/* InputMethodRequests.java -- handles text insertion via input methods
   Copyright (C) 2002, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package java.awt.im;

import java.awt.Rectangle;
import java.awt.font.TextHitInfo;
import java.text.AttributedCharacterIterator;
import java.text.AttributedCharacterIterator.Attribute;

/**
 * This interface handles requests made by input methods on text editing
 * components. A component must specify a handler for input methods that
 * implements this interface, and which supports one of two user interfaces:
 * <ul><li><em>on-the-spot</em>: composed text is shown in place</li>
 * <li><em>below-the-spot</em>: composed text is in a separate window,
 * usually below the main text window, until it is committed into place at
 * the insertion point, overwriting any selected text</li></ul>
 *
 * @author Eric Blake (ebb9@email.byu.edu)
 * @see Component#getInputMethodRequests()
 * @see InputMethodListener
 * @since 1.2
 * @status updated to 1.4
 */
public interface InputMethodRequests
{
  /**
   * Gets the location of a given offset of the text. This can be used to
   * position a composition window near the location of where the composed
   * text will be inserted.
   *
   * <p>If the component has composed text (from the most recent
   * InputMethodEvent), then offset 0 indicates the location of the first
   * character of this composed text. Otherwise, the offset is ignored, and
   * the location should be the beginning of the final line of selected
   * text (in horizontal left-to-right text, like English, this would be the
   * lower left corner of the selction; in vertical top-to-bottom text, like
   * Chinese, this would be the top right corner of the selection).
   *
   * <p>The location returned is a 0-thickness caret (either horizontal or
   * vertical, depending on text flow), mapped to absolute screen coordinates.
   *
   * @param offset offset within composed text, or null
   * @return the screen location of the caret at the offset
   */
  Rectangle getTextLocation(TextHitInfo offset);

  /**
   * Get the text offset for the given screen coordinate. The offset is
   * relative to the composed text, and the return is null if it is outside
   * the range of composed text. For example, this can be used to find
   * where a mouse click should pop up a text composition window.
   *
   * @param x the x screen coordinate
   * @param y the y screen coordinate
   * @return a text hit info describing the composed text offset
   */
  TextHitInfo getLocationOffset(int x, int y);

  /**
   * Gets the offset where the committed text exists in the text editing
   * component. This can be used to examine the text surrounding the insert
   * position.
   *
   * @return the offset of the insert position
   */
  int getInsertPositionOffset();

  /**
   * Gets an interator which provides access to the text and its attributes,
   * except for the uncommitted text. The input method may provide a list of
   * attributes it is interested in; and the iterator need not provide
   * information on the remaining attributes. If the attribute list is null,
   * the iterator must list all attributes.
   *
   * @param beginIndex the index of the first character in the iteration
   * @param endIndex the index of the last character in the iteration
   * @param attributes a list of attributes interested in, or null
   * @return an iterator over the region of text with its attributes
   */
  AttributedCharacterIterator getCommittedText(int beginIndex, int endIndex,
                                               Attribute[] attributes);

  /**
   * Gets the length of committed text.
   *
   * @return the number of committed characters
   */
  int getCommittedTextLength();

  /**
   * Gets the latest committed text, and removes it from the component's text
   * body. This allows an input method to provide an "Undo" command. In
   * general, this should only be supported immediately after a commit, and
   * not when other actions intervene; if not supported, simply return null.
   * The input method may provide a list of attributes it is interested in;
   * and the iterator need not provide information on the remaining attributes.
   * If the attribute list is null, the iterator must list all attributes.
   *
   * @param attributes a list of attributes interested in, or null
   * @return the latest committed text, or null
   */
  AttributedCharacterIterator cancelLatestCommittedText
    (Attribute[] attributes);

  /**
   * Gets the currently selected text. One use of this is to implement a
   * "Reconvert" feature in an input method, which modifies the selection
   * based on the text in the composition window. The input method may
   * provide a list of attributes it is interested in; and the iterator need
   * not provide information on the remaining attributes. If the attribute
   * list is null, the iterator must list all attributes.
   *
   * @param attributes a list of attributes interested in, or null
   * @return the current selection
   */
  AttributedCharacterIterator getSelectedText(Attribute[] attributes);
} // interface InputMethodRequests