PullToRefreshListView.java

package com.costum.android.widget;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.AbsListView.OnScrollListener;

import com.daifan.R;

/*Copyright (C) 2011 Johan Nilsson <http://markupartist.com>

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

public class PullToRefreshListView extends ListView implements OnScrollListener {

	private static final int TAP_TO_REFRESH = 1;
	private static final int PULL_TO_REFRESH = 2;
	private static final int RELEASE_TO_REFRESH = 3;
	protected static final int REFRESHING = 4;

	protected static final String TAG = "PullToRefreshListView";

	private OnRefreshListener mOnRefreshListener;

	/**
	 * Listener that will receive notifications every time the list scrolls.
	 */
	private OnScrollListener mOnScrollListener;
	protected LayoutInflater mInflater;

	// header
	private RelativeLayout mRefreshView;
	private TextView mRefreshViewText;
	private ImageView mRefreshViewImage;
	private ProgressBar mRefreshViewProgress;
	private TextView mRefreshViewLastUpdated;

	protected int mCurrentScrollState;
	protected int mRefreshState;

	private RotateAnimation mFlipAnimation;
	private RotateAnimation mReverseFlipAnimation;

	private int mRefreshViewHeight;
	private int mRefreshOriginalTopPadding;
	private int mLastMotionY;

	private boolean mBounceHack;

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

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

	public PullToRefreshListView(Context context, AttributeSet attrs,
			int defStyle) {
		super(context, attrs, defStyle);
		init(context);
	}

	protected void init(Context context) {
		// Load all of the animations we need in code rather than through XML
		mFlipAnimation = new RotateAnimation(0, -180,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		mFlipAnimation.setInterpolator(new LinearInterpolator());
		mFlipAnimation.setDuration(250);
		mFlipAnimation.setFillAfter(true);
		mReverseFlipAnimation = new RotateAnimation(-180, 0,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f,
				RotateAnimation.RELATIVE_TO_SELF, 0.5f);
		mReverseFlipAnimation.setInterpolator(new LinearInterpolator());
		mReverseFlipAnimation.setDuration(250);
		mReverseFlipAnimation.setFillAfter(true);

		mInflater = (LayoutInflater) context
				.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

		// header
		mRefreshView = (RelativeLayout) mInflater.inflate(
				R.layout.new_pull_to_refresh_header, this, false);
		mRefreshViewText = (TextView) mRefreshView
				.findViewById(R.id.pull_to_refresh_text);
		mRefreshViewImage = (ImageView) mRefreshView
				.findViewById(R.id.pull_to_refresh_image);
		mRefreshViewProgress = (ProgressBar) mRefreshView
				.findViewById(R.id.pull_to_refresh_progress);
		mRefreshViewLastUpdated = (TextView) mRefreshView
				.findViewById(R.id.pull_to_refresh_updated_at);

		mRefreshViewImage.setMinimumHeight(50);
		mRefreshView.setOnClickListener(new OnClickRefreshListener());
		mRefreshOriginalTopPadding = mRefreshView.getPaddingTop();

		mRefreshState = TAP_TO_REFRESH;

		addHeaderView(mRefreshView);

		super.setOnScrollListener(this);

		measureView(mRefreshView);
		mRefreshViewHeight = mRefreshView.getMeasuredHeight();
	}

	@Override
	protected void onAttachedToWindow() {
		//have to ask super to attach to window, otherwise it won't scroll in jelly bean.
		super.onAttachedToWindow();
		setSelection(1);
	}

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

		setSelection(1);
	}

	/**
	 * Set the listener that will receive notifications every time the list
	 * scrolls.
	 * 
	 * @param l
	 *            The scroll listener.
	 */
	@Override
	public void setOnScrollListener(OnScrollListener l) {
		mOnScrollListener = l;
	}

	/**
	 * Register a callback to be invoked when this list should be refreshed.
	 * 
	 * @param onRefreshListener
	 *            The callback to run.
	 */
	public void setOnRefreshListener(OnRefreshListener onRefreshListener) {
		mOnRefreshListener = onRefreshListener;
	}

	/**
	 * Set a text to represent when the list was last updated.
	 * 
	 * @param lastUpdated
	 *            Last updated at.
	 */
	public void setLastUpdated(CharSequence lastUpdated) {
		if (lastUpdated != null) {
			mRefreshViewLastUpdated.setVisibility(View.VISIBLE);
			mRefreshViewLastUpdated.setText(lastUpdated);
		} else {
			mRefreshViewLastUpdated.setVisibility(View.GONE);
		}
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		final int y = (int) event.getY();
		mBounceHack = false;

		switch (event.getAction()) {
		case MotionEvent.ACTION_UP:
			if (!isVerticalScrollBarEnabled()) {
				setVerticalScrollBarEnabled(true);
			}
			if (getFirstVisiblePosition() == 0 && mRefreshState != REFRESHING) {
				if ((mRefreshView.getBottom() >= mRefreshViewHeight || mRefreshView
						.getTop() >= 0) && mRefreshState == RELEASE_TO_REFRESH) {
					// Initiate the refresh
					mRefreshState = REFRESHING;
					prepareForRefresh();
					onRefresh();
				} else if (mRefreshView.getBottom() < mRefreshViewHeight
						|| mRefreshView.getTop() <= 0) {
					// Abort refresh and scroll down below the refresh view
					resetHeader();
					setSelection(1);
				}
			}
			break;
		case MotionEvent.ACTION_DOWN:
			mLastMotionY = y;
			break;
		case MotionEvent.ACTION_MOVE:
			applyHeaderPadding(event);
			break;
		}
		return super.onTouchEvent(event);
	}

	private void applyHeaderPadding(MotionEvent ev) {
		// getHistorySize has been available since API 1
		int pointerCount = ev.getHistorySize();

		for (int p = 0; p < pointerCount; p++) {
			if (mRefreshState == RELEASE_TO_REFRESH) {
				if (isVerticalFadingEdgeEnabled()) {
					setVerticalScrollBarEnabled(false);
				}

				int historicalY = (int) ev.getHistoricalY(p);

				// Calculate the padding to apply, we divide by 1.7 to
				// simulate a more resistant effect during pull.
				int topPadding = (int) (((historicalY - mLastMotionY) - mRefreshViewHeight) / 1.7);

				mRefreshView.setPadding(mRefreshView.getPaddingLeft(),
						topPadding, mRefreshView.getPaddingRight(),
						mRefreshView.getPaddingBottom());
			}
		}
	}

	/**
	 * Sets the header padding back to original size.
	 */
	private void resetHeaderPadding() {
		mRefreshView.setPadding(mRefreshView.getPaddingLeft(),
				mRefreshOriginalTopPadding, mRefreshView.getPaddingRight(),
				mRefreshView.getPaddingBottom());
	}

	/**
	 * Resets the header to the original state.
	 */
	private void resetHeader() {
		if (mRefreshState != TAP_TO_REFRESH) {
			mRefreshState = TAP_TO_REFRESH;

			resetHeaderPadding();

			// Set refresh view text to the pull label
			mRefreshViewText.setText(R.string.pull_to_refresh_tap_label);
			// Replace refresh drawable with arrow drawable
			mRefreshViewImage
					.setImageResource(R.drawable.ic_pulltorefresh_arrow);
			// Clear the full rotation animation
			mRefreshViewImage.clearAnimation();
			// Hide progress bar and arrow.
			mRefreshViewImage.setVisibility(View.GONE);
			mRefreshViewProgress.setVisibility(View.GONE);
		}
	}

	private void measureView(View child) {
		ViewGroup.LayoutParams p = child.getLayoutParams();
		if (p == null) {
			p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
					ViewGroup.LayoutParams.WRAP_CONTENT);
		}

		int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
		int lpHeight = p.height;
		int childHeightSpec;
		if (lpHeight > 0) {
			childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
					MeasureSpec.EXACTLY);
		} else {
			childHeightSpec = MeasureSpec.makeMeasureSpec(0,
					MeasureSpec.UNSPECIFIED);
		}
		child.measure(childWidthSpec, childHeightSpec);
	}

	public void onScroll(AbsListView view, int firstVisibleItem,
			int visibleItemCount, int totalItemCount) {
		// When the refresh view is completely visible, change the text to say
		// "Release to refresh..." and flip the arrow drawable.
		if (mCurrentScrollState == SCROLL_STATE_TOUCH_SCROLL
				&& mRefreshState != REFRESHING) {
			if (firstVisibleItem == 0) {
				mRefreshViewImage.setVisibility(View.VISIBLE);
				if ((mRefreshView.getBottom() >= mRefreshViewHeight + 20 || mRefreshView
						.getTop() >= 0) && mRefreshState != RELEASE_TO_REFRESH) {
					mRefreshViewText
							.setText(R.string.pull_to_refresh_release_label);
					mRefreshViewImage.clearAnimation();
					mRefreshViewImage.startAnimation(mFlipAnimation);
					mRefreshState = RELEASE_TO_REFRESH;
				} else if (mRefreshView.getBottom() < mRefreshViewHeight + 20
						&& mRefreshState != PULL_TO_REFRESH) {
					mRefreshViewText
							.setText(R.string.pull_to_refresh_pull_label);
					if (mRefreshState != TAP_TO_REFRESH) {
						mRefreshViewImage.clearAnimation();
						mRefreshViewImage.startAnimation(mReverseFlipAnimation);
					}
					mRefreshState = PULL_TO_REFRESH;
				}
			} else {
				mRefreshViewImage.setVisibility(View.GONE);
				resetHeader();
			}
		} else if (mCurrentScrollState == SCROLL_STATE_FLING
				&& firstVisibleItem == 0 && mRefreshState != REFRESHING) {
			setSelection(1);
			mBounceHack = true;
		} else if (mBounceHack && mCurrentScrollState == SCROLL_STATE_FLING) {
			setSelection(1);
		}

		if (mOnScrollListener != null) {
			mOnScrollListener.onScroll(view, firstVisibleItem,
					visibleItemCount, totalItemCount);
		}
	}

	public void onScrollStateChanged(AbsListView view, int scrollState) {
		mCurrentScrollState = scrollState;

		if (mCurrentScrollState == SCROLL_STATE_IDLE) {
			mBounceHack = false;
		}

		if (mOnScrollListener != null) {
			mOnScrollListener.onScrollStateChanged(view, scrollState);
		}

	}

	public void prepareForRefresh() {
		resetHeaderPadding();

		mRefreshViewImage.setVisibility(View.GONE);
		// We need this hack, otherwise it will keep the previous drawable.
		mRefreshViewImage.setImageDrawable(null);
		mRefreshViewProgress.setVisibility(View.VISIBLE);

		// Set refresh view text to the refreshing label
		mRefreshViewText.setText(R.string.pull_to_refresh_refreshing_label);

		mRefreshState = REFRESHING;
	}

	public void onRefresh() {
		Log.d(TAG, "onRefresh");

		if (mOnRefreshListener != null) {
			mOnRefreshListener.onRefresh();
		}
	}

	/**
	 * Resets the list to a normal state after a refresh.
	 * 
	 * @param lastUpdated
	 *            Last updated at.
	 */
	public void onRefreshComplete(CharSequence lastUpdated) {
		setLastUpdated(lastUpdated);
		onRefreshComplete();
	}

	/**
	 * Resets the list to a normal state after a refresh.
	 */
	public void onRefreshComplete() {
		Log.d(TAG, "onRefreshComplete");

		resetHeader();

		// If refresh view is visible when loading completes, scroll down to
		// the next item.
		if (mRefreshView.getBottom() > 0) {
			invalidateViews();
			setSelection(1);
		}
	}

	/**
	 * Invoked when the refresh view is clicked on. This is mainly used when
	 * there's only a few items in the list and it's not possible to drag the
	 * list.
	 */
	private class OnClickRefreshListener implements OnClickListener {

		public void onClick(View v) {
			if (mRefreshState != REFRESHING) {
				prepareForRefresh();
				onRefresh();
			}
		}

	}

	/**
	 * Interface definition for a callback to be invoked when list should be
	 * refreshed.
	 */
	public interface OnRefreshListener {
		/**
		 * Called when the list should be refreshed.
		 * <p>
		 * A call to {@link com.costum.android.widget.PullToRefreshListView #onRefreshComplete()} is
		 * expected to indicate that the refresh has completed.
		 */
		public void onRefresh();
	}

}