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 ImageViewer
Dim pt As Point
 
instance.CenterAtPoint(pt)

public virtual void CenterAtPoint( 
   Point pt
)

 function Leadtools.Windows.Controls.ImageViewer.CenterAtPoint( 
   pt 
)

public:
virtual void CenterAtPoint( 
   Point pt
)

Parameters

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

The control will position the scrollbars according to user cursor moves, therefore, this method is only functional if the control has visible scrollbars (SizeMode is SizeMode.Normal or SizeMode.FitWidth and the view port is less than the image size).

The control will call this method during InteractiveMode.Pan.

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

Copy Code

Private Sub ZoomAndCenter(ByVal viewer As ImageViewer, 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 Rect = Rect.Intersect(New Rect(0, 0, viewer.ActualWidth, viewer.ActualHeight), New Rect(viewer.PhysicalSize))

      ' Get the center of what you see in physical coordinates
      Dim center As Point = New Point(rc.Left + rc.Width / 2 * scaleFactor, rc.Top + rc.Height / 2 * scaleFactor)

      ' Set the new scale factor
      viewer.ScaleFactor = scaleFactor

      ' Bring the old center into the center of the view
      viewer.CenterAtPoint(center)
   End If
End Sub

void ZoomAndCenter(ImageViewer 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
      Rect rc = Rect.Intersect(new Rect(0, 0, viewer.ActualWidth, viewer.ActualHeight), new Rect(viewer.PhysicalSize));

      // Get the center of what you see in physical coordinates
      Point center = new Point(rc.Left + rc.Width / 2 * scaleFactor, rc.Top + rc.Height / 2 * scaleFactor);

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

      // Bring the old center into the center of the view
      viewer.CenterAtPoint(center);
   }
}

void ZoomAndCenter(ImageViewer 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
      LeadRect rc = LeadRect.Intersect(new LeadRect(0, 0, (int)viewer.ActualWidth, (int)viewer.ActualHeight), new LeadRect(0, 0, (int)viewer.PhysicalSize.Width, (int)viewer.PhysicalSize.Height));

      // Get the center of what you see in physical coordinates
      Point center = new Point(rc.Left + rc.Width / 2 * scaleFactor, rc.Top + rc.Height / 2 * scaleFactor);

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

      // Bring the old center into the center of the view
      viewer.CenterAtPoint(center);
   }
}

Private Sub ZoomAndCenter(ByVal viewer As ImageViewer, 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 LeadRect = LeadRect.Intersect(New LeadRect(0, 0, CInt(viewer.ActualWidth), CInt(viewer.ActualHeight)), New LeadRect(0, 0, CInt(viewer.PhysicalSize.Width), CInt(viewer.PhysicalSize.Height)))

      ' Get the center of what you see in physical coordinates
      Dim center As Point = New Point(rc.Left + rc.Width / 2 * scaleFactor, rc.Top + rc.Height / 2 * scaleFactor)

      ' Set the new scale factor
      viewer.ScaleFactor = scaleFactor

      ' Bring the old center into the center of the view
      viewer.CenterAtPoint(center)
   End If
End Sub

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

ImageViewer Class
ImageViewer Members