自定义下拉刷新组件

package com.example.customclass;

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.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.ScrollView;import android.widget.Scroller;

import com.example.test.R;

/** * Created by LI on 2016/1/5. */public class RefershLinearLayout extends LinearLayout {    ImageView direction;    ProgressBar bar;    Scroller scroller;    View header;    Context mContext;    int headerHeightPix;    int lastY;    FreshListener freshListener;    enum Status{        refreshing,normal,pulldown    }    public int status;    public RefershLinearLayout(Context context) {        super(context);    }

    public RefershLinearLayout(Context context, AttributeSet attrs) {        super(context, attrs);        mContext = context;        scroller = new Scroller(mContext);        init();    }

    private void init() {        header = LayoutInflater.from(mContext).inflate(R.layout.header,null);        bar = (ProgressBar) header.findViewById(R.id.bar);        direction = (ImageView) header.findViewById(R.id.direction);        headerHeightPix = (int) (50*mContext.getResources().getDisplayMetrics().density);        LayoutParams params = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,headerHeightPix);        params.topMargin = (0-headerHeightPix);        addView(header, params);        status = 0;    }

    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        int y= (int) ev.getRawY();        Log.i("LIJILONG", "onInterceptTouchEvent()");        switch(ev.getAction()){            case MotionEvent.ACTION_DOWN:                lastY = y;                break;            case MotionEvent.ACTION_MOVE:                int m = y - lastY;                lastY = y;                if(m>=2.0 &&canScroll()) {                    Log.i("LIJILONG" ,"canScroll() true");                    return true;                }                break;        }        return false;    }

    @Override    public boolean onTouchEvent(MotionEvent event) {        if(status == 2){            Log.i("lijilong", "onTouchEvent status = "+status);            return false;        }        int y = (int) event.getRawY();        switch(event.getAction()){            case MotionEvent.ACTION_DOWN:                lastY = y;                break;            case MotionEvent.ACTION_MOVE:                int m = y - lastY;                lastY = y;                moveLayout(m);                break;            case MotionEvent.ACTION_UP:                flying();                break;        }

        return true;    }

    private void flying() {        LayoutParams params = (LayoutParams) header.getLayoutParams();        int marginTop = params.topMargin;        if(marginTop >= 0){            //refresh();            bar.setVisibility(View.VISIBLE);            direction.setVisibility(View.GONE);            scroller.startScroll(0, marginTop, 0, 0 - marginTop);            invalidate();//            params.topMargin = 0;//            header.setLayoutParams(params);//            header.invalidate();//            invalidate();//            invalidate();            status = 2;            if(freshListener !=null){                freshListener.onFresh();            }        }else{            //returnInit();            scroller.startScroll(0, marginTop, 0 ,0-(headerHeightPix+marginTop));            invalidate();            status = 0;

        }    }    public void finishFresh(){        status = 0;        bar.setVisibility(View.GONE);        scroller.startScroll(0, 0, 0, (0 - headerHeightPix));//        LayoutParams params = (LayoutParams) header.getLayoutParams();//        int marginTop = params.topMargin;//        params.topMargin = (0-headerHeightPix);//        header.setLayoutParams(params);//        header.invalidate();

    }

    private void moveLayout(int m) {        Log.i("lijilong","moveLayout");        LayoutParams params = (LayoutParams) header.getLayoutParams();        int margintop = params.topMargin;            direction.setVisibility(View.VISIBLE);            bar.setVisibility(View.GONE);            if(margintop >= 0){                direction.setImageResource(R.drawable.refresh_arrow_up);            }else{                direction.setImageResource(R.drawable.refresh_arrow_down);            }            int position_y = (int) (margintop + m*0.3);            params.topMargin = position_y;            header.setLayoutParams(params);           // header.invalidate();            //invalidate();            status = 1;    }

    @Override    public void computeScroll() {        super.computeScroll();        if (scroller.computeScrollOffset()) {//scroll 动作还未结束

            int i = this.scroller.getCurrY();            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) this.header                    .getLayoutParams();            int k = Math.max(i, (0-headerHeightPix));            lp.topMargin = k;            this.header.setLayoutParams(lp);            postInvalidate();        }    }

    private boolean canScroll() {        // TODO Auto-generated method stub        View childView;        if (getChildCount() > 1) {            Log.e("lijilong","getChildCount="+getChildCount());            for(int i=0;i<getChildCount();i++){                Log.e("lijilong",getChildAt(i).toString());            }            childView = this.getChildAt(1);            if (childView instanceof ListView) {                int top = ((ListView) childView).getChildAt(0).getTop();                int pad = ((ListView) childView).getListPaddingTop();                if ((Math.abs(top - pad)) < 3                        && ((ListView) childView).getFirstVisiblePosition() == 0) {                    return true;                } else {                    return false;                }            } else if (childView instanceof ScrollView) {                if (((ScrollView) childView).getScrollY() == 0) {                    return true;                } else {                    return false;                }            }

        }        Log.i("LIJILONG","canScroll false");        return false;    }

    public void setListener(FreshListener listener){        freshListener = listener;    }   public interface FreshListener{        public void onFresh();

    }}