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/*
* Copyright (C) 2013 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 com.android.dreams.phototable;
import android.content.Context;
import android.content.SharedPreferences;
import android.database.Cursor;
/**
* Common implementation for sources that load images from a cursor.
*/
public abstract class CursorPhotoSource extends PhotoSource {
// An invalid cursor position to represent the uninitialized state.
protected static final int UNINITIALIZED = -1;
// An invalid cursor position to represent the error state.
protected static final int INVALID = -2;
public CursorPhotoSource(Context context, SharedPreferences settings) {
super(context, settings);
}
public CursorPhotoSource(Context context, SharedPreferences settings, PhotoSource fallback) {
super(context, settings, fallback);
}
@Override
protected ImageData naturalNext(ImageData current) {
if (current.cursor == null || current.cursor.isClosed()) {
openCursor(current);
}
findPosition(current);
current.cursor.moveToPosition(current.position);
current.cursor.moveToNext();
ImageData data = null;
if (!current.cursor.isAfterLast()) {
data = unpackImageData(current.cursor, null);
data.cursor = current.cursor;
data.uri = current.uri;
data.position = current.cursor.getPosition();
}
return data;
}
@Override
protected ImageData naturalPrevious(ImageData current) {
if (current.cursor == null || current.cursor.isClosed()) {
openCursor(current);
}
findPosition(current);
current.cursor.moveToPosition(current.position);
current.cursor.moveToPrevious();
ImageData data = null;
if (!current.cursor.isBeforeFirst()) {
data = unpackImageData(current.cursor, null);
data.cursor = current.cursor;
data.uri = current.uri;
data.position = current.cursor.getPosition();
}
return data;
}
@Override
protected void donePaging(ImageData current) {
if (current.cursor != null && !current.cursor.isClosed()) {
current.cursor.close();
}
}
protected abstract void openCursor(ImageData data);
protected abstract void findPosition(ImageData data);
protected abstract ImageData unpackImageData(Cursor cursor, ImageData data);
}
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