title: Connect a slider to control zoom on qml Camera
body: <p>I am using Camera to take movies.<br>
  I want to use a slider to zooming video like zoom of google map.<br>
  I've found another <a href="https://stackoverflow.com/questions/32991233/how-to-scale-a-particular-point-in-a-video-in-qml#">Question on SO</a> but the proposed solution works for click whereas I would like to develop a solution for slider.<br>
  I wrote code that is not working correctly.
  I have not found error, but video size will be very large, then I do not see video.<br>
  I try to set digitalZoom for camera but I have this error:
  <strong>The camera doesn't support zooming.</strong> .I know my camera does not support "DigitalZoom" and "OpticalZoom". I want to find a way to zoom in on video taken from camera.<br>
  <strong><a href="https://cdn.shopify.com/s/files/1/1089/1350/products/4023XC_large.png?v=1460917620" rel="nofollow noreferrer">My camera is dino ccd.</a></strong>
  Excuse me friends, I can not add comment, I have this error: "You must have 50 reputation to comment".</p>
  
  <pre><code>VideoOutput {
       id: viewfinder
       source: camera
       anchors.fill: parent
       focus : true                                
       transform: [
           Scale {
               id: zoomScale
           },
           Translate {
               id: zoomTranslate
           }
        ]
  
        //Keys.onLeftPressed: viewfinder.seek(viewfinder.position - 5000)
        //Keys.onRightPressed: viewfinder.seek(viewfinder.position + 5000)
  
        MouseArea {
             anchors.fill: parent
             acceptedButtons: Qt.AllButtons
             onClicked: {
                var zoomIn = mouse.button === Qt.LeftButton;
                zoomScale.origin.x = mouse.x;
                zoomScale.origin.y = mouse.y;
             }
        }
  
        Slider {
            id:zoomVideo
            orientation: Qt.Vertical
            minimumValue: 0
            maximumValue: 100
            stepSize: 10
  
            onValueChanged: {
                zoomScale.xScale = zoomVideo.value
                zoomScale.yScale = zoomVideo.value
            }
        }
    }
  </code></pre>