AutoDisposeImage Property

C#
Visual Basic
Objective-C
Java

public bool AutoDisposeImage {get; set;}

'Declaration

Public Property AutoDisposeImage As Boolean

Property Value

true if the image in Image is automatically disposed when a new image is set; otherwise, false. Default value is true.

By default, whenever you set a new image into the Image property, the old image (if any) is disposed. Set the value of this property to false to prevent disposing of the old image.

This sample loads two images to demonstrate how the AutoDisposeImage property affects whether the item image remains usable.

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

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Imports Leadtools
Imports Leadtools.Controls
Imports Leadtools.Codecs
Imports Leadtools.Drawing

Public Sub RasterPictureBox_AutoDisposeImage(ByVal viewer As RasterPictureBox)
   ' 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")

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

   ' Make sure the AutoDisposeImage property of the viewer is set to true
   viewer.AutoDisposeImage = 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 AutoDisposeImage 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 AutoDisposeImage property of the viewer is set to false
   viewer.AutoDisposeImage = 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 AutoDisposeImage 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()
   codecs.Dispose()
End Sub

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

using Leadtools;
using Leadtools.Controls;
using Leadtools.Codecs;
using Leadtools.Drawing;

public void RasterPictureBox_AutoDisposeImage()
{
   RasterPictureBox viewer = new RasterPictureBox();
   // 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");

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

   // Make sure the AutoDisposeImage property of the viewer is set to true
   viewer.AutoDisposeImage = 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 AutoDisposeImage 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 AutoDisposeImage property of the viewer is set to false
   viewer.AutoDisposeImage = 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 AutoDisposeImage 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();
   codecs.Dispose();
}

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

Target Platforms

Reference

RasterPictureBox Class
RasterPictureBox Members