Zoom by Ratio Snippet

///<summary>Zoom in ActiveView using a ratio of the current extent.</summary>
///  
///<param name="activeView">An IActiveView interface.</param>
///<param name="zoomRatio">A Double that is the ratio to zoom in. Less that 1 zooms in (Example: .75), greater than 1 zooms out (Example: 2).</param>
///   
///<remarks>Both the width and height ratio of the zoomed area is preserved.</remarks>
public void ZoomByRatio(ESRI.ArcGIS.Carto.IActiveView activeView, System.Double zoomRatio)
{
  if(activeView == null || zoomRatio < 0)
  {
    return;
  }
  ESRI.ArcGIS.Geometry.IEnvelope envelope = activeView.Extent;
  envelope.Expand(zoomRatio, zoomRatio, true);
  activeView.Extent = envelope;
  activeView.Refresh();
}

'''<summary>Zoom in ActiveView using a ratio of the current extent.</summary>
'''  
'''<param name="activeView">An IActiveView interface.</param>
'''<param name="zoomRatio">A Double that is the ratio to zoom in. Less that 1 zooms in (Example: .75), greater than 1 zooms out (Example: 2).</param>
'''   
'''<remarks>Both the width and height ratio of the zoomed area is preserved.</remarks>
Public Sub ZoomByRatio(ByVal activeView As ESRI.ArcGIS.Carto.IActiveView, ByVal zoomRatio As System.Double)

  If activeView Is Nothing OrElse zoomRatio < 0 Then
    Return
  End If

  Dim envelope As ESRI.ArcGIS.Geometry.IEnvelope = activeView.Extent
  envelope.Expand(zoomRatio, zoomRatio, True)
  activeView.Extent = envelope
  activeView.Refresh()

End Sub