KeyEventCompat.java revision 791f31bbba40b8b51694a1b2cdc804f360786ed1 
1/*
2 * Copyright (C) 2011 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 android.support.v4.view;
18
19import android.view.KeyEvent;
20
21/**
22 * Helper for accessing features in {@link KeyEvent} introduced after
23 * API level 4 in a backwards compatible fashion.
24 */
25public class KeyEventCompat {
26    /**
27     * Interface for the full API.
28     */
29    interface KeyEventVersionImpl {
30        public int normalizeMetaState(int metaState);
31        public boolean metaStateHasModifiers(int metaState, int modifiers);
32        public boolean metaStateHasNoModifiers(int metaState);
33        public void startTracking(KeyEvent event);
34        public boolean isTracking(KeyEvent event);
35    }
36
37    /**
38     * Interface implementation that doesn't use anything about v4 APIs.
39     */
40    static class BaseKeyEventVersionImpl implements KeyEventVersionImpl {
41        private static final int META_MODIFIER_MASK =
42                KeyEvent.META_SHIFT_ON | KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON
43                | KeyEvent.META_ALT_ON | KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON
44                | KeyEvent.META_SYM_ON;
45
46        // Mask of all lock key meta states.
47        private static final int META_ALL_MASK = META_MODIFIER_MASK;
48
49        private static int metaStateFilterDirectionalModifiers(int metaState,
50                int modifiers, int basic, int left, int right) {
51            final boolean wantBasic = (modifiers & basic) != 0;
52            final int directional = left | right;
53            final boolean wantLeftOrRight = (modifiers & directional) != 0;
54
55            if (wantBasic) {
56                if (wantLeftOrRight) {
57                    throw new IllegalArgumentException("bad arguments");
58                }
59                return metaState & ~directional;
60            } else if (wantLeftOrRight) {
61                return metaState & ~basic;
62            } else {
63                return metaState;
64            }
65        }
66
67        @Override
68        public int normalizeMetaState(int metaState) {
69            if ((metaState & (KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON)) != 0) {
70                metaState |= KeyEvent.META_SHIFT_ON;
71            }
72            if ((metaState & (KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON)) != 0) {
73                metaState |= KeyEvent.META_ALT_ON;
74            }
75            return metaState & META_ALL_MASK;
76        }
77
78        @Override
79        public boolean metaStateHasModifiers(int metaState, int modifiers) {
80            metaState = normalizeMetaState(metaState) & META_MODIFIER_MASK;
81            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
82                    KeyEvent.META_SHIFT_ON, KeyEvent.META_SHIFT_LEFT_ON, KeyEvent.META_SHIFT_RIGHT_ON);
83            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
84                    KeyEvent.META_ALT_ON, KeyEvent.META_ALT_LEFT_ON, KeyEvent.META_ALT_RIGHT_ON);
85            return metaState == modifiers;
86        }
87
88        @Override
89        public boolean metaStateHasNoModifiers(int metaState) {
90            return (normalizeMetaState(metaState) & META_MODIFIER_MASK) == 0;
91        }
92
93        @Override
94        public void startTracking(KeyEvent event) {
95        }
96
97        @Override
98        public boolean isTracking(KeyEvent event) {
99            return false;
100        }
101    }
102
103    static class EclairKeyEventVersionImpl extends BaseKeyEventVersionImpl {
104        @Override
105        public void startTracking(KeyEvent event) {
106            KeyEventCompatEclair.startTracking(event);
107        }
108
109        @Override
110        public boolean isTracking(KeyEvent event) {
111            return KeyEventCompatEclair.isTracking(event);
112        }
113    }
114
115    /**
116     * Interface implementation for devices with at least v11 APIs.
117     */
118    static class HoneycombKeyEventVersionImpl extends EclairKeyEventVersionImpl {
119        @Override
120        public int normalizeMetaState(int metaState) {
121            return KeyEventCompatHoneycomb.normalizeMetaState(metaState);
122        }
123
124        @Override
125        public boolean metaStateHasModifiers(int metaState, int modifiers) {
126            return KeyEventCompatHoneycomb.metaStateHasModifiers(metaState, modifiers);
127        }
128
129        @Override
130        public boolean metaStateHasNoModifiers(int metaState) {
131            return KeyEventCompatHoneycomb.metaStateHasNoModifiers(metaState);
132        }
133    }
134
135    /**
136     * Select the correct implementation to use for the current platform.
137     */
138    static final KeyEventVersionImpl IMPL;
139    static {
140        if (android.os.Build.VERSION.SDK_INT >= 11) {
141            IMPL = new HoneycombKeyEventVersionImpl();
142        } else {
143            IMPL = new BaseKeyEventVersionImpl();
144        }
145    }
146
147    // -------------------------------------------------------------------
148
149    public static int normalizeMetaState(int metaState) {
150        return IMPL.normalizeMetaState(metaState);
151    }
152
153    public static boolean metaStateHasModifiers(int metaState, int modifiers) {
154        return IMPL.metaStateHasModifiers(metaState, modifiers);
155    }
156
157    public static boolean metaStateHasNoModifiers(int metaState) {
158        return IMPL.metaStateHasNoModifiers(metaState);
159    }
160
161    public static boolean hasModifiers(KeyEvent event, int modifiers) {
162        return IMPL.metaStateHasModifiers(event.getMetaState(), modifiers);
163    }
164
165    public static boolean hasNoModifiers(KeyEvent event) {
166        return IMPL.metaStateHasNoModifiers(event.getMetaState());
167    }
168
169    public static void startTracking(KeyEvent event) {
170        IMPL.startTracking(event);
171    }
172
173    public static boolean isTracking(KeyEvent event) {
174        return IMPL.isTracking(event);
175    }
176}
177