Rich Text Box how to highlight text block

Question

I need a certain portion of my text in RTB to be highlighted not in the sense of changing the font style/color, but in the sense of making a block selection with a particular color. This is similar to how Visual Studio highlights a line during debug mode.

How can I accomplish this feature using RTB or rather, is it even possible? If it isn't possible, I'd like to hear another way of performing the above task.

Answer 1

Yes you can set the BackColor of a RichTextBox Selection using the RichTextBox.SelectionBackColor Property.

int blockStart = 1; //arbitrary numbers to test
int blockLength = 15;
richTextBox1.SelectionStart = blockStart;
richTextBox1.SelectionLength = blockLength;
richTextBox1.SelectionBackColor = Color.Yellow;

Answer 2

I think you are looking for ScintillaNET.

On the other hand if you want to do this by yourself in RTB then you can do it by first finding the lineNumber using TextBoxBase.Lines property. Then ...

//Select the line from it's number
startIndex = richTextBox.GetFirstCharIndexFromLine(lineNumber);
richTextBox.Select(startIndex, length);

//Set the selected text fore and background color
richTextBox.SelectionColor = System.Drawing.Color.White;
richTextBox.SelectionBackColor= System.Drawing.Color.Blue;