<DescriptionAttribute("Automatically disposes the item images when them item is removed from the control or when the control is disposed.")>
<CategoryAttribute("Behavior")>
Public Property AutoDisposeImages As Boolean

Visual Basic (Usage)	Copy Code
Dim instance As RasterImageList Dim value As Boolean   instance.AutoDisposeImages = value   value = instance.AutoDisposeImages

[DescriptionAttribute("Automatically disposes the item images when them item is removed from the control or when the control is disposed.")]
[CategoryAttribute("Behavior")]
public bool AutoDisposeImages {get; set;}

[DescriptionAttribute("Automatically disposes the item images when them item is removed from the control or when the control is disposed.")]
[CategoryAttribute("Behavior")]
public:
property bool AutoDisposeImages {
   bool get();
   void set (bool value);
}

Return Value

This example removes an item from the control and demonstrates how the AutoDisposeImages property effects whether the item image remains usable.

Visual Basic

Copy Code

Public Sub RasterImageList_AutoDisposeImages(ByVal imageList As RasterImageList)     ' Make sure the AutoDisposeImages property is set to true     imageList.AutoDisposeImages = True     MessageBox.Show("Removing an item then accessing its image with AutoDisposeImages set to true")     ' Remove the first item     Dim item As RasterImageListItem = imageList.Items(0)     imageList.Items.RemoveAt(0)     ' Try to save this item's image into a disk file     ' This will throw an exception since the item image has been disposed of     ' as a result of having the AutoDisposeImages false set to true     RasterCodecs.Startup()     Dim codecs As RasterCodecs = New RasterCodecs()     Try         codecs.Save(item.Image, LeadtoolsExamples.Common.ImagesPath.Path + "Test.jpg", RasterImageFormat.Jpeg, 24)         MessageBox.Show("Image saved correctly")     Catch ex As Exception         MessageBox.Show(ex.Message)     End Try     RasterCodecs.Shutdown()     MessageBox.Show("Removing an item then accessing its image with AutoDisposeImages set to false")     ' Now remove the next item, this time make sure to set the     ' AutoDisposeImages property to false before you remove the item     ' from the control collection     item = imageList.Items(0)     imageList.AutoDisposeImages = False     imageList.Items.RemoveAt(0)     imageList.AutoDisposeImages = True     ' Try to save this item's image into a disk file     ' This time, this should work correcly since the control did not dispose     ' the item image.     Try         codecs.Save(item.Image, LeadtoolsExamples.Common.ImagesPath.Path + "Test.jpg", RasterImageFormat.Jpeg, 24)         MessageBox.Show("Image saved correctly")     Catch ex As Exception         MessageBox.Show(ex.Message)     End Try End Sub

C#

Copy Code

public void RasterImageList_AutoDisposeImages(RasterImageList imageList)  {     // Make sure the AutoDisposeImages property is set to true     imageList.AutoDisposeImages = true;     MessageBox.Show("Removing an item then accessing its image with AutoDisposeImages set to true");       // Remove the first item     RasterImageListItem item = imageList.Items[0];     imageList.Items.RemoveAt(0);       // Try to save this item's image into a disk file     // This will throw an exception since the item image has been dispose     // as a result of having the AutoDisposeImages false set to true     RasterCodecs.Startup();     RasterCodecs codecs = new RasterCodecs();     try     {        codecs.Save(item.Image, LeadtoolsExamples.Common.ImagesPath.Path + "Test.jpg", RasterImageFormat.Jpeg, 24);        MessageBox.Show("Image saved correctly");     }     catch(Exception ex)     {        MessageBox.Show(ex.Message);     }     RasterCodecs.Shutdown();       MessageBox.Show("Removing an item then accessing its image with AutoDisposeImages set to false");       // Now remove the next item, this time make sure to set the     // AutoDisposeImages property to false before you remove the item     // from the control collection     item = imageList.Items[0];       imageList.AutoDisposeImages = false;     imageList.Items.RemoveAt(0);     imageList.AutoDisposeImages = true;       // Try to save this item's image into a disk file     // This time, this should work correcly since the control did not dispose     // the item image.     try     {        codecs.Save(item.Image, LeadtoolsExamples.Common.ImagesPath.Path + "Test.jpg", RasterImageFormat.Jpeg, 24);        MessageBox.Show("Image saved correctly");     }     catch(Exception ex)     {        MessageBox.Show(ex.Message);     }  }

When the value of the AutoDisposeImages is set to true, the RasterImageList control will automatically call the RasterImage.Dispose method on an item's RasterImageListItem.Image when the item is removed from the Items collection or when the control itself is disposed.

The control will check if an image is used with multiple items (for example, if multiple items are using the same image but to show different pages). In this case, the control will correctly dispose the image only once.

If you setup the items with images that you do not want to dispose of and are going to re-use somewhere else, you need to set the value of the AutoDisposeImages property of the RasterImageList control to false.

You can also temporarily change the value of the AutoDisposeImages property if you want to save the item image before you dispose it. For example, set the AutoDisposeImages property to false, call Remove on the Items collection to remove the item, then re-set the AutoDisposeImages property back to true.

Note that if you set the AutoDisposeImages value to false and you do not dispose the item images youself, the .NET garbage collector will eventually detect that these images are not used anymore and will dispose them for you when the control and any other reference to these images are no longer used in your application.

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Reference