Android Open Source - FootyNews Parallax List View Helper

From Project

Back to project page FootyNews.
License

The source code is released under:
MIT License
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Java Source Code

package com.nirhart.parallaxscroll.views;
//from  w  w  w . ja  v  a  2 s  .c  o m
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.TranslateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;

import com.nirhart.parallaxscroll.R;

public class ParallaxListViewHelper implements OnScrollListener {

  private static final float DEFAULT_PARALLAX_FACTOR = 1.9F;
  private static final boolean DEFAULT_IS_CIRCULAR = false;
  private float parallaxFactor = DEFAULT_PARALLAX_FACTOR;
  private ParallaxedView parallaxedView;
  private boolean isCircular;
  private OnScrollListener listener = null;
  private ListView listView;

  protected ParallaxListViewHelper(Context context, AttributeSet attrs, ListView listView) {
    init(context, attrs, listView);
  }

  protected void init(Context context, AttributeSet attrs, ListView listView) {
    this.listView = listView;
    TypedArray typeArray = context.obtainStyledAttributes(attrs, R.styleable.ParallaxScroll);
    this.parallaxFactor = typeArray.getFloat(R.styleable.ParallaxScroll_parallax_factor, DEFAULT_PARALLAX_FACTOR);
    this.isCircular = typeArray.getBoolean(R.styleable.ParallaxScroll_circular_parallax, DEFAULT_IS_CIRCULAR);
    typeArray.recycle();
  }

  protected void setOnScrollListener(OnScrollListener l) {
    this.listener = l;
  }
  
  protected void addParallaxedHeaderView(View v) {
    addParallaxedView(v);
  }

  protected void addParallaxedHeaderView(View v, Object data, boolean isSelectable) {
    addParallaxedView(v);
  }

  protected void addParallaxedView(View v) {
    this.parallaxedView = new ListViewParallaxedItem(v);
  }

  protected void parallaxScroll() {
    if (isCircular)
      circularParallax();
    else
      headerParallax();
  }

  private void circularParallax() {
    if (listView.getChildCount() > 0) {
      int top = -listView.getChildAt(0).getTop();
      float factor = parallaxFactor;
      fillParallaxedViews();
      parallaxedView.setOffset((float)top / factor);
    }
  }

  private void headerParallax() {
    if (parallaxedView != null) {
      if (listView.getChildCount() > 0) {
        int top = -listView.getChildAt(0).getTop();
        float factor = parallaxFactor;
        parallaxedView.setOffset((float)top / factor);
      }
    }
  }

  private void fillParallaxedViews() {
    if (parallaxedView == null || parallaxedView.is(listView.getChildAt(0)) == false) {
      if (parallaxedView != null) {
        parallaxedView.setOffset(0);
        parallaxedView.setView(listView.getChildAt(0));
      } else {
        parallaxedView = new ListViewParallaxedItem(listView.getChildAt(0));
      }
    }
  }
  
  @Override
  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    parallaxScroll();
    if (this.listener != null)
      this.listener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
  }

  @Override
  public void onScrollStateChanged(AbsListView view, int scrollState) {
    if (this.listener != null)
      this.listener.onScrollStateChanged(view, scrollState);
  }
  
  protected class ListViewParallaxedItem extends ParallaxedView {

    public ListViewParallaxedItem(View view) {
      super(view);
    }

    @Override
    protected void translatePreICS(View view, float offset) {
      TranslateAnimation ta = new TranslateAnimation(0, 0, offset, offset);
      ta.setDuration(0);
      ta.setFillAfter(true);
      view.setAnimation(ta);
      ta.start();
    }
  }
}
Java Source Code List
