Android自定义ImageView实现在图片上添加图层效果

<RelativeLayout  
 android:layout_width="match_parent" 
 android:layout_height="wrap_content"> 
<SelectableRoundedImageView    
 android:id="@+id/imageView"    
 style="@style/margin_distance"    
 android:layout_width="match_parent"    
 android:layout_height="0dp"    
 android:layout_weight="1"    
 android:background="@drawable/youxuan_bg_shape_normol"    
 android:contentDescription="@string/app_name"    
 android:padding="1dp"    
 android:scaleType="centerCrop" />  
<ImageView    
 android:id="@+id/iv_empty_pic"    
 android:layout_width="wrap_content"    
 android:layout_height="wrap_content"    
 android:layout_centerInParent="true" />
</RelativeLayout>

public class CenterImage extends ImageView {  
private Paint paint;  
private boolean isCenterImgShow;  
private Bitmap bitmap;  
public void setCenterImgShow(boolean centerImgShow) {    
  isCenterImgShow = centerImgShow;    
  if (isCenterImgShow) {      
  bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);      
  invalidate();    
  }  
 }  
 public CenterImage(Context context) {    
  super(context);    
  init();  
 }  
public CenterImage(Context context, AttributeSet attrs) {    
  super(context, attrs);    
  init();  
 }  
public CenterImage(Context context, AttributeSet attrs, int defStyleAttr) {    
  super(context, attrs, defStyleAttr);    
  init();  
 }  
private void init() {    
  paint = new Paint();  
 }  
@Override  
protected void onDraw(Canvas canvas) {    
 super.onDraw(canvas);    
 if (isCenterImgShow && bitmap != null) {      
 canvas.drawBitmap(bitmap, getMeasuredWidth() / 2 - bitmap.getWidth() / 2, getMeasuredHeight() / 2 - bitmap.getHeight() / 2, paint);    
 }  
 }
}

<com.henanjianye.soon.communityo2o.view.CenterImage   
  android:id="@+id/goodsImage"   
  android:layout_width="match_parent"  
  android:layout_height="100dp"  
  android:layout_alignParentEnd="true"  
  android:layout_alignParentRight="true"  
  android:contentDescription="@string/app_name"  
  android:scaleType="centerCrop"  
  android:src="@mipmap/yijia_default_bg" />

CenterImage mGoodsImg =(CenterImage)findViewById(R.id.GoodsImage);
mGoodsImg.setCenterImgShow(true);