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Changed Event
See Also  Example
Leadtools Namespace > RasterImage Class : Changed Event



Occurs when the image data or attributes has changed.

Syntax

Visual Basic (Declaration) 
Public Event Changed() As EventHandler(Of RasterImageChangedEventArgs)
Visual Basic (Usage)Copy Code
Dim instance As RasterImage
Dim handler As EventHandler(Of RasterImageChangedEventArgs)
 
AddHandler instance.Changed, handler
C# 
public event EventHandler<RasterImageChangedEventArgs> Changed()
C++/CLI 
public:
event EventHandler<RasterImageChangedEventArgs>^ Changed();

Example

Visual BasicCopy Code
Public Sub ChangedExample()
   RasterCodecs.Startup()
   Dim codecs As RasterCodecs = New RasterCodecs()

   Dim srcFileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"

   ' Load the image
   Dim img As RasterImage = codecs.Load(srcFileName)

   ' Subscribe to the Changed event of this image
   AddHandler img.Changed, AddressOf img_Changed

   ' Call a few methods and image processing commands that changes the image
   Console.WriteLine("Calling FlipViewPerspective")
   img.FlipViewPerspective(True)

   Console.WriteLine("Calling RotateViewPerspective")
   img.RotateViewPerspective(90)

   Console.WriteLine("Calling FlipCommand")
   Dim flip As FlipCommand = New FlipCommand(True)
   flip.Run(img)

   ' Now disable firing the events and call the methods again
   Console.WriteLine("Disabling the events")
   img.DisableEvents()

   Console.WriteLine("Calling FlipViewPerspective")
   img.FlipViewPerspective(True)

   Console.WriteLine("Calling RotateViewPerspective")
   img.RotateViewPerspective(90)

   Console.WriteLine("Calling FlipCommand while")
   flip.Run(img)

   ' Re-enable the events and fire it manually
   Console.WriteLine("Re-enabling the events")
   img.EnableEvents()

   Console.WriteLine("Firing the event manually")
   Dim flags As RasterImageChangedFlags = RasterImageChangedFlags.Data Or RasterImageChangedFlags.ViewPerspective
   Dim e As RasterImageChangedEventArgs = New RasterImageChangedEventArgs(flags)

   img.OnChanged(e)

   ' Clean up
   RemoveHandler img.Changed, AddressOf img_Changed
   img.Dispose()
   codecs.Dispose()
   RasterCodecs.Shutdown()
End Sub

Private Sub img_Changed(ByVal sender As Object, ByVal e As RasterImageChangedEventArgs)
   ' Show the changed flags
   Console.WriteLine("Changed: {0}", e.Flags)
End Sub
C#Copy Code
public void ChangedExample() 
{ 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string srcFileName = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"; 
 
   // Load the image 
   RasterImage img = codecs.Load(srcFileName); 
 
   // Subscribe to the Changed event of this image 
   img.Changed += new EventHandler<RasterImageChangedEventArgs>(img_Changed); 
 
   // Call a few methods and image processing commands that changes the image 
   Console.WriteLine("Calling FlipViewPerspective"); 
   img.FlipViewPerspective(true); 
 
   Console.WriteLine("Calling RotateViewPerspective"); 
   img.RotateViewPerspective(90); 
 
   Console.WriteLine("Calling FlipCommand"); 
   FlipCommand flip = new FlipCommand(true); 
   flip.Run(img); 
 
   // Now disable firing the events and call the methods again 
   Console.WriteLine("Disabling the events"); 
   img.DisableEvents(); 
 
   Console.WriteLine("Calling FlipViewPerspective"); 
   img.FlipViewPerspective(true); 
 
   Console.WriteLine("Calling RotateViewPerspective"); 
   img.RotateViewPerspective(90); 
 
   Console.WriteLine("Calling FlipCommand while"); 
   flip.Run(img); 
 
   // Re-enable the events and fire it manually 
   Console.WriteLine("Re-enabling the events"); 
   img.EnableEvents(); 
 
   Console.WriteLine("Firing the event manually"); 
   RasterImageChangedFlags flags = RasterImageChangedFlags.Data | RasterImageChangedFlags.ViewPerspective; 
   RasterImageChangedEventArgs e = new RasterImageChangedEventArgs(flags); 
 
   img.OnChanged(e); 
 
   // Clean up 
   img.Changed -= new EventHandler<RasterImageChangedEventArgs>(img_Changed); 
   img.Dispose(); 
   codecs.Dispose(); 
   RasterCodecs.Shutdown(); 
} 
 
void img_Changed(object sender, RasterImageChangedEventArgs e) 
{ 
   // Show the changed flags 
   Console.WriteLine("Changed: {0}", e.Flags); 
}

Remarks

When the data or attributes of a RasterImage object changes, the Changed event is fired with information of what has changed. For example, you can subscribe to this event to get notified when the RasterImage object has been changed and need to be updated in your user interface by re-painting it.

For more information, refer to RasterImageChangedEventArgs.

Requirements

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

See Also