AccessibilityUtils.java revision 9a81ce92c381007affe6bb2310bf94c9856eaae1 
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.support.v4.view.MotionEventCompat;
25import android.util.Log;
26import android.view.MotionEvent;
27import android.view.accessibility.AccessibilityEvent;
28import android.view.accessibility.AccessibilityManager;
29import android.view.inputmethod.EditorInfo;
30
31import com.android.inputmethod.compat.AccessibilityManagerCompatUtils;
32import com.android.inputmethod.compat.AudioManagerCompatWrapper;
33import com.android.inputmethod.compat.InputTypeCompatUtils;
34import com.android.inputmethod.compat.MotionEventCompatUtils;
35import com.android.inputmethod.compat.SettingsSecureCompatUtils;
36import com.android.inputmethod.latin.R;
37
38public class AccessibilityUtils {
39    private static final String TAG = AccessibilityUtils.class.getSimpleName();
40    private static final String CLASS = AccessibilityUtils.class.getClass().getName();
41    private static final String PACKAGE = AccessibilityUtils.class.getClass().getPackage()
42            .getName();
43
44    private static final AccessibilityUtils sInstance = new AccessibilityUtils();
45
46    private Context mContext;
47    private AccessibilityManager mAccessibilityManager;
48    private AudioManagerCompatWrapper mAudioManager;
49
50    /*
51     * Setting this constant to {@code false} will disable all keyboard
52     * accessibility code, regardless of whether Accessibility is turned on in
53     * the system settings. It should ONLY be used in the event of an emergency.
54     */
55    private static final boolean ENABLE_ACCESSIBILITY = true;
56
57    public static void init(InputMethodService inputMethod) {
58        if (!ENABLE_ACCESSIBILITY)
59            return;
60
61        // These only need to be initialized if the kill switch is off.
62        sInstance.initInternal(inputMethod);
63        KeyCodeDescriptionMapper.init();
64        AccessibleInputMethodServiceProxy.init(inputMethod);
65        AccessibleKeyboardViewProxy.init(inputMethod);
66    }
67
68    public static AccessibilityUtils getInstance() {
69        return sInstance;
70    }
71
72    private AccessibilityUtils() {
73        // This class is not publicly instantiable.
74    }
75
76    private void initInternal(Context context) {
77        mContext = context;
78        mAccessibilityManager = (AccessibilityManager) context
79                .getSystemService(Context.ACCESSIBILITY_SERVICE);
80
81        final AudioManager audioManager = (AudioManager) context
82                .getSystemService(Context.AUDIO_SERVICE);
83        mAudioManager = new AudioManagerCompatWrapper(audioManager);
84    }
85
86    /**
87     * Returns {@code true} if touch exploration is enabled. Currently, this
88     * means that the kill switch is off, the device supports touch exploration,
89     * and a spoken feedback service is turned on.
90     *
91     * @return {@code true} if touch exploration is enabled.
92     */
93    public boolean isTouchExplorationEnabled() {
94        return ENABLE_ACCESSIBILITY
95                && mAccessibilityManager.isEnabled()
96                && AccessibilityManagerCompatUtils.isTouchExplorationEnabled(mAccessibilityManager);
97    }
98
99    /**
100     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
101     * event. This is used to determine whether the event should be processed by
102     * the touch exploration code within the keyboard.
103     *
104     * @param event The event to check.
105     * @return {@true} is the event is a touch exploration event
106     */
107    public boolean isTouchExplorationEvent(MotionEvent event) {
108        final int action = event.getAction();
109
110        return action == MotionEventCompatUtils.ACTION_HOVER_ENTER
111                || action == MotionEventCompatUtils.ACTION_HOVER_EXIT
112                || action == MotionEventCompat.ACTION_HOVER_MOVE;
113    }
114
115    /**
116     * Returns whether the device should obscure typed password characters.
117     * Typically this means speaking "dot" in place of non-control characters.
118     *
119     * @return {@code true} if the device should obscure password characters.
120     */
121    public boolean shouldObscureInput(EditorInfo editorInfo) {
122        if (editorInfo == null)
123            return false;
124
125        // The user can optionally force speaking passwords.
126        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
127            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
128                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
129            if (speakPassword)
130                return false;
131        }
132
133        // Always speak if the user is listening through headphones.
134        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn())
135            return false;
136
137        // Don't speak if the IME is connected to a password field.
138        return InputTypeCompatUtils.isPasswordInputType(editorInfo.inputType);
139    }
140
141    /**
142     * Sends the specified text to the {@link AccessibilityManager} to be
143     * spoken.
144     *
145     * @param text the text to speak
146     */
147    public void speak(CharSequence text) {
148        if (!mAccessibilityManager.isEnabled()) {
149            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
150            return;
151        }
152
153        // The following is a hack to avoid using the heavy-weight TextToSpeech
154        // class. Instead, we're just forcing a fake AccessibilityEvent into
155        // the screen reader to make it speak.
156        final AccessibilityEvent event = AccessibilityEvent
157                .obtain(AccessibilityEvent.TYPE_VIEW_FOCUSED);
158
159        event.setPackageName(PACKAGE);
160        event.setClassName(CLASS);
161        event.setEventTime(SystemClock.uptimeMillis());
162        event.setEnabled(true);
163        event.getText().add(text);
164
165        mAccessibilityManager.sendAccessibilityEvent(event);
166    }
167
168    /**
169     * Handles speaking the "connect a headset to hear passwords" notification
170     * when connecting to a password field.
171     *
172     * @param editorInfo The input connection's editor info attribute.
173     * @param restarting Whether the connection is being restarted.
174     */
175    public void onStartInputViewInternal(EditorInfo editorInfo, boolean restarting) {
176        if (shouldObscureInput(editorInfo)) {
177            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
178            speak(text);
179        }
180    }
181}
182