Android 自定义ImageView出现的问题

package com.qnear.wechat;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
这是自定义的类
来源:http://www.cnblogs.com/goagent/p/5159126.html

public class ImageViewPlus extends ImageView {
private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG);
private Bitmap mRawBitmap;
private BitmapShader mShader;
private Matrix mMatrix = new Matrix();

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

@Override
protected  void onDraw(Canvas canvas){
    Bitmap rawBitmap = getBitmap(getDrawable());
    if(rawBitmap!=null){
        int viewWidth = getWidth();
        int viewHeight = getHeight();
        int viewMinSize = Math.min(viewWidth, viewHeight);
        float dstWidth = viewMinSize;
        float dstHeight = viewMinSize;
        if(mShader==null||!rawBitmap.equals(mRawBitmap)){
            mRawBitmap = rawBitmap;
            mShader = new BitmapShader(mRawBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        }
        if(mShader!=null){
            mMatrix.setScale(dstWidth/rawBitmap.getWidth(),dstHeight/rawBitmap.getHeight());
            mShader.setLocalMatrix(mMatrix);
        }
        mPaintBitmap.setShader(mShader);
        float radius =viewMinSize/2.0f;
        canvas.drawCircle(radius,radius,radius,mPaintBitmap);
    }else{
        super.onDraw(canvas);
    }

}

private Bitmap getBitmap(Drawable drawable) {
    if(drawable instanceof BitmapDrawable){
        return ((BitmapDrawable) drawable).getBitmap();
    }else if(drawable instanceof ColorDrawable){
        Rect rect = drawable.getBounds();
        int width = rect.right - rect.left;
        int height = rect.bottom - rect.top;
        int color = ((ColorDrawable) drawable).getColor();
        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        canvas.drawARGB(Color.alpha(color),Color.red(color),Color.blue(color),Color.green(color));
        return bitmap;
    }else{
        return null;
    }
}

}
这是引用语句：
android:layout_width="150dp"
android:layout_height="150dp"
android:src="@drawable/mwinbag"
android:scaleType="centerInside"
android:layout_marginTop="146dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
然后我就遇到了这个问题：

一个显示正常，一个黑屏

你为什么要用模拟器呢？？

用真机看看呢，以真机效果为准吧。

经测试，真机没问题，但是为什么用模拟器会出现这种情况呢

可能是机器系统的问题