CODEWITHSUNDEEP
c#.netwinformsrichtextbox
Snoop
Snoop

Reputation: 1065

How do I avoid having my Rich Text Box, "scroll bar," freeze up?

My issue is in the .NET framework using C# to create a simple form application that contains a rich text box (RTB) control.

Briefly the issue I am experiencing is that when trying to clear the contents (.Text) of the RTB, the scroll bar doesn't go away. I would like to know if there is anything inherently wrong with the way I am using the RTB. I apologize, but the site will not allow me to post images yet. So if there is a misunderstanding regarding what "doesn't go away" means, please ask!

So first, I write data to the box using the following code snippet:

// append the new message
this.rtb_receive_0.Text += message;
this.rtb_receive_0.SelectionStart = this.rtb_receive_0.Text.Length;
this.rtb_receive_0.ScrollToCaret();

Later on, I clear the RTB contents (RTB.Text) with the following code:

this.rtb_receive_0.Text = String.Empty;
this.rtb_receive_0.Refresh();

In the above code I have attempted to fix my problem with the, "Refresh," method. However it does not seem to be doing the job.

When I clear the RTB contents, the scroll bar does not go away... I noticed that if I grab another window and drag it over the top of the application, that the frozen scroll bar disappears. Also, I can minimize the application, then maximize it again and the bar will disappear. There has to be a way to prevent this frozen scroll bar from happening in the first place though.

Per the answer, here was the fix to stop the bar from freezing up:

this.rtb_receive_0.Text = String.Empty;
this.rtb_receive_0.Clear();
this.rtb_receive_0.ScrollBars = RichTextBoxScrollBars.None;
this.rtb_receive_0.ScrollBars = RichTextBoxScrollBars.Vertical;
this.rtb_receive_0.Refresh();

Upvotes: 1

Views: 2396

Answers (4)

Sudhansu Kumar Sahu
Sudhansu Kumar Sahu

Reputation: 1

I tried with Refresh(); Update(); Invalidate();,but it didn't worked for me.

I solved this problem using following three lines :-

        RitchTextBox.Clear(); //Clearing text in RichTextBox
        RitchTextBox.ScrollBars = RichTextBoxScrollBars.None; //Remove scroll
        RitchTextBox.ScrollBars = RichTextBoxScrollBars.Vertical; //Again add scroll

Try those above three lines. It will work 100%.

Upvotes: 0

Code Novice
Code Novice

Reputation: 2398

I was having this same problem. I solved it by calling the Invalidate() method which forces the control to repaint. 

Me.RichTextBox.Clear()
'Call Invalidate in order to force the RichTextBox to repaint.  I do this so that any 
'Visible Scroll bars are removed after clearing the Text
Me.RichTextBox.Invalidate()

Upvotes: 0

Romijn
Romijn

Reputation: 1

What helped for me was just calling the refresh() method twice. Very ugly, but it does the job.

Hmm, after more thorough testing this ugly fix proved to be not so much of a fix afterall. It helps, but still some glitches. refresh(); update(); seems like a better solution.

Upvotes: 0

sab669
sab669

Reputation: 4104

Have you tried simply just programatically setting the Scrollbars property on the RTB?

myRichTextBox.ScrollBars = RichTextBoxScrollBars.None;

Edit: I think I misinterpreted what you needed. Searching around, I found this similar post on another forum: http://www.vbforums.com/showthread.php?793671-RESOLVED-RichTextBox-Visual-Bug

This user is setting the value of an RTB based on a selection in a list view. When a new value is set and does not require a scrollbar it doesn't re-draw and still shows the bar.

It seems like adding myRichTextBox.Clear(); myRichTextBox.Refresh(); should help. In this case that user is also programatically setting the ScrollBars property as well.

Also, are you able to determine how many lines of text can fit in the RichTextBox before a scrollbar is needed? I suppose that might vary based on system settings on the machine, but you might just be able to programatically check myrtb.Scrollbars = (myrtb.Lines.Length > X) ? Vertical : None; (excuse the psuedo code syntax)

Upvotes: 1

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