ItemChanged Event

The event handler receives an argument of type ImageViewerItemChangedEventArgs containing data related to this event. The following ImageViewerItemChangedEventArgs properties provide information specific to this event.

This event occurs when any of the items inside this ImageViewer changes. The ImageViewerItemChangedEventArgs will contain the item that has been changed in ImageViewerItemChangedEventArgs.Item and the reason for the change in ImageViewerItemChangedEventArgs.Reason.

Change the value of the following properties or calling the methods programmatically or by the viewer will raise the ItemChanged event with the specified reason:

The viewer automatically listens to these events internally and will perform the necessary action, for example, if any property that affect the transformation changes, UpdateTransform will be called. If the property change requires rendering only, then the item will be invalidated.

This example will track the ItemChanged and ItemError event and show information on them.

Run the demo, click the Example button.

Start with the ImageViewer example, remove all the code inside the example function (search for the "// TODO: add example code here" comment) and insert the following code:

• 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
Imports Leadtools.ImageProcessing
Imports Leadtools.ImageProcessing.Color

AddHandler _imageViewer.ItemChanged,
Sub(sender, e)
   Dim item As ImageViewerItem = e.Item
   Dim sb As New StringBuilder()
   sb.AppendFormat("ItemChanged:{0} Reason:{1} Size:{2} Res:{3}", _imageViewer.Items.IndexOf(item), e.Reason, item.Size, item.Resolution)
   If Not item.Image Is Nothing Then
      sb.AppendFormat(" Image: {0}bpp {1} by {2}", item.Image.BitsPerPixel, item.Image.Width, item.Image.Height)
   Else
      sb.AppendFormat(" Image: null")
   End If
   Console.WriteLine(sb.ToString())
   If Not item.Url Is Nothing Then
      Console.WriteLine("  Url:" & item.Url.ToString())
   End If
End Sub

using Leadtools;
using Leadtools.Controls;
using Leadtools.Codecs;
using Leadtools.Drawing;
using Leadtools.ImageProcessing;
using Leadtools.ImageProcessing.Color;

_imageViewer.ItemChanged += (sender, e) =>
{
   var item = e.Item;
   var sb = new StringBuilder();
   sb.AppendFormat("ItemChanged:{0} Reason:{1} Size:{2} Res:{3}", _imageViewer.Items.IndexOf(item), e.Reason, item.Size, item.Resolution);
   if (item.Image != null)
      sb.AppendFormat(" Image: {0}bpp {1} by {2}", item.Image.BitsPerPixel, item.Image.Width, item.Image.Height);
   else
      sb.AppendFormat(" Image: null");
   Console.WriteLine(sb.ToString());
   if (item.Url != null)
      Console.WriteLine("  Url:" + item.Url.ToString());
};

Target Platforms

Reference

ImageViewer Class
ImageViewer Members