DO LOOP String.IsNullOrEmpty Threading VB.NET

[SyGC]

Hey All,

im trying to simply display an image depending on whether a text box has been populated or not. To do this im using the String.IsNullOr Empty(My String) approach.

Becuase the image will change depending on the textbox field state the String.IsNullOr Empty(My String) is placed in a DO LOOP and Thread

    Private Sub backgroundprocess()

        Dim Results As String = Results_TextBox2.Text


        Do
            If String.IsNullOrEmpty(Results) = True Then

                Gif = True
            Else
                Gif = False
            End If

        Loop
        Application.DoEvents()
        Thread.Sleep(1000)

    End Sub

The Boolean return of Gif then determines the visible property of the image(picturebo x)

Private Sub Button1_Click

        If GIf = True Then
            PictureBox1.Visible = True
        ElseIf GIf = False Then
            PictureBox1.Visible = False
        End If

This is all being used as a 'cheat' (Due to time constraints) to display a gif image during any times when a delay in results is expected (Like a progress bar)

The text field being populated is returning the results of a trace route.
IF the text field is empty (Waiting for the process to finish and System.IO.Strea mReader to read to end) then the gif will be displayed. Once the text field has been populated with the results (System.IO.Stre amWriter writing to it) the gif image will not be displayed anymore.

Any thoughts? If you want to see the whole code let me know :P

Thanks in advance as always,

Sy

[vanc]

I'm not quite sure about your idea but I can see your dummy code is on the right track. Though, there are some points that I don't understand in your code. The first thing is Do ... Loop, is it should be Do While () .. Loop, otherwise this code will become infinite loop and the main thread has no chance to run!!!
To revise your idea, your code should be like
<dummy code>
Do While (targetTextBox. Text != "")
Thread.Sleep(10 00); //this is not main thread
Loop
DisplayGif(); //this is function to display your image
</dummy code>

If you don't understand how to do it in details. Feel free to ask. Cheers.

[SyGC]

I'm not quite sure about your idea but I can see your dummy code is on the right track. Though, there are some points that I don't understand in your code. The first thing is Do ... Loop, is it should be Do While () .. Loop, otherwise this code will become infinite loop and the main thread has no chance to run!!!
To revise your idea, your code should be like
<dummy code>
Do While (targetTextBox. Text != "")
Thread.Sleep(10 00); //this is not main thread
Loop
DisplayGif(); //this is function to display your image
</dummy code>

If you don't understand how to do it in details. Feel free to ask. Cheers.

Hi Vanc

Yea doing the DO While LOOP makes much more sense. The issue hasnt been resolved though.

Ive put in the button click event the following;

        

        Dim GifThread As Thread
        GifThread = New Thread(AddressOf Me.backgroundprocess)
        GifThread.Start()

        GifPicBox.Visible = True

        If GIf = True Then

            GifPicBox.Visible = False

        End If

and This as the background process;

        Dim Results As String = L2T_Results.Text


        Do While L2T_Results.Text = ""

            GIf = True

        Loop
        Thread.Sleep(1000)

GIf is declared as a global variable as Boolean ' Dim GIf As Boolean'

So as i see it. On button click picture box visibility = true and is shown...however it isnt getting the boolean result back to set visibility to 'false' when the text field is till empty (Both 'String.IsEmpty orNull and .text= "" have been used)

Im sure im being a plank with this...full code would be .....

   Dim GIf As Boolean

    Private Sub backgroundprocess()

        Dim Results As String = L2T_Results.Text


        'Do While String.IsNullOrEmpty(Results)

        Do While L2T_Results.Text = ""

            GIf = True

        Loop
        Thread.Sleep(1000)

    End Sub

    Private Sub ping_PButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ping_PButton.Click

        Dim GifThread As Thread
        GifThread = New Thread(AddressOf Me.backgroundprocess)
        GifThread.Start()

        GifPicBox.Visible = True

        If GIf = True Then

            GifPicBox.Visible = True

        End If

        code....

End Sub

]#

Thanks again

Sy