MagnifyGlassEffect Class

'Declaration
 
Public Class MagnifyGlassEffect 
   Inherits System.Windows.Media.Effects.ShaderEffect
   Implements System.Windows.Media.Animation.IAnimatable 

Class MagnifyGlassEffectExampleWindow
      Inherits Window
      Private theViewer As ImageViewer
      Public Sub New()
         Dim sp As New StackPanel()
         Content = sp

         theViewer = New ImageViewer()

         theViewer.HorizontalAlignment = HorizontalAlignment.Center
         theViewer.VerticalAlignment = VerticalAlignment.Top
         theViewer.ImageHorizontalAlignment = HorizontalAlignment.Left
         theViewer.ImageVerticalAlignment = VerticalAlignment.Top

         sp.Children.Add(theViewer)

         ' Load an image into the viewer
         theViewer.Source = New BitmapImage(New Uri(System.IO.Path.Combine(LEAD_VARS.ImagesDir, "Cannon.jpg")))

         Title = "MagnifyGlassEffect - Click and and move the mouse cursor on the image to see the effect"

         AddHandler theViewer.PreviewMouseDown, AddressOf theViewer_PreviewMouseDown
         AddHandler theViewer.MouseMove, AddressOf theViewer_MouseMove
         AddHandler theViewer.MouseUp, AddressOf theViewer_MouseUp
      End Sub

      Private Sub theViewer_PreviewMouseDown(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
         Dim effect As New MagnifyGlassEffect()

         Dim pos As Point = e.GetPosition(theViewer)

         Dim source As BitmapSource = DirectCast(theViewer.Source, BitmapSource)
         If Not source Is Nothing Then
            effect.Center = New Point( _
               (1.0 * pos.X) / source.PixelWidth, _
               (1.0 * pos.Y) / source.PixelHeight)

            effect.Radius = 0.25
            effect.AspectRatio = 1.0
            effect.ScaleFactor = 2.0
            effect.Color = Colors.Blue
            effect.Border = 1
            effect.CrossHairs = 1
            theViewer.ImageEffect = effect
         End If
      End Sub

      Private Sub theViewer_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
         Dim effect As MagnifyGlassEffect = DirectCast(theViewer.ImageEffect, MagnifyGlassEffect)
         If Not effect Is Nothing Then
            Dim pos As Point = e.GetPosition(theViewer)

            Dim source As BitmapSource = DirectCast(theViewer.Source, BitmapSource)
            If Not source Is Nothing Then
               effect.Center = New Point( _
                  (1.0 * pos.X) / source.PixelWidth, _
                  (1.0 * pos.Y) / source.PixelHeight)
            End If
         End If
      End Sub

      Private Sub theViewer_MouseUp(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
         If Not theViewer.ImageEffect Is Nothing Then
            theViewer.ImageEffect = Nothing
         End If
      End Sub
   End Class

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class