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AutoDisposeImages Property

Summary

Gets or sets a value indicating whether to auto dispose the old image when a new image is set into this RasterImageViewer.

Syntax

C++/CLI

C++

public virtual bool AutoDisposeImages { get; set; }

public: 
virtual property bool AutoDisposeImages { 
   bool get(); 
   void set (    bool ); 
}

public:  
   virtual property bool AutoDisposeImages 
   { 
      bool get() 
      void set(bool value) 
   }

Property Value

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

Remarks

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.

Example

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

using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Drawing; 
 
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:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms