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POCannot use Window control simultaneously in two threads
 

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  1. POCannot use Window control simultaneously in two threads
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    <p>From the Page_load event of Window1 I'm calling a function of a public class and passing parameter as the same Window1. After the function is called, a thread is started. The thread is called on Page_Loaded event of Window1. The code is like this:</p> <pre><code>Private Sub StartScreen_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded Try TmHeartbeat.Stop() TmHeartbeat.Interval = 600000 TmHeartbeat.Start() ResetVariables() FormLoadSetting(Me) SetButtonProperty(btnEnglish, "\Images\ButtonBgBig.png", GetFormLabel("Start Screen", "Common", "Button English")) SetButtonProperty(btnSpanish, "\Images\ButtonBgBig.png", GetFormLabel("Start Screen", "Common", "Button Spanish")) SetDisplayTimer(DGT, False, Me, 1800000) MediaElement1.Source = New Uri(GetPath("Images\EnglishVideo\" &amp; GetFormLabel("Start Screen", "Common", "Video"))) If GetFormLabel("Start Screen", "Common", "Audio") &lt;&gt; "" Then PlayAudio(APlay, GetFormLabel("Start Screen", "Common", "Audio")) End If Dim AudioPlay As New System.Media.SoundPlayer Dim sc As New Screenshot sc.TakeScreenshot(Me) Catch ex As Exception AliLogFileEntry(TransactionType.ErrorOnForm, "Error In Function: StartScreen_Loaded: " &amp; Me.Title &amp; ", ErrorMessage: " &amp; ex.Message) End Try End Sub </code></pre> <p>The function <code>TakeScreenshot(Me)</code> which is in class <code>Screenshot</code> is called. Along with the Screenshot class, I also have another class named <code>GetScreenshot</code> and a function <code>TakeScreenshot1</code>. The code for the class file is like this:</p> <pre><code>Imports System.IO Imports System.Threading Public Class Screenshot Public Sub TakeScreenshot(ByVal formname As Window) Dim GT As New GetScreenshot GT.source = formname Dim newThread As New Thread(AddressOf GT.TakeScreenshot1) newThread.Start() End Sub End Class Public Class GetScreenshot Public source As Window Public Function TakeScreenshot1() Thread.Sleep(2000) If OG.GetValue("TakeScreenshot") &lt;&gt; "0" Then Try AliLogFileEntry(TransactionType.System, "In Function: TakeScreenshot") Dim scale As Double = OG.GetValue("Screenshot_Scale") / 100 AliLogFileEntry(TransactionType.System, "In Function: GetJpgImage") Dim renderHeight As Double = source.RenderSize.Height * scale Dim renderWidth As Double = source.RenderSize.Width * scale Dim renderTarget As New RenderTargetBitmap(CInt(Math.Truncate(renderWidth)), CInt(Math.Truncate(renderHeight)), 96, 96, PixelFormats.Pbgra32) Dim sourceBrush As New VisualBrush(source) Dim drawingVisual As New DrawingVisual() Dim drawingContext As DrawingContext = drawingVisual.RenderOpen() Using drawingContext drawingContext.PushTransform(New ScaleTransform(scale, scale)) drawingContext.DrawRectangle(sourceBrush, Nothing, New Rect(New Point(0, 0), New Point(source.RenderSize.Width, source.RenderSize.Height))) End Using renderTarget.Render(drawingVisual) Dim jpgEncoder As New JpegBitmapEncoder() jpgEncoder.QualityLevel = 100 jpgEncoder.Frames.Add(BitmapFrame.Create(renderTarget)) Dim _imageArray As [Byte]() Using outputStream As New MemoryStream() jpgEncoder.Save(outputStream) _imageArray = outputStream.ToArray() End Using Dim screenshot As Byte() = _imageArray Dim dir As DirectoryInfo = New DirectoryInfo("Screenshots") If Not dir.Exists Then dir = Directory.CreateDirectory(dir.FullName) Dim path As String = AppDomain.CurrentDomain.BaseDirectory Dim fileStream As New IO.FileStream("Screenshots\" &amp; source.Title &amp; ".jpg", FileMode.Create, FileAccess.ReadWrite) Dim binaryWriter As New IO.BinaryWriter(fileStream) binaryWriter.Write(screenshot) binaryWriter.Close() Catch ex As Exception AliLogFileEntry(TransactionType.ErrorOnForm, "Error In Function: TakeScreenshot , ErrorMessage: " &amp; ex.Message) End Try End If End Function End Class </code></pre> <p>When I debug this file, I get this error: <img src="https://i.stack.imgur.com/QtXgg.jpg" alt="enter image description here"></p> <p>And the error is generated on line </p> <pre><code>Dim sourceBrush As New VisualBrush(source) </code></pre> <p>Pleas help</p>
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    1. PO
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      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USFarhan Mukadam
    1. USFarhan Mukadam
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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      1. PTAnswer
    1. VO
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      1. POCannot use Window control simultaneously in two threads
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
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      1. POCannot use Window control simultaneously in two threads
      1. This table or related slice is empty.
      1. VTUpMod
    1. COOn what line is it actually raising the exception? `ex.ToString()` What is needed is `If Source.InvokeRequired Then Source.Invoke` (the pattern is a bit bigger but a quick search would give you more info)
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      1. POCannot use Window control simultaneously in two threads
      1. USNiKiZe
 

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