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IsVideoPreviewAvailable Method

Summary

Determines whether there is an available video preview.

Syntax

C#
VB
C++
public bool IsVideoPreviewAvailable() 
  
Public Function IsVideoPreviewAvailable() As Boolean 
public: 
bool IsVideoPreviewAvailable();  

Return Value

true if the video preview is started; otherwise, false.

Remarks

This function is used to determine whether the video preview has started. Start the video preview by calling the WiaSession.StartVideoPreview method.

Example

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Wia; 
 
public void IsVideoPreviewAvailableExample(IntPtr parent) 
{ 
   if (!WiaSession.IsAvailable(WiaVersion.Version1)) 
   { 
      MessageBox.Show("WIA version 1.0 not installed."); 
      return; 
   } 
 
   WiaSession wiaSession = new WiaSession(); 
   wiaSession.Startup(WiaVersion.Version1); 
 
   DialogResult res = wiaSession.SelectDeviceDlg(parent, WiaDeviceType.StreamingVideo, WiaSelectSourceFlags.NoDefault); 
   if (res != DialogResult.OK) 
   { 
      MessageBox.Show("Error selecting WIA device."); 
      wiaSession.Shutdown(); 
      return; 
   } 
 
   // start the video preview 
   wiaSession.StartVideoPreview(parent, false); 
 
   // determine whether a video preview is available 
   bool available = wiaSession.IsVideoPreviewAvailable(); 
   if (!available) 
   { 
      MessageBox.Show("No streaming video available."); 
      wiaSession.EndVideoPreview(); 
      wiaSession.Shutdown(); 
      return; 
   } 
 
   // Resize the video preview area to fit the parent window. 
   // I am calling this resize function here only for demonstration purposes, but you 
   // should call it in your window resize event. 
   wiaSession.ResizeVideoPreview(true); 
 
   // acquire an image from the video source. 
   string takenPictureFileName = wiaSession.AcquireImageFromVideo(); 
 
   string strMsg = String.Format("Acquired image was saved to the following path:\n{0}", takenPictureFileName); 
   MessageBox.Show(strMsg); 
 
   wiaSession.EndVideoPreview(); 
   wiaSession.Shutdown(); 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Wia 
 
<TestMethod()> _ 
Public Sub IsVideoPreviewAvailableExample(ByVal parent As IntPtr) 
   If (Not wiaSession.IsAvailable(WiaVersion.Version1)) Then 
      MessageBox.Show("WIA version 1.0 not installed.") 
      Return 
   End If 
 
   Dim session As WiaSession = New WiaSession() 
   session.Startup(WiaVersion.Version1) 
 
   Dim res As DialogResult = session.SelectDeviceDlg(parent, WiaDeviceType.StreamingVideo, WiaSelectSourceFlags.NoDefault) 
   If res <> DialogResult.OK Then 
      MessageBox.Show("Error selecting WIA device.") 
      session.Shutdown() 
      Return 
   End If 
 
   ' start the video preview 
   wiaSession.StartVideoPreview(parent, False) 
 
   ' determine whether a video preview is available 
   Dim available As Boolean = wiaSession.IsVideoPreviewAvailable() 
   If (Not available) Then 
      MessageBox.Show("No streaming video available.") 
      wiaSession.EndVideoPreview() 
      wiaSession.Shutdown() 
      Return 
   End If 
 
   'Resize the video preview area to fit the parent window. 
   'I am calling this resize function here only for demonstration purposes, but you 
   'should call it in your window resize event. 
   wiaSession.ResizeVideoPreview(True) 
 
   ' acquire an image from the video source. 
   Dim takenPictureFileName As String = wiaSession.AcquireImageFromVideo() 
 
   Dim strMsg As String = String.Format("Acquired image was saved to the following path:\n{0}", takenPictureFileName) 
   MessageBox.Show(strMsg) 
 
   wiaSession.EndVideoPreview() 
   session.Shutdown() 
End Sub 

Requirements

Target Platforms

Help Version 19.0.2017.10.18
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