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    }
34
35    /**
36     * Interface implementation that doesn't use anything about v4 APIs.
37     */
38    static class BaseKeyEventVersionImpl implements KeyEventVersionImpl {
39        private static final int META_MODIFIER_MASK =
40                KeyEvent.META_SHIFT_ON | KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON
41                | KeyEvent.META_ALT_ON | KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON
42                | KeyEvent.META_SYM_ON;
43
44        // Mask of all lock key meta states.
45        private static final int META_ALL_MASK = META_MODIFIER_MASK;
46
47        private static int metaStateFilterDirectionalModifiers(int metaState,
48                int modifiers, int basic, int left, int right) {
49            final boolean wantBasic = (modifiers & basic) != 0;
50            final int directional = left | right;
51            final boolean wantLeftOrRight = (modifiers & directional) != 0;
52
53            if (wantBasic) {
54                if (wantLeftOrRight) {
55                    throw new IllegalArgumentException("bad arguments");
56                }
57                return metaState & ~directional;
58            } else if (wantLeftOrRight) {
59                return metaState & ~basic;
60            } else {
61                return metaState;
62            }
63        }
64
65        @Override
66        public int normalizeMetaState(int metaState) {
67            if ((metaState & (KeyEvent.META_SHIFT_LEFT_ON | KeyEvent.META_SHIFT_RIGHT_ON)) != 0) {
68                metaState |= KeyEvent.META_SHIFT_ON;
69            }
70            if ((metaState & (KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_RIGHT_ON)) != 0) {
71                metaState |= KeyEvent.META_ALT_ON;
72            }
73            return metaState & META_ALL_MASK;
74        }
75
76        @Override
77        public boolean metaStateHasModifiers(int metaState, int modifiers) {
78            metaState = normalizeMetaState(metaState) & META_MODIFIER_MASK;
79            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
80                    KeyEvent.META_SHIFT_ON, KeyEvent.META_SHIFT_LEFT_ON, KeyEvent.META_SHIFT_RIGHT_ON);
81            metaState = metaStateFilterDirectionalModifiers(metaState, modifiers,
82                    KeyEvent.META_ALT_ON, KeyEvent.META_ALT_LEFT_ON, KeyEvent.META_ALT_RIGHT_ON);
83            return metaState == modifiers;
84        }
85
86        @Override
87        public boolean metaStateHasNoModifiers(int metaState) {
88            return (normalizeMetaState(metaState) & META_MODIFIER_MASK) == 0;
89        }
90    }
91
92    /**
93     * Interface implementation for devices with at least v11 APIs.
94     */
95    static class HoneycombKeyEventVersionImpl implements KeyEventVersionImpl {
96        @Override
97        public int normalizeMetaState(int metaState) {
98            return KeyEventCompatHoneycomb.normalizeMetaState(metaState);
99        }
100
101        @Override
102        public boolean metaStateHasModifiers(int metaState, int modifiers) {
103            return KeyEventCompatHoneycomb.metaStateHasModifiers(metaState, modifiers);
104        }
105
106        @Override
107        public boolean metaStateHasNoModifiers(int metaState) {
108            return KeyEventCompatHoneycomb.metaStateHasNoModifiers(metaState);
109        }
110    }
111
112    /**
113     * Select the correct implementation to use for the current platform.
114     */
115    static final KeyEventVersionImpl IMPL;
116    static {
117        if (android.os.Build.VERSION.SDK_INT >= 11) {
118            IMPL = new HoneycombKeyEventVersionImpl();
119        } else {
120            IMPL = new BaseKeyEventVersionImpl();
121        }
122    }
123
124    // -------------------------------------------------------------------
125
126    public static int normalizeMetaState(int metaState) {
127        return IMPL.normalizeMetaState(metaState);
128    }
129
130    public static boolean metaStateHasModifiers(int metaState, int modifiers) {
131        return IMPL.metaStateHasModifiers(metaState, modifiers);
132    }
133
134    public static boolean metaStateHasNoModifiers(int metaState) {
135        return IMPL.metaStateHasNoModifiers(metaState);
136    }
137
138    public static boolean hasModifiers(KeyEvent event, int modifiers) {
139        return IMPL.metaStateHasModifiers(event.getMetaState(), modifiers);
140    }
141
142    public static boolean hasNoModifiers(KeyEvent event) {
143        return IMPL.metaStateHasNoModifiers(event.getMetaState());
144    }
145}
146