HorizontalListView.java

package com.jiuqi.njt.widget;

import android.content.Context;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ListView;

/**
 * 自定义支持横向滚动的ListView
 * @author 农民伯伯
 * @version 2011-12-4
 *
 */
public class HorizontalListView extends ListView {

	/** 手势 */
	private GestureDetector mGesture;
	/** 列头 */
	public LinearLayout mListHead;
	/** 偏移坐标 */
	private int mOffset = 0;
	/** 屏幕宽度 */
	private int screenWidth;

	/** 构造函数 */
	public HorizontalListView(Context context, AttributeSet attrs) {
		super(context, attrs);
		mGesture = new GestureDetector(context, mOnGesture);
	}

	/** 分发触摸事件 */
	@Override
	public boolean dispatchTouchEvent(MotionEvent ev) {
		super.dispatchTouchEvent(ev);
		return mGesture.onTouchEvent(ev);
	}

	/** 手势 */
	private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {

		@Override
		public boolean onDown(MotionEvent e) {
			return true;
		}

		@Override
		public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
				float velocityY) {
			return false;
		}

		/** 滚动 */
		@Override
		public boolean onScroll(MotionEvent e1, MotionEvent e2,
				float distanceX, float distanceY) {
			synchronized (HorizontalListView.this) {
				int moveX = (int) distanceX;
				int curX = mListHead.getScrollX();
				int scrollWidth = getWidth();
				int dx = moveX;
				//控制越界问题
				if (curX + moveX < 0)
					dx = 0;
				if (curX + moveX + getScreenWidth() > scrollWidth)
					dx = scrollWidth - getScreenWidth() - curX;

				mOffset += dx;
				//根据手势滚动Item视图
				for (int i = 0, j = getChildCount(); i < j; i++) {
					View child = ((ViewGroup) getChildAt(i)).getChildAt(1);
					if (child.getScrollX() != mOffset)
						child.scrollTo(mOffset, 0);
				}
				mListHead.scrollBy(dx, 0);
			}
			requestLayout();
			return true;
		}
	};

	
	/**
	 * 获取屏幕可见范围内最大屏幕
	 * @return
	 */
	public int getScreenWidth() {
		if (screenWidth == 0) {
			screenWidth = getContext().getResources().getDisplayMetrics().widthPixels;
			if (getChildAt(0) != null) {
				screenWidth -= ((ViewGroup) getChildAt(0)).getChildAt(0)
						.getMeasuredWidth();
			} else if (mListHead != null) {
				//减去固定第一列
				screenWidth -= mListHead.getChildAt(0).getMeasuredWidth();
			}
		}
		return screenWidth;
	}

	/** 获取列头偏移量 */
	public int getHeadScrollX() {
		return mListHead.getScrollX();
	}
}