title: flutter : Get Local position of Gesture Detector
body: <p>I have problems to get real local position on gesture detector widget using pan update.</p>
  <pre><code>new Center(    
    child new Container(
         height: 150.0,
         width: 150.0,
         decoration: new BoxDecoration(
           borderRadius: new BorderRadius.circular(5.0),
           color: Colors.white,
        ),
        child: new GestureDetector(
        onPanUpdate: (details) =&gt; onPanUpdate(context, details),
        child: new CustomPaint(
           painter: new MyPainter(
               points: points,
               limitBottom:height - 125.0,
               limitTop: 10.0,
               limitLeft: 5.0,
               limitRight: width - 55.0
           ),
         ),
      ),
    ),  
  )
  </code></pre>
  <p>when I print the the Offset of global position &amp;&amp; local position, I've got same value for both of them. in Result it was painted outside of my Container widget.  Is there anything I missed to get local position?</p>