<CategoryAttribute("Behavior")>
<DescriptionAttribute("Indicating whether to auto dispose the old image when a new image is set into this control")>
Public Overridable Property AutoDisposeImages As Boolean

Dim instance As RasterImageViewer
Dim value As Boolean
 
instance.AutoDisposeImages = value
 
value = instance.AutoDisposeImages

[CategoryAttribute("Behavior")]
[DescriptionAttribute("Indicating whether to auto dispose the old image when a new image is set into this control")]
public virtual bool AutoDisposeImages {get; set;}

[CategoryAttribute("Behavior")]
[DescriptionAttribute("Indicating whether to auto dispose the old image when a new image is set into this control")]
public:
virtual property bool AutoDisposeImages {
   bool get();
   void set (    bool value);
}

Private Sub viewer_ImageChanged(ByVal sender As Object, ByVal e As EventArgs)
      Dim viewer As RasterImageViewer = CType(IIf(TypeOf sender Is RasterImageViewer, sender, Nothing), RasterImageViewer)
      Dim s As String
      If Not viewer.Image Is Nothing Then
         s = String.Format("Image Changed: New Width {0}, NewHeight {1}", viewer.Image.Width, viewer.Image.Height)
      Else
         s = "No Image"
      End If
      Console.WriteLine(s)
   End Sub

   Public Sub RasterImageViewer_AutoDisposeImages(ByVal viewer As RasterImageViewer)
      ' Load two image2
      Dim codecs As RasterCodecs = New RasterCodecs()
      Dim file1 As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")
      Dim file2 As String = Path.Combine(LEAD_VARS.ImagesDir, "Image2.cmp")

      AddHandler viewer.ImageChanged, AddressOf viewer_ImageChanged

      Dim image1 As RasterImage = codecs.Load(file1)
      Dim image2 As RasterImage = codecs.Load(file2)

      ' Make sure the AutoDisposeImages property of the viewer is set to true
      viewer.AutoDisposeImages = True

      ' Set the first image into the viewer
      viewer.Image = image1

      ' Now set the second image into the viewer (this disposes the first image since the AutoDisposeImages property is true)
      viewer.Image = image2

      ' Try to access the first image, it generates a NullReferenceException exception since the image has been disposed
      MessageBox.Show("Try to access the first image, it generates a NullReferenceException exception since the image has been disposed.")
      Try
         Dim width As Integer = image1.Width
         MessageBox.Show(String.Format("Width is {0} pixels", width))
      Catch ex As NullReferenceException
         MessageBox.Show(ex.Message)
      End Try

      ' Set the image to null (will dispose the second image as well)
      viewer.Image = Nothing

      ' Now re-load the two images
      image1 = codecs.Load(file1)
      image2 = codecs.Load(file2)

      ' Make sure the AutoDisposeImages property of the viewer is set to false
      viewer.AutoDisposeImages = False

      ' Set the first image into the viewer
      viewer.Image = image1

      ' Now set the second image into the viewer (this will not disposes the first image since the AutoDisposeImages property is false)
      viewer.Image = image2

      ' Try to access the first image, it should work fine this time
      Try
         Dim width As Integer = image1.Width
         MessageBox.Show(String.Format("Width is {0} pixels", width))
      Catch ex As NullReferenceException
         MessageBox.Show(ex.Message)
      End Try

      ' Set the image to null (will not dispose the second image)
      viewer.Image = Nothing

      ' We should now dispose the two images manually
      image1.Dispose()
      image2.Dispose()

      RemoveHandler viewer.ImageChanged, AddressOf viewer_ImageChanged
   End Sub

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

private void viewer_ImageChanged(object sender, EventArgs e)
   {
      RasterImageViewer viewer = sender as RasterImageViewer;
      string s;
      if (viewer.Image != null)
         s = string.Format("Image Changed: New Width {0}, NewHeight {1}", viewer.Image.Width, viewer.Image.Height);
      else s = "No Image";
      Console.WriteLine(s);
   }

   public void RasterImageViewer_AutoDisposeImages(RasterImageViewer viewer)
   {
      // Load two image2
      RasterCodecs codecs = new RasterCodecs();
      string file1 = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp");
      string file2 = Path.Combine(LEAD_VARS.ImagesDir, "Image2.cmp");

      viewer.ImageChanged += new EventHandler(viewer_ImageChanged);

      RasterImage image1 = codecs.Load(file1);
      RasterImage image2 = codecs.Load(file2);

      // Make sure the AutoDisposeImages property of the viewer is set to true
      viewer.AutoDisposeImages = true;

      // Set the first image into the viewer
      viewer.Image = image1;

      // Now set the second image into the viewer (this disposes the first image since the AutoDisposeImages property is true)
      viewer.Image = image2;

      // Try to access the first image, it generates a NullReferenceException exception since the image has been disposed
      MessageBox.Show("Try to access the first image, it generates a NullReferenceException exception since the image has been disposed.");
      try
      {
         int width = image1.Width;
         MessageBox.Show(string.Format("Width is {0} pixels", width));
      }
      catch (NullReferenceException ex)
      {
         MessageBox.Show(ex.Message);
      }

      // Set the image to null (will dispose the second image as well)
      viewer.Image = null;

      // Now re-load the two images
      image1 = codecs.Load(file1);
      image2 = codecs.Load(file2);

      // Make sure the AutoDisposeImages property of the viewer is set to false
      viewer.AutoDisposeImages = false;

      // Set the first image into the viewer
      viewer.Image = image1;

      // Now set the second image into the viewer (this will not disposes the first image since the AutoDisposeImages property is false)
      viewer.Image = image2;

      // Try to access the first image, it should work fine this time
      try
      {
         int width = image1.Width;
         MessageBox.Show(string.Format("Width is {0} pixels", width));
      }
      catch (NullReferenceException ex)
      {
         MessageBox.Show(ex.Message);
      }

      // Set the image to null (will not dispose the second image)
      viewer.Image = null;

      // We should now dispose the two images manually
      image1.Dispose();
      image2.Dispose();

      viewer.ImageChanged -= new EventHandler(viewer_ImageChanged);
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}