Advanced Magnifying Glass

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

Start Visual Studio .NET.
Open the project that you created in the tutorial, Using the Magnifying Glass.
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
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):

[Visual Basic]


             Imports System.Drawing.Drawing2D
             Imports Leadtools.Drawing

[C#]


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

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

[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();
                  }
               }

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

Build, and Run the program to test it.