AccessibilityUtils.java revision 34b2b5e694758390126ffa3b1c7d752cdde7a05c 
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.SettingsSecureCompatUtils;
32import com.android.inputmethod.latin.InputTypeUtils;
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        AccessibleKeyboardViewProxy.init(inputMethod);
62    }
63
64    public static AccessibilityUtils getInstance() {
65        return sInstance;
66    }
67
68    private AccessibilityUtils() {
69        // This class is not publicly instantiable.
70    }
71
72    private void initInternal(Context context) {
73        mContext = context;
74        mAccessibilityManager = (AccessibilityManager) context
75                .getSystemService(Context.ACCESSIBILITY_SERVICE);
76
77        final AudioManager audioManager = (AudioManager) context
78                .getSystemService(Context.AUDIO_SERVICE);
79        mAudioManager = new AudioManagerCompatWrapper(audioManager);
80    }
81
82    /**
83     * Returns {@code true} if touch exploration is enabled. Currently, this
84     * means that the kill switch is off, the device supports touch exploration,
85     * and a spoken feedback service is turned on.
86     *
87     * @return {@code true} if touch exploration is enabled.
88     */
89    public boolean isTouchExplorationEnabled() {
90        return ENABLE_ACCESSIBILITY
91                && mAccessibilityManager.isEnabled()
92                && mAccessibilityManager.isTouchExplorationEnabled();
93    }
94
95    /**
96     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
97     * event. This is used to determine whether the event should be processed by
98     * the touch exploration code within the keyboard.
99     *
100     * @param event The event to check.
101     * @return {@true} is the event is a touch exploration event
102     */
103    public boolean isTouchExplorationEvent(MotionEvent event) {
104        final int action = event.getAction();
105
106        return action == MotionEvent.ACTION_HOVER_ENTER
107                || action == MotionEvent.ACTION_HOVER_EXIT
108                || action == MotionEvent.ACTION_HOVER_MOVE;
109    }
110
111    /**
112     * Returns whether the device should obscure typed password characters.
113     * Typically this means speaking "dot" in place of non-control characters.
114     *
115     * @return {@code true} if the device should obscure password characters.
116     */
117    public boolean shouldObscureInput(EditorInfo editorInfo) {
118        if (editorInfo == null)
119            return false;
120
121        // The user can optionally force speaking passwords.
122        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
123            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
124                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
125            if (speakPassword)
126                return false;
127        }
128
129        // Always speak if the user is listening through headphones.
130        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn())
131            return false;
132
133        // Don't speak if the IME is connected to a password field.
134        return InputTypeUtils.isPasswordInputType(editorInfo.inputType);
135    }
136
137    /**
138     * Sends the specified text to the {@link AccessibilityManager} to be
139     * spoken.
140     *
141     * @param text the text to speak
142     */
143    public void speak(CharSequence text) {
144        if (!mAccessibilityManager.isEnabled()) {
145            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
146            return;
147        }
148
149        // The following is a hack to avoid using the heavy-weight TextToSpeech
150        // class. Instead, we're just forcing a fake AccessibilityEvent into
151        // the screen reader to make it speak.
152        final AccessibilityEvent event = AccessibilityEvent
153                .obtain(AccessibilityEvent.TYPE_VIEW_FOCUSED);
154
155        event.setPackageName(PACKAGE);
156        event.setClassName(CLASS);
157        event.setEventTime(SystemClock.uptimeMillis());
158        event.setEnabled(true);
159        event.getText().add(text);
160
161        mAccessibilityManager.sendAccessibilityEvent(event);
162    }
163
164    /**
165     * Handles speaking the "connect a headset to hear passwords" notification
166     * when connecting to a password field.
167     *
168     * @param editorInfo The input connection's editor info attribute.
169     * @param restarting Whether the connection is being restarted.
170     */
171    public void onStartInputViewInternal(EditorInfo editorInfo, boolean restarting) {
172        if (shouldObscureInput(editorInfo)) {
173            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
174            speak(text);
175        }
176    }
177}
178