java.lang.NullPointerException
            at android.view.GLES20Canvas.drawBitmap(GLES20Canvas.java:789)
            at android.view.GLES20RecordingCanvas.drawBitmap(GLES20RecordingCanvas.java:118)
            at com.administrator_example.weixin6_0.ChangeColorIconwithText.onDraw(ChangeColorIconwithText.java:100)   

 canvas.drawBitmap(mIconBitmap,null,mIconRect,null); 这行代码报错了  怎样解决 求大神解惑