Android Studio 圆形头像

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.graphics.Xfermode;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.graphics.PorterDuff;

/**
* Created by Administrator on 2016/1/2 0002.
*/
public class PorterDuffViewImage extends ImageView {

private Paint mpaint;
private static Xfermode xfermode;
private static Bitmap bitmap;
private RectF rect;

public PorterDuffViewImage(Context context) {
super(context);
init();
}

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

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

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int width = getWidth();
int height = getHeight();
Bitmap.Config config = Bitmap.Config.ARGB_8888;
Canvas canvas1 = null;
BitmapDrawable drawable = (BitmapDrawable)getDrawable();
drawable.setBounds(0, 0, width, height);
drawable.draw(canvas);
if (bitmap == null){
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
rect = new RectF(0,0,width,height);
bitmap = Bitmap.createBitmap(width, height, config);
canvas1 = new Canvas(bitmap);
canvas1.drawOval(rect, paint);
}
mpaint.setXfermode(xfermode);
canvas.drawBitmap(bitmap,0,0,mpaint);
}

private void init(){
setLayerType(LAYER_TYPE_SOFTWARE,null);
xfermode = new PorterDuffXfermode(PorterDuff.Mode.DST_IN);
mpaint = new Paint(Paint.ANTI_ALIAS_FLAG);
}

}