AccessibilityUtils.java revision bca7e4e9a2ed07d5d87f4dce9f793e40edb09691 
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    }
72
73    public static AccessibilityUtils getInstance() {
74        return sInstance;
75    }
76
77    private AccessibilityUtils() {
78        // This class is not publicly instantiable.
79    }
80
81    private void initInternal(final Context context) {
82        mContext = context;
83        mAccessibilityManager =
84                (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);
85        mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
86    }
87
88    /**
89     * Returns {@code true} if accessibility is enabled. Currently, this means
90     * that the kill switch is off and system accessibility is turned on.
91     *
92     * @return {@code true} if accessibility is enabled.
93     */
94    public boolean isAccessibilityEnabled() {
95        return ENABLE_ACCESSIBILITY && mAccessibilityManager.isEnabled();
96    }
97
98    /**
99     * Returns {@code true} if touch exploration is enabled. Currently, this
100     * means that the kill switch is off, the device supports touch exploration,
101     * and system accessibility is turned on.
102     *
103     * @return {@code true} if touch exploration is enabled.
104     */
105    public boolean isTouchExplorationEnabled() {
106        return isAccessibilityEnabled() && mAccessibilityManager.isTouchExplorationEnabled();
107    }
108
109    /**
110     * Returns {@true} if the provided event is a touch exploration (e.g. hover)
111     * event. This is used to determine whether the event should be processed by
112     * the touch exploration code within the keyboard.
113     *
114     * @param event The event to check.
115     * @return {@true} is the event is a touch exploration event
116     */
117    public boolean isTouchExplorationEvent(final MotionEvent event) {
118        final int action = event.getAction();
119        return action == MotionEvent.ACTION_HOVER_ENTER
120                || action == MotionEvent.ACTION_HOVER_EXIT
121                || action == MotionEvent.ACTION_HOVER_MOVE;
122    }
123
124    /**
125     * Returns whether the device should obscure typed password characters.
126     * Typically this means speaking "dot" in place of non-control characters.
127     *
128     * @return {@code true} if the device should obscure password characters.
129     */
130    @SuppressWarnings("deprecation")
131    public boolean shouldObscureInput(final EditorInfo editorInfo) {
132        if (editorInfo == null) return false;
133
134        // The user can optionally force speaking passwords.
135        if (SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD != null) {
136            final boolean speakPassword = Settings.Secure.getInt(mContext.getContentResolver(),
137                    SettingsSecureCompatUtils.ACCESSIBILITY_SPEAK_PASSWORD, 0) != 0;
138            if (speakPassword) return false;
139        }
140
141        // Always speak if the user is listening through headphones.
142        if (mAudioManager.isWiredHeadsetOn() || mAudioManager.isBluetoothA2dpOn()) {
143            return false;
144        }
145
146        // Don't speak if the IME is connected to a password field.
147        return InputTypeUtils.isPasswordInputType(editorInfo.inputType);
148    }
149
150    /**
151     * Sets the current auto-correction word and typed word. These may be used
152     * to provide the user with a spoken description of what auto-correction
153     * will occur when a key is typed.
154     *
155     * @param suggestedWords the list of suggested auto-correction words
156     * @param typedWord the currently typed word
157     */
158    public void setAutoCorrection(final SuggestedWords suggestedWords, final String typedWord) {
159        if (suggestedWords.mWillAutoCorrect) {
160            mAutoCorrectionWord = suggestedWords.getWord(SuggestedWords.INDEX_OF_AUTO_CORRECTION);
161            mTypedWord = typedWord;
162        } else {
163            mAutoCorrectionWord = null;
164            mTypedWord = null;
165        }
166    }
167
168    /**
169     * Obtains a description for an auto-correction key, taking into account the
170     * currently typed word and auto-correction.
171     *
172     * @param keyCodeDescription spoken description of the key that will insert
173     *            an auto-correction
174     * @param shouldObscure whether the key should be obscured
175     * @return a description including a description of the auto-correction, if
176     *         needed
177     */
178    public String getAutoCorrectionDescription(
179            final String keyCodeDescription, final boolean shouldObscure) {
180        if (!TextUtils.isEmpty(mAutoCorrectionWord)) {
181            if (!TextUtils.equals(mAutoCorrectionWord, mTypedWord)) {
182                if (shouldObscure) {
183                    // This should never happen, but just in case...
184                    return mContext.getString(R.string.spoken_auto_correct_obscured,
185                            keyCodeDescription);
186                }
187                return mContext.getString(R.string.spoken_auto_correct, keyCodeDescription,
188                        mTypedWord, mAutoCorrectionWord);
189            }
190        }
191
192        return keyCodeDescription;
193    }
194
195    /**
196     * Sends the specified text to the {@link AccessibilityManager} to be
197     * spoken.
198     *
199     * @param view The source view.
200     * @param text The text to speak.
201     */
202    public void announceForAccessibility(final View view, final CharSequence text) {
203        if (!mAccessibilityManager.isEnabled()) {
204            Log.e(TAG, "Attempted to speak when accessibility was disabled!");
205            return;
206        }
207
208        // The following is a hack to avoid using the heavy-weight TextToSpeech
209        // class. Instead, we're just forcing a fake AccessibilityEvent into
210        // the screen reader to make it speak.
211        final AccessibilityEvent event = AccessibilityEvent.obtain();
212
213        event.setPackageName(PACKAGE);
214        event.setClassName(CLASS);
215        event.setEventTime(SystemClock.uptimeMillis());
216        event.setEnabled(true);
217        event.getText().add(text);
218
219        // Platforms starting at SDK version 16 (Build.VERSION_CODES.JELLY_BEAN) should use
220        // announce events.
221        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
222            event.setEventType(AccessibilityEventCompat.TYPE_ANNOUNCEMENT);
223        } else {
224            event.setEventType(AccessibilityEvent.TYPE_VIEW_FOCUSED);
225        }
226
227        final ViewParent viewParent = view.getParent();
228        if ((viewParent == null) || !(viewParent instanceof ViewGroup)) {
229            Log.e(TAG, "Failed to obtain ViewParent in announceForAccessibility");
230            return;
231        }
232
233        viewParent.requestSendAccessibilityEvent(view, event);
234    }
235
236    /**
237     * Handles speaking the "connect a headset to hear passwords" notification
238     * when connecting to a password field.
239     *
240     * @param view The source view.
241     * @param editorInfo The input connection's editor info attribute.
242     * @param restarting Whether the connection is being restarted.
243     */
244    public void onStartInputViewInternal(final View view, final EditorInfo editorInfo,
245            final boolean restarting) {
246        if (shouldObscureInput(editorInfo)) {
247            final CharSequence text = mContext.getText(R.string.spoken_use_headphones);
248            announceForAccessibility(view, text);
249        }
250    }
251
252    /**
253     * Sends the specified {@link AccessibilityEvent} if accessibility is
254     * enabled. No operation if accessibility is disabled.
255     *
256     * @param event The event to send.
257     */
258    public void requestSendAccessibilityEvent(final AccessibilityEvent event) {
259        if (mAccessibilityManager.isEnabled()) {
260            mAccessibilityManager.sendAccessibilityEvent(event);
261        }
262    }
263}
264