Richtextbox 在新文本前面加上颜色

Question

I have used a richtextbox to display logs in my WinForms.

Language used is C#.

The software is used for inserting data of Bank Branches and after start of new Branch I want to display a text with new color.

I have seen the link Color different parts of a RichTextBox string and implemeted it successfully.

My problem is I want to prepend the new line instead of append. That is the new line will be displayed on top.

I am able to do this by changing the code to box.Text=DateTime.Now.ToString("dd-MM-yyyy-hh-mm-ss") + ": " + text + box.Text

But the color is changing for the entire text.

This is the procedure used for append

            box.SelectionStart = box.TextLength;
        box.SelectionLength = 0;

        box.SelectionColor = color;

        box.AppendText(DateTime.Now.ToString("dd-MM-yyyy-hh-mm-ss") + ": " + text);
        box.SelectionColor = box.ForeColor;

This is what I have done:

            box.Text=DateTime.Now.ToString("dd-MM-yyyy-hh-mm-ss") + ": " + text + box.text;
        box.SelectionStart = 0;
        box.SelectionLength = text.length;
        box.SelectionColor = color;

But this is not working.

Answer 1

1) Never directly change the Text property of an already formatted RichtTextBox

2) To append use the RTB.AppendText function

3) To insert at any other position p , including the beginning use this:

rtb.SelectionStart = s;            // set the cursor to the target position
rtb.Selection.Length = 0;          // nothing selected, yet
rtb.SelectedText = yourNewText;    // this inserts the new text 

Now you can add the formatting you want:

rtb.SelectionStart = s;            // now we prepare the new formatting..
rtb.SelectionLength = yourNewText.Length;   //.. by selecting the text
rtb.SelectionColor = Color.Blue;   // and/or whatever you want to do..
...

Answer 2

    // Prepend, normal on first line, rest of lines gray italic

    private void PrependToRichTextbox(RichTextBox rt, string msg)
    {
        rt.SelectionStart = 0;
        rt.SelectionLength = 0;
        rt.SelectedText = msg + Environment.NewLine;

        int linecount = 0;
        foreach (var line in rt.Lines)
        {
            rt.Select(rt.GetFirstCharIndexFromLine(linecount), line.Length);
            rt.SelectionColor = linecount == 0 ? Color.Black : Color.Gray;
            Font currentFont = rt.SelectionFont;
            FontStyle newFontStyle;
            newFontStyle = linecount == 0 ? FontStyle.Regular : FontStyle.Italic;
            rt.SelectionFont = new Font(
               currentFont.FontFamily,
               currentFont.Size,
               newFontStyle
            );
            linecount++;
        }
    }