CODEWITHSUNDEEP
c#winforms
Buksy
Buksy

Reputation: 12218

RichTextBox formatting and restoring cursor and scrollbar position

I have RichTextBox in which I format text, I have there multiple text selections and formats.

Because of that, after the formatting is done, the scrollbars positions of RichTextBox isn't the same.

How am I able to save and restore scrollbar position same (easy) way as I can save cursor position?

protected override void OnTextChanged(EventArgs e)
{
  // Save cursor position
  int cursor_position = this.SelectionStart;

  // Format text
  Highlight();

  // Restore position
  this.SelectionLength = 0;
  this.SelectionStart = cursor_position;
}

Upvotes: 0

Views: 813

Answers (1)

Buksy
Buksy

Reputation: 12218

I have seen many posts here that were solving this by handling scroll messages.

I have managed this simplier way, so if anyone have the same problem, you can use this way. It is not perfect (if there is a half of line displayed at the top, it will be scrolled), but is enough I think :).

protected override void OnTextChanged(EventArgs e)
{
    // Get first and last displayed character
    int start = this.GetCharIndexFromPosition(new Point(0, 0));
    int end = this.GetCharIndexFromPosition(new Point(this.ClientSize.Width, this.ClientSize.Height));

    // Save cursor position
    int cursor_position = this.SelectionStart;
    int cursor_lenght = this.SelectionLength;

    // Your formatting
    Highlight();

    // Scroll to the last character and then to the first + line width
    this.SelectionLength = 0;
    this.SelectionStart = end;
    this.ScrollToCaret();
    this.SelectionStart = start + this.Lines[this.GetLineFromCharIndex(start)].Length+1;
    this.ScrollToCaret();

    // Finally, set cursor to original position
    this.SelectionStart = cursor_position;
}

Upvotes: 1

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