package com.wasu.widgets.focuswidget;

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.ScrollView;

import cn.com.wasu.main.R;
/**
 * 当你使用滚动窗口焦点错乱的时候，就可以使用这个控件.
 * <p>
 * 使用方法和滚动窗口是一样的，具体查看DEMO吧.
 * <p>
 * 如果想改变滚动的系数，R.dimen.fading_edge
 * <p>
 * 
 * @author danxingxi
 */
public class SmoothVorizontalScrollView extends ScrollView {

	public SmoothVorizontalScrollView(Context context) {
		super(context, null, 0);
	}

	public SmoothVorizontalScrollView(Context context, AttributeSet attrs) {
		super(context, attrs, 0);
	}

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

	@Override
	protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
		if (getChildCount() == 0)
			return 0;
		int height = getHeight();
		int screenTop = getScrollY();
		int screenBottom = screenTop + height;
		int fadingEdge = this.getResources().getDimensionPixelSize(R.dimen.d_80dp);
		if (rect.top > 0) {
			screenTop += fadingEdge;
		}
		if (rect.bottom < getChildAt(0).getHeight()) {
			screenBottom -= fadingEdge;
		}
		//
		int scrollYDelta = 0;
		if (rect.bottom > screenBottom && rect.top > screenTop) {
			if (rect.height() > height) {
				scrollYDelta += (rect.top - screenTop);
			} else {
				scrollYDelta += (rect.bottom - screenBottom);
			}
			int bottom = getChildAt(0).getBottom();
			int distanceToBottom = bottom - screenBottom;
			scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
		} else if (rect.top < screenTop && rect.bottom < screenBottom) {
			if (rect.height() > height) {
				scrollYDelta -= (screenBottom - rect.bottom);
			} else {
				scrollYDelta -= (screenTop - rect.top);
			}
			scrollYDelta = Math.max(scrollYDelta, -getScrollY());
		}
		return scrollYDelta;
	}

}