Take the following steps to create a project that uses advanced features of the Magnifying Glass:

1. Start Visual Studio .NET.
2. Open the project that you created in the tutorial, Using the Magnifying Glass.
3. In the "Solution Explorer" window, right-click on the "References" folder, and select "Add Reference…" from the context menu. In the "Add Reference" dialog box, select the ".NET" tab and browse to Leadtools For .NET "<LEADTOOLS_INSTALLDIR>\Bin\DotNet\Win32 " folder and select the following DLLs:
   • Leadtools.Drawing.dll
4. Switch to Form1 code view (right-click Form1 in the solution explorer then select View Code ) and add the following lines at the beginning of the file (after the existing Imports / using statements):

5. [Visual Basic]

                Imports System.Drawing.Drawing2D
                Imports Leadtools.Drawing
                
   

   [C#]

                using System.Drawing.Drawing2D;
                using Leadtools.Drawing;
                
   

6. Add the following code to derive your own class from RasterMagnifyGlass, and override OnPaintBorder, OnPaintCrosshair and OnPaintImage. For Visual Basic, put this code at the end of the file. For #, put this code just inside the namespace.

   [Visual Basic]

                  ' My own class, derived from Leadtools.WinForms.RasterMagnifyGlass
                  Public Class MyMagGlass : Inherits RasterMagnifyGlass
                     Protected Overrides Sub OnPaintBorder(ByVal g As Graphics, ByVal centerPoint As Point)
                        g.DrawEllipse(Pens.Blue, centerPoint.X - (Size.Width / 2), centerPoint.Y - (Size.Height / 2), Size.Width - 1, Size.Height - 1)
                     End Sub
                
                     Protected Overrides Sub OnPaintCrosshair(ByVal g As Graphics, ByVal centerPoint As Point)
                        g.DrawRectangle(Pens.Red, centerPoint.X - 10, centerPoint.Y - 10, 20, 20)
                     End Sub
                     
                     Protected Overrides Sub OnPaintImage(ByVal g As Graphics, ByVal centerPoint As Point)
                        Dim t As Transformer = New Transformer(Viewer.Transform)
                        Dim rcDst As LeadRect = New LeadRect(centerPoint.X - (Size.Width / 2), centerPoint.Y - (Size.Height / 2), Size.Width - 1, Size.Height - 1)
                        Dim rcTemp As Rectangle = New Rectangle(rcDst.Left, rcDst.Top, rcDst.Width, rcDst.Height)
                        rcTemp = Rectangle.Round(rcTemp)
                        Dim rcSrc As LeadRect = New LeadRect(rcTemp.Left, rcTemp.Top, rcTemp.Width, rcTemp.Height)
                        
                        Dim gstate As GraphicsState = g.Save()
                        Dim path As GraphicsPath = New GraphicsPath()
                        path.AddEllipse(rcTemp)
                        Dim rgn As Region = New Region(path)
                        path.Dispose()
                        
                        Viewer.Image.DisableEvents()
                        Dim contrast As Integer = Viewer.Image.PaintContrast
                        Viewer.Image.PaintContrast = 1000
                        
                        g.Clip = rgn
                        RasterImagePainter.Paint(Viewer.Image, g, rcSrc, rcSrc, rcDst, rcDst, Viewer.PaintProperties)
                        Viewer.Image.PaintContrast = contrast
                        Viewer.Image.EnableEvents()
                        
                        g.Restore(gstate)
                        rgn.Dispose()
                     End Sub
                  End Class
                
   

7. [C#]

                  //My own class, derived from Leadtools.WinForms.RasterMagnifyGlass
                  public class MyMagGlass : RasterMagnifyGlass
                  {
                     protected override void OnPaintBorder(Graphics g, Point centerPoint)
                     {
                        g.DrawEllipse(Pens.Blue, centerPoint.X - (Size.Width / 2), centerPoint.Y - (Size.Height / 2), Size.Width - 1, Size.Height - 1);
                     }
               
                     protected override void OnPaintCrosshair(Graphics g, Point centerPoint)
                     {
                        g.DrawRectangle(Pens.Red, centerPoint.X - 10, centerPoint.Y - 10, 20, 20);
                     }
                     
                     protected override void OnPaintImage(Graphics g, Point centerPoint)
                     {
                        Transformer t = new Transformer(Viewer.Transform);
                        LeadRect rcDst = new LeadRect(centerPoint.X - (Size.Width / 2), centerPoint.Y - (Size.Height / 2), Size.Width - 1, Size.Height - 1);
                        Rectangle rcTemp = new Rectangle(rcDst.Left, rcDst.Top, rcDst.Width, rcDst.Height);
                        rcTemp = Rectangle.Round(rcTemp);
                        LeadRect rcSrc = new LeadRect(rcTemp.Left, rcTemp.Top, rcTemp.Width, rcTemp.Height);
                        GraphicsState gstate = g.Save();
                        GraphicsPath path = new GraphicsPath();
                        path.AddEllipse(rcTemp);
                        Region rgn = new Region(path);
                        path.Dispose();
                        Viewer.Image.DisableEvents();
                        int contrast = Viewer.Image.PaintContrast;
                        Viewer.Image.PaintContrast = 1000;
                        g.Clip = rgn;
                        RasterImagePainter.Paint(Viewer.Image, g, rcSrc, rcSrc, rcDst, rcDst, Viewer.PaintProperties);
                        Viewer.Image.PaintContrast = contrast;
                        Viewer.Image.EnableEvents();
                        g.Restore(gstate);
                        rgn.Dispose();
                     }
                  }
                
   

8. In the code for the Load event for Form1, add the following line, just before the line that sets the InteractiveMode property:

   [Visual Basic]

                 
                RasterImageViewer1.MagnifyGlass = New MyMagGlass 'set the MagGlass
                
   

   [C#]

                 
                rasterImageViewer1.MagnifyGlass = new MyMagGlass(); //set the MagGlass to my derived class
                
   

9. Build, and Run the program to test it.

 

 

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