How do I tell which line has been doubleclicked in a multiline textbox

[jeffsteed]

I am using VisualStudio 2005 to create an application in C#.

I have a scrollable, multiline textbox where I want the user to be able to doubleclick any given line to put that line in another textbox. How do I tell which line has been doubleclicked? The event argument contains only x,y information and I don't want to have to do the math to figure out which of the visible lines contains that point.

Any ideas?

[Plater]

Hmm, double clicking text normally ( I think?) has the habbit of selecting an entire word/section of words. Perhaps the selectedtext property can help?

Another idea might be to switch to a ListBox (if possible) and then you can get the index of the entry they clicked and copy it over?

EDIT:
Textboxes appear to have this function GetCharIndexFromPosition() which gets a charindex from a point (which would be your X,Y from double clicking)
And then use GetLineFromCharIndex() to get the line index.
Then you can probably use .Lines[lineIndex] to get the text?

[jeffsteed]

I actually figured out a way to do it that involves using the SelectionStart property. I tried to allow for cases where the user clicks on the first line, clicks in the very first character possition, the last line or after the last line. I have not tried it much but this seems to work as I intended:

private void StatusTextBox_DoubleClick(object sender, EventArgs e)
      {
         int StartOfLine;
         int EndOfLine;
 
         /////
         // Find where the line starts by backing up a character at a time until
         // there are no more characters or a newline character is found.
         /////
         for(StartOfLine = StatusTextBox.SelectionStart; StartOfLine >= 0; StartOfLine--)
            {
            if(StatusTextBox.Text[StartOfLine] == '\n')
               {
               StartOfLine++; // advance 1 char so newline is not part of selected line.
               break;
               }
            }
         if(-1 == StartOfLine)   // if no newline found start selection with 1st char in TextBox
            {
            StartOfLine = 0;
            }
 
         /////
         // Find where the line ends by going forward a character at a time until
         // there are no more characters or a newline character is found.
         /////
         for(EndOfLine = StatusTextBox.SelectionStart; EndOfLine < StatusTextBox.Text.Length; EndOfLine++)
            {
            if(StatusTextBox.Text[EndOfLine] == '\n')
               {
               EndOfLine--; // go back 1 char so newline is not part of selected line.
               break;
               }
            }
         if(StatusTextBox.Text.Length == EndOfLine)   // if no newline found start selection with 1st char in TextBox
            {
            EndOfLine = StatusTextBox.Text.Length; // selection ends with last character
            }
 
         StatusTextBox.SelectionStart = StartOfLine;
         StatusTextBox.SelectionLength = EndOfLine - StartOfLine;
 
         GenericCommandTextBox.Text = StatusTextBox.SelectedText;
         Update();
      } // End of StatusTextBox_DoubleClick()
 

[jeffsteed]

Thanks for pointing me to the 2 functions. They look like they can be used for a more elegant solution than mine.

Hmm, double clicking text normally ( I think?) has the habbit of selecting an entire word/section of words. Perhaps the selectedtext property can help?

Another idea might be to switch to a ListBox (if possible) and then you can get the index of the entry they clicked and copy it over?

EDIT:
Textboxes appear to have this function GetCharIndexFromPosition() which gets a charindex from a point (which would be your X,Y from double clicking)
And then use GetLineFromCharIndex() to get the line index.
Then you can probably use .Lines[lineIndex] to get the text?