/talkback_preics/src/com/google/android/marvin/talkback/StatusProvider.java

  1/*
  2 * Copyright (C) 2010 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.google.android.marvin.talkback;
 18
 19import android.content.ContentProvider;
 20import android.content.ContentValues;
 21import android.database.Cursor;
 22import android.database.MatrixCursor;
 23import android.net.Uri;
 24
 25/*
 26 * This content provider enables TalkBack to provide its status (running or not)
 27 * to other applications.
 28 *
 29 * Applications can check if any screen readers are running by doing the
 30 * following:
 31 *
 32 * 1. Detect all installed screen readers by using Intents.
 33 *    Screen reader services are expected to respond to intent filters for
 34 *    action = "android.accessibilityservice.AccessibilityService" and
 35 *    category = "android.accessibilityservice.category.FEEDBACK_SPOKEN".
 36 *
 37 * 2. For the list of screen readers installed, check their status provider.
 38 *    Screen readers are expected to implement:
 39 *    <packagename>.providers.StatusProvider.
 40 *    For example, in TalkBack, the status provider is:
 41 *    com.google.android.marvin.talkback.providers.StatusProvider
 42 *
 43 * 3. The status provider returns 0 for inactive, and
 44 *    1 for active.
 45 *
 46 * @author clchen@google.com (Charles L. Chen)
 47 */
 48
 49public class StatusProvider extends ContentProvider {
 50    private class StatusCursor extends MatrixCursor {
 51        private int status;
 52
 53        public StatusCursor() {
 54            super(new String[] {""});
 55        }
 56
 57        public void setStatus(int status) {
 58            this.status = status;
 59        }
 60
 61        @Override
 62        public int getCount() {
 63            return 1;
 64        }
 65
 66        @Override
 67        public String getString(int column) {
 68            return String.valueOf(status);
 69        }
 70
 71        @Override
 72        public int getInt(int column) {
 73            return status;
 74        }
 75    }
 76
 77    @Override
 78    public int delete(Uri uri, String selection, String[] selectionArgs) {
 79        return 0;
 80    }
 81
 82    @Override
 83    public String getType(Uri uri) {
 84        return null;
 85    }
 86
 87    @Override
 88    public Uri insert(Uri uri, ContentValues values) {
 89        return null;
 90    }
 91
 92    @Override
 93    public boolean onCreate() {
 94        return true;
 95    }
 96
 97    @Override
 98    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
 99            String sortOrder) {
100        StatusCursor cursor = new StatusCursor();
101        if (TalkBackService.isServiceInitialized()) {
102            cursor.setStatus(TalkBackService.RESULT_TALKBACK_ENABLED);
103        } else {
104            cursor.setStatus(TalkBackService.RESULT_TALKBACK_DISABLED);
105        }
106        return cursor;
107    }
108
109    @Override
110    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
111        return 0;
112    }
113}