android显示圆形图片

package com.*.widget;
 
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.Path;
import android.graphics.Region;
import android.util.AttributeSet;
import android.widget.ImageView;
 
/**
 * 
 * android circle imageView
 * @author Block Cheng
 *
 */
public class CircleImageView extends ImageView {
 
    Path path;
    public PaintFlagsDrawFilter mPaintFlagsDrawFilter;// 毛边过滤
    Paint paint;
     
    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
        init();
    }
 
    public CircleImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        init();
    }
 
    public CircleImageView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        init();
    }
    public void init(){
        mPaintFlagsDrawFilter = new PaintFlagsDrawFilter(0,
                Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);
        paint = new Paint();
        paint.setAntiAlias(true);
        paint.setFilterBitmap(true);
        paint.setColor(Color.WHITE);
         
    }
     
    @Override
    protected void onDraw(Canvas cns) {
        // TODO Auto-generated method stub
        float h = getMeasuredHeight()- 3.0f;
        float w = getMeasuredWidth()- 3.0f;
        if (path == null) {
            path = new Path();
            path.addCircle(
                    w/2.0f
                    , h/2.0f
                    , (float) Math.min(w/2.0f, (h / 2.0))
                    , Path.Direction.CCW);
            path.close();
        }
        cns.drawCircle(w/2.0f, h/2.0f,  Math.min(w/2.0f, h / 2.0f) + 1.5f, paint);
         int saveCount = cns.getSaveCount();
        cns.save();
        cns.setDrawFilter(mPaintFlagsDrawFilter);
        cns.clipPath(path,Region.Op.REPLACE);
        cns.setDrawFilter(mPaintFlagsDrawFilter);
        cns.drawColor(Color.WHITE);
        super.onDraw(cns);
        cns.restoreToCount(saveCount);
    }
     
}