Android Open Source - paged-listview Paged List View

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Back to project page paged-listview.

License

The source code is released under:

MIT License

Java Source Code

package com.github.alexkolpa.pagedlistview;
//from w  ww.  j a  v  a  2s . c o m
import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;

import android.content.Context;
import android.content.res.TypedArray;
import android.database.DataSetObserver;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ListView;

public class PagedListView extends ListView {

  public interface Pageable {
    void onLoadMoreItems();
    boolean hasMoreItems();
  }

  private boolean mFooterContained = false;
  private boolean mIsLoading;
  private Pageable mPageable;
  private View mLoadingView;
  private ViewGroup mFooterView;
  private OnScrollListener mOnScrollListener;
  private ListAdapter mAdapter;
  private DataSetObserver mDataObserver;

  private int mPreviousTotal;

  public PagedListView(Context context) {
    super(context);
    init();
  }

  public PagedListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
    loadAttributes(attrs);
  }

  public PagedListView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
    loadAttributes(attrs);
  }

  private void init() {
    mIsLoading = false;

    mFooterView = new LinearLayout(getContext());
    mFooterView.setLayoutParams(new LayoutParams(MATCH_PARENT, WRAP_CONTENT));

    addFooterView(mFooterView, null, false);

    super.setOnScrollListener(new PagedScrollListener());
  }

  private void loadAttributes(AttributeSet attributeSet) {
    TypedArray typedArray = getContext().obtainStyledAttributes(attributeSet, R.styleable.PagedListView);
    int loadingViewId = typedArray.getResourceId(R.styleable.PagedListView_plv_loadingView, R.layout.default_loading_view);
    typedArray.recycle();

    setLoadingView(loadingViewId);
  }

  /**
   * Set Pageable behind this PagedListView
   * @param pageable the Pageable that handles the loading of new data
   */
  public void setPageable(Pageable pageable) {
    mPageable = pageable;
  }

  public boolean isLoading() {
    return mIsLoading;
  }

  /**
   * Set the loading state of the View
   * @param loading whether the view is currently loading
   */
  public void setLoading(boolean loading) {
    mIsLoading = loading;

    checkAndToggleLoadingVisibility();
  }

  /**
   * Inflates and adds a new loading view into the list's footer
   * @param loadingViewId resource id of view to be inflated
   */
  public void setLoadingView(int loadingViewId) {
    View loadingView = LayoutInflater.from(getContext()).inflate(loadingViewId, mFooterView, false);
    setLoadingView(loadingView, true);
  }

  /**
   * Set a new view as the loading view
   * @param loadingView the view to be used to indicate a loading list
   * @param addToFooter Whether the view should be added to the footer
   */
  public void setLoadingView(View loadingView, boolean addToFooter) {
    if(mFooterView.indexOfChild(mLoadingView) != -1) {
      mFooterView.removeView(mLoadingView);
    }

    if(addToFooter && loadingView != null) {
      mFooterView.addView(loadingView);
    }

    mFooterContained = addToFooter;

    mLoadingView = loadingView;

    checkAndToggleLoadingVisibility();
  }

  private void checkAndToggleLoadingVisibility() {
    if(mLoadingView != null) {
      if(mFooterContained) {
        //Due to a layout issue with views inside a ListView, setting visibility to GONE behaves the same as
        // INVISIBLE, which is not what we want. So we actively remove the view from the footer view.
        if(mIsLoading) {
          mFooterView.addView(mLoadingView);
        }
        else {
          mFooterView.removeView(mLoadingView);
        }
      }
      else {
        mLoadingView.setVisibility(mIsLoading? VISIBLE : GONE);
      }
    }
  }

  /**
   * Sets the new loading view in the footer
   * @param loadingView view to be shown on loading
   */
  public void setLoadingView(View loadingView) {
    setLoadingView(loadingView, true);
  }

  @Override
  public void setAdapter(ListAdapter adapter) {
    super.setAdapter(adapter);

    if(mAdapter != null && mDataObserver != null) {
      mAdapter.unregisterDataSetObserver(mDataObserver);
    }

    mAdapter = adapter;

    if(mAdapter != null) {
      mDataObserver = new PagedDataSetObserver();
      mAdapter.registerDataSetObserver(mDataObserver);
      mDataObserver.onChanged();
    }
  }

  @Override
  public void setOnScrollListener(OnScrollListener l) {
    mOnScrollListener = l;
  }

  private class PagedScrollListener implements OnScrollListener {

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
      if(mOnScrollListener != null) {
        mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
      }

      if(mIsLoading && totalItemCount != mPreviousTotal) {
        mIsLoading = false;

        mPreviousTotal = totalItemCount;

        checkAndToggleLoadingVisibility();
      }

      if(mPageable != null && mPageable.hasMoreItems() && !mIsLoading &&
          ((firstVisibleItem + visibleItemCount) > totalItemCount - 1)) {
        mIsLoading = true;

        checkAndToggleLoadingVisibility();

        mPageable.onLoadMoreItems();
      }
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
      if(mOnScrollListener != null) {
        mOnScrollListener.onScrollStateChanged(view, scrollState);
      }
    }
  }

  private class PagedDataSetObserver extends DataSetObserver {
    @Override
    public void onChanged() {
      super.onChanged();
      checkAndUpdatePreviousTotal();
    }

    @Override
    public void onInvalidated() {
      super.onInvalidated();
      checkAndUpdatePreviousTotal();
    }

    private void checkAndUpdatePreviousTotal() {
      int empty = getAdapter().getCount();
      if(empty == getHeaderViewsCount() + getFooterViewsCount()) {
        mPreviousTotal = empty;
      }
    }
  }
}

Java Source Code List

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