android 圆形 ImageView

import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.Bitmap.Config;  
import android.graphics.Canvas;  
import android.graphics.Paint;  
import android.graphics.PorterDuff.Mode;  
import android.graphics.PorterDuffXfermode;  
import android.graphics.Rect;  
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;  
import android.graphics.drawable.Drawable;  
import android.util.AttributeSet;  
import android.widget.ImageView;  
  
/** 
 * 圆形的Imageview 
 * @since 2012-11-02 
 *  
 * @author bingyang.djj 
 *  
 */  
public class CircleImageView extends ImageView {  
    private Paint paint = new Paint();  
  
    public CircleImageView(Context context) {  
        super(context);  
    }  
  
    public CircleImageView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
    }  
  
    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
    }  
  
    @Override  
    protected void onDraw(Canvas canvas) {  
  
        Drawable drawable = getDrawable();  
        if (null != drawable) {  
            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();  
            Bitmap b = toRoundCorner(bitmap, 14);  
           // final Rect rect = new Rect(0, 0, b.getWidth(), b.getHeight());  
            final Rect rect = new Rect(0, 0, b.getWidth(),b.getHeight());  
            Rect rect1= new Rect(0, 0, this.getWidth(),this.getHeight());  
            paint.reset();  
            canvas.drawBitmap(b, rect, rect1, paint);  
  
        } else {  
            super.onDraw(canvas);  
        }  
    }  
  
    private Bitmap toRoundCorner(Bitmap bitmap, int pixels) {  
        Bitmap outBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(outBitmap);
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(rect);
        final float roundPX = bitmap.getWidth() / 2 < bitmap.getHeight() / 2 ? bitmap.getWidth() : bitmap.getHeight();
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPX, roundPX, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return outBitmap;  
    }  
}