HardwareKeyboardEventDecoder.java revision 09291050a028192a39fd745c6696df1c504eb38b 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.inputmethod.event;
18
19import android.view.KeyCharacterMap;
20import android.view.KeyEvent;
21
22import com.android.inputmethod.latin.Constants;
23
24/**
25 * A hardware event decoder for a hardware qwerty-ish keyboard.
26 *
27 * The events are always hardware keypresses, but they can be key down or key up events, they
28 * can be dead keys, they can be meta keys like shift or ctrl... This does not deal with
29 * 10-key like keyboards; a different decoder is used for this.
30 */
31public class HardwareKeyboardEventDecoder implements HardwareEventDecoder {
32    final int mDeviceId;
33
34    public HardwareKeyboardEventDecoder(final int deviceId) {
35        mDeviceId = deviceId;
36        // TODO: get the layout for this hardware keyboard
37    }
38
39    @Override
40    public Event decodeHardwareKey(final KeyEvent keyEvent) {
41        // KeyEvent#getUnicodeChar() does not exactly returns a unicode char, but rather a value
42        // that includes both the unicode char in the lower 21 bits and flags in the upper bits,
43        // hence the name "codePointAndFlags". {@see KeyEvent#getUnicodeChar()} for more info.
44        final int codePointAndFlags = keyEvent.getUnicodeChar();
45        // The keyCode is the abstraction used by the KeyEvent to represent different keys that
46        // do not necessarily map to a unicode character. This represents a physical key, like
47        // the key for 'A' or Space, but also Backspace or Ctrl or Caps Lock.
48        final int keyCode = keyEvent.getKeyCode();
49        final boolean isKeyRepeat = (0 != keyEvent.getRepeatCount());
50        if (KeyEvent.KEYCODE_DEL == keyCode) {
51            return Event.createHardwareKeypressEvent(Event.NOT_A_CODE_POINT, Constants.CODE_DELETE,
52                    null /* next */, isKeyRepeat);
53        }
54        if (keyEvent.isPrintingKey() || KeyEvent.KEYCODE_SPACE == keyCode
55                || KeyEvent.KEYCODE_ENTER == keyCode) {
56            if (0 != (codePointAndFlags & KeyCharacterMap.COMBINING_ACCENT)) {
57                // A dead key.
58                return Event.createDeadEvent(
59                        codePointAndFlags & KeyCharacterMap.COMBINING_ACCENT_MASK, keyCode,
60                        null /* next */);
61            }
62            if (KeyEvent.KEYCODE_ENTER == keyCode) {
63                // The Enter key. If the Shift key is not being pressed, this should send a
64                // CODE_ENTER to trigger the action if any, or a carriage return otherwise. If the
65                // Shift key is being pressed, this should send a CODE_SHIFT_ENTER and let
66                // Latin IME decide what to do with it.
67                if (keyEvent.isShiftPressed()) {
68                    return Event.createHardwareKeypressEvent(Event.NOT_A_CODE_POINT,
69                            Constants.CODE_SHIFT_ENTER, null /* next */, isKeyRepeat);
70                } else {
71                    return Event.createHardwareKeypressEvent(Constants.CODE_ENTER, keyCode,
72                            null /* next */, isKeyRepeat);
73                }
74            }
75            // If not Enter, then this is just a regular keypress event for a normal character
76            // that can be committed right away, taking into account the current state.
77            return Event.createHardwareKeypressEvent(codePointAndFlags, keyCode, null /* next */,
78                    isKeyRepeat);
79        }
80        return Event.createNotHandledEvent();
81    }
82}
83