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

Visual Basic (Usage)	Copy Code
Dim instance As RasterImageViewer Dim pt As Point   instance.CenterAtPoint(pt)

public virtual void CenterAtPoint( 
   Point pt
)

public:
virtual void CenterAtPoint( 
   Point pt
) 

Parameters

pt

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

This example shows a method to change the viewer scale factor (zoom) while keeping the viewer centered.

Visual Basic

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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

C#

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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: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Reference