type, out long startOffset, out long endOffset)
string | getTextAtOffset (in long offset, in TEXT_BOUNDARY_TYPE type, out long startOffset, out long endOffset)
string | getTextAfterOffset (in long offset, in TEXT_BOUNDARY_TYPE type, out long startOffset, out long endOffset)
unsigned long | getCharacterAtOffset (in long offset)
string | getAttributeValue (in long offset, in string attributeName, out long startOffset, out long endOffset, out boolean defined)
string | getAttributes (in long offset, out long startOffset, out long endOffset)
string | getDefaultAttributes ()
void | getCharacterExtents (in long offset, out long x, out long y, out long width, out long height, in short coordType)
long | getOffsetAtPoint (in long x, in long y, in short coordType)
long | getNSelections ()
void | getSelection (in long selectionNum, out long startOffset, out long endOffset)
boolean | addSelection (in long startOffset, in long endOffset)
boolean | removeSelection (in long selectionNum)
boolean | setSelection (in long selectionNum, in long startOffset, in long endOffset)
void | getRangeExtents (in long startOffset, in long endOffset, out long x, out long y, out long width, out long height, in short coordType)
RangeList | getBoundedRanges (in long x, in long y, in long width, in long height, in short coordType, in TEXT_CLIP_TYPE xClipType, in TEXT_CLIP_TYPE yClipType)
AttributeSet | getAttributeRun (in long offset, out long startOffset, out long endOffset, in boolean includeDefaults)
AttributeSet | getDefaultAttributeSet ()
## Data Fields
readonly attribute long | characterCount
readonly attribute long | caretOffset

## Detailed Description

The text interface should be implemented by objects which place textual information onscreen as character strings or glyphs. The text interface allows access to textual content, including display attributes and semantic hints associated with runs of text, and access to bounding box information for glyphs and substrings. It also allows portions of textual content to be selected, if the object's StateSet includes STATE_SELECTABLE_TEXT.

In some cases a Text object may have, as its content, an empty string. In particular this can occur in the case of Hypertext objects which do not display explicitly textual information onscreen, as Hypertext is derived from the Text interface.

See also:
  Hypertext.

Typographic and semantic attributes of onscreen textual content, for instance typeface, weight, language, and such qualities as 'emphasis' or 'blockquote', are represented as text attributes. Contiguous sequences of characters over which these attributes are unchanged are referred to as "attribute runs", and are available via Text::getAttributeRun. Where possible, implementing clients will report textual attributes which are the same over the entire text object, for instance those inherited from a default or document-scope style, via getDefaultAttributes instead of reporting them explicitly for each character. Therefore, for any span of text, the attributes in effect are the union of the set returned by Text::getDefaultAttributes, and the set returned at a particular character offset via Text::getAttributeRun.

Note:
  Events that may be emitted by instances of Text include:
  - `"object:text-attributes-changed"` The attributes of a range of text, or the range over which attributes apply, has changed.
  - `"object:text-changed"` The text content of this object has changed.
  - `"object:text-bounds-changed"` The character bounds of a text object have changed, for instance in response to a reformatting or reflow operation.
  - `"object:text-caret-moved"` The character offset of the text caret (visible or notional) within this object has changed. Events of this type may also be generated when an onscreen text caret appears or disappears.
  - `"object:text-selection-changed"` The range or number of text selections within this text object has changed.
  In some cases, objects which are not onscreen may implement Text, but if such objects implement Component, their potential visibility should be examined (via comparison with STATE_VISIBLE and STATE_SHOWING) before exposing them to the user. Objects which implement Text but not Component may be encountered in special-purpose interfaces or as special ¨accessibility¨ extensions to visual interfaces to allow non-graphical access to application features. These instances should be considered the exception, rather than the rule.

## Member Typedef Documentation

typedef sequence<Range> Accessibility::Text::RangeList

## Member Function Documentation

boolean Accessibility::Text::addSelection | ( | in long | startOffset,
|  | in long | endOffset |
| ) |  |  |

The result of calling addSelection on objects which already have one selection present, and which do not include STATE_MULTISELECTABLE, is undefined, other than the return value.

Returns:
  `True` of the selection was successfully added, `False` otherwise. Selection may fail if the object does not support selection of text (see STATE_SELECTABLE_TEXT), if the object does not support multiple selections and a selection is already defined, or for other reasons (for instance if the user does not have permission to copy the text into the relevant selection buffer).

AttributeSet Accessibility::Text::getAttributeRun | ( | in long | offset,
|  | out long | startOffset,
|  | out long | endOffset,
|  | in boolean | includeDefaults |
| ) |  |  |

Query a particular text object for the text attributes defined at a given offset, obtaining the start and end of the "attribute run" over which these attributes are currently invariant. Text attributes are those presentational, typographic, or semantic attributes or qualitites which apply to a range of text specifyable by starting and ending offsets. Attributes relevant to localization should be provided in accordance with the w3c "Internationalization and Localization Markup Requirements", http://www.w3.org/TR/2005/WD-itsreq-20051122/ Other text attributes should choose their names and value semantics in accordance with relevant standards such as CSS level 2 (http://www.w3.org/TR/1998/REC-CSS2-19980512), XHTML 1.0 (http://www.w3.org/TR/2002/REC-xhtml1-20020801), and WICD (http://www.w3.org/TR/2005/WD-WICD-20051121/). Those attributes from the aforementioned specifications and recommendations which do not concern typographic, presentational, or semantic aspects of text should be exposed via the more general Accessible::getAttributes() API (if at all).

For example, CSS attributes which should be exposed on text (either as default attributes, or as explicitly-set attributes when non-default values are specified in the content view) include the Font attributes (i.e. "css2:font-weight", "css2:font-style"), the "css2:color" and "css2:background-color" attributes, and "css2:text-decoration" attribute.

If includeDefaults is TRUE, then this AttributeSet should include the default attributes as well as those which are explicitly assigned to the attribute run in question. startOffset and endOffset will be back-filled to indicate the start and end of the attribute run which contains 'offset' - an attribute run is a contiguous section of text whose attributes are homogeneous.

Parameters:

  | offset | the offset of the character whose attributes will be reported. -1 means the offset of the character to be inserted at the caret location.
  | startOffset | backfilled with the starting offset of the character range over which all text attributes match those of `offset`, i.e. the start of the homogeneous attribute run including `offset`.
  | endOffset | backfilled with the offset of the first character past the character range over which all text attributes match those of `offset`, i.e. the character immediately after the homogeneous attribute run including `offset`.
  | includeDefaults | if False, the call should only return those attributes which are explicitly set on the current attribute run, omitting any attributes which are inherited from the default values. See also Text::getDefaultAttributes.

Note:
  Clients seeking annotations or properties of a more general nature, which are not specific to the onscreen textual content of objects and cannot logically be applied to specific character offset ranges, should use Accessible::getAttributes instead. The attributes returned by Text::getAttributeRun (with or without 'default attributes'), are distinct from the properties/attributes returned by Accessible::getAttributes.

See also:
  Accessible::getAttributes

Returns:
  the AttributeSet defined at offset, optionally including the 'default' attributes.

Since:
  AT-SPI 1.7.0

string Accessibility::Text::getAttributes | ( | in long | offset,
|  | out long | startOffset,
|  | out long | endOffset |
| ) |  |  |

getAttributes is deprecated in favor of getAttributeRun.

Returns:
  the attributes at offset, as a semicolon-delimited set of colon-delimited name-value pairs.

See also:
  getAttributeRun

string Accessibility::Text::getAttributeValue | ( | in long | offset,
|  | in string | attributeName,
|  | out long | startOffset,
|  | out long | endOffset,
|  | out boolean | defined |
| ) |  |  |

Get the string value of a named attribute at a given offset, if defined.

Parameters:

  | offset | the offset of the character for which the attribute run is to be obtained.
  | attributeName | the name of the attribute for which the value is to be returned, if defined.
  | startOffset | back-filled with the offset of the first character in the attribute run containing the character at `offset`.
  | endOffset | back-filled with the offset of the first character past the end of the attribute run containing the character at `offset`.
  | defined | back-filled with `True` if the attributeName has a defined value at `offset`, `False` otherwise.

Returns:
  the value of attribute (name-value pair) corresponding to "name", if defined.

RangeList Accessibility::Text::getBoundedRanges | ( | in long | x,
|  | in long | y,
|  | in long | width,
|  | in long | height,
|  | in short | coordType,
|  | in TEXT_CLIP_TYPE | xClipType,
|  | in TEXT_CLIP_TYPE | yClipType |
| ) |  |  |

Return the text content within a bounding box, as a list of Range structures. Depending on the TEXT_CLIP_TYPE parameters, glyphs which are clipped by the bounding box (i.e. which lie partially inside and partially outside it) may or may not be included in the ranges returned.

Note:
  This method may be of particular interest to screen review algorithms.

See also:
  TEXT_CLIP_TYPE.

Parameters:

  | x | the minimum x ( i.e. leftmost) coordinate of the bounding box.
  | y | the minimum y coordinate of the bounding box.
  | width | the horizontal size of the bounding box. The rightmost bound of the bounding box is (x + width);
  | height | the vertical size of the bounding box. The maximum y value of the bounding box is (y + height);
  | coordType | If 0, the above coordinates are interpreted as pixels relative to corner of the screen; if 1, the coordinates are interpreted as pixels relative to the corner of the containing toplevel window.
  | xClipType | determines whether text which intersects the bounding box in the x direction is included.
  | yClipType | determines whether text which intersects the bounding box in the y direction is included.

unsigned long Accessibility::Text::getCharacterAtOffset | ( | in long | offset | ) |

Returns:
  an unsigned long integer whose value corresponds to the UCS-4 representation of the character at the specified text offset, or 0 if offset is out of range.

void Accessibility::Text::getCharacterExtents | ( | in long | offset,
|  | out long | x,
|  | out long | y,
|  | out long | width,
|  | out long | height,
|  | in short | coordType |
| ) |  |  |

Obtain a the bounding box, as x, y, width, and height, of the character or glyph at a particular character offset in this object's text content. The coordinate system in which the results are reported is specified by coordType. If an onscreen glyph corresponds to multiple character offsets, for instance if the glyph is a ligature, the bounding box reported will include the entire glyph and therefore may apply to more than one character offset.

Parameters:

  | offset | the character offset of the character or glyph being queried.
  | x | the minimum horizontal coordinate of the bounding box of the glyph representing the character at `offset`.
  | y | the minimum vertical coordinate of the bounding box of the glyph representing the character at `offset`.
  | width | the horizontal extent of the bounding box of the glyph representing the character at `offset`.
  | height | the vertical extent of the bounding box of the glyph representing the character at `offset`.
  | coordType | If 0, the results will be reported in screen coordinates, i.e. in pixels relative to the upper-left corner of the screen, with the x axis pointing right and the y axis pointing down. If 1, the results will be reported relative to the containing toplevel window, with the x axis pointing right and the y axis pointing down.

string Accessibility::Text::getDefaultAttributes | ( |  | ) |

Deprecated in favor of getDefaultAttributeSet.

Returns:
  the attributes which apply to the entire text content, but which were not explicitly specified by the content creator.

See also:
  getDefaultAttributeSet

AttributeSet Accessibility::Text::getDefaultAttributeSet | ( |  | ) |

Return an AttributeSet containing the text attributes which apply to all text in the object by virtue of the default settings of the document, view, or user agent; e.g. those attributes which are implied rather than explicitly applied to the text object. For instance, an object whose entire text content has been explicitly marked as 'bold' will report the 'bold' attribute via getAttributeRun(), whereas an object whose text weight is inspecified may report the default or implied text weight in the default AttributeSet.

Since:
  AT-SPI 1.7.0

long Accessibility::Text::getNSelections | ( |  | ) |

Obtain the number of separate, contiguous selections in the current Text object. Text objects which do not implement selection of discontiguous text regions will always return '0' or '1'. Note that "contiguous" is defined by continuity of the offsets, i.e. a text 'selection' is defined by a start/end offset pair. In the case of bidirectional text, this means that a continguous selection may appear visually discontiguous, and vice-versa.

Returns:
  the number of contiguous selections in the current Text object.

long Accessibility::Text::getOffsetAtPoint | ( | in long | x,
|  | in long | y,
|  | in short | coordType |
| ) |  |  |

Get the offset of the character at a given onscreen coordinate. The coordinate system used to interpret x and y is determined by parameter coordType.

Parameters:

  | x |
  | y |
  | coordType | if 0, the input coordinates are interpreted relative to the entire screen, if 1, they are relative to the toplevel window containing this Text object.

Returns:
  the text offset (as an offset into the character array) of the glyph whose onscreen bounds contain the point x,y, or -1 if the point is outside the bounds of any glyph.

void Accessibility::Text::getRangeExtents | ( | in long | startOffset,
|  | in long | endOffset,
|  | out long | x,
|  | out long | y,
|  | out long | width,
|  | out long | height,
|  | in short | coordType |
| ) |  |  |

Obtain the bounding box which entirely contains a given text range. Negative values may be returned for the bounding box parameters in the event that all or part of the text range is offscreen or not mapped to the screen.

Parameters:

  | startOffset | the offset of the first character in the specified range.
  | endOffset | the offset of the character immediately after the last character in the specified range.
  | x | an integer parameter which is back-filled with the minimum horizontal coordinate of the resulting bounding box.
  | y | an integer parameter which is back-filled with the minimum vertical coordinate of the resulting bounding box.
  | width | an integer parameter which is back-filled with the horizontal extent of the bounding box.
  | height | an integer parameter which is back-filled with the vertical extent of the bounding box.
  | coordType | If 0, the above coordinates are reported in pixels relative to corner of the screen; if 1, the coordinates are reported relative to the corner of the containing toplevel window.

void Accessibility::Text::getSelection | ( | in long | selectionNum,
|  | out long | startOffset,
|  | out long | endOffset |
| ) |  |  |

The result of calling getSelection with an out-of-range selectionNum (i.e. for a selection which does not exist) is not strictly defined, but should set endOffset equal to startOffset.

string Accessibility::Text::getText | ( | in long | startOffset,
|  | in long | endOffset |
| ) |  |  |

Obtain all or part of the onscreen textual content of a Text object. If endOffset is specified as "-1", then this method will return the entire onscreen textual contents of the Text object.

Note:
  'onscreen' in this context means "potentially onscreen", this method does not perform any sort of coordinate visibility clipping or window-stack-ordering clipping. The text thus reported corresponds to the text which would be presented onscreen if the object implementing the Text interface were entirely unobscured.

Returns:
  the textual content of the current Text object beginning startOffset (inclusive) up to but not including the character at endOffset.

string Accessibility::Text::getTextAfterOffset | ( | in long | offset,
|  | in TEXT_BOUNDARY_TYPE | type,
|  | out long | startOffset,
|  | out long | endOffset |
| ) |  |  |

Obtain a subset of the text content of an object which entirely follows `offset`, delimited by character, word, line, or sentence boundaries as specified by `type`. The starting and ending offsets of the resulting substring are returned in `startOffset` and `endOffset`. By definition, if such a substring exists, `startOffset` must be greater than `offset`.

Parameters:

  | offset | the offset from which the substring search begins, and which must lie before the returned substring.
  | type | the text-boundary delimiter which determines whether the returned text constitures a character, word, line, or sentence (and possibly attendant whitespace), and whether the start or ending of such a substring forms the boundary condition.
  | startOffset | back-filled with the starting offset of the resulting substring, if one exists.
  | endOffset | back-filled with the offset of the character immediately following the resulting substring, if one exists.

See also:
  TEXT_BOUNDARY_TYPE

Returns:
  a string which is a substring of the text content of the object, delimited by the specified boundary condition.

string Accessibility::Text::getTextAtOffset | ( | in long | offset,
|  | in TEXT_BOUNDARY_TYPE | type,
|  | out long | startOffset,
|  | out long | endOffset |
| ) |  |  |

Obtain a subset of the text content of an object which includes the specified `offset`, delimited by character, word, line, or sentence boundaries as specified by `type`. The starting and ending offsets of the resulting substring are returned in `startOffset` and `endOffset`.

Parameters:

  | offset | the offset from which the substring search begins, and which must lie within the returned substring.
  | type | the text-boundary delimiter which determines whether the returned text constitures a character, word, line, or sentence (and possibly attendant whitespace), and whether the start or ending of such a substring forms the boundary condition.
  | startOffset | back-filled with the starting offset of the resulting substring, if one exists.
  | endOffset | back-filled with the offset of the character immediately following the resulting substring, if one exists.

See also:
  TEXT_BOUNDARY_TYPE

Returns:
  a string which is a substring of the text content of the object, delimited by the specified boundary condition.

string Accessibility::Text::getTextBeforeOffset | ( | in long | offset,
|  | in TEXT_BOUNDARY_TYPE | type,
|  | out long | startOffset,
|  | out long | endOffset |
| ) |  |  |

Obtain a subset of the text content of an object which entirely precedes `offset`, delimited by character, word, line, or sentence boundaries as specified by `type`. The starting and ending offsets of the resulting substring are returned in `startOffset` and `endOffset`. By definition, if such a substring exists, `endOffset` is less than or equal to `offset`.

Parameters:

  | offset | the offset from which the substring search begins.
  | type | the text-boundary delimiter which determines whether the returned text constitures a character, word, line, or sentence (and possibly attendant whitespace), and whether the start or ending of such a substring forms the boundary condition.
  | startOffset | back-filled with the starting offset of the resulting substring, if one exists.
  | endOffset | back-filled with the offset of the character immediately following the resulting substring, if one exists.

See also:
  TEXT_BOUNDARY_TYPE

Returns:
  a string which is a substring of the text content of the object, delimited by the specified boundary condition.

boolean Accessibility::Text::removeSelection | ( | in long | selectionNum | ) |

Deselect the text contained in the specified selectionNum, if such a selection exists, otherwise do nothing. Removal of a non-existant selectionNum has no effect.

Returns:
  `True` if the selection was successfully removed, `False` otherwise.

boolean Accessibility::Text::setCaretOffset | ( | in long | offset | ) |

Programmatically move the text caret (visible or virtual, as above) to a given position.

Parameters:

  | offset | a long int indicating the desired character offset. Not all implementations of Text will honor setCaretOffset requests, so the return value below should be checked by the client.

Returns:
  `TRUE` if the request was carried out, or `FALSE` if the caret could not be moved to the requested position.

boolean Accessibility::Text::setSelection | ( | in long | selectionNum,
|  | in long | startOffset,
|  | in long | endOffset |
| ) |  |  |

Modify an existing selection's start or ending offset.

Calling setSelection for a selectionNum that is not already defined has no effect. The result of calling setSelection with a selectionNum greater than 0 for objects that do not include STATE_MULTISELECTABLE is undefined.

Parameters:

  | selectionNum | indicates which of a set of non-contiguous selections to modify.
  | startOffset | the new starting offset for the selection
  | endOffset | the new ending offset for the selection

Returns:
  `True` if the selection corresponding to selectionNum is successfully modified, `False` otherwise.

## Field Documentation

readonly attribute long Accessibility::Text::caretOffset

The current offset of the text caret in the Text object. This caret may be virtual, e.g. non-visual and notional-only, but if an onscreen representation of the caret position is visible, it will correspond to this offset. The caret offset is given as a character offset, as opposed to a byte offset into a text buffer or a column offset.

readonly attribute long Accessibility::Text::characterCount

The total current number of characters in the Text object, including whitespace and non-spacing characters.

The documentation for this interface was generated from the following file:

- /home/gnome-dev/src/at-spi/idl/Accessibility_Text.idl