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;
20import android.view.View;
21
22/**
23 * Helper for accessing features in {@link KeyEvent} introduced after
24 * API level 4 in a backwards compatible fashion.
25 */
26public class KeyEventCompat {
27    /**
28     * Interface for the full API.
29     */
30    interface KeyEventVersionImpl {
31        public int normalizeMetaState(int metaState);
32        public boolean metaStateHasModifiers(int metaState, int modifiers);
33        public boolean metaStateHasNoModifiers(int metaState);
34        public void startTracking(KeyEvent event);
35        public boolean isTracking(KeyEvent event);
36        public Object getKeyDispatcherState(View view);
37        public boolean dispatch(KeyEvent event, KeyEvent.Callback receiver, Object state,
38                    Object target);
39    }
40
41    /**
42     * Interface implementation that doesn't use anything about v4 APIs.
43     */
44    static class BaseKeyEventVersionImpl implements KeyEventVersionImpl {
45        private static final int META_MODIFIER_MASK =
46                KeyEvent.META_SHIFT_ON | KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON
47                | KeyEvent.META_ALT_ON | KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON
48                | KeyEvent.META_SYM_ON;
49
50        // Mask of all lock key meta states.
51        private static final int META_ALL_MASK = META_MODIFIER_MASK;
52
53        private static int metaStateFilterDirectionalModifiers(int metaState,
54                int modifiers, int basic, int left, int right) {
55            final boolean wantBasic = (modifiers & basic) != 0;
56            final int directional = left | right;
57            final boolean wantLeftOrRight = (modifiers & directional) != 0;
58
59            if (wantBasic) {
60                if (wantLeftOrRight) {
61                    throw new IllegalArgumentException("bad arguments");
62                }
63                return metaState & ~directional;
64            } else if (wantLeftOrRight) {
65                return metaState & ~basic;
66            } else {
67                return metaState;
68            }
69        }
70
71        @Override
72        public int normalizeMetaState(int metaState) {
73            if ((metaState & (KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON)) != 0) {
74                metaState |= KeyEvent.META_SHIFT_ON;
75            }
76            if ((metaState & (KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON)) != 0) {
77                metaState |= KeyEvent.META_ALT_ON;
78            }
79            return metaState & META_ALL_MASK;
80        }
81
82        @Override
83        public boolean metaStateHasModifiers(int metaState, int modifiers) {
84            metaState = normalizeMetaState(metaState) & META_MODIFIER_MASK;
85            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
86                    KeyEvent.META_SHIFT_ON, KeyEvent.META_SHIFT_LEFT_ON, KeyEvent.META_SHIFT_RIGHT_ON);
87            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
88                    KeyEvent.META_ALT_ON, KeyEvent.META_ALT_LEFT_ON, KeyEvent.META_ALT_RIGHT_ON);
89            return metaState == modifiers;
90        }
91
92        @Override
93        public boolean metaStateHasNoModifiers(int metaState) {
94            return (normalizeMetaState(metaState) & META_MODIFIER_MASK) == 0;
95        }
96
97        @Override
98        public void startTracking(KeyEvent event) {
99        }
100
101        @Override
102        public boolean isTracking(KeyEvent event) {
103            return false;
104        }
105
106        @Override
107        public Object getKeyDispatcherState(View view) {
108            return null;
109        }
110
111        @Override
112        public boolean dispatch(KeyEvent event, KeyEvent.Callback receiver, Object state,
113                    Object target) {
114            return event.dispatch(receiver);
115        }
116    }
117
118    static class EclairKeyEventVersionImpl extends BaseKeyEventVersionImpl {
119        @Override
120        public void startTracking(KeyEvent event) {
121            KeyEventCompatEclair.startTracking(event);
122        }
123
124        @Override
125        public boolean isTracking(KeyEvent event) {
126            return KeyEventCompatEclair.isTracking(event);
127        }
128
129        @Override
130        public Object getKeyDispatcherState(View view) {
131            return KeyEventCompatEclair.getKeyDispatcherState(view);
132        }
133
134        @Override
135        public boolean dispatch(KeyEvent event, KeyEvent.Callback receiver, Object state,
136                    Object target) {
137            return KeyEventCompatEclair.dispatch(event, receiver, state, target);
138        }
139    }
140
141    /**
142     * Interface implementation for devices with at least v11 APIs.
143     */
144    static class HoneycombKeyEventVersionImpl extends EclairKeyEventVersionImpl {
145        @Override
146        public int normalizeMetaState(int metaState) {
147            return KeyEventCompatHoneycomb.normalizeMetaState(metaState);
148        }
149
150        @Override
151        public boolean metaStateHasModifiers(int metaState, int modifiers) {
152            return KeyEventCompatHoneycomb.metaStateHasModifiers(metaState, modifiers);
153        }
154
155        @Override
156        public boolean metaStateHasNoModifiers(int metaState) {
157            return KeyEventCompatHoneycomb.metaStateHasNoModifiers(metaState);
158        }
159    }
160
161    /**
162     * Select the correct implementation to use for the current platform.
163     */
164    static final KeyEventVersionImpl IMPL;
165    static {
166        if (android.os.Build.VERSION.SDK_INT >= 11) {
167            IMPL = new HoneycombKeyEventVersionImpl();
168        } else {
169            IMPL = new BaseKeyEventVersionImpl();
170        }
171    }
172
173    // -------------------------------------------------------------------
174
175    public static int normalizeMetaState(int metaState) {
176        return IMPL.normalizeMetaState(metaState);
177    }
178
179    public static boolean metaStateHasModifiers(int metaState, int modifiers) {
180        return IMPL.metaStateHasModifiers(metaState, modifiers);
181    }
182
183    public static boolean metaStateHasNoModifiers(int metaState) {
184        return IMPL.metaStateHasNoModifiers(metaState);
185    }
186
187    public static boolean hasModifiers(KeyEvent event, int modifiers) {
188        return IMPL.metaStateHasModifiers(event.getMetaState(), modifiers);
189    }
190
191    public static boolean hasNoModifiers(KeyEvent event) {
192        return IMPL.metaStateHasNoModifiers(event.getMetaState());
193    }
194
195    public static void startTracking(KeyEvent event) {
196        IMPL.startTracking(event);
197    }
198
199    public static boolean isTracking(KeyEvent event) {
200        return IMPL.isTracking(event);
201    }
202
203    public static Object getKeyDispatcherState(View view) {
204        return IMPL.getKeyDispatcherState(view);
205    }
206
207    public static boolean dispatch(KeyEvent event, KeyEvent.Callback receiver, Object state,
208                Object target) {
209        return IMPL.dispatch(event, receiver, state, target);
210    }
211}
212