/*
* Copyright (c) 2012, Codename One and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Codename One designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Codename One through http://www.codenameone.com/ if you
* need additional information or have any questions.
*/
package com.codename1.ui;
import com.codename1.components.InfiniteProgress;
import com.codename1.components.InfiniteScrollAdapter;
import com.codename1.ui.layouts.BoxLayout;
/**
* <p>This abstract Container can scroll indefinitely (or at least until
* we run out of data).
* This class uses the {@link com.codename1.components.InfiniteScrollAdapter} to bring more data and the pull to
* refresh feature to refresh current displayed data.</p>
* <p>
* The sample code shows the usage of the nestoria API to fill out an infinitely scrolling list.
* </p>
* <script src="https://gist.github.com/codenameone/9e2f7984beb22d9e372c.js"></script>
* <img src="https://www.codenameone.com/img/developer-guide/components-infinitescrolladapter.png" alt="Sample usage of infinite scroll adapter" />
* <script src="https://gist.github.com/codenameone/22efe9e04e2b8986dfc3.js"></script>
*
* @author Chen
*/
public abstract class InfiniteContainer extends Container {
private int amount = 10;
private boolean amountSet;
private boolean requestingResults;
private InfiniteScrollAdapter adapter;
/**
* Creates the InfiniteContainer.
* The InfiniteContainer is created with BoxLayout Y layout.
*/
public InfiniteContainer() {
setLayout(new BoxLayout(BoxLayout.Y_AXIS));
setScrollableY(true);
}
/**
* Creates the InfiniteContainer.
* The InfiniteContainer is created with BoxLayout Y layout.
*
* @param amount the number of items to fetch in each call to fetchComponents
*/
public InfiniteContainer(int amount) {
this();
this.amount = amount;
if(amount <= 0){
throw new IllegalArgumentException("amount must be greater then zero");
}
amountSet = true;
}
@Override
void resetScroll() {
}
boolean shouldContinue(Component[] cmps) {
if(amountSet) {
return cmps.length == amount;
} else {
return cmps != null && cmps.length > 0;
}
}
@Override
protected void initComponent() {
super.initComponent();
createInfiniteScroll();
addPullToRefresh(new Runnable() {
public void run() {
refresh();
}
});
}
/**
* This refreshes the UI in a similar way to the "pull to refresh" functionality
*/
public void refresh() {
if(isAsync()) {
Display.getInstance().invokeAndBlock(new Runnable() {
public void run() {
refreshImpl();
}
});
return;
}
refreshImpl();
}
void refreshImpl() {
requestingResults = true;
Component[] components = fetchComponents(0, amount);
if (components == null) {
components = new Component[0];
}
final Component[] cmps = components;
if(!Display.getInstance().isEdt()) {
Display.getInstance().callSerially(new Runnable() {
public void run() {
removeAll();
InfiniteScrollAdapter.addMoreComponents(InfiniteContainer.this, cmps, shouldContinue(cmps));
requestingResults = false;
}
});
} else {
removeAll();
InfiniteScrollAdapter.addMoreComponents(InfiniteContainer.this, cmps, shouldContinue(cmps));
requestingResults = false;
}
}
void fetchMore() {
if (requestingResults) {
return;
}
requestingResults = true;
Component[] components = fetchComponents(getComponentCount() - 1, amount);
if (components == null) {
components = new Component[0];
}
final Component[] cmps = components;
if(!Display.getInstance().isEdt()) {
Display.getInstance().callSerially(new Runnable() {
public void run() {
InfiniteScrollAdapter.addMoreComponents(InfiniteContainer.this, cmps, shouldContinue(cmps));
requestingResults = false;
}
});
} else {
InfiniteScrollAdapter.addMoreComponents(InfiniteContainer.this, cmps, shouldContinue(cmps));
requestingResults = false;
}
}
private void createInfiniteScroll() {
adapter = InfiniteScrollAdapter.createInfiniteScroll(this, new Runnable() {
public void run() {
if(isAsync()) {
Display.getInstance().scheduleBackgroundTask(new Runnable() {
public void run() {
fetchMore();
}
});
} else {
fetchMore();
}
}
});
}
/**
* Indicates whether {@link #fetchComponents(int, int)} should be invoked asynchronously off the EDT
* @return this is set to true for compatibility with older versions of the infinite container
*/
protected boolean isAsync() {
return false;
}
/**
* <p>This is an abstract method that should be implemented by the sub classes
* to fetch the data.</p>
* <p><b>When {@link #isAsync()} is overriden to return true this method is invoked on a background thread</b>.
* Notice that in this case the method might cause EDT violations warnings, since the
* subclasses will need to create the Components off the EDT. While these are EDT violations they
* probably won't cause problems for more code.</p>
* <p>Sub classes should preform their networking/data fetching here.</p>
*
*
* @param index the index from which to bring data
* @param amount the size of components to bring
*
* @return Components array of the returned data, size of the array can be the
* size of the amount or smaller, if there is no more data to fetch the method should return null.
*/
public abstract Component[] fetchComponents(int index, int amount);
/**
* Lets us manipulate the infinite progress object e.g. set the animation image etc.
* @return the infinite progress component underlying this container
*/
public InfiniteProgress getInfiniteProgress() {
return adapter.getInfiniteProgress();
}
}