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/*
* 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 android.arch.paging.integration.testapp;
import android.arch.paging.PositionalDataSource;
import android.graphics.Color;
import android.support.annotation.ColorInt;
import android.support.annotation.NonNull;
import java.util.ArrayList;
import java.util.List;
/**
* Sample data source with artificial data.
*/
class ItemDataSource extends PositionalDataSource<Item> {
private static final int COUNT = 500;
@ColorInt
private static final int[] COLORS = new int[] {
Color.RED,
Color.BLUE,
Color.BLACK,
};
private static int sGenerationId;
private final int mGenerationId = sGenerationId++;
private List<Item> loadRangeInternal(int startPosition, int loadCount) {
List<Item> items = new ArrayList<>();
int end = Math.min(COUNT, startPosition + loadCount);
int bgColor = COLORS[mGenerationId % COLORS.length];
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
for (int i = startPosition; i != end; i++) {
items.add(new Item(i, "item " + i, bgColor));
}
return items;
}
// TODO: open up this API in PositionalDataSource?
private static int computeFirstLoadPosition(int position, int firstLoadSize,
int pageSize, int size) {
int roundedPageStart = Math.round(position / pageSize) * pageSize;
// minimum start position is 0
roundedPageStart = Math.max(0, roundedPageStart);
// maximum start pos is that which will encompass end of list
int maximumLoadPage = ((size - firstLoadSize + pageSize - 1) / pageSize) * pageSize;
roundedPageStart = Math.min(maximumLoadPage, roundedPageStart);
return roundedPageStart;
}
@Override
public void loadInitial(int requestedStartPosition, int requestedLoadSize,
int pageSize, @NonNull InitialLoadCallback<Item> callback) {
requestedStartPosition = computeFirstLoadPosition(
requestedStartPosition, requestedLoadSize, pageSize, COUNT);
requestedLoadSize = Math.min(COUNT - requestedStartPosition, requestedLoadSize);
List<Item> data = loadRangeInternal(requestedStartPosition, requestedLoadSize);
callback.onResult(data, requestedStartPosition, COUNT);
}
@Override
public void loadRange(int startPosition, int count, @NonNull LoadCallback<Item> callback) {
List<Item> data = loadRangeInternal(startPosition, count);
callback.onResult(data);
}
}
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