EventHandler Problem

Question

Hello everyone, I'm pretty new to C# so for my first project I deceided to create a simple Notepad clone, except it will be much more powerful including tabbed files. It has been pretty easy until now...

I wanted to add Syntax Highlighting to my notepad, I am using Duncan Harris' code to do this. I have two files right now, Main.cs - The main Form class and Utilities.cs - I have moved all of the Syntax highlighting functions into this class.

So, my question is: Why doesn't this code work?

Main.cs
private void Parse() { Util.Parse(); }
private void ParseLine(string line) { Util.ParseLine(line); }
private void TextChangedEvent(object sender, EventArgs e) { Util.TextChangedEvent(null, null); }

---

Utilities.cs

private Form _form;

private TabControl _tabs;

public void Controller(Form form, TabControl tabs)
{
_form = form;
_tabs = tabs;
}

public void Parse()
{

RichTextBox rtb = (RichTextBox)_tabs.SelectedTab.Controls[0];

/* THIS IS THE PROBLEM LINE */

rtb.TextChanged += new EventHandler(this.TextChangedEvent);

}

public void TextChangedEvent(object sender, EventArgs e)

{

RichTextBox rtb = (RichTextBox)_tabs.SelectedTab.Controls[0];

// Calculate the starting position of the current line.

int start = 0, end = 0;

for (start = rtb.SelectionStart - 1; start > 0; start--)

{

if (rtb.Text[start] == '\n') { start++; break; }

}

if (start < 0)

return;

// Calculate the end position of the current line.

for (end = rtb.SelectionStart; end < rtb.Text.Length; end++)

{

if (rtb.Text[end] == '\n') break;

}

// Extract the current line that is being edited.

String line = rtb.Text.Substring(start, end - start);

// Backup the users current selection point.

int selectionStart = rtb.SelectionStart;

int selectionLength = rtb.SelectionLength;

// Split the line into tokens.

Regex r = new Regex("([ \\t{}();])");

string[] tokens = r.Split(line);

int index = start;

foreach (string token in tokens)

{

// Set the token's default color and font.

rtb.SelectionStart = index;

rtb.SelectionLength = token.Length;

rtb.SelectionColor = Color.Black;

rtb.SelectionFont = new Font("Courier New", 10, FontStyle.Regular);

// Check for a comment.

if (token == "//" || token.StartsWith("//"))

{

// Find the start of the comment and then extract the whole comment.

int length = line.Length - (index - start);

string commentText = rtb.Text.Substring(index, length);

rtb.SelectionStart = index;

rtb.SelectionLength = length;

rtb.SelectionColor = Color.LightGreen;

rtb.SelectionFont = new Font("Courier New", 10, FontStyle.Regular);

break;

}

// Check whether the token is a keyword.

String[] keywords = { "public", "void", "using", "static", "class", "int", "if", "for", "each", "string" };

for (int i = 0; i < keywords.Length; i++)

{

if (keywords[i] == token)

{

// Apply alternative color and font to highlight keyword.

rtb.SelectionColor = Color.Blue;

rtb.SelectionFont = new Font("Courier New", 10, FontStyle.Bold);

break;

}

}

index += token.Length;

}

// Restore the users current selection point.

rtb.SelectionStart = selectionStart;

rtb.SelectionLength = selectionLength;

}

---

Again, a lot of this code is not mine, but Duncan Harris' This code works when not moved into a new class. Sorry for the large amount of code, it is just the problem area.

Thanks for any help you can give.