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POVB.NET Syntax Highlighting in a Rich Text Box
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copied!<p>I'm coding a simple code editor for a very simple scripting language we use at work. My syntax highlighting code works fine if I do it on the entire <code>RichTextBox</code> (<code>rtbMain</code>) but when I try to get it to work on just that line, so I can run the function with <code>rtbMain</code> changes, it gets weird. I can't seem to figure out why. Am I even going about this the right way?</p> <p><code>rtbMain</code> is the main text box. <code>frmColors.lbRegExps</code> is a listbox of words to highlight (later it will have slightly more powerful regular expressions.) <code>frmColor.lbHexColors</code> is another listbox with the corresponding hex colors for the words.</p> <pre><code>Private Sub HighLight(ByVal All As Boolean) Dim RegExp As System.Text.RegularExpressions.MatchCollection Dim RegExpMatch As System.Text.RegularExpressions.Match Dim FirstCharIndex As Integer = rtbMain.GetFirstCharIndexOfCurrentLine Dim CurrentLine As Integer = rtbMain.GetLineFromCharIndex(FirstCharIndex) Dim CurrentLineText As String = rtbMain.Lines(CurrentLine) Dim CharsToCurrentLine As Integer = rtbMain.SelectionStart Dim PassNumber As Integer = 0 LockWindowUpdate(Me.Handle.ToInt32) 'Let's lock the window so it doesn't scroll all crazy. If All = True Then 'Highlight everything. For Each pass In frmColors.lbRegExps.Items RegExp = System.Text.RegularExpressions.Regex.Matches(LCase(rtbMain.Text), LCase(pass)) For Each RegExpMatch In RegExp rtbMain.Select(RegExpMatch.Index, RegExpMatch.Length) rtbMain.SelectionColor = ColorTranslator.FromHtml(frmColors.lbHexColors.Items(PassNumber)) Next PassNumber += 1 Next Else 'Highlight just that row. For Each pass In FrmColors.lbRegExps.Items RegExp = System.Text.RegularExpressions.Regex.Matches(LCase(CurrentLineText), LCase(pass)) For Each RegExpMatch In RegExp rtbMain.Select(RegExpMatch.Index + (CharsToCurrentLine - RegExpMatch.Length), RegExpMatch.Length) rtbMain.SelectionColor = Color.Blue Next Next End If rtbMain.Select(CharsToCurrentLine, 0) 'Reset colors and positon and then unlock drawing. rtbMain.SelectionColor = Color.Black LockWindowUpdate(0) End Sub </code></pre>

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