package org.ovirt.mobile.movirt.ui;
import android.widget.AbsListView;
/**
* Credits : https://github.com/codepath/android_guides/wiki/Endless-Scrolling-with-AdapterViews
*/
public abstract class EndlessScrollListener implements AbsListView.OnScrollListener {
private int visibleThreshold = 5;
private int currentPage = 0;
private int previousTotalItemCount = 0;
private boolean loading = true;
private int startingPageIndex = 0;
public EndlessScrollListener() {
}
// but first we check if we are waiting for the previous load to finish.
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
// If the total item count is zero and the previous isn't, assume the
// list is invalidated and should be reset back to initial state
if (totalItemCount < previousTotalItemCount) {
this.currentPage = this.startingPageIndex;
this.previousTotalItemCount = totalItemCount;
if (totalItemCount == 0) {
this.loading = true;
}
}
// If it’s still loading, we check to see if the dataset count has
// changed, if so we conclude it has finished loading and update the current page
// number and total item count.
if (loading && (totalItemCount > previousTotalItemCount)) {
loading = false;
previousTotalItemCount = totalItemCount;
currentPage++;
}
// If it isn’t currently loading, we check to see if we have breached
// the visibleThreshold and need to reload more data.
// If we do need to reload some more data, we execute onLoadMore to fetch the data.
if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
onLoadMore(currentPage + 1, totalItemCount);
loading = true;
}
}
// Defines the process for actually loading more data based on page
public abstract void onLoadMore(int page, int totalItemsCount);
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
public void resetListener() {
visibleThreshold = 5;
currentPage = 0;
previousTotalItemCount = 0;
loading = true;
startingPageIndex = 0;
}
}