| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package androidx.contentpager.content; |
| |
| import static androidx.core.util.Preconditions.checkArgument; |
| |
| import android.app.LoaderManager; |
| import android.app.LoaderManager.LoaderCallbacks; |
| import android.content.Context; |
| import android.content.Loader; |
| import android.database.Cursor; |
| import android.os.Bundle; |
| import android.util.Log; |
| |
| import androidx.annotation.NonNull; |
| |
| /** |
| * A {@link ContentPager.QueryRunner} that executes queries using a {@link LoaderManager}. |
| * Use this when preparing {@link ContentPager} to run in an Activity or Fragment scope. |
| */ |
| public final class LoaderQueryRunner implements ContentPager.QueryRunner { |
| |
| private static final boolean DEBUG = false; |
| private static final String TAG = "LoaderQueryRunner"; |
| private static final String CONTENT_URI_KEY = "contentUri"; |
| |
| private final Context mContext; |
| private final LoaderManager mLoaderMgr; |
| |
| public LoaderQueryRunner(@NonNull Context context, @NonNull LoaderManager loaderMgr) { |
| mContext = context; |
| mLoaderMgr = loaderMgr; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") // feels spurious. But can't commit line :80 w/o this. |
| public void query(final @NonNull Query query, @NonNull final Callback callback) { |
| if (DEBUG) Log.d(TAG, "Handling query: " + query); |
| |
| LoaderCallbacks callbacks = new LoaderCallbacks<Cursor>() { |
| @Override |
| public Loader<Cursor> onCreateLoader(final int id, final Bundle args) { |
| if (DEBUG) Log.i(TAG, "Loading results for query: " + query); |
| checkArgument(id == query.getId(), "Id doesn't match query id."); |
| |
| return new android.content.CursorLoader(mContext) { |
| @Override |
| public Cursor loadInBackground() { |
| return callback.runQueryInBackground(query); |
| } |
| }; |
| } |
| |
| @Override |
| public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { |
| if (DEBUG) Log.i(TAG, "Finished loading: " + query); |
| mLoaderMgr.destroyLoader(query.getId()); |
| callback.onQueryFinished(query, cursor); |
| } |
| |
| @Override |
| public void onLoaderReset(Loader<Cursor> loader) { |
| if (DEBUG) Log.w(TAG, "Ignoring loader reset for query: " + query); |
| } |
| }; |
| |
| mLoaderMgr.restartLoader(query.getId(), null, callbacks); |
| } |
| |
| @Override |
| public boolean isRunning(@NonNull Query query) { |
| Loader<Cursor> loader = mLoaderMgr.getLoader(query.getId()); |
| return loader != null && loader.isStarted(); |
| // Hmm, when exactly would the loader not be started? Does it imply that it will |
| // be starting at some point? |
| } |
| |
| @Override |
| public void cancel(@NonNull Query query) { |
| mLoaderMgr.destroyLoader(query.getId()); |
| } |
| } |