1 /* 2 * Copyright (C) 2017 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 17 package com.example.android.contentproviderpaging; 18 19 import android.app.Activity; 20 import android.app.LoaderManager; 21 import android.content.ContentResolver; 22 import android.content.CursorLoader; 23 import android.content.Loader; 24 import android.database.Cursor; 25 import android.os.Bundle; 26 import android.support.annotation.Nullable; 27 import android.support.v4.app.Fragment; 28 import android.support.v7.widget.LinearLayoutManager; 29 import android.support.v7.widget.RecyclerView; 30 import android.util.Log; 31 import android.view.LayoutInflater; 32 import android.view.View; 33 import android.view.ViewGroup; 34 import android.widget.Button; 35 import android.widget.Toast; 36 37 import java.util.concurrent.atomic.AtomicInteger; 38 39 /** 40 * Fragment that works as a client for accessing the DocumentsProvider 41 * ({@link ImageProvider}. 42 */ 43 public class ImageClientFragment extends Fragment { 44 45 private static final String TAG = "ImageClientFragment"; 46 47 /** The number of fetched images in a single query to the DocumentsProvider. */ 48 private static final int LIMIT = 10; 49 50 private ImageAdapter mAdapter; 51 52 private LinearLayoutManager mLayoutManager; 53 54 private final LoaderCallback mLoaderCallback = new LoaderCallback(); 55 56 /** 57 * The offset position for the ContentProvider to be used as a starting position to fetch 58 * the images from. 59 */ 60 private AtomicInteger mOffset = new AtomicInteger(0); 61 62 public static ImageClientFragment newInstance() { 63 64 Bundle args = new Bundle(); 65 66 ImageClientFragment fragment = new ImageClientFragment(); 67 fragment.setArguments(args); 68 return fragment; 69 } 70 71 @Nullable 72 @Override 73 public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, 74 @Nullable Bundle savedInstanceState) { 75 return inflater.inflate(R.layout.fragment_image_client, container, false); 76 } 77 78 @Override 79 public void onViewCreated(View rootView, @Nullable Bundle savedInstanceState) { 80 super.onViewCreated(rootView, savedInstanceState); 81 82 final Activity activity = getActivity(); 83 84 RecyclerView recyclerView = (RecyclerView) activity.findViewById(R.id.recyclerview); 85 if (mLayoutManager == null) { 86 mLayoutManager = new LinearLayoutManager(activity); 87 } 88 recyclerView.setLayoutManager(mLayoutManager); 89 if (mAdapter == null) { 90 mAdapter = new ImageAdapter(activity); 91 } 92 recyclerView.setAdapter(mAdapter); 93 recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() { 94 @Override 95 public void onScrolled(RecyclerView recyclerView, int dx, int dy) { 96 int lastVisiblePosition = mLayoutManager.findLastVisibleItemPosition(); 97 if (lastVisiblePosition >= mAdapter.getFetchedItemCount()) { 98 Log.d(TAG, 99 "Fetch new images. LastVisiblePosition: " + lastVisiblePosition 100 + ", NonEmptyItemCount: " + mAdapter.getFetchedItemCount()); 101 102 int pageId = lastVisiblePosition / LIMIT; 103 // Fetch new images once the last fetched item becomes visible 104 activity.getLoaderManager() 105 .restartLoader(pageId, null, mLoaderCallback); 106 } 107 } 108 }); 109 110 final Button showButton = rootView.findViewById(R.id.button_show); 111 showButton.setOnClickListener(new View.OnClickListener() { 112 @Override 113 public void onClick(View view) { 114 activity.getLoaderManager().restartLoader(0, null, mLoaderCallback); 115 showButton.setVisibility(View.GONE); 116 } 117 }); 118 } 119 120 private class LoaderCallback implements LoaderManager.LoaderCallbacks<Cursor> { 121 122 @Override 123 public Loader<Cursor> onCreateLoader(int id, Bundle args) { 124 final Activity activity = ImageClientFragment.this.getActivity(); 125 return new CursorLoader(activity) { 126 @Override 127 public Cursor loadInBackground() { 128 Bundle bundle = new Bundle(); 129 bundle.putInt(ContentResolver.QUERY_ARG_OFFSET, mOffset.intValue()); 130 bundle.putInt(ContentResolver.QUERY_ARG_LIMIT, LIMIT); 131 return activity.getContentResolver() 132 .query(ImageContract.CONTENT_URI, null, bundle, null); 133 } 134 }; 135 } 136 137 @Override 138 public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) { 139 Bundle extras = cursor.getExtras(); 140 int totalSize = extras.getInt(ContentResolver.EXTRA_TOTAL_SIZE); 141 mAdapter.setTotalSize(totalSize); 142 int beforeCount = mAdapter.getFetchedItemCount(); 143 while (cursor.moveToNext()) { 144 String displayName = cursor.getString(cursor.getColumnIndex( 145 ImageContract.Columns.DISPLAY_NAME)); 146 String absolutePath = cursor.getString(cursor.getColumnIndex( 147 ImageContract.Columns.ABSOLUTE_PATH)); 148 149 ImageAdapter.ImageDocument imageDocument = new ImageAdapter.ImageDocument(); 150 imageDocument.mAbsolutePath = absolutePath; 151 imageDocument.mDisplayName = displayName; 152 mAdapter.add(imageDocument); 153 } 154 int cursorCount = cursor.getCount(); 155 if (cursorCount == 0) { 156 return; 157 } 158 Activity activity = ImageClientFragment.this.getActivity(); 159 mAdapter.notifyItemRangeChanged(beforeCount, cursorCount); 160 int offsetSnapShot = mOffset.get(); 161 String message = activity.getResources() 162 .getString(R.string.fetched_images_out_of, offsetSnapShot + 1, 163 offsetSnapShot + cursorCount, totalSize); 164 mOffset.addAndGet(cursorCount); 165 Toast.makeText(activity, message, Toast.LENGTH_LONG).show(); 166 } 167 168 @Override 169 public void onLoaderReset(Loader<Cursor> loader) { 170 171 } 172 } 173 } 174
