(NET) NET (2012 год)

How to intercept exception & console output & debug trace and show it in textbox.

This is a common pattern to catch up all message of exception, console output and debug trace in windows desktop application and show all of it in textbox.

  ...   
   5:  Public Class StartForm
  ...   
  15:      Private Sub StartForm_Load(sender As Object, e As EventArgs) Handles Me.Load
  16:          Text &= " (" & My.Application.Info.Version.ToString & ")"
  17:          Try
  ...   
  26:              Dim TextBoxListener = New TextBoxTraceListener(MsgBox1)
  27:              Trace.Listeners.Add(TextBoxListener)
  28:              Dim ConsoleWriter = New ConsoleWriter()
  29:              AddHandler ConsoleWriter.WriteEvent, AddressOf consoleWriter_WriteEvent
  30:              AddHandler ConsoleWriter.WriteLineEvent, AddressOf consoleWriter_WriteLineEvent
  31:              Console.SetOut(ConsoleWriter)
  ...   
  35:              If Not My.Computer.FileSystem.FileExists(IO.Path.Combine(TempDirectory, Inkscape)) Then
  36:                  MsgBox1.Text = "This program use Inkscape library, please install Inkscape firstly."
  37:                  MsgBox1.WriteLog("https://inkscape.org/")
  38:              Else
  39:                  MsgBox1.Text = "Start " & Now
  40:                  MsgBox1.Select(0, 0)
  41:              End If
  42:          Catch ex As Exception
  43:              MsgBox1.WriteLog(ex.Message)
  44:          End Try
  45:      End Sub
  46:   
  47:      Private Sub consoleWriter_WriteLineEvent(sender As Object, e As ConsoleWriterEventArgs)
  48:          MsgBox1.WriteLog(e.Value)
  49:      End Sub
  50:   
  51:      Private Sub consoleWriter_WriteEvent(sender As Object, e As ConsoleWriterEventArgs)
  52:          MsgBox1.WriteLog(e.Value)
  53:      End Sub
  54:   

This is module to intercept write to trace log, usually as debug.print


   1:      Public Class TextBoxTraceListener
   2:          Inherits TraceListener
   3:   
   4:          Private _target As TextBox
   5:          Private _invokeWrite As StringSendDelegate
   6:   
   7:          'Delegate to invoke on the text box
   8:          Private Delegate Sub StringSendDelegate(ByVal message As String)
   9:   
  10:          'Create a new text box trace listener that writes to the 
  11:          Public Sub New(ByVal target As TextBox)
  12:              _target = target
  13:              _invokeWrite = New StringSendDelegate(AddressOf SendString)
  14:          End Sub
  15:   
  16:          'Writes a string to the textbox
  17:          Public Overrides Sub Write(ByVal message As String)
  18:              _target.Invoke(_invokeWrite, New Object() {message})
  19:          End Sub
  20:   
  21:          'Writes a string followed by a new line character to the textbox
  22:          Public Overrides Sub WriteLine(ByVal message As String)
  23:              _target.Invoke(_invokeWrite, New Object() {message & Environment.NewLine})
  24:          End Sub
  25:   
  26:          'Method passed for invokation by the text box
  27:          Private Sub SendString(ByVal message As String)
  28:              _target.Text += message
  29:          End Sub
  30:      End Class

This is module to intercept writing to console in windows desktop application.


   1:  Imports System.IO
   2:  Imports System.Text
   3:   
   4:  Public Class ConsoleWriterEventArgs
   5:      Inherits EventArgs
   6:   
   7:      Public Property Value As String
   8:   
   9:      Public Sub New(ByVal value As String)
  10:          value = value
  11:      End Sub
  12:  End Class
  13:   
  14:  Public Class ConsoleWriter
  15:      Inherits TextWriter
  16:   
  17:      Public Event WriteEvent As EventHandler(Of ConsoleWriterEventArgs)
  18:      Public Event WriteLineEvent As EventHandler(Of ConsoleWriterEventArgs)
  19:   
  20:      Public Overrides ReadOnly Property Encoding As Encoding
  21:          Get
  22:              Return Encoding.UTF8
  23:          End Get
  24:      End Property
  25:   
  26:      Public Overrides Sub Write(ByVal value As String)
  27:          RaiseEvent WriteEvent(Me, New ConsoleWriterEventArgs(value))
  28:          MyBase.Write(value)
  29:      End Sub
  30:   
  31:      Public Overrides Sub WriteLine(ByVal value As String)
  32:          RaiseEvent WriteLineEvent(Me, New ConsoleWriterEventArgs(value))
  33:          MyBase.WriteLine(value)
  34:      End Sub
  35:   
  36:   
  37:  End Class

And this is main extension function to add text and scroll is to end of log.


   1:  Imports System.Runtime.CompilerServices
   2:   
   3:  Module Log
   4:   
   5:      <Extension>
   6:      Public Sub WriteLog(T As TextBox, TXT As String)
   7:          T.Text &= vbCrLf & TXT
   8:          T.Refresh()
   9:          T.SelectionStart = T.TextLength
  10:          T.ScrollToCaret()
  11:      End Sub
  12:   
  13:  End Module


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