CenterAtPoint Method

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public virtual void CenterAtPoint( 
   Point pt
)

'Declaration
 
Public Overridable Sub CenterAtPoint( _
   ByVal pt As Point _
)

'Usage
 
Dim instance As RasterImageViewer
Dim pt As Point
 
instance.CenterAtPoint(pt)

public virtual void CenterAtPoint( 
   Point pt
)

 function Leadtools.WinForms.RasterImageViewer.CenterAtPoint( 
   pt 
)

public:
virtual void CenterAtPoint( 
   Point pt
)

Parameters

pt: The point at which to center the image display, in client coordinates.

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Sub ZoomAndCenter(ByVal viewer As RasterImageViewer, ByVal scaleFactor As Double)
   ' Minimum and maximum scale factors allowed (change if you have to)
   Const minimumScaleFactor As Double = 0.05
   Const maximumScaleFactor As Double = 11
   ' Normalize the scale factor based on min and max
   scaleFactor = Math.Max(minimumScaleFactor, Math.Min(maximumScaleFactor, scaleFactor))

   ' Check if we need to change the scale factor for the viewer
   If (viewer.ScaleFactor <> scaleFactor) Then
      ' Get the current center in logical units
      ' We will use this point later to re-center the viewer

      ' Get what you see in physical coordinates
      Dim rc As Rectangle = Rectangle.Intersect(viewer.PhysicalViewRectangle, viewer.ClientRectangle)
      ' Get the center of what you see in physical coordinates
      Dim center As New PointF(rc.Left + rc.Width \ 2, rc.Top + rc.Height \ 2)
      Dim t As New Transformer(viewer.Transform)
      ' Get the center of what you see in logical coordinates
      center = t.PointToLogical(center)

      ' Set the new scale factor
      viewer.ScaleFactor = scaleFactor

      ' Bring the original center into the view center

      t = New Transformer(viewer.Transform)
      ' Get the center of what you saw before the zoom in physical coordinates
      center = t.PointToPhysical(center)
      ' Bring the old center into the center of the view
      viewer.CenterAtPoint(Point.Round(center))
   End If
End Sub

void ZoomAndCenter(RasterImageViewer viewer, double scaleFactor)
{
   // Minimum and maximum scale factors allowed (change if you have to)
   const double minimumScaleFactor = 0.05;
   const double maximumScaleFactor = 11;
   // Normalize the scale factor based on min and max
   scaleFactor = Math.Max(minimumScaleFactor, Math.Min(maximumScaleFactor, scaleFactor));

   // Check if we need to change the scale factor for the viewer
   if(viewer.ScaleFactor != scaleFactor)
   {
      // Get the current center in logical units
      // We will use this point later to re-center the viewer

      // Get what you see in physical coordinates
      Rectangle rc = Rectangle.Intersect(viewer.PhysicalViewRectangle, viewer.ClientRectangle);
      // Get the center of what you see in physical coordinates
      PointF center = new PointF(rc.Left + rc.Width / 2, rc.Top + rc.Height / 2);
      Transformer t = new Transformer(viewer.Transform);
      // Get the center of what you see in logical coordinates
      center = t.PointToLogical(center);

      // Set the new scale factor
      viewer.ScaleFactor = scaleFactor;

      // Bring the original center into the view center

      t = new Transformer(viewer.Transform);
      // Get the center of what you saw before the zoom in physical coordinates
      center = t.PointToPhysical(center);
      // Bring the old center into the center of the view
      viewer.CenterAtPoint(Point.Round(center));
   }
}

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterImageViewer Class
RasterImageViewer Members