android viewgrop(实现了事件监听/手动滑动)

package com.example.myviewgroup;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;


public class MyViewgroup extends ViewGroup {
    private int itemWidth;
    private int itemHeight;
    private int groupWidth;
    private int childcount;
    private float downpos;
    private int startx;
    private boolean isclick = false;
    private boolean autoplayflag=true;
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            autoplay();

            handler.sendEmptyMessageDelayed(0, 2000);
        }
    };

    /**
     * 自动播放
     */
    private void autoplay() {
        if(!autoplayflag)return;
        int index = getScrollX() / itemWidth;
        if (index == 1) {//轮播图前后有重复的条目
            scrollTo(groupWidth - itemWidth * 2, 0);
        } else
            scrollTo(startx - itemWidth, 0);
        if (index == childcount - 2) {
            scrollTo(itemWidth, 0);
        } else {
            scrollTo((index + 1) * itemWidth, 0);
        }
    }

    public MyViewgroup(Context context) {
        super(context);
    }

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

    public MyViewgroup(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (changed) {
            for (int i = 0; i < childcount; i++) {
                View view = getChildAt(i);
                view.layout(itemWidth * i, 0, itemWidth * (i + 1), itemHeight);
            }

        }
        scrollTo(itemWidth, 0);//因为轮播图前后各有一个重复的条目，所以要设置显示第二个。
        handler.sendEmptyMessageDelayed(0, 2000);//
    }


    /**
     * 接口回调处理响应点击事件
     */

    private ClickListener clickListener;

    public void setonclickistener(ClickListener clickListener) {
        this.clickListener = clickListener;
    }

    public interface ClickListener {
        public void onclik(View view);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        super.onTouchEvent(event);
        int action = event.getAction();
        float move = 0;
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                autoplayflag=false;//当点击轮播图停止自动播放
                isclick = true;//点击事件标记，true 为点击 false 为滑动事件
                startx = 0;
                downpos = 0f;
                downpos = event.getX();
                startx = getScrollX();
                break;
            case MotionEvent.ACTION_MOVE:
                isclick = false;
                move = event.getX();
                int distance = (int) (move - downpos);
                scrollBy(-distance, 0);
                downpos = move;
                break;
            case MotionEvent.ACTION_UP:
                int index = startx / itemWidth;//视图索引从0开始
                if (isclick) {
                    isclick = true;
                    processOnclick(getChildAt(index));
                    return true;
                }
                int endx = getScrollX();
                int res = endx - startx; //负数为向右滑动，正数为向左滑动
                if (Math.abs(res) > itemWidth / 6) {//滑动到视图超过六分之一时再切换
                    if (res < 0) {
                        if (index == 1) {//轮播图前后有重复的条目
                            scrollTo(groupWidth - itemWidth * 2, 0);
                        } else
                            scrollTo(startx - itemWidth, 0);
                    } else {
                        if (index == childcount - 2) {
                            scrollTo(itemWidth, 0);
                        } else {
                            scrollTo((index + 1) * itemWidth, 0);
                        }
                    }
                } else {
                    scrollTo(index * itemWidth, 0);
                }
                autoplayflag=true;
                break;
        }
        return true;
    }

    private void processOnclick(View child) {
        clickListener.onclik(child);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {

        return true;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        childcount = getChildCount();
        if (childcount > 0) {
            measureChildren(widthMeasureSpec, heightMeasureSpec);
            View child = getChildAt(0);

            itemWidth = child.getMeasuredWidth();

            itemHeight = child.getMeasuredHeight();

            groupWidth = itemWidth * childcount;
            setMeasuredDimension(groupWidth, itemHeight);
        } else if (childcount == 0) {
            setMeasuredDimension(0, 0);
        }
    }
}