RichTextBox and Inserting at Caret Positions

Question

Here is the deal: I have a RichTextBox control and it works fine. The problem is that there is a button "Insert Current DateTime" which adds/injects the current datetime into the RichTextBox. The user can enter the datetime anywhere where the caret is pointing. This involves complicated string manipulation and stuff.

Any ideas how to get the current caret position. Whenever I get RichTextBox.CaretPositon it seems it is pointing to the start of the RichTextBox and not where the actual caret is.

UPDATE 1:

The date time button click code:

 private void DateTimeStampButton_Click(object sender, RoutedEventArgs e)
        {
            //TextRange tr = new TextRange(textBox.Selection.Start, textBox.Selection.End);
            var tr = new TextRange(textBox.Document.ContentStart, textBox.Document.ContentEnd);

            if(tr.Text.Length == 2)
            {
                if(tr.Text == "\r\n")
                {
                    tr.Text = tr.Text.TrimStart(new[] { '\r', '\n' }); 
                }
            }

            textBox.CaretPosition.InsertTextInRun(DateTime.Now.ToShortDateString() + " " + DateTime.Now.ToShortTimeString() + ":  ");

            DateTimeStampButton.Focusable = false;
        }

 private void SharpRichTextBox_LostFocus(object sender, RoutedEventArgs e)
        {
            SetValue(TextProperty, Text);

            var binding = BindingOperations.GetBinding(this, TextProperty);

            if (binding == null) return;

            if (binding.UpdateSourceTrigger == UpdateSourceTrigger.Default || binding.UpdateSourceTrigger == UpdateSourceTrigger.LostFocus)
            {
                // if (TextProperty != null) BindingOperations.GetBindingExpression(this, TextProperty).UpdateSource();
            }
        }






public string Text
        {
            get
            {
                var newValue = new TextRange(Document.ContentStart, Document.ContentEnd).Text.RemoveNewLineAndReturn(); 
                return newValue; 
            }
            set
            {
                if (!String.IsNullOrEmpty(value))
                {
                    SetValue(TextProperty, value.RemoveNewLineAndReturn());
                    Document.Blocks.Clear(); 
                    Document.Blocks.Add(new Paragraph(new Run(value))); 
                    OnPropertyChanged("Text"); 
                }
            }
        }

UPDATE 2:

Turned out the problem was with the DateTime button being Focusable. I turned it to be not focusable and it worked as expected. When focus was lost on the RichTextBox it was resetting the caret position. It happened only once since in the code the btn_DateTime was dynamically being set as Focusable = false. I placed Focusable = false in XAML and everything worked fine from the start.

Answer 1

I'm using this code to successfully do what you are attempting:

private void insertNowButton_Click(object sender, RoutedEventArgs e)
{
    //NOTE:  The caret position does not change.
    richTextBox1.CaretPosition.InsertTextInRun(DateTime.Now.ToString());
}

EDIT: Addressing Update 1

private void DateTimeStampButton_Click(object sender, RoutedEventArgs e)
{
    var tr = new TextRange(textBox.Document.ContentStart, textBox.Document.ContentEnd);

    if (tr.Text.Length == 2)
    {
        if (tr.Text == "\r\n")
        {
            tr.Text = tr.Text.TrimStart(new[] { '\r', '\n' });
        }
    }

    /* Changing the text is the only way I can get the date to insert at the beginning */
    tr.Text = "I need a beer at ";

    textBox.CaretPosition.InsertTextInRun(DateTime.Now.ToString());
}

It looks like SetValue is changing the text so based on my test that actually changing the text resets the caret, I would agree with you that SetValue is causing the problem...

Answer 2

I tried this solution with WPFToolkit.Extended RichTextBox and it didn't work for me. However I found another one and thought it would be good to post it in here in case someone else could use it.

My problem was also that the after I clicked a button that is supposed to append text at the caret location, it instead adds it at the beginning of the RichTextBox.

So The solution I found is similar to the one in here -

RichTextBox CaretPosition physical location

Instead of using CaretPosition I used RichTextBox.Selection.Start.InsertTextInRun("SomeText").

It considered the selection's start as the caret position even though no selection was made and therefore was good enough for me.

I hope someone will find this useful :)

Answer 3

This worked for me:

private void InsertText(String text, RichTextBox rtb)
{
    rtb.CaretPosition = rtb.CaretPosition.GetPositionAtOffset(0, LogicalDirection.Forward);
    rtb.CaretPosition.InsertTextInRun(text);
}

I found the code here:

How do I move the caret a certain number of positions in a WPF RichTextBox?