Setting the cursor's current line on a .NET TextBox

Question

In .NET, you can easily get the line number of the cursor location of a TextBox (i.e. the "current line") by using GetLineFromCharIndex and SelectionStart:

var currentLine = textBox1.GetLineFromCharIndex(textBox1.SelectionStart);

Is there a "clean/native" way to set the cursor in a given line of a Textbox (i.e. set the "current line")? Or at least a "clean/native" way to get the char index of the first character of a given line (something like getCharIndexFromLine, the opposite of the function I put before)?

A way to do it would involve iterating over the first N-1 elements of the Lines property of the TextBox and summing their lengths plus the lengths of the linebreaks. Any other idea?

Answer 1

There is a GetFirstCharIndexFromLine() function that is available:

int myLine = 3;
int pos = textBox1.GetFirstCharIndexFromLine(myLine);
if (pos > -1) {
  textBox1.Select(pos, 0);
}

Answer 2

This was the best I could come up with:

private void SetCursorLine(TextBox textBox, int line)
{
    int seed = 0, pos = -1;
    line -= 1;

    if(line == 0) pos = 0;
    else
        for (int i = 0; i < line; i++)
        {
            pos = textBox.Text.IndexOf(Environment.NewLine, seed) + 2;
            seed = pos;
        }

    if(pos != -1) textBox.Select(pos, 0);
}

If you want to start counting lines at 0 remove the line -= 1; segment.