PropertyChanged Event

Summary

Occurs when a property value in this ImageViewer changes.

Syntax

C++

public event PropertyChangedEventHandler PropertyChanged

Public Event PropertyChanged As System.ComponentModel.PropertyChangedEventHandler

public:  
   event System::ComponentModel::PropertyChangedEventHandler^ PropertyChanged

Remarks

Most of the properties of this ImageViewer will fire the PropertyChanged event when the value changes. When this happens, the value of System.ComponentModel.PropertyChangedEventArgs.PropertyName of the event data will be set to the name of the property that was changed. For example, the System.ComponentModel.PropertyChangedEventArgs.PropertyName will be set to "UseDpi" when UseDpi changes and "ScrollOffset" when ScrollOffset changes.

Example

Run the demo and now as you click the Example button, the label is updated.

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:

using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
 
 
if (_firstCall) 
{ 
   _firstCall = false; 
   // Subscribe to PropertyChanged event 
   _imageViewer.PropertyChanged += (sender, e) => 
   { 
      if (e.PropertyName == "Flip") 
      { 
         if (_imageViewer.Flip) 
            _label.Text = "Image is flipped"; 
         else 
            _label.Text = "Image is not flipped"; 
      } 
   }; 
} 
 
// Change the flip state of the image 
_imageViewer.Flip = !_imageViewer.Flip;

Imports Leadtools 
Imports Leadtools.Controls 
Imports Leadtools.Codecs 
Imports Leadtools.Drawing 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Color 
Imports LeadtoolsControlsExamples.LeadtoolsExamples.Common 
 
Public Sub ImageViewer_PropertyChanged() 
   If _firstCall Then 
      _firstCall = False 
      ' Subscribe to PropertyChanged event 
      AddHandler _imageViewer.PropertyChanged, 
         Sub(sender, e) 
            If e.PropertyName = "Flip" Then 
               If _imageViewer.Flip Then 
                  _label.Text = "Image is flipped" 
               Else 
                  _label.Text = "Image is not flipped" 
               End If 
            End If 
         End Sub 
   End If 
 
   ' Change the flip state of the image 
   _imageViewer.Flip = Not _imageViewer.Flip 
End Sub

Event Data

Parameter	Type	Description
sender	object	The source of the event.
e	System.ComponentModel.PropertyChangedEventArgs	The event data.

Requirements

Target Platforms

Reference

ImageViewer Class

ImageViewer Members

Leadtools.Controls Namespace

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Help Version 21.0.2021.7.2

Leadtools.Controls Assembly

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Getting Started

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Leadtools.Controls Namespace

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