Fastest way to append text to a richtextbox?

问题

I have a application with a RichTextBox control where a procedure is adding text almost all the time:

RichTextBox1.Text += vbNewLine & "Title: " & AlbumName
RichTextBox1.Text += vbNewLine & "Genre: " & AlbumGenre
RichTextBox1.Text += vbNewLine & "Year : " & AlbumYear
RichTextBox1.Text += vbNewLine & "Url  : " & AlbumLink

' The slow thing I think is here:
RichTextBox1.SelectionStart = RichTextBox1.Text.Length

RichTextBox1.ScrollToCaret

The problem is when the richtextbox has about more than 50 lines, when has more lines it turns more slowly to append the new text (obvious).

I need to find a better way to accelerate the process, to loose at least a insignificant speed when richtextbox line-count reaches 1.000 (for example).

The reason of this question is because I want to do the the things in the right way, I don't like my app to be slow when my richtextbox has much lines.

Please, I need info, ideas and/or examples (no matter if in C# or VBNET). Thankyou.

回答1:

Use a StringBuilder and assign Text in one go.

Unless you rewrite the RichTextBox control I dont think you'll be able to speed up this function:

' The slow thing I think is here:
RichTextBox1.SelectionStart = RichTextBox1.Text.Length

For better speed consider these alternatives:

Fast-Colored-TextBox-for-syntax-highlighting

ScintillaNET

Icsharpcode TextEditor

Here is how you do the scrolling to end with Fast-Colored-TextBox-for-syntax-highlighting:

 Editor.ScrollLeft();
 Editor.Navigate(Editor.Lines.Count - 1);

Here is how you do the scrolling to end with Scintella.Net: Vertical scroll Scintilla Textbox during Text Changed event Disclaimer: I dont work for any of these companies.

Update:

StringBuilder sb = new StringBuilder();
sb.AppendLine("Title: ");
sb.Append(AlbumName);
sb.AppendLine("Genre: ");
sb.Append(AlbumGenre);
sb.AppendLine("Year : ");
sb.Append(AlbumYear);
sb.AppendLine("Url  : ");
sb.Append(AlbumLink);
RichTextBox1.Text = sb.ToString();

回答2:

This is an older post - but I wanted to help out future generations!

I've been having the SAME issue - and finally found a solution... First off, if you do not need the extra formatting use a TextBox instead (from my studies, it's faster and auto-scrolls to the end).

If you need the formatting of individual lines of text, RichTextBox is the way to go, but MAKE SURE you turn .HideSelection to false (it's true by default). This will cause the richtextbox to scroll to the end, so you do not need .ScrollToCaret

Here is what I am using after I've set all the property values for the rich textbox:

private void appendOutput(String msg){
    richTextBoxOutput.AppendText(msg + "\r\n");
}


private void appendError(String msg, bool clearPrior){
    if (clearPrior){
        richTextBoxOutput.Clear();
    }

    richTextBoxOutput.SelectionColor = Color.Red;
    richTextBoxOutput.SelectedText = msg + "\r\n";
}

UPDATE

To be more clear, setting .HideSelection to false and avoiding .ScrollToCaret greatly improved my program's speed.

回答3:

If first suggested option doesn't work for you, you can try the following. It's in C#, but I am sure you can convert it for VB.

    StringBuilder text = new StringBuilder(RichTextBox1.Text);
    text.AppendFormat("{0}Title: {1}", Environment.NewLine, AlbumName);
    text.AppendFormat("{0}Genre: {1}", Environment.NewLine, AlbumGenre);
    text.AppendFormat("{0}Year: {1}", Environment.NewLine, AlbumYear);
    text.AppendFormat("{0}Url: {1}", Environment.NewLine, AlbumLink);

    RichTextBox1.Text = text.ToString();
    RichTextBox1.SelectionStart = RichTextBox1.Text.Length;
    RichTextBox1.ScrollToCaret;

回答4:

The StringBuilder class was built for speed. Try that and see if that speeds up your process.

回答5:

Simply set .Visible to false, before adding lines of text.

It will stop the Form from redrawing every time you add a line.

Set .Visible back to true, when done adding lines.

来源：https://stackoverflow.com/questions/16703901/fastest-way-to-append-text-to-a-richtextbox

标签

.net

vb.net

richtextbox