Problem Writing to Multi-Line Textbox and Streamwriter at Same Time

[System Engineer]

Hello,

I'm scanning a JPG image file pixel by pixel and writing the results to a streamwriter (output.txt)...This part works perfectly.

I'm now trying to list the same information to a multi-line textbox (textbox1) but it only lists the last line once it completes.

I want all of the lines to list in the textbox and scroll as it scans the JPG file.

Here's my Code:

Private Sub Pixel_Button_Click(sender As System.Object, e As System.EventArgs) Handles Pixel_Button.Click
Dim PixelImage As New Bitmap(Picture1.Image, Picture1.Width, Picture1.Height)
Dim Writer As New System.IO.StreamWriter("C:\Users\Scott\Downloads\output.txt")
For i As Integer = 0 To PixelImage.Width - 1
For j As Integer = 0 To PixelImage.Height - 1
Dim pixel As Color = PixelImage.GetPixel(i, j)
Writer.WriteLine("Coordinates: " & j & "," & i & " - " & pixel.ToString)
TextBox1.Text = "Coordinates: " & j & "," & i & " - " & pixel.ToString
Next j
Next i
Writer.Close()
MessageBox.Show("Pixel Scan Completed!")
End Sub

I appreciate any help I can get.

Thanks

[OptionBase1]

Because inside your nested loops you are assigning a new value to TextBox1.Text each iteration, rather than appending to what is already present in TextBox1.Text.

You should probably use a StringBuilder object, append text to this StringBuilder object inside the nested loops, and then after the loops complete you assign the value of this StringBuilder object to TextBox1.Text.

[jmcilhinney]

That's because you keep setting the Text property over and over, thus replacing the existing value. You should be calling the AppendText method.

[System Engineer]

Thanks...I now understand that I'm overwriting the value each time...

I used the StringWriter and dumped to textbox after loop completes.

Works great...Thanks for your help!

[OptionBase1]

TextBox1.AppendText("Read the error message")

[System Engineer]

Got it...

I used the StringWriter and dumped to textbox after loop completes.

Works great...Thanks for your help!

[jmcilhinney]

OptionBase1 is correct. You could call AppendText on the TextBox but there would be little point because you wouldn't see the result until the end anyway, and it would slow things down. Using the StringBuilder is the right way to go but you should actually take it a step further. Use only the StringBuilder in the loop and then, at the end, call ToString on it to get the entire text as a String. You can then assign that to the Text property of the TextBox but also pass call File.WriteAllText and pass that String to write it all to the file in one go too.

[System Engineer]

Exactly what I did...Great minds think alike...Thanks!