Android自定义带圆角的ImageView

package com.yizooo.yizooo.ui;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.RectF;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.ImageView;
import com.lidroid.xutils.bitmap.core.AsyncDrawable;
/**
* Created by 雪宝宝 on 2016/3/27.
* 自定义圆角工具
*/
public class RoundImageView extends ImageView {
private Paint paint;
public RoundImageView(Context context) {
this(context,null);
}
public RoundImageView(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public RoundImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
paint = new Paint();
}
/**
* 绘制圆角矩形图片
*/
@Override
protected void onDraw(Canvas canvas) {
Drawable drawable = getDrawable();
Bitmap bitmap = null;
if (null != drawable && drawable instanceof BitmapDrawable ) {
BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
bitmap = bitmapDrawable.getBitmap();
//Bitmap bitmap =( (BitmapDrawable)drawable).getBitmap();
Bitmap b = getRoundBitmap(bitmap, 10);
final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight());
final Rect rectDest = new Rect(0,0,getWidth(),getHeight());
paint.reset();
canvas.drawBitmap(b, rectSrc, rectDest, paint);
}//防止出现类型转换异常
else if(this.getDrawable() instanceof AsyncDrawable){
bitmap = Bitmap
.createBitmap(
getWidth(),
getHeight(),
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565);
Canvas canvas1 = new Canvas(bitmap);
// canvas.setBitmap(bitmap);
drawable.setBounds(0, 0, getWidth(),
getHeight());
drawable.draw(canvas1);
}
else {
super.onDraw(canvas);
}
}
/**
* 获取圆角矩形图片方法
* @param bitmap
* @param roundPx,一般设置成14
* @return Bitmap
* @author caizhiming
*/
private Bitmap getRoundBitmap(Bitmap bitmap, int roundPx) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
int x = bitmap.getWidth();
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
}

<?xml version="1.0" encoding="utf-8"? 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipelayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"  
<com.yizooo.yizooo.ui.RoundImageView
android:id="@+id/item_frag_news_icon"
android:layout_width="@dimen/dp_47"
android:layout_height="@dimen/dp_50"
android:scaleType="fitXY"
android:src="@mipmap/fuwutongzhi"
android:layout_margin="@dimen/dp_10"
/ 
</RelativeLayout