AccessibilityUtils.java revision c6435f92a80c6664870f9d1a4bb2a1c5153ef2c3 
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 com.android.inputmethod.accessibility;
18
19import android.content.Context;
20import android.inputmethodservice.InputMethodService;
21import android.media.AudioManager;
22import android.os.SystemClock;
23import android.provider.Settings;
24import android.util.Log;
25import android.view.MotionEvent;
26import android.view.accessibility.AccessibilityEvent;
27import android.view.accessibility.AccessibilityManager;
28import android.view.inputmethod.EditorInfo;
29
30import com.android.inputmethod.compat.AudioManagerCompatWrapper;
31import com.android.inputmethod.compat.InputTypeCompatUtils;
32import com.android.inputmethod.compat.SettingsSecureCompatUtils;
33import com.android.inputmethod.latin.R;
34
35public class AccessibilityUtils {
36    private static final String TAG = AccessibilityUtils.class.getSimpleName();
37    private static final String CLASS = AccessibilityUtils.class.getClass().getName();
38    private static final String PACKAGE = AccessibilityUtils.class.getClass().getPackage()
39            .getName();
40
41    private static final AccessibilityUtils sInstance = new AccessibilityUtils();
42
43    private Context mContext;
44    private AccessibilityManager mAccessibilityManager;
45    private AudioManagerCompatWrapper mAudioManager;
46
47    /*
48     * Setting this constant to {@code false} will disable all keyboard
49     * accessibility code, regardless of whether Accessibility is turned on in
50     * the system settings. It should ONLY be used in the event of an emergency.
51     */
52    private static final boolean ENABLE_ACCESSIBILITY = true;
53
54    public static void init(InputMethodService inputMethod) {
55        if (!ENABLE_ACCESSIBILITY)
56            return;
57
58        // These only need to be initialized if the kill switch is off.
59        sInstance.initInternal(inputMethod);
60        KeyCodeDescriptionMapper.init();
61        AccessibleInputMethodServiceProxy.init(inputMethod);
62        AccessibleKeyboardViewProxy.init(inputMethod);
63    }
64
65    public static AccessibilityUtils getInstance() {
66        return sInstance;
67    }
68
69    private AccessibilityUtils() {
70        // This class is not publicly instantiable.
71    }
72
73    private void initInternal(Context context) {
74        mContext = context;
75        mAccessibilityManager = (AccessibilityManager) context
76                .getSystemService(Context.ACCESSIBILITY_SERVICE);
77
78        final AudioManager audioManager = (AudioManager) context
79                .getSystemService(Context.AUDIO_SERVICE);
80        mAudioManager = new AudioManagerCompatWrapper(audioManager);
81    }
82
83    /**
84     * Returns {@code true} if touch exploration is enabled. Currently, this
85     * means that the kill switch is off, the device supports touch exploration,
86     * and a spoken feedback service is turned on.
87     *
88     * @return {@code true} if touch exploration is enabled.
89     */
90    public boolean isTouchExplorationEnabled() {
91        return ENABLE_ACCESSIBILITY
92                && mAccessibilityManager.isEnabled()
93                && mAccessibilityManager.isTouchExplorationEnabled();
94    }
95
96    /**
97     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
98     * event. This is used to determine whether the event should be processed by
99     * the touch exploration code within the keyboard.
100     *
101     * @param event The event to check.
102     * @return {@true} is the event is a touch exploration event
103     */
104    public boolean isTouchExplorationEvent(MotionEvent event) {
105        final int action = event.getAction();
106
107        return action == MotionEvent.ACTION_HOVER_ENTER
108                || action == MotionEvent.ACTION_HOVER_EXIT
109                || action == MotionEvent.ACTION_HOVER_MOVE;
110    }
111
112    /**
113     * Returns whether the device should obscure typed password characters.
114     * Typically this means speaking "dot" in place of non-control characters.
115     *
116     * @return {@code true} if the device should obscure password characters.
117     */
118    public boolean shouldObscureInput(EditorInfo editorInfo) {
119        if (editorInfo == null)
120            return false;
121
122        // The user can optionally force speaking passwords.
123        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
124            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
125                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
126            if (speakPassword)
127                return false;
128        }
129
130        // Always speak if the user is listening through headphones.
131        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn())
132            return false;
133
134        // Don't speak if the IME is connected to a password field.
135        return InputTypeCompatUtils.isPasswordInputType(editorInfo.inputType);
136    }
137
138    /**
139     * Sends the specified text to the {@link AccessibilityManager} to be
140     * spoken.
141     *
142     * @param text the text to speak
143     */
144    public void speak(CharSequence text) {
145        if (!mAccessibilityManager.isEnabled()) {
146            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
147            return;
148        }
149
150        // The following is a hack to avoid using the heavy-weight TextToSpeech
151        // class. Instead, we're just forcing a fake AccessibilityEvent into
152        // the screen reader to make it speak.
153        final AccessibilityEvent event = AccessibilityEvent
154                .obtain(AccessibilityEvent.TYPE_VIEW_FOCUSED);
155
156        event.setPackageName(PACKAGE);
157        event.setClassName(CLASS);
158        event.setEventTime(SystemClock.uptimeMillis());
159        event.setEnabled(true);
160        event.getText().add(text);
161
162        mAccessibilityManager.sendAccessibilityEvent(event);
163    }
164
165    /**
166     * Handles speaking the "connect a headset to hear passwords" notification
167     * when connecting to a password field.
168     *
169     * @param editorInfo The input connection's editor info attribute.
170     * @param restarting Whether the connection is being restarted.
171     */
172    public void onStartInputViewInternal(EditorInfo editorInfo, boolean restarting) {
173        if (shouldObscureInput(editorInfo)) {
174            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
175            speak(text);
176        }
177    }
178}
179