Back to project page GridImageSearch.
The source code is released under:
Copyright (c) 2014 Keithen Hayenga Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the So...
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package com.codepath.gridimagesearch; /*ww w . j a v a 2 s . co m*/ import android.widget.AbsListView; import android.widget.AbsListView.OnScrollListener; public abstract class EndlessScrollListener implements OnScrollListener { // The minimum amount of items to have below your current scroll position // before loading more. private int visibleThreshold = 5; // The current offset index of data you have loaded private int currentPage = 0; // The total number of items in the dataset after the last load private int previousTotalItemCount = 0; // True if we are still waiting for the last set of data to load. private boolean loading = true; // Sets the starting page index private int startingPageIndex = 0; public EndlessScrollListener() { } public EndlessScrollListener(int visibleThreshold) { this.visibleThreshold = visibleThreshold; } public EndlessScrollListener(int visibleThreshold, int startPage) { this.visibleThreshold = visibleThreshold; this.startingPageIndex = startPage; this.currentPage = startPage; } // This happens many times a second during a scroll, so be wary of the code you place here. // We are given a few useful parameters to help us work out if we need to load some more data, // 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) { // Don't take any action on changed } }