PoppyListViewHelper.java

package com.roboo.like.google.views.helper;

import android.app.Activity;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewParent;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.ListView;

import com.nineoldandroids.view.ViewPropertyAnimator;
import com.roboo.like.google.staggeredgrid.StaggeredGridView;
import com.roboo.like.google.views.StickyGridHeadersGridView;
import com.roboo.like.google.views.StickyListHeadersListView;

public class PoppyListViewHelper
{
	public enum PoppyViewPosition
	{
		TOP, BOTTOM
	};

	private static final int SCROLL_TO_TOP = -1;

	private static final int SCROLL_TO_BOTTOM = 1;

	private static final int SCROLL_DIRECTION_CHANGE_THRESHOLD = 5;

	private Activity mActivity;
	private LayoutInflater mLayoutInflater;

	private View mPoppyView;

	private int mScrollDirection = 0;

	private int mPoppyViewHeight = -1;

	private PoppyViewPosition mPoppyViewPosition;

	public PoppyListViewHelper(Activity activity, PoppyViewPosition position)
	{
		mActivity = activity;
		mLayoutInflater = LayoutInflater.from(activity);
		mPoppyViewPosition = position;
	}

	public PoppyListViewHelper(Activity activity)
	{
		this(activity, PoppyViewPosition.BOTTOM);
	}

	// for ListView
	public View createPoppyViewOnAbsListView(int listViewId, int poppyViewResId, OnScrollListener onScrollListener)
	{
		ListView listView = null;
		AbsListView view = (AbsListView) mActivity.findViewById(listViewId);
		if (view instanceof ListView)
		{
			listView = (ListView) view;
		}
		else if (view instanceof GridView)
		{

		}
		if (null != listView)
		{
			if (listView.getHeaderViewsCount() != 0)
			{
				throw new IllegalArgumentException("use createPoppyViewOnListView with headerResId parameter");
			}
			if (listView.getFooterViewsCount() != 0)
			{
				throw new IllegalArgumentException("poppyview library doesn't support listview with footer");
			}
		}
		mPoppyView = mLayoutInflater.inflate(poppyViewResId, null);
		initPoppyViewOnAbsListView(view, onScrollListener);
		return mPoppyView;
	}

	public View createPoppyViewOnListView(int listViewId, int poppyViewResId)
	{
		return createPoppyViewOnAbsListView(listViewId, poppyViewResId, null);
	}

	private void setPoppyViewOnView(View view)
	{
		LayoutParams lp = view.getLayoutParams();
		ViewParent parent = view.getParent();
		ViewGroup group = (ViewGroup) parent;
		int index = group.indexOfChild(view);
		final FrameLayout newContainer = new FrameLayout(mActivity);
		group.removeView(view);
		group.addView(newContainer, index, lp);
		newContainer.addView(view);
		final FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
		layoutParams.gravity = mPoppyViewPosition == PoppyViewPosition.BOTTOM ? Gravity.BOTTOM : Gravity.TOP;
		if (isPlusMarginBottom(view))
		{
			int bottomMargin = (int) (48 * mActivity.getResources().getDisplayMetrics().density);
			layoutParams.bottomMargin = bottomMargin;
		}
		newContainer.addView(mPoppyView, layoutParams);
		group.invalidate();
	}

	private boolean isPlusMarginBottom(View view)
	{
		return view instanceof StickyListHeadersListView ||view instanceof StickyGridHeadersGridView || view instanceof StaggeredGridView;
	}

	private void onScrollPositionChanged(int oldScrollPosition, int newScrollPosition)
	{
		int newScrollDirection;
		System.out.println(oldScrollPosition + " ->" + newScrollPosition);

		if (newScrollPosition < oldScrollPosition)
		{
			newScrollDirection = SCROLL_TO_TOP;
		}
		else
		{
			newScrollDirection = SCROLL_TO_BOTTOM;
		}

		if (newScrollDirection != mScrollDirection)
		{
			mScrollDirection = newScrollDirection;
			translateYPoppyView();
		}
	}

	private void translateYPoppyView()
	{
		mPoppyView.post(new Runnable()
		{
			public void run()
			{
				if (mPoppyViewHeight <= 0)
				{
					mPoppyViewHeight = mPoppyView.getHeight();
				}
				int translationY = 0;
				switch (mPoppyViewPosition)
				{
				case BOTTOM:
					translationY = mScrollDirection == SCROLL_TO_TOP ? 0 : mPoppyViewHeight;
					break;
				case TOP:
					translationY = mScrollDirection == SCROLL_TO_TOP ? -mPoppyViewHeight : 0;
					break;
				}
				ViewPropertyAnimator.animate(mPoppyView).setDuration(300).translationY(translationY);
			}
		});
	}

	private void initPoppyViewOnAbsListView(AbsListView listView, final OnScrollListener onScrollListener)
	{
		setPoppyViewOnView(listView);
		listView.setOnScrollListener(new OnScrollListener()
		{
			int mScrollPosition;

			public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
			{
				if (onScrollListener != null)
				{
					onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
				}
				View topChild = view.getChildAt(0);
				int newScrollPosition = 0;
				if (topChild == null)
				{
					newScrollPosition = 0;
				}
				else
				{
					newScrollPosition = -topChild.getTop() + view.getFirstVisiblePosition() * topChild.getHeight();
				}

				if (Math.abs(newScrollPosition - mScrollPosition) >= SCROLL_DIRECTION_CHANGE_THRESHOLD)
				{
					onScrollPositionChanged(mScrollPosition, newScrollPosition);
				}

				mScrollPosition = newScrollPosition;
			}

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