OnPaintCrosshair Method

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

protected virtual void OnPaintCrosshair( 
   Graphics graphics,
   Point centerPoint
)

'Declaration
 
Protected Overridable Sub OnPaintCrosshair( _
   ByVal graphics As Graphics, _
   ByVal centerPoint As Point _
)

'Usage
 
Dim instance As RasterMagnifyGlass
Dim graphics As Graphics
Dim centerPoint As Point
 
instance.OnPaintCrosshair(graphics, centerPoint)

protected virtual void OnPaintCrosshair( 
   Graphics graphics,
   Point centerPoint
)

 function Leadtools.WinForms.RasterMagnifyGlass.OnPaintCrosshair( 
   graphics ,
   centerPoint 
)

protected:
virtual void OnPaintCrosshair( 
   Graphics^ graphics,
   Point centerPoint
)

Parameters

graphics: The Graphics object used to paint.
centerPoint: The center point of the Magnifying Glass rectangle

You can override this method in order to paint your own crosshair for the Magnifying Glass. Call the base class implementation for the default behavior.

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

Private Class MyRasterMagnifyGlass : Inherits RasterMagnifyGlass
   Public Sub New()
      Shape = RasterMagnifyGlassShape.Border3D
   End Sub
   Protected Overrides Sub OnPaintBorder(ByVal graphics As Graphics, ByVal centerPoint As Point)
      Dim width As Integer = (Size.Width - 2) \ 2
      Dim height As Integer = (Size.Height - 2) \ 2

      Dim rc As Rectangle = New Rectangle(centerPoint.X - width, centerPoint.Y - height, 2 * width, 2 * height)
      graphics.DrawRectangle(Pens.Blue, rc)
   End Sub

   Protected Overrides Sub OnPaintCrosshair(ByVal graphics As Graphics, ByVal centerPoint As Point)
      Dim width As Integer = (Size.Width - 2) \ 2
      Dim height As Integer = (Size.Height - 2) \ 2
      Dim p1 As Point = New Point(centerPoint.X - width, centerPoint.Y - height)
      Dim p2 As Point = New Point(centerPoint.X + width, centerPoint.Y + height)
      graphics.DrawLine(Pens.Red, p1, p2)

      p1 = New Point(centerPoint.X + width, centerPoint.Y - height)
      p2 = New Point(centerPoint.X - width, centerPoint.Y + height)
      graphics.DrawLine(Pens.Red, p1, p2)
   End Sub
End Class

Private Sub viewer_MagnifyGlassChanged(ByVal sender As Object, ByVal e As EventArgs)
   MessageBox.Show("Custom Magnify Glass being used -- red X for crosshair, blue for border")
End Sub

Public Sub RasterImageViewer_MagnifyGlass(ByVal viewer As RasterImageViewer)
   AddHandler viewer.MagnifyGlassChanged, AddressOf viewer_MagnifyGlassChanged
   viewer.MagnifyGlass = New MyRasterMagnifyGlass()
   viewer.InteractiveMode = RasterViewerInteractiveMode.MagnifyGlass

   RemoveHandler viewer.MagnifyGlassChanged, AddressOf viewer_MagnifyGlassChanged
End Sub

class MyRasterMagnifyGlass : RasterMagnifyGlass
{
   public MyRasterMagnifyGlass()
   {
      Shape = RasterMagnifyGlassShape.Border3D;
   }
   protected override void OnPaintBorder(Graphics graphics, Point centerPoint)
   {
      int width = (Size.Width - 2) / 2;
      int height = (Size.Height - 2) / 2;

      Rectangle rc = new Rectangle(centerPoint.X - width, centerPoint.Y - height, 2*width, 2*height);
      graphics.DrawRectangle(Pens.Blue, rc);
   }

   protected override void OnPaintCrosshair(Graphics graphics, Point centerPoint)
   {
      int width = (Size.Width - 2) / 2;
      int height = (Size.Height - 2) / 2;
      Point p1 = new Point(centerPoint.X - width, centerPoint.Y - height);
      Point p2 = new Point(centerPoint.X + width, centerPoint.Y + height);
      graphics.DrawLine(Pens.Red, p1, p2);

      p1 = new Point(centerPoint.X + width, centerPoint.Y - height);
      p2 = new Point(centerPoint.X - width, centerPoint.Y + height);
      graphics.DrawLine(Pens.Red, p1, p2);
   }
}

private void viewer_MagnifyGlassChanged(object sender, EventArgs e)
{
   MessageBox.Show("Custom Magnify Glass being used -- red X for crosshair, blue for border");
}

public void RasterImageViewer_MagnifyGlass(RasterImageViewer viewer)
{
   viewer.MagnifyGlassChanged+= new EventHandler(viewer_MagnifyGlassChanged);
   viewer.MagnifyGlass = new MyRasterMagnifyGlass();
   viewer.InteractiveMode = RasterViewerInteractiveMode.MagnifyGlass;

   viewer.MagnifyGlassChanged -= new EventHandler(viewer_MagnifyGlassChanged);
}

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

RasterMagnifyGlass Class
RasterMagnifyGlass Members