RichTextBox questions

[Getox]

Is there anyway to highlight certain words/letters like If, Else, New and others?

[Diesel]

Syntax highlighting is complex.

 

But, I suppose if you want a lightweight version, you could make a collection of all the keywords and check on keypress (or textchanged) to see if the word currently being typed in is a keyword, if so highlight it.

 

Here is a very simple example:

 

http://www.c-sharpcorner.com/Code/2003/June/SyntaxHighlightInRichTextBoxP2.asp

[Getox]

Um... I use windows forms... VB.net....

[Diesel]

It's all the same

 

   Private Sub TextChangedEvent(ByVal sender As Object, ByVal e As EventArgs)
       ' Calculate the starting position of the current line.
       Dim end As Integer = 0
       Dim start As Integer = 0
       start = (m_rtb.SelectionStart - 1)
       Do While (start > 0)
           If (m_rtb.Text(start) = vbLf) Then
               start = (start + 1)
               'TODO: Warning!!! break;If
           End If
           start = (start - 1)
       Loop
       ' Calculate the end position of the current line.
       end = m_rtb.SelectionStart
       Do While (end < m_rtb.Text.Length)
           If (m_rtb.Text(end) = vbLf) Then
               'TODO: Warning!!! break;If
           End If
           end = (end + 1)
       Loop
       ' Extract the current line that is being edited.
       Dim line As String = m_rtb.Text.Substring(start, (end - start))
       ' Backup the users current selection point.
       Dim selectionStart As Integer = m_rtb.SelectionStart
       Dim selectionLength As Integer = m_rtb.SelectionLength
       ' Split the line into tokens.
       Dim r As Regex = New Regex("([ \"& vbTab&"{}();])")
       Dim tokens() As String = r.Split(line)
       Dim index As Integer = start
       For Each token As String In tokens
           ' Set the token's default color and font.
           m_rtb.SelectionStart = index
           m_rtb.SelectionLength = token.Length
           m_rtb.SelectionColor = Color.Black
           m_rtb.SelectionFont = New Font("Courier New", 10, FontStyle.Regular)
           ' Check whether the token is a keyword. 
           Dim keywords() As String
           "public"
           "void"
           "using"
           "static"
           "class"
           
           Dim i As Integer = 0
           Do While (i < keywords.Length)
               If (keywords(i) = token) Then
                   ' Apply alternative color and font to highlight keyword. 
                   m_rtb.SelectionColor = Color.Blue
                   m_rtb.SelectionFont = New Font("Courier New", 10, FontStyle.Bold)
                   'TODO: Warning!!! break;If
               End If
               i = (i + 1)
           Loop
           index = (index + token.Length)
       Next
       ' Restore the users current selection point. 
       m_rtb.SelectionStart = selectionStart
       m_rtb.SelectionLength = selectionLength
   End Sub

[Nate Bross]

I've said it before, and other people have said it too. 'If you look hard at C# code, it is very easy, time consuming yes, but easy to convert to vb.net.'

 

// Calculate the starting position of the current line.
int start = 0, end = 0;
for (start = m_rtb.SelectionStart - 1; start > 0; start--) {
if (m_rtb.Text[start] == '\n') { start++; break; }
}

// Calculate the end position of the current line.
for (end = m_rtb.SelectionStart; end < m_rtb.Text.Length; end++) {
if (m_rtb.Text[end] == '\n') break;
} 

Converted to VB

' Calculate the starting position of the current line.
Dim start As Integer =  0,end As Integer =  0 
For start = m_rtb.SelectionStart - 1 To  0- 1  Step  start - 1
If m_rtb.Text(start) = vbCrLf Then
 start = start + 1
End If
Next

' Calculate the end position of the current line.
For end = m_rtb.SelectionStart To  m_rtb.Text.Length- 1  Step  end + 1
If m_rtb.Text(end) = vbCrLf Then
 Exit For
End If
Next

 

I haven't got time to convert the entire thing, but you get the idea.

[Nate Bross]

That's great, we posted at the same time, but you submitted first.

[Diesel]

@Nate

 

I swear your location 5 minutes ago said Chi-Town, now it says tempe

[Getox]

@Diesel: So how would i go about using that code on my current RichTextBox?

[Diesel]

Add an event handler

 

AddHandler myRtf.TextChanged, AddressOf(this.TextChangedEvent)

[Nate Bross]

It did say Chi-Town, for Chicago. But I moved to Tempe Arizona three weeks ago and forgot to change it. I know...off topic...

[Getox]

It's all the same

 

   Private Sub TextChangedEvent(ByVal sender As Object, ByVal e As EventArgs)
       ' Calculate the starting position of the current line.
       Dim end As Integer = 0
       Dim start As Integer = 0
       start = (m_rtb.SelectionStart - 1)
       Do While (start > 0)
           If (m_rtb.Text(start) = vbLf) Then
               start = (start + 1)
               'TODO: Warning!!! break;If
           End If
           start = (start - 1)
       Loop
       ' Calculate the end position of the current line.
       end = m_rtb.SelectionStart
       Do While (end < m_rtb.Text.Length)
           If (m_rtb.Text(end) = vbLf) Then
               'TODO: Warning!!! break;If
           End If
           end = (end + 1)
       Loop
       ' Extract the current line that is being edited.
       Dim line As String = m_rtb.Text.Substring(start, (end - start))
       ' Backup the users current selection point.
       Dim selectionStart As Integer = m_rtb.SelectionStart
       Dim selectionLength As Integer = m_rtb.SelectionLength
       ' Split the line into tokens.
       Dim r As Regex = New Regex("([ \"& vbTab&"{}();])")
       Dim tokens() As String = r.Split(line)
       Dim index As Integer = start
       For Each token As String In tokens
           ' Set the token's default color and font.
           m_rtb.SelectionStart = index
           m_rtb.SelectionLength = token.Length
           m_rtb.SelectionColor = Color.Black
           m_rtb.SelectionFont = New Font("Courier New", 10, FontStyle.Regular)
           ' Check whether the token is a keyword. 
           Dim keywords() As String
           "public"
           "void"
           "using"
           "static"
           "class"
           
           Dim i As Integer = 0
           Do While (i < keywords.Length)
               If (keywords(i) = token) Then
                   ' Apply alternative color and font to highlight keyword. 
                   m_rtb.SelectionColor = Color.Blue
                   m_rtb.SelectionFont = New Font("Courier New", 10, FontStyle.Bold)
                   'TODO: Warning!!! break;If
               End If
               i = (i + 1)
           Loop
           index = (index + token.Length)
       Next
       ' Restore the users current selection point. 
       m_rtb.SelectionStart = selectionStart
       m_rtb.SelectionLength = selectionLength
   End Sub

This code dont work in vb.net..

[Diesel]

I translated it with a tool.

Shouldn't be that hard to fix it up man!

 

Change this

Dim keywords() As String

to this

 

Dim keywords() As String = {"public","void","using", "static", "class"}

 

and fix whatever else is wrong.