gecko-dev/accessible/interfaces/nsIAccessibleText.idl

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

typedef long AccessibleTextBoundary;

interface nsIAccessible;
interface nsIArray;
interface nsIPersistentProperties;
interface nsIAccessibleTextRange;

[scriptable, builtinclass, uuid(a4cc7576-45bb-44c5-b347-d9cb3ca4de9f)]
interface nsIAccessibleText : nsISupports
{
  // In parameters for character offsets:
  //  -1 will be treated as the equal to the end of the text
  //  -2 will be treated as the caret position
  const int32_t TEXT_OFFSET_END_OF_TEXT = -1;
  const int32_t TEXT_OFFSET_CARET       = -2;

  // A single Unicode character. For a user-perceived character, see
  // BOUNDARY_CLUSTER.
  const AccessibleTextBoundary BOUNDARY_CHAR = 0;
  const AccessibleTextBoundary BOUNDARY_WORD_START = 1;
  const AccessibleTextBoundary BOUNDARY_WORD_END = 2;
  const AccessibleTextBoundary BOUNDARY_SENTENCE_START = 3; // don't use, deprecated
  const AccessibleTextBoundary BOUNDARY_SENTENCE_END = 4;  // don't use, deprecated
  const AccessibleTextBoundary BOUNDARY_LINE_START = 5;
  const AccessibleTextBoundary BOUNDARY_LINE_END = 6;
  const AccessibleTextBoundary BOUNDARY_PARAGRAPH = 7;
  // A grapheme cluster, AKA user-perceived character. This might consist of
  // multiple Unicode characters, but a user will perceive this as a single
  // character and it is treated as such by the caret, selection, etc.
  const AccessibleTextBoundary BOUNDARY_CLUSTER = 8;

  /**
   * The current current caret offset.
   * If set < 0 then caret will be placed  at the end of the text
   */
  attribute long caretOffset;

  void getCaretRect(out long x, out long y, out long width, out long height);

  readonly attribute long characterCount;
  readonly attribute long selectionCount;

    /**
      * String methods may need to return multibyte-encoded strings,
      * since some locales can't be encoded using 16-bit chars.
      * So the methods below might return UTF-16 strings, or they could
      * return "string" values which are UTF-8.
      */
  AString getText (in long startOffset, in long endOffset);

  AString getTextAfterOffset (in long offset,
                              in AccessibleTextBoundary boundaryType,
                              out long startOffset,
                              out long endOffset);

  AString getTextAtOffset (in long offset,
                           in AccessibleTextBoundary boundaryType,
                           out long startOffset,
                           out long endOffset);

  AString getTextBeforeOffset (in long offset,
                               in AccessibleTextBoundary boundaryType,
                               out long startOffset,
                               out long endOffset);

    /**
      * It would be better to return an unsigned long here,
      * to allow unicode chars > 16 bits
      */
  wchar getCharacterAtOffset (in long offset);

  /**
   * Get the accessible start/end offsets around the given offset,
   * return the text attributes for this range of text.
   *
   * @param  includeDefAttrs   [in] points whether text attributes applied to
   *                           the entire accessible should be included or not.
   * @param  offset            [in] text offset
   * @param  rangeStartOffset  [out] start offset of the range of text
   * @param  rangeEndOffset    [out] end offset of the range of text
   */
  nsIPersistentProperties getTextAttributes(in boolean includeDefAttrs,
                                            in long offset,
                                            out long rangeStartOffset,
                                            out long rangeEndOffset);

  /**
   * Return the text attributes that apply to the entire accessible.
   */
  readonly attribute nsIPersistentProperties defaultTextAttributes;

  /**
   * 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.
   *
   * @param offset - Index of the character for which to return its bounding
   *                  box. The valid range is 0..length.
   * @param x - X coordinate of the bounding box of the referenced character.
   * @param y - Y coordinate of the bounding box of the referenced character.
   * @param width - Width of the bounding box of the referenced character.
   * @param height - Height of the bounding box of the referenced character.
   * @param coordType - Specifies if the coordinates are relative to the screen
   *                    or to the parent window (see constants declared in
   *                    nsIAccessibleCoordinateType).
  */
  void getCharacterExtents (in long offset,
                            out long x,
                            out long y,
                            out long width,
                            out long height,
                            in unsigned long coordType);

  void getRangeExtents (in long startOffset,
                        in long endOffset,
                        out long x,
                        out long y,
                        out long width,
                        out long height,
                        in unsigned long coordType);

  /**
   * Get the text offset at the given point, or return -1
   * if no character exists at that point
   *
   * @param 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 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 coordType - Screen coordinates or window coordinates (see constants
   *                    declared in nsIAccessibleCoordinateType).
   * @return offset - Index of the character under the given point or -1 if
   *                  the point is invalid or there is no character under
   *                  the point.
   */
  long getOffsetAtPoint (in long x, in long y,
                         in unsigned long coordType);

  void getSelectionBounds (in long selectionNum,
                           out long startOffset,
                           out long endOffset);

  /**
   * Set the bounds for the given selection range.
   * A reverse range where the start offset is larger than the end offset is
   * acceptable. The caretOffset will be set to the endOffset argument.
   */
  void setSelectionBounds (in long selectionNum,
                           in long startOffset,
                           in long endOffset);

  void addSelection (in long startOffset, in long endOffset);

  void removeSelection (in long selectionNum);


  /**
   * Makes a specific part of string visible on screen.
   *
   * @param startIndex  0-based character offset
   * @param endIndex    0-based character offset - the offset of the
   *                    character just past the last character of the
   *                    string
   * @param scrollType  defines how to scroll (see nsIAccessibleScrollType for
   *                    available constants)
   */
  void scrollSubstringTo(in long startIndex, in long endIndex,
                         in unsigned long scrollType);

  /**
   * Moves the top left of a substring to a specified location.
   *
   * @param startIndex      0-based character offset
   * @param endIndex        0-based character offset - the offset of the
   *                        character just past the last character of
   *                        the string
   * @param coordinateType  specifies the coordinates origin (for available
   *                        constants refer to nsIAccessibleCoordinateType)
   * @param x               defines the x coordinate
   * @param y               defines the y coordinate
   */
  void scrollSubstringToPoint(in long startIndex, in long endIndex,
                              in unsigned long coordinateType,
                              in long x, in long y);

  /**
   * Return an array of disjoint ranges for selected text within the text control
   * or otherwise the document this accessible belongs to.
   */
  readonly attribute nsIArray selectionRanges;
};

/*
 Assumptions:

 Using wstring (UCS2) instead of string encoded in UTF-8.
 Multibyte encodings (or at least potentially multi-byte
 encodings) would be preferred for the reasons cited above.

 The following methods will throw an exception on failure
 (since not every text component will allow every operation):
 setSelectionBounds, addSelection, removeSelection, setCaretOffset.

 we assume that all text components support the idea of
 a caret offset, whether visible or "virtual".  If this
 isn't the case, caretOffset can be made readonly and
 a setCaretOffset method provided which throws an exception
 on failure (as with *selection methods above).
*/