AccessibleText.idl

/*************************************************************************
 *
 *  File Name (AccessibleText.idl)
 *
 *  IAccessible2 IDL Specification
 *
 *  Copyright (c) Linux Foundation 2007, 2008
 *  Copyright (c) IBM Corp. 2006
 *  Copyright (c) Sun Microsystems, Inc. 2000, 2006
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License version 2.1, as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 ************************************************************************/

import "objidl.idl";
import "oaidl.idl";
import "oleacc.idl";
import "IA2CommonTypes.idl";

/** A structure containing a substring and the start and end offsets in the enclosing string.
 
 IAccessibleText::newText and IAccessibleText::oldText return this struct.
*/
typedef struct IA2TextSegment {
  BSTR text;	///< A copy of a segment of text taken from an enclosing paragraph.
  long start;	///< Index of the first character of the segment in the enclosing text.  
  long end;		///< Index of the character following the last character of the segment in the enclosing text. 
} IA2TextSegment;

/** This enum defines values which specify a text boundary type.

 IA2_TEXT_BOUNDARY_SENTENCE is optional.  When a method doesn't implement this 
 method it must return S_FALSE.  Typically this feature would not be implemented
 by an application.  However, if the application developer was not satisfied with
 how screen readers have handled the reading of sentences this boundary type
 could be implemented and screen readers could use the application's version of a 
 sentence rather than the screen reader's.

 The rest of the boundary types must be supported.

 This enum is used in IAccessibleText::textBeforeOffset, IAccessibleText::textAtOffset,
 and IAccessibleText::textAfterOffset.
*/

enum IA2TextBoundaryType {
  IA2_TEXT_BOUNDARY_CHAR,		/**< Typically, a single character is returned.  In some cases more than
								 one character is returned, for example, when a document contains field
								 data such as a field containing a date, time, or footnote reference.
								 In this case the caret can move over several characters in one movement
								 of the caret.  Note that after the caret moves, the caret offset changes
								 by the number of characters in the field, e.g. by 8 characters in the 
								 following date: 03/26/07. */
  IA2_TEXT_BOUNDARY_WORD,		/**< The range provided matches the range observed when the application
								 processes the Ctrl + left arrow and Ctrl + right arrow key sequences.
								 Typically this is from the start of one word to the start of the next, but
								 various applications are inconsistent in the handling of the end of a line. */
  IA2_TEXT_BOUNDARY_SENTENCE,	///< Range is from start of one sentence to the start of another sentence.
  IA2_TEXT_BOUNDARY_PARAGRAPH,	///< Range is from start of one paragraph to the start of another paragraph.
  IA2_TEXT_BOUNDARY_LINE,		/**< Range is from start of one line to the start of another line. This
                                 often means that an end-of-line character will appear at the end of the
								 range. However in the case of some applications an end-of-line character
								 indicates the end of a paragraph and the lines composing the paragraph,
								 other than the last line, do not contain an end of line character. */
  IA2_TEXT_BOUNDARY_ALL			///< Using this value will cause all text to be returned.
};

/** @brief This interface gives read-only access to text.

 The %IAccessibleText interface should be implemented by all components 
  that present textual information on the display like  buttons, 
  text entry fields, or text portions of the document window.  The interface 
  provides access to the text's content, attributes, and spatial location.  
  However, text can not be modified with this interface.  That is the task 
  of the IAccessibleEditableText interface.
        
 The text length, i.e. the number of characters in the text, is
  returned by IAccessibleText::nCharacters. All methods that operate 
  on particular characters (e.g. IAccessibleText::textAtOffset) use character 
  indices from 0 to length-1. All methods that operate on character positions 
  (e.g. IAccessibleText::text) use indices from 0 to length.

 Please note that accessible text does not necessarily support selection.  
  In this case it should behave as if there where no selection.  An empty 
  selection is used for example to express the current cursor position.

 Refer to @ref _specialOffsets 
  "Special Offsets for use in the IAccessibleText and IAccessibleEditableText Methods" 
  for information about special offsets that can be used in %IAccessibleText methods.

 E_FAIL is returned in the following cases
 @li endOffset < startOffset
 @li endoffset > length
*/
[object, uuid(24FD2FFB-3AAD-4a08-8335-A3AD89C0FB4B)]
interface IAccessibleText : IUnknown
{

  /** @brief Adds a text selection
   @param [in] startOffset
    Starting offset ( 0 based).
   @param [in] endOffset
    Offset of first character after new selection (0 based).
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT addSelection
    (
     [in] long startOffset,
     [in] long endOffset
    );

  /** @brief Returns text attributes.
   @param [in] offset
    Text offset (0 based)
   @param [out] startOffset    
    The starting offset of the character range over which all text attributes match 
	those of offset. (0 based)
   @param [out] endOffset    
    The offset of the first character past the character range over which all text 
	attributes match those of offset. (0 based)
   @param [out] textAttributes  
    A string of attributes describing the text.  The attributes are described in the
    <a href="http://www.linuxfoundation.org/en/Accessibility/IAccessible2/TextAttributes">
    text attributes specification</a> on the %IAccessible2 web site.
   @retval S_OK
   @retval S_FALSE if there is nothing to return, [out] values are 0s and NULL respectively 
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s and NULL respectively 
        
  */
  [propget] HRESULT attributes
    (
     [in] long offset,	
     [out] long *startOffset,
     [out] long *endOffset,	
     [out, retval] BSTR *textAttributes
    );

  /** @brief Returns the position of the caret.

   Returns the 0-based offset of the caret within the text.  If the text is 
   implemented as a tree of text objects with embed characters in higher levels
   representing substrings of child text objects and the caret is in one of the 
   child text objects, then the offset in the higher level text object would be
   at the embed character representing child text object that contains the caret.

   For example, if the string "one two three" is implemented as a two text objects,
   with a top level text object containing an embed character "one ? three" and a
   child text object containing "two" and if the caret is in the descendant object
   just before the 'o' in "two", then:
   <ul>
   <li>the caretOffset for the "one ? three" object would be 4, matching the embed character</li>
   <li>the caretOffset for "two" would be 2, matching the "o"</li>
   </ul>
   The caret position/offset is that of the character logically following it, e.g.
   to the right of it in a left to right language.
   @param [out] offset
    The returned offset is relative to the text represented by this object.
   @retval S_OK
   @retval S_FALSE if the caret is not currently active on this object, i.e. the
    caret is located on some other object.  The returned offset value will be -1.
   @note S_FALSE (and an offset of -1) will not be returned if the caret is somewhere
   in the text object or one of its descendants. 
  */
  [propget] HRESULT caretOffset
    (
     [out, retval] long *offset
    );


  /** @brief Returns the bounding box of the specified position.
        
   The virtual character after the last character of the represented
    text, i.e. the one at position length is a special case. It represents the 
    current input position and will therefore typically be queried by AT more 
    often than other positions.  Because it does not represent an existing character 
    its bounding box is defined in relation to preceding characters.  It should be 
    roughly equivalent to the bounding box of some character when inserted at the 
    end of the text.  Its height typically being the maximal height of all the
    characters in the text or the height of the preceding character, its width being 
    at least one pixel so that the bounding box is not degenerate.

   Note that the index 'length' is not always valid.  Whether it is or not is 
    implementation dependent.  It typically is when text is editable or otherwise 
    when on the screen the caret can be placed behind the text.  You can be sure 
    that the index is valid after you have received a ::IA2_EVENT_TEXT_CARET_MOVED
    event for this index.
   @param [in] offset
    Index of the character for which to return its bounding box. The valid range 
    is 0..length.
   @param [in] coordType
    Specifies if the coordinates are relative to the screen or to the parent window.
   @param [out] x
    X coordinate of the top left corner of the bounding box of the referenced character. 
   @param [out] y
    Y coordinate of the top left corner of the bounding box of the referenced character. 
   @param [out] width
    Width of the bounding box of the referenced character. 
   @param [out] height
    Height of the bounding box of the referenced character. 
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s 
  */
  [propget] HRESULT characterExtents
    (
     [in] long offset,
     [in] enum IA2CoordinateType coordType,
     [out] long *x,
     [out] long *y,
     [out] long *width,
     [out, retval] long *height
    );


  /** @brief Returns the number of active non-contiguous selections
   @param [out] nSelections
   @retval S_OK
  */
  [propget] HRESULT nSelections
    (
     [out, retval] long *nSelections
    );

  /** @brief Returns the text position for the specified screen position.
    
   Given a point return the zero-based index of the character under that
   point.  The same functionality could be achieved by using the bounding
   boxes for each character as returned by IAccessibleText::characterExtents.
   The method IAccessibleText::offsetAtPoint, however, can be implemented 
   more efficiently.
            
   @param [in] x
    The position's x value for which to look up the index of the character that
	is rendered on to the display at that point.
   @param [in] y
    The position's y value for which to look up the index of the character that
	is rendered on to the display at that point.            
   @param [in] coordType
    Screen coordinates or window coordinates.
   @param [out] offset
    Index of the character under the given point or -1 if the point
    is invalid or there is no character under the point.
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed, [out] value is 0 
    */
  [propget] HRESULT offsetAtPoint
    (
     [in] long x,
     [in] long y,
     [in] enum IA2CoordinateType coordType,
     [out, retval] long *offset
    );

  /** @brief Returns the character offsets of Nth active text selection
   @param [in] selectionIndex
    Index of selection (0 based).
   @param [out] startOffset
    0 based offset of first selected character
   @param [out] endOffset
    0 based offset of one past the last selected character.
   @retval S_OK
   @retval S_FALSE if there is nothing to return, [out] values are 0s 
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s 
  */
  [propget] HRESULT selection
    (
     [in] long selectionIndex,
     [out] long *startOffset,
     [out, retval] long *endOffset
    );

  /** @brief Returns the substring between the two given indices.

   The substring starts with the character at startOffset (inclusive) and up to 
    the character at endOffset (exclusive), if startOffset is less or equal 
    endOffste.  If endOffset is lower than startOffset, the result is the same 
    as a call with the two arguments being exchanged.

   The whole text can be requested by passing the indices zero and 
    IAccessibleText::nCharacters. If both indices have the same value, an empty 
	string is returned.
   @param [in] startOffset
    Index of the first character to include in the returned string. The valid range 
    is 0..length.
   @param [in] endOffset
    Index of the last character to exclude in the returned string. The valid range 
    is 0..length.
   @param [out] text
    Returns the substring starting with the character at startOffset (inclusive) 
    and up to the character at endOffset (exclusive), if startOffset is less than 
    or equal to endOffset.
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed, [out] value is NULL
   @note The returned string may be longer than endOffset-startOffset bytes if text 
   contains multi-byte characters.
  */
  [propget] HRESULT text
    (
     [in] long startOffset,
     [in] long endOffset,
     [out, retval] BSTR *text
    );

  /** @brief Returns a text portion before the given position.
    
   Returns the substring of the specified text type that is located before the 
    given character and does not include it. The result of this method should be 
    same as a result for IAccessibleText::textAtOffset with a suitably decreased 
    index value.

   For example, if text type is ::IA2_TEXT_BOUNDARY_WORD, then the complete 
    word that is closest to and located before offset is returned.

   If the index is valid, but no suitable word (or other boundary type) is found, a
    NULL pointer is returned.

   @param [in] offset
    Index of the character for which to return the text part before it.  The index 
    character will not be part of the returned string. The valid range is 0..length.
   @param [in] boundaryType
    The type of the text portion to return.  See ::IA2TextBoundaryType for the 
	complete list.
   @param [out] startOffset
    0 based offset of first character.
   @param [out] endOffset
    0 based offset of one past the last character.
   @param [out] text
    Returns the requested text portion.  This portion may be empty or invalid when 
    no appropriate text portion is found or text type is invalid.
   @retval S_OK
   @retval S_FALSE if the requested boundary type is not implemented, such as 
    ::IA2_TEXT_BOUNDARY_SENTENCE, or if there is nothing to return; 
	[out] values are 0s and NULL respectively 
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s and NULL respectively 
  */
  [propget] HRESULT textBeforeOffset
    (
     [in] long offset,
     [in] enum IA2TextBoundaryType boundaryType,
     [out] long *startOffset,
     [out] long *endOffset,
     [out, retval] BSTR *text
    );

  /** @brief Returns a text portion after the given position.
    
   Returns the substring of the specified text type that is located after the 
    given character and does not include it. The result of this method should be 
    same as a result for IAccessibleText::textAtOffset with a suitably increased 
    index value.

   For example, if text type is ::IA2_TEXT_BOUNDARY_WORD, then the complete 
    word that is closest to and located after offset is returned.

   If the index is valid, but no suitable word (or other text type) is found, a 
    NULL pointer is returned.

   @param [in] offset
    Index of the character for which to return the text part before it.  The index 
    character will not be part of the returned string. The valid range is 0..length.
   @param [in] boundaryType
    The type of the text portion to return.  See ::IA2TextBoundaryType for the complete 
    list.
   @param [out] startOffset
    0 based offset of first character.
   @param [out] endOffset
    0 based offset of one past the last character.
   @param [out] text
    Returns the requested text portion.  This portion may be empty or invalid when 
    no appropriate text portion is found or text type is invalid.
   @retval S_OK
   @retval S_FALSE if the requested boundary type is not implemented, such as 
    ::IA2_TEXT_BOUNDARY_SENTENCE, or if there is nothing to return; 
	[out] values are 0s and NULL respectively 
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s and NULL respectively 
  */
  [propget] HRESULT textAfterOffset
    (
     [in] long offset,
     [in] enum IA2TextBoundaryType boundaryType,
     [out] long *startOffset,
     [out] long *endOffset,
     [out, retval] BSTR *text
    );

  /** @brief Returns a text portion that spans the given position.
    
   Returns the substring of the specified text type at the specified offset.

   If the index is valid, but no suitable word (or other text type) is found, a 
    NULL pointer is returned.

   @param [in] offset
    Index of the character for which to return the text part before it.  The index 
    character will not be part of the returned string. The valid range is 0..length.
   @param [in] boundaryType
    The type of the text portion to return.  See ::IA2TextBoundaryType for the complete 
    list.
   @param [out] startOffset
    0 based offset of first character.
   @param [out] endOffset
    0 based offset of one past the last character.
   @param [out] text
    Returns the requested text portion.  This portion may be empty or invalid when 
    no appropriate text portion is found or text type is invalid.
   @retval S_OK
   @retval S_FALSE if the requested boundary type is not implemented, such as 
    ::IA2_TEXT_BOUNDARY_SENTENCE, or if there is nothing to return; 
	[out] values are 0s and NULL respectively 
   @retval E_INVALIDARG if bad [in] passed, [out] values are 0s and NULL respectively 
  */
  [propget] HRESULT textAtOffset
    (
     [in] long offset,
     [in] enum IA2TextBoundaryType boundaryType,
     [out] long *startOffset,
     [out] long *endOffset,
     [out, retval] BSTR *text
    );

  /** @brief Unselects a range of text.
   @param [in] selectionIndex
    Index of selection to remove (0 based).
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT removeSelection
    (
     [in] long selectionIndex
    );

  /** @brief Sets the position of the caret.

   The caret position/offset is that of the character logically following it,
   e.g. to the right of it in a left to right language.

   Setting the caret position may or may not alter the current selection.  A 
    change of the selection is notified to the accessibility event listeners with 
    an ::IA2_EVENT_TEXT_SELECTION_CHANGED event.

   When the new caret position differs from the old one (which, of course, is the 
    standard case) this is notified to the accessibility event listeners with an
    ::IA2_EVENT_TEXT_CARET_MOVED event.
   @param [in] offset
    The new index of the caret.  This caret is actually placed to the left side of 
    the character with that index.  An index of 0 places the caret so that the next 
    insertion goes before the first character.  An index of IAccessibleText::nCharacters 
	leads to insertion after the last character.
   @retval S_OK
   @retval E_FAIL if the caret cannot be set
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT setCaretOffset
    (
     [in] long offset
    );

  /** @brief Changes the bounds of an existing selection.
   @param [in] selectionIndex
    Index of selection to change (0 based)
   @param [in] startOffset
    New starting offset (0 based)
   @param [in] endOffset
    New ending offset (0 based) - the offset of the character just past the last character of the selection.
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT setSelection
    (
     [in] long selectionIndex,
     [in] long startOffset,
     [in] long endOffset
    );

  /** @brief Returns total number of characters.

   Note that this may be different than the total number of bytes required to store the 
    text, if the text contains multi-byte characters.
   @param [out] nCharacters
   @retval S_OK
  */
  [propget] HRESULT nCharacters
    (
     [out, retval] long *nCharacters
    );

  /** @brief Makes a specific part of string visible on screen.
   @param [in] startIndex
    0 based character offset.
   @param [in] endIndex
    0 based character offset - the offset of the character just past the last character of the string.
   @param [in] scrollType
    Defines where the object should be placed on the screen.
   @retval S_OK
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT scrollSubstringTo
    (
     [in] long startIndex,
     [in] long endIndex,
	 [in] enum IA2ScrollType scrollType
    );

  /** @brief Moves the top left of a substring to a specified location.

   @param [in] startIndex
    0 based character offset.
   @param [in] endIndex
    0 based character offset - the offset of the character just past the last character of the string.
   @param [in] coordinateType
    Specifies whether the coordinates are relative to the screen or the parent object.
   @param [in] x
    Defines the x coordinate.
   @param [in] y
    Defines the y coordinate.
   @retval S_OK
   @retval S_FALSE if the object is already at the specified location.
   @retval E_INVALIDARG if bad [in] passed
  */
  HRESULT scrollSubstringToPoint
    (
     [in] long startIndex,
     [in] long endIndex,
     [in] enum IA2CoordinateType coordinateType,
	 [in] long x,
	 [in] long y 
    );

  /** @brief Returns any inserted text.

   Provided for use by the ::IA2_EVENT_TEXT_INSERTED and ::IA2_EVENT_TEXT_UPDATED 
    event handlers.

   This data is only guaranteed to be valid while the thread notifying the event 
   continues. Once the handler has returned, the validity of the data depends on 
   how the server manages the life cycle of its objects. Also, note that the server 
   may have different life cycle management strategies for controls depending on 
   whether or not a control manages its children. Lists, trees, and tables can have 
   a large number of children and thus it's possible that the child objects for those 
   controls would only be created as needed. Servers should document their life cycle 
   strategy as this will be of interest to assistive technology or script engines 
   accessing data out of process or from other threads. Servers only need to save the 
   last inserted block of text and a scope of the entire application is adequate.

   @param [out] newText
    The text that was just inserted.
   @retval S_OK
   @retval S_FALSE if there is nothing to return, [out] value is NULL
  */
  [propget] HRESULT newText
    (
	 [out, retval] IA2TextSegment *newText
	);

  /** @brief Returns any removed text.

   Provided for use by the IA2_EVENT_TEXT_REMOVED/UPDATED event handlers.
   
   This data is only guaranteed to be valid while the thread notifying the event 
   continues. Once the handler has returned, the validity of the data depends on 
   how the server manages the life cycle of its objects. Also, note that the server 
   may have different life cycle management strategies for controls depending on 
   whether or not a control manages its children. Lists, trees, and tables can have 
   a large number of children and thus it's possible that the child objects for those 
   controls would only be created as needed. Servers should document their life cycle 
   strategy as this will be of interest to assistive technology or script engines 
   accessing data out of process or from other threads. Servers only need to save the 
   last removed block of text and a scope of the entire application is adequate.

   @param [out] oldText
    The text that was just removed.
   @retval S_OK
   @retval S_FALSE if there is nothing to return, [out] value is NULL
  */
  [propget] HRESULT oldText
    (
	 [out, retval] IA2TextSegment *oldText
	);

}