AccessibilityUtils.java revision 7a78127a56bc427fbc690cb0561c415a81064e64 
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.media.AudioManager;
21import android.os.Build;
22import android.os.SystemClock;
23import android.provider.Settings;
24import android.support.v4.view.accessibility.AccessibilityEventCompat;
25import android.text.TextUtils;
26import android.util.Log;
27import android.view.MotionEvent;
28import android.view.View;
29import android.view.ViewGroup;
30import android.view.ViewParent;
31import android.view.accessibility.AccessibilityEvent;
32import android.view.accessibility.AccessibilityManager;
33import android.view.inputmethod.EditorInfo;
34
35import com.android.inputmethod.compat.SettingsSecureCompatUtils;
36import com.android.inputmethod.latin.R;
37import com.android.inputmethod.latin.SuggestedWords;
38import com.android.inputmethod.latin.utils.InputTypeUtils;
39
40public final class AccessibilityUtils {
41    private static final String TAG = AccessibilityUtils.class.getSimpleName();
42    private static final String CLASS = AccessibilityUtils.class.getClass().getName();
43    private static final String PACKAGE =
44            AccessibilityUtils.class.getClass().getPackage().getName();
45
46    private static final AccessibilityUtils sInstance = new AccessibilityUtils();
47
48    private Context mContext;
49    private AccessibilityManager mAccessibilityManager;
50    private AudioManager mAudioManager;
51
52    /** The most recent auto-correction. */
53    private String mAutoCorrectionWord;
54
55    /** The most recent typed word for auto-correction. */
56    private String mTypedWord;
57
58    /*
59     * Setting this constant to {@code false} will disable all keyboard
60     * accessibility code, regardless of whether Accessibility is turned on in
61     * the system settings. It should ONLY be used in the event of an emergency.
62     */
63    private static final boolean ENABLE_ACCESSIBILITY = true;
64
65    public static void init(final Context context) {
66        if (!ENABLE_ACCESSIBILITY) return;
67
68        // These only need to be initialized if the kill switch is off.
69        sInstance.initInternal(context);
70        KeyCodeDescriptionMapper.init();
71        AccessibleKeyboardViewProxy.init(context);
72    }
73
74    public static AccessibilityUtils getInstance() {
75        return sInstance;
76    }
77
78    private AccessibilityUtils() {
79        // This class is not publicly instantiable.
80    }
81
82    private void initInternal(final Context context) {
83        mContext = context;
84        mAccessibilityManager =
85                (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);
86        mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
87    }
88
89    /**
90     * Returns {@code true} if accessibility is enabled. Currently, this means
91     * that the kill switch is off and system accessibility is turned on.
92     *
93     * @return {@code true} if accessibility is enabled.
94     */
95    public boolean isAccessibilityEnabled() {
96        return ENABLE_ACCESSIBILITY && mAccessibilityManager.isEnabled();
97    }
98
99    /**
100     * Returns {@code true} if touch exploration is enabled. Currently, this
101     * means that the kill switch is off, the device supports touch exploration,
102     * and system accessibility is turned on.
103     *
104     * @return {@code true} if touch exploration is enabled.
105     */
106    public boolean isTouchExplorationEnabled() {
107        return isAccessibilityEnabled() && mAccessibilityManager.isTouchExplorationEnabled();
108    }
109
110    /**
111     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
112     * event. This is used to determine whether the event should be processed by
113     * the touch exploration code within the keyboard.
114     *
115     * @param event The event to check.
116     * @return {@true} is the event is a touch exploration event
117     */
118    public boolean isTouchExplorationEvent(final MotionEvent event) {
119        final int action = event.getAction();
120        return action == MotionEvent.ACTION_HOVER_ENTER
121                || action == MotionEvent.ACTION_HOVER_EXIT
122                || action == MotionEvent.ACTION_HOVER_MOVE;
123    }
124
125    /**
126     * Returns whether the device should obscure typed password characters.
127     * Typically this means speaking "dot" in place of non-control characters.
128     *
129     * @return {@code true} if the device should obscure password characters.
130     */
131    @SuppressWarnings("deprecation")
132    public boolean shouldObscureInput(final EditorInfo editorInfo) {
133        if (editorInfo == null) return false;
134
135        // The user can optionally force speaking passwords.
136        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
137            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
138                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
139            if (speakPassword) return false;
140        }
141
142        // Always speak if the user is listening through headphones.
143        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn()) {
144            return false;
145        }
146
147        // Don't speak if the IME is connected to a password field.
148        return InputTypeUtils.isPasswordInputType(editorInfo.inputType);
149    }
150
151    /**
152     * Sets the current auto-correction word and typed word. These may be used
153     * to provide the user with a spoken description of what auto-correction
154     * will occur when a key is typed.
155     *
156     * @param suggestedWords the list of suggested auto-correction words
157     * @param typedWord the currently typed word
158     */
159    public void setAutoCorrection(final SuggestedWords suggestedWords, final String typedWord) {
160        if (suggestedWords.mWillAutoCorrect) {
161            mAutoCorrectionWord = suggestedWords.getWord(SuggestedWords.INDEX_OF_AUTO_CORRECTION);
162            mTypedWord = typedWord;
163        } else {
164            mAutoCorrectionWord = null;
165            mTypedWord = null;
166        }
167    }
168
169    /**
170     * Obtains a description for an auto-correction key, taking into account the
171     * currently typed word and auto-correction.
172     *
173     * @param keyCodeDescription spoken description of the key that will insert
174     *            an auto-correction
175     * @param shouldObscure whether the key should be obscured
176     * @return a description including a description of the auto-correction, if
177     *         needed
178     */
179    public String getAutoCorrectionDescription(
180            final String keyCodeDescription, final boolean shouldObscure) {
181        if (!TextUtils.isEmpty(mAutoCorrectionWord)) {
182            if (!TextUtils.equals(mAutoCorrectionWord, mTypedWord)) {
183                if (shouldObscure) {
184                    // This should never happen, but just in case...
185                    return mContext.getString(R.string.spoken_auto_correct_obscured,
186                            keyCodeDescription);
187                }
188                return mContext.getString(R.string.spoken_auto_correct, keyCodeDescription,
189                        mTypedWord, mAutoCorrectionWord);
190            }
191        }
192
193        return keyCodeDescription;
194    }
195
196    /**
197     * Sends the specified text to the {@link AccessibilityManager} to be
198     * spoken.
199     *
200     * @param view The source view.
201     * @param text The text to speak.
202     */
203    public void announceForAccessibility(final View view, final CharSequence text) {
204        if (!mAccessibilityManager.isEnabled()) {
205            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
206            return;
207        }
208
209        // The following is a hack to avoid using the heavy-weight TextToSpeech
210        // class. Instead, we're just forcing a fake AccessibilityEvent into
211        // the screen reader to make it speak.
212        final AccessibilityEvent event = AccessibilityEvent.obtain();
213
214        event.setPackageName(PACKAGE);
215        event.setClassName(CLASS);
216        event.setEventTime(SystemClock.uptimeMillis());
217        event.setEnabled(true);
218        event.getText().add(text);
219
220        // Platforms starting at SDK version 16 (Build.VERSION_CODES.JELLY_BEAN) should use
221        // announce events.
222        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
223            event.setEventType(AccessibilityEventCompat.TYPE_ANNOUNCEMENT);
224        } else {
225            event.setEventType(AccessibilityEvent.TYPE_VIEW_FOCUSED);
226        }
227
228        final ViewParent viewParent = view.getParent();
229        if ((viewParent == null) || !(viewParent instanceof ViewGroup)) {
230            Log.e(TAG, "Failed to obtain ViewParent in announceForAccessibility");
231            return;
232        }
233
234        viewParent.requestSendAccessibilityEvent(view, event);
235    }
236
237    /**
238     * Handles speaking the "connect a headset to hear passwords" notification
239     * when connecting to a password field.
240     *
241     * @param view The source view.
242     * @param editorInfo The input connection's editor info attribute.
243     * @param restarting Whether the connection is being restarted.
244     */
245    public void onStartInputViewInternal(final View view, final EditorInfo editorInfo,
246            final boolean restarting) {
247        if (shouldObscureInput(editorInfo)) {
248            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
249            announceForAccessibility(view, text);
250        }
251    }
252
253    /**
254     * Sends the specified {@link AccessibilityEvent} if accessibility is
255     * enabled. No operation if accessibility is disabled.
256     *
257     * @param event The event to send.
258     */
259    public void requestSendAccessibilityEvent(final AccessibilityEvent event) {
260        if (mAccessibilityManager.isEnabled()) {
261            mAccessibilityManager.sendAccessibilityEvent(event);
262        }
263    }
264}
265