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/* -*- Mode: IDL; 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"

interface mozIDOMWindow;
interface nsITextInputProcessorCallback;

webidl Event;

/**
 * An nsITextInputProcessor instance is associated with a top level widget which
 * handles native IME.  It's associated by calling beginInputTransaction() or
 * beginInputTransactionForTests().  While an instance has composition, nobody
 * can steal the rights to make composition on the top level widget.  In other
 * words, if another instance is composing on a top level widget, either
 * beginInputTransaction() or beginInputTransactionForTests() returns false
 * (i.e., not throws an exception).
 *
 * NOTE: See nsITextInputProcessorCallback.idl for examples of |callback| in
 *       following examples,
 *
 * Example #1 JS-IME can start composition like this:
 *
 *   var TIP = Components.classes["@mozilla.org/text-input-processor;1"].
 *               createInstance(Components.interfaces.nsITextInputProcessor);
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   // Create a keyboard event if the following compositionc change is caused
 *   // by a key event.
 *   var keyEvent =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // Set new composition string first
 *   TIP.setPendingCompositionString("some-words-are-inputted");
 *   // Set clause information.
 *   TIP.appendClauseToPendingComposition(23, TIP.ATTR_RAW_CLAUSE);
 *   // Set caret position, this is optional.
 *   TIP.setCaretInPendingComposition(23);
 *   // Flush the pending composition
 *   if (!TIP.flushPendingComposition(keyEvent)) {
 *     // If it returns false, it fails to start composition.
 *     return;
 *   }
 *
 * Example #2 JS-IME can separate composition string to two or more clauses:
 *
 *   // Create a keyboard event if the following compositionc change is caused
 *   // by a key event.
 *   var keyEvent =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // First, set composition string again
 *   TIP.setPendingCompositionString("some-words-are-inputted");
 *   // Then, if "are" is selected to convert, there are 3 clauses:
 *   TIP.appendClauseToPendingComposition(11, TIP.ATTR_CONVERTED_CLAUSE);
 *   TIP.appendClauseToPendingComposition(3,  TIP.ATTR_SELECTED_CLAUSE);
 *   TIP.appendClauseToPendingComposition(9,  TIP.ATTR_CONVERTED_CLAUSE);
 *   // Show caret at the beginning of the selected clause
 *   TIP.setCaretInPendingComposition(11);
 *   // Flush the pending composition.  Note that if there is a composition,
 *   // flushPendingComposition() won't return false.
 *   TIP.flushPendingComposition(keyEvent);
 *
 * Example #3 JS-IME can commit composition with specific string with this:
 *
 *   // Create a keyboard event if the following compositionc change is caused
 *   // by a key event.
 *   var keyEvent1 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-directly-inputted");
 *   TIP.appendClauseToPendingComposition(28, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition(keyEvent1);
 *   // Create a keyboard event if the following commit composition is caused
 *   // by a key event.
 *   var keyEvent2 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // This is useful when user selects a commit string from candidate list UI
 *   // which is provided by JS-IME.
 *   TIP.commitCompositionWith("selected-words-from-candidate-list", keyEvent2);
 *
 * Example #4 JS-IME can commit composition with the last composition string
 *            without specifying commit string:
 *
 *   // Create a keyboard event if the following compositionc change is caused
 *   // by a key event.
 *   var keyEvent1 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-will-be-commited");
 *   TIP.appendClauseToPendingComposition(27, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition(keyEvent1);
 *   // Create a keyboard event if the following commit is caused by a key
 *   // event.
 *   var keyEvent2 =
 *     new KeyboardEvent("", { key: "Enter", code: "Enter",
                               keyCode: KeyboardEvent.DOM_VK_RETURN });
 *   // This is useful when user just type Enter key.
 *   TIP.commitComposition(keyEvent2);
 *
 * Example #5 JS-IME can cancel composition with this:
 *
 *   // Create a keyboard event if the following composition change is caused
 *   // by a key event.
 *   var keyEvent1 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-will-be-canceled");
 *   TIP.appendClauseToPendingComposition(27, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition(keyEvent1);
 *   // Create a keyboard event if the following canceling composition is
 *   // caused by a key event.
 *   var keyEvent2 =
 *     new KeyboardEvent("", { key: "Escape", code: "Escape",
                               keyCode: KeyboardEvent.DOM_VK_ESCAPE });
 *   // This is useful when user doesn't want to commit the composition.
 *   // FYI: This is same as TIP.commitCompositionWith("") for now.
 *   TIP.cancelComposition(keyEvent2);
 *
 * Example #6 JS-IME can insert text only with commitCompositionWith():
 *
 *   // Create a keyboard event if the following inserting text is caused by a
 *   // key event.
 *   var keyEvent1 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   TIP.commitCompositionWith("Some words", keyEvent1);
 *
 * Example #7 JS-IME can start composition explicitly:
 *
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   // Create a keyboard event if the following starting composition is caused
 *   // by a key event.
 *   var keyEvent1 =
 *     new KeyboardEvent("", { key: "foo", code: "bar", keyCode: buzz });
 *   // If JS-IME don't want to show composing string in the focused editor,
 *   // JS-IME can dispatch only compositionstart event with this.
 *   if (!TIP.startComposition(keyEvent1)) {
 *     // Failed to start composition.
 *     return;
 *   }
 *   // And when user selects a result from UI of JS-IME, commit with it.
 *   // Then, the key event should be null.
 *   TIP.commitCompositionWith("selected-words");
 *
 * Example #8 JS-IME or JS-Keyboard should dispatch key events even during
 *            composition (non-printable key case):
 *
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to dispatch key events
 *   }
 *
 *   // You don't need to specify .keyCode value if it's non-printable key
 *   // because it can be computed from .key value.
 *   // If you specify non-zero value to .keyCode, it'll be used.
 *   var keyEvent = new KeyboardEvent("", { code: "Enter", key: "Enter" });
 *   if (TIP.keydown(keyEvent)) {
 *     // Handle its default action
 *   }
 *
 *   // Even if keydown event was consumed, keyup event should be dispatched.
 *   if (TIP.keyup(keyEvent)) {
 *     // Handle its default action
 *   }
 *
 * Example #9 JS-IME or JS-Keyboard should dispatch key events even during
 *            composition (printable key case):
 *
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to dispatch key events
 *   }
 *
 *   // You need to specify .keyCode value if it's printable key.
 *   // The rules of .keyCode value is documented in MDN:
 *   //   https://developer.mozilla.org/docs/Web/API/KeyboardEvent.keyCode
 *   //
 *   //   #1 If the key location is DOM_KEY_LOCATION_NUMPAD and NumLock is
 *   //      active, you should specify DOM_VK_NUMPAD[0-9], DOM_VK_MULTIPLY,
 *   //      DOM_VK_ADD, DOM_VK_SEPARATOR, DOM_VK_SUBTRACT, DOM_VK_DECIMAL or
 *   //      DOM_VK_DIVIDE.
 *   //   #2 If the key is Spacebar, use DOM_VK_SPACE.
 *   //
 *   //   Following rules are printable keys in DOM_KEY_LOCATION_STANDARD.
 *   //   .keyCode value for a key shouldn't be changed by modifier states:
 *   //     #1 If the key can input [0-9] with any modifier state (except
 *   //        NumLock state), the value should be DOM_VK_[0-9].
 *   //     #2 Otherwise, and if the key inputs an ASCII alphabet with no
 *   //        active modifiers, use DOM_VK_[A-Z].
 *   //     #3 Otherwise, and if the key inputs an ASCII alphabet with no
 *   //        active modifiers except Shift key state, use DOM_VK_[A-Z] for
 *   //        the shifted character.  E.g., if a key causes non-alphabet
 *   //        character such as "@" or a Unicode character without Shift key
 *   //        but "a" is inputted when Shift key is pressed, the proper
 *   //        keyCode is DOM_VK_A.
 *   //     #4 Otherwise, and if the key inputs another ASCII character with
 *   //        no modifier states, use a proper value for the character.  E.g.,
 *   //        if the key inputs "*" without Shift key state, it should be
 *   //        DOM_VK_ASTERISK.
 *   //     #5 Otherwise, and if the key inputs another ASCII character with
 *   //        Shift key state, use a proper value for the character.  E.g.,
 *   //        if a key causes a Unicode character without Shift key but "&"
 *   //        is inputted when Shift key is pressed, the proper keyCode is
 *   //        DOM_VK_AMPERSAND.
 *   //     See above document for the other cases.
 *   //
 *   // NOTE: If the software keyboard is 10-key like simple phone,
 *   //       We don't have common rules to decide its .keyCode value.
 *   //       Above rules should be used when the JS-Keyboard emulates PC
 *   //       keyboard.
 *   // .key value should be inputting character by the key with current
 *   // modifier state.
 *   // .code value should be empty string if the JS-Keyboard isn't emulating
 *   // physical keyboard.  Otherwise, use same value with physical keyboard's
 *   // same key.
 *   var keyEvent = new KeyboardEvent("", { code: "KeyA", key: "a",
 *                                          keyCode: KeyboardEvent.DOM_VK_A });
 *   if (TIP.keydown(keyEvent)) {
 *     // Handle its default action
 *   }
 *
 *   // Even if keydown event was consumed, keyup event should be dispatched.
 *   if (TIP.keyup(keyEvent)) {
 *     // Handle its default action
 *   }
 *
 * Example #10 JS-Keyboard doesn't need to initialize modifier states at
 *             calling either keydown() or keyup().
 *
 *   // Neither beginInputTransaction() nor beginInputTransactionForTests()
 *   // resets modifier state.
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to dispatch key events
 *   }
 *
 *   var leftShift = new KeyboardEvent("", { code: "ShiftLeft", key: "Shift" });
 *
 *   // This causes following key events will be shifted automatically.
 *   TIP.keydown(leftShift);
 *
 *   var rightShift =
 *     new KeyboardEvent("", { code: "ShiftRight", key: "Shift" });
 *
 *   TIP.keydown(rightShift);
 *
 *   // keyup of one of shift key doesn't cause inactivating "Shift" state.
 *   TIP.keyup(rightShift);
 *
 *   // This causes inactivating "Shift" state completely.
 *   TIP.keyup(leftShift);
 */

[scriptable, builtinclass, uuid(47ae2181-2e98-4d58-84a2-b8db6764ce9a)]
interface nsITextInputProcessor : nsISupports
{
  /**
   * Returns true if this instance was dispatched compositionstart but hasn't
   * dispatched compositionend yet.
   */
  readonly attribute boolean hasComposition;

  /**
   * When you create an instance, you must call beginInputTransaction() first
   * except when you created the instance for automated tests.
   *
   * @param aWindow         A DOM window.  The instance will look for a top
   *                        level widget from this.
   * @param aCallback       Callback interface which handles requests to
   *                        IME and notifications to IME.  This must not be
   *                        null.
   * @return                If somebody uses internal text input service for a
   *                        composition, this returns false.  Otherwise, returns
   *                        true.  I.e., only your TIP can create composition
   *                        when this returns true.  If this returns false,
   *                        your TIP should wait next chance.
   */
  boolean beginInputTransaction(in mozIDOMWindow aWindow,
                                in nsITextInputProcessorCallback aCallback);

  /**
   * When you create an instance for automated test, you must call
   * beginInputTransaction(), first.  See beginInputTransaction() for more
   * detail of this.
   * Note that aCallback can be null.  If it's null, nsITextInputProcessor
   * implementation will handle them automatically.
   */
  [optional_argc] boolean
    beginInputTransactionForTests(
      in mozIDOMWindow aWindow,
      [optional] in nsITextInputProcessorCallback aCallback);

  /**
   * startComposition() dispatches compositionstart event explicitly.
   * IME does NOT need to call this typically since compositionstart event
   * is automatically dispatched by sendPendingComposition() if
   * compositionstart event hasn't been dispatched yet.  If this is called
   * when compositionstart has already been dispatched, this throws an
   * exception.
   *
   * @param aKeyboardEvent  Key event which causes starting composition.
   *                        If its type value is "keydown", this method
   *                        dispatches only keydown event first.  Otherwise,
   *                        dispatches keydown first and keyup at last.
   *                        key value and keyCode values of keydown event
   *                        are set to "Process" and DOM_VK_PROCESSKEY
   *                        automatically.  You can prevent this behavior
   *                        with KEY_DONT_MARK_KEYDOWN_AS_PROCESSED.
   * @param aKeyFlags       See KEY_* constants.
   * @return                Returns true if composition starts normally.
   *                        Otherwise, returns false because it might be
   *                        canceled by the web application.
   */
  [optional_argc]
    boolean startComposition([optional] in Event aKeyboardEvent,
                             [optional] in unsigned long aKeyFlags);

  /**
   * Set new composition string.  Pending composition will be flushed by
   * a call of flushPendingComposition().  However, if the new composition
   * string isn't empty, you need to call appendClauseToPendingComposition() to
   * fill all characters of aString with one or more clauses before flushing.
   * Note that if you need to commit or cancel composition, use
   * commitComposition(), commitCompositionWith() or cancelComposition().
   */
  void setPendingCompositionString(in AString aString);

  // ATTR_RAW_CLAUSE means that the clause hasn't been selected nor converted
  // yet.
  const unsigned long ATTR_RAW_CLAUSE           = 0x02;
  // ATTR_SELECTED_RAW_CLAUSE means that the clause hasn't been converted yet
  // but is selected for converting to the other string.
  const unsigned long ATTR_SELECTED_RAW_CLAUSE  = 0x03;
  // ATTR_CONVERTED_CLAUSE means that the clause has already been converted but
  // is not selected.  This does NOT mean that this clause isn't modifiable.
  const unsigned long ATTR_CONVERTED_CLAUSE     = 0x04;
  // ATTR_SELECTED_CLAUSE means that the clause has already been converted and
  // is selected.  In other words, the clause is being converted.
  const unsigned long ATTR_SELECTED_CLAUSE      = 0x05;

  /**
   * Append a clause to the pending composition.
   *
   * If you need to fill the pending composition string with a clause, you
   * should call this once.  For example:
   *   appendClauseToPendingComposition(compositionString.length,
   *                                    ATTR_RAW_CLAUSE);
   * is enough.  If you need to separate the pending composition string to
   * multiple clauses, you need to call this multiple times. For example,
   * if your pending composition string has three clauses and the second clause
   * is being converted:
   *  appendClauseToPendingComposition(firstClauseLength,
   *                                   ATTR_CONVERTED_CLAUSE);
   *  appendClauseToPendingComposition(secondClauseLength,
   *                                   ATTR_SELECTED_CLAUSE);
   *  appendClauseToPendingComposition(thirdClauseLength,
   *                                   ATTR_CONVERTED_CLAUSE);
   * Note that if sum of aLength mismatches length of the pending composition
   * string, flushPendingComposition() will throw an exception.  I.e.,
   * |firstClauseLength + secondClauseLength + thirdClauseLength| must be
   * same as the length of pending composition string.
   *
   * TODO: Should be able to specify custom clause style.
   *
   * @param aLength         Length of the clause.
   * @param aAttribute      One of ATTR_* constants.
   */
  void appendClauseToPendingComposition(in unsigned long aLength,
                                        in unsigned long aAttribute);

  /**
   * Set caret offset in the pending composition string.  If you don't need to
   * show a caret, you don't need to call this.
   *
   * @param aOffset         Caret offset in the pending composition string.
   *                        This must be between 0 and length of the pending
   *                        composition string.
   */
  void setCaretInPendingComposition(in unsigned long aOffset);

  /**
   * flushPendingComposition() must be called after
   * setPendingCompositionString() and appendClauseToPendingComposition()
   * (setCaretInPendingComposition() is optional) are called.
   *
   * Note that compositionstart will be automatically dispatched if this is
   * called when there is no composition.
   *
   * Note that if sum of lengths of appended clauses are not same as composition
   * string or caret offset is larger than the composition string length, this
   * throws an exception.
   *
   * @param aKeyboardEvent  Key event which causes the composition string.
   *                        If its type value is "keydown", this method
   *                        dispatches only keydown event first.  Otherwise,
   *                        dispatches keydown first and keyup at last.
   *                        key value and keyCode values of keydown event
   *                        are set to "Process" and DOM_VK_PROCESSKEY
   *                        automatically.  You can prevent this behavior
   *                        with KEY_DONT_MARK_KEYDOWN_AS_PROCESSED.
   * @param aKeyFlags       See KEY_* constants.
   * @return                Returns true if there is a composition already or
   *                        starting composition automatically.
   *                        Otherwise, i.e., if it cannot start composition
   *                        automatically, e.g., canceled by web apps, returns
   *                        false.
   */
  [optional_argc]
    boolean flushPendingComposition(
      [optional] in Event aKeyboardEvent,
      [optional] in unsigned long aKeyFlags);

  /**
   * commitComposition() will commit composition with the last composition
   * string.  If there is no composition, this will throw an exception.
   *
   * @param aKeyboardEvent  Key event which causes the commit composition.
   *                        If its type value is "keydown", this method
   *                        dispatches only keydown event first.  Otherwise,
   *                        dispatches keydown first and keyup at last.
   *                        key value and keyCode values of keydown event
   *                        are set to "Process" and DOM_VK_PROCESSKEY
   *                        automatically.  You can prevent this behavior
   *                        with KEY_DONT_MARK_KEYDOWN_AS_PROCESSED.
   * @param aKeyFlags       See KEY_* constants.
   */
  [optional_argc]
    void commitComposition([optional] in Event aKeyboardEvent,
                           [optional] in unsigned long aKeyFlags);

  /**
   * commitCompositionWith() will commit composition with the specific string.
   * If there is no composition, this will start composition and commit it
   * with the specified string.
   *
   * @param aCommitString   The string to be committed.
   * @param aKeyboardEvent  Key event which causes the commit composition.
   *                        If its type value is "keydown", this method
   *                        dispatches only keydown event first.  Otherwise,
   *                        dispatches keydown first and keyup at last.
   *                        key value and keyCode values of keydown event
   *                        are set to "Process" and DOM_VK_PROCESSKEY
   *                        automatically.  You can prevent this behavior
   *                        with KEY_DONT_MARK_KEYDOWN_AS_PROCESSED.
   * @param aKeyFlags       See KEY_* constants.
   * @return                Returns true if there is a composition already or
   *                        starting composition automatically.
   *                        Otherwise, i.e., if it cannot start composition
   *                        automatically, e.g., canceled by web apps, returns
   *                        false.
   */
  [optional_argc]
    boolean commitCompositionWith(in AString aCommitString,
                                  [optional] in Event aKeyboardEvent,
                                  [optional] in unsigned long aKeyFlags);

  /**
   * cancelComposition() will cancel composition.  This is for now the same as
   * calling commitComposition("").  However, in the future, this might work
   * better.  If your IME needs to cancel composition, use this instead of
   * commitComposition().
   *
   * Note that if you tries to cancel composition when there is no composition,
   * this throws an exception.
   *
   * @param aKeyboardEvent  Key event which causes the canceling composition.
   *                        If its type value is "keydown", this method
   *                        dispatches only keydown event first.  Otherwise,
   *                        dispatches keydown first and keyup at last.
   *                        key value and keyCode values of keydown event
   *                        are set to "Process" and DOM_VK_PROCESSKEY
   *                        automatically.  You can prevent this behavior
   *                        with KEY_DONT_MARK_KEYDOWN_AS_PROCESSED.
   * @param aKeyFlags       See KEY_* constants.
   */
  [optional_argc]
    void cancelComposition([optional] in Event aKeyboardEvent,
                           [optional] in unsigned long aKeyFlags);

  // Specifying KEY_DEFAULT_PREVENTED can dispatch key events whose
  // defaultPrevented are true.  Note that if this is specified, keypress event
  // won't be fired.
  const unsigned long KEY_DEFAULT_PREVENTED                        = 0x00000001;
  // If KEY_NON_PRINTABLE_KEY is specified and the .key value isn't valid
  // key name, the methods will throws an exception.  In other words, this
  // flag prevents to dispatch key events with wrong key values and to cause
  // such key events input the key values as text.
  const unsigned long KEY_NON_PRINTABLE_KEY                        = 0x00000002;
  // If KEY_FORCE_PRINTABLE_KEY is specified and even if the .key value is a
  // registered key name, it's treated as inputting text value.
  const unsigned long KEY_FORCE_PRINTABLE_KEY                      = 0x00000004;
  // If KEY_KEEP_KEY_LOCATION_STANDARD is specified when its .location is not
  // initialized or initialized with 0, the value isn't computed with .code
  // value.  Note that if .location is initialized with non-zero value,
  // this flag causes throwing an exception.
  // NOTE: This is not recommended to use except for tests.
  const unsigned long KEY_KEEP_KEY_LOCATION_STANDARD               = 0x00000008;
  // If KEY_KEEP_KEYCODE_ZERO is specified when its .keyCode is not initialized
  // or initialized with 0, the value isn't computed with .key value when it
  // represents non-printable key.  Note that if .keyCode is initialized with
  // non-zero value, this flag causes throwing an exception.
  const unsigned long KEY_KEEP_KEYCODE_ZERO                        = 0x00000010;
  // If KEY_DONT_DISPATCH_MODIFIER_KEY_EVENT is specified when the key event is
  // a modifier key's, keydown() and keyup() only modifies its modifier state
  // without dispatching key events.  This is useful for testing odd behavior
  // or emulating legacy API behavior.
  const unsigned long KEY_DONT_DISPATCH_MODIFIER_KEY_EVENT         = 0x00000020;
  // If KEY_DONT_MARK_KEYDOWN_AS_PROCESSED is specified, key value and keyCode
  // value of keydown event are not changed to "Process" and DOM_VK_PROCESSKEY.
  const unsigned long KEY_DONT_MARK_KEYDOWN_AS_PROCESSED           = 0x00000040;
  // If KEY_MARK_KEYUP_AS_PROCESSED is specified, key value and keyCode value
  // of keyup event are changed to "Process" and DOM_VK_PROCESSKEY.
  const unsigned long KEY_MARK_KEYUP_AS_PROCESSED                  = 0x00000080;

  // These values can be used to do bitwise operation with the return value of
  // the keydown() method.
  const unsigned long KEYEVENT_NOT_CONSUMED                        = 0x00000000;
  const unsigned long KEYDOWN_IS_CONSUMED                          = 0x00000001;
  const unsigned long KEYPRESS_IS_CONSUMED                         = 0x00000002;

  /**
   * keydown() may dispatch a keydown event and some keypress events if
   * preceding keydown event isn't consumed and they are necessary.
   * Note that even if this is called during composition, key events may not
   * be dispatched.  In this case, this returns false.
   *
   * You should initialize at least .key value and .code value of the event.
   * Additionally, if you try to emulate a printable key, .keyCode value should
   * be specified if there is proper key value.  See the comment of above
   * example how to decide .keyCode value of a printable key.  On the other
   * hand, .keyCode value is automatically computed when you try to emulate
   * non-printable key.  However, if you try to emulate physical keyboard of
   * desktop platform, you need to specify proper value explicitly because
   * the mapping table of this API isn't enough to emulate the behavior of
   * Gecko for desktop platforms.
   *
   * NOTE: Even if this has composition, JS-Keyboard should call keydown() and
   *       keyup().  Although, with the default preferences and normal
   *       conditions, DOM key events won't be fired during composition.
   *       However, they MAY be dispatched for some reasons, e.g., the web
   *       content listens only key events, or if the standard DOM event spec
   *       will be changed in the future.
   *
   * @param aKeyboardEvent  Must be a keyboard event which should be dispatched
   *                        as a keydown event and keypress events.
   *                        #1 Note that you don't need to set charCode value
   *                        because it's computed from its key value.
   *                        #2 If code value is set properly and location value
   *                        isn't specified (i.e., 0), the location value will
   *                        be guessed from the code value.
   *                        #3 Non-defined code names are not allowed. If your
   *                        key isn't registered, file a bug. If your key isn't
   *                        defined by any standards, use "" (empty string).
   *                        #4 .keyCode is guessed from .key value if the key
   *                        name is registered and .keyCode isn't initialized.
   *                        #5 modifier key states, e.g., .shiftKey, are
   *                        ignored.  Instead, modifier states are managed by
   *                        each instance and set automatically.
   * @param aKeyFlags       Special flags.  The values can be some of KEY_*
   *                        constants.
   * @return                KEYEVENT_NOT_CONSUMED, if the keydown event nor
   *                        the following keypress event(s) are consumed.
   *                        KEYDOWN_IS_CONSUMED, if the keydown event is
   *                        consumed. No keypress event will be dispatched in
   *                        this case.
   *                        KEYPRESS_IS_CONSUMED, if the keypress event(s) is
   *                        consumed when dispatched.
   *                        Note that keypress event is always consumed by
   *                        native code for the printable keys (indicating the
   *                        default action has been taken).
   */
  [optional_argc]
    unsigned long keydown(in Event aKeyboardEvent,
                          [optional] in unsigned long aKeyFlags);

  /**
   * Similar to keydown(), but this dispatches only a keyup event.
   */
  [optional_argc]
    boolean keyup(in Event aKeyboardEvent,
                  [optional] in unsigned long aKeyFlags);

  /**
   * getModifierState() returns modifier state managed by this instance.
   *
   * @param aModifier       One of modifier key names.  This doesn't support
   *                        virtual modifiers like "Accel".
   * @return                true if the modifier key is active.  Otherwise,
   *                        false.
   */
  boolean getModifierState(in AString aModifierKey);

  /**
   * shareModifierStateOf() makes the instance shares modifier state of
   * another instance.  When this is called, the instance refers the modifier
   * state of another instance.  After that, changes to either this and the
   * other instance's modifier state is synchronized.
   *
   * @param aOther          Another instance which will be referred by the
   *                        instance.  If this is null, the instance restarts
   *                        to manage modifier state independently.
   */
  void shareModifierStateOf(in nsITextInputProcessor aOther);

  /**
   * Helper method to get usual |.code| value of non-printable keys.
   *
   * @param aKeyValue       A predefined key value such as "Enter".
   *                        If this is not a proper non-printable key value
   *                        or a proper key value but not in usual keyboard of
   *                        the platform, this returns empty string.
   * @param aLocation       The |.location| value.  This is important if
   *                        the key may be in different location.
   *                        E.g., Left vs. Right or Standard vs. Numpad.
   *                        If this is undefined or null, it'll be treated
   *                        as Standard or Left.
   * @return                One of a code value of well-known key on usual
   *                        keyboard on the platform, or empty string.
   */
  [optional_argc]
    AString computeCodeValueOfNonPrintableKey(
              in AString aKeyValue,
              [optional] in jsval aLocation);

  /**
   * Helper method to guess |.code| value of a printable key which is in usual
   * keyboard of the platform and when active keyboard layout is US-English.
   * Note that this is not aware of option key mapping on macOS.
   *
   * @param aKeyValue          The key value. Must be a character which can
   *                           be inputted with US-English keyboard layout.
   * @param aLocation          The location of the key.  This is important
   *                           to distinguish whether the key is in Standard
   *                           or Numpad. If this is undefined or null, will
   *                           be treated as Standard.
   * @return                   Returns empty string if there is no proper key.
   */
  [optional_argc]
    AString guessCodeValueOfPrintableKeyInUSEnglishKeyboardLayout(
              in AString aKeyValue,
              [optional] in jsval aLocation);

  /**
   * Helper method to guess |.keyCode| value of a printable key which is in
   * usual keyboard of the platform and when active keyboard layout is
   * US-English.
   * Note that this is not aware of option key mapping on macOS.
   *
   * @param aKeyValue          The key value.  Must be a character which can
   *                           be inputted with US-English keyboard layout.
   * @param aLocation          The location of the key.  This is important
   *                           to distinguish whether the key is in Standard
   *                           our Numpad.  If this is undefined or null,
   *                           will be treated as Standard.
   * @return                   Returns 0 if there is no proper key to input
   *                           aKeyValue with US-English keyboard layout.
   */
  [optional_argc]
    unsigned long guessKeyCodeValueOfPrintableKeyInUSEnglishKeyboardLayout(
                    in AString aKeyValue,
                    [optional] in jsval aLocation);
};

%{C++
#define TEXT_INPUT_PROCESSOR_CID \
  { 0xcaaab47f, 0x1e31, 0x478e, \
    { 0x89, 0x19, 0x97, 0x09, 0x04, 0xe9, 0xcb, 0x72 } }
#define TEXT_INPUT_PROCESSOR_CONTRACTID \
  "@mozilla.org/text-input-processor;1"
%}