Question

I can’t find a way to determine the caret position in the RTB while i’m selecting text. SelectionStart is not an option.

I want to detect the direction of selection whether its backward or forward. I’m trying to achieve this in SelectionChanged event. Any tips would be appreciated.

EDIT:

I solved it by registering mouse movement direction (X axis) with mouseDown and mouseUp events.

Code:

bool IsMouseButtonPushed = false;
int selectionXPosition = 0, sDirection=0;

private void richTextBox_SelectionChanged(object sender, EventArgs e)
{
    if (sDirection==2)//forward
    {
        //dosomething
    }
}

private void richTextBox_MouseMove(object sender, MouseEventArgs e)
{
    if (IsMouseButtonPushed && (selectionXPosition - e.X) > 0)//backward
    {
        sDirection = 1;
    }
    else if (IsMouseButtonPushed && (selectionXPosition - e.X) < 0)//forward
    {
        sDirection = 2;
    }
}

private void richTextBox_MouseDown(object sender, MouseEventArgs e)
{
    IsMouseButtonPushed = true;
    selectionXPosition = e.X;
}

private void richTextBox_MouseUp(object sender, MouseEventArgs e)
{
    IsMouseButtonPushed = false;
}

What are other ways to do it?

Answer 1

SelectionStart and SelectionLength properties changes during left side selection and SelectionLength changes during right side selection.

Simple solution:

int tempStart;
int tempLength;

private void richTextBox1_SelectionChanged(object sender, EventArgs e)
{
    if (richTextBox1.SelectionType != RichTextBoxSelectionTypes.Empty)
    {
        if (richTextBox1.SelectionStart != tempStart)
            lblSelectionDesc.Text = "Left" + "\n";
        else if( richTextBox1.SelectionLength != tempLength)
            lblSelectionDesc.Text = "Right" + "\n";
    }
    else
    {
        lblSelectionDesc.Text = "Empty" + "\n";
    }

    tempStart = richTextBox1.SelectionStart;
    tempLength = richTextBox1.SelectionLength;

    lblSelectionDesc.Text += "Start: " + richTextBox1.SelectionStart.ToString() + "\n";
    lblSelectionDesc.Text += "Length: " + richTextBox1.SelectionLength.ToString() + "\n";
}

Controls:

RitchTextBox + 2xLabels

1. I am not sure why but even after disabling AutoWordSelection my mouse select whole words. Unfortunately for my solution this leads to selection direction change.
2. You might probably use property change events for this.