LatinIME/java/src/com/android/inputmethod/event/Event.java

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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.inputmethod.event;
/**
* Class representing a generic input event as handled by Latin IME.
*
* This contains information about the origin of the event, but it is generalized and should
* represent a software keypress, hardware keypress, or d-pad move alike.
* Very importantly, this does not necessarily result in inputting one character, or even anything
* at all - it may be a dead key, it may be a partial input, it may be a special key on the
* keyboard, it may be a cancellation of a keypress (e.g. in a soft keyboard the finger of the
* user has slid out of the key), etc. It may also be a batch input from a gesture or handwriting
* for example.
* The combiner should figure out what to do with this.
*/
public class Event {
// Should the types below be represented by separate classes instead? It would be cleaner
// but probably a bit too much
// An event we don't handle in Latin IME, for example pressing Ctrl on a hardware keyboard.
final public static int EVENT_NOT_HANDLED = 0;
// A character that is already final, for example pressing an alphabetic character on a
// hardware qwerty keyboard.
final public static int EVENT_COMMITTABLE = 1;
// A dead key, which means a character that should combine with what is coming next. Examples
// include the "^" character on an azerty keyboard which combines with "e" to make "ê", or
// AltGr+' on a dvorak international keyboard which combines with "e" to make "é". This is
// true regardless of the language or combining mode, and should be seen as a property of the
// key - a dead key followed by another key with which it can combine should be regarded as if
// the keyboard actually had such a key.
final public static int EVENT_DEAD = 2;
// A toggle event is triggered by a key that affects the previous character. An example would
// be a numeric key on a 10-key keyboard, which would toggle between 1 - a - b - c with
// repeated presses.
final public static int EVENT_TOGGLE = 3;
// A mode event instructs the combiner to change modes. The canonical example would be the
// hankaku/zenkaku key on a Japanese keyboard, or even the caps lock key on a qwerty keyboard
// if handled at the combiner level.
final public static int EVENT_MODE_KEY = 4;
final private static int NOT_A_CODE_POINT = 0;
final private int mType; // The type of event - one of the constants above
// The code point associated with the event, if relevant. This is a unicode code point, and
// has nothing to do with other representations of the key. It is only relevant if this event
// is the right type: COMMITTABLE or DEAD or TOGGLE, but for a mode key like hankaku/zenkaku or
// ctrl, there is no code point associated so this should be NOT_A_CODE_POINT to avoid
// unintentional use of its value when it's not relevant.
final public int mCodePoint;
// The next event, if any. Null if there is no next event yet.
final public Event mNextEvent;
// This method is private - to create a new event, use one of the create* utility methods.
private Event(final int type, final int codePoint, final Event next) {
mType = type;
mCodePoint = codePoint;
mNextEvent = next;
}
public static Event createDeadEvent(final int codePoint, final Event next) {
return new Event(EVENT_DEAD, codePoint, next);
}
public static Event createCommittableEvent(final int codePoint, final Event next) {
return new Event(EVENT_COMMITTABLE, codePoint, next);
}
public static Event createNotHandledEvent() {
return new Event(EVENT_NOT_HANDLED, NOT_A_CODE_POINT, null);
}
public boolean isCommittable() {
return EVENT_COMMITTABLE == mType;
}
public boolean isDead() {
return EVENT_DEAD == mType;
}
}