AccessibilityUtils.java revision 2ac5988f84b5c38d313951a3d7faddebf5f25e04 
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.AccessibilityManagerCompatWrapper;
31import com.android.inputmethod.compat.AudioManagerCompatWrapper;
32import com.android.inputmethod.compat.InputTypeCompatUtils;
33import com.android.inputmethod.compat.MotionEventCompatUtils;
34import com.android.inputmethod.compat.SettingsSecureCompatUtils;
35import com.android.inputmethod.latin.R;
36
37public class AccessibilityUtils {
38    private static final String TAG = AccessibilityUtils.class.getSimpleName();
39    private static final String CLASS = AccessibilityUtils.class.getClass().getName();
40    private static final String PACKAGE = AccessibilityUtils.class.getClass().getPackage()
41            .getName();
42
43    private static final AccessibilityUtils sInstance = new AccessibilityUtils();
44
45    private Context mContext;
46    private AccessibilityManager mAccessibilityManager;
47    private AccessibilityManagerCompatWrapper mCompatManager;
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        mCompatManager = new AccessibilityManagerCompatWrapper(mAccessibilityManager);
81
82        final AudioManager audioManager = (AudioManager) context
83                .getSystemService(Context.AUDIO_SERVICE);
84        mAudioManager = new AudioManagerCompatWrapper(audioManager);
85    }
86
87    /**
88     * Returns {@code true} if touch exploration is enabled. Currently, this
89     * means that the kill switch is off, the device supports touch exploration,
90     * and a spoken feedback service is turned on.
91     *
92     * @return {@code true} if touch exploration is enabled.
93     */
94    public boolean isTouchExplorationEnabled() {
95        return ENABLE_ACCESSIBILITY
96                && mAccessibilityManager.isEnabled()
97                && mCompatManager.isTouchExplorationEnabled();
98    }
99
100    /**
101     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
102     * event. This is used to determine whether the event should be processed by
103     * the touch exploration code within the keyboard.
104     *
105     * @param event The event to check.
106     * @return {@true} is the event is a touch exploration event
107     */
108    public boolean isTouchExplorationEvent(MotionEvent event) {
109        final int action = event.getAction();
110
111        return action == MotionEventCompatUtils.ACTION_HOVER_ENTER
112                || action == MotionEventCompatUtils.ACTION_HOVER_EXIT
113                || action == MotionEventCompatUtils.ACTION_HOVER_MOVE;
114    }
115
116    /**
117     * Returns whether the device should obscure typed password characters.
118     * Typically this means speaking "dot" in place of non-control characters.
119     *
120     * @return {@code true} if the device should obscure password characters.
121     */
122    public boolean shouldObscureInput(EditorInfo editorInfo) {
123        if (editorInfo == null)
124            return false;
125
126        // The user can optionally force speaking passwords.
127        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
128            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
129                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
130            if (speakPassword)
131                return false;
132        }
133
134        // Always speak if the user is listening through headphones.
135        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn())
136            return false;
137
138        // Don't speak if the IME is connected to a password field.
139        return InputTypeCompatUtils.isPasswordInputType(editorInfo.inputType);
140    }
141
142    /**
143     * Sends the specified text to the {@link AccessibilityManager} to be
144     * spoken.
145     *
146     * @param text the text to speak
147     */
148    public void speak(CharSequence text) {
149        if (!mAccessibilityManager.isEnabled()) {
150            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
151            return;
152        }
153
154        // The following is a hack to avoid using the heavy-weight TextToSpeech
155        // class. Instead, we're just forcing a fake AccessibilityEvent into
156        // the screen reader to make it speak.
157        final AccessibilityEvent event = AccessibilityEvent
158                .obtain(AccessibilityEvent.TYPE_VIEW_FOCUSED);
159
160        event.setPackageName(PACKAGE);
161        event.setClassName(CLASS);
162        event.setEventTime(SystemClock.uptimeMillis());
163        event.setEnabled(true);
164        event.getText().add(text);
165
166        mAccessibilityManager.sendAccessibilityEvent(event);
167    }
168
169    /**
170     * Handles speaking the "connect a headset to hear passwords" notification
171     * when connecting to a password field.
172     *
173     * @param editorInfo The input connection's editor info attribute.
174     * @param restarting Whether the connection is being restarted.
175     */
176    public void onStartInputViewInternal(EditorInfo editorInfo, boolean restarting) {
177        if (shouldObscureInput(editorInfo)) {
178            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
179            speak(text);
180        }
181    }
182}
183