TIP: XAML Markup & Entities (Dynamic)

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   Hi,

Sometimes you need to insert dynamically generated text from XAML unaware sources (such as user input, log files, etc...). Trying to include this text may cause the markup to be invalid and prevent the CJ controls from displaying the markup properly.

To prevent this, you should sanitize all plain-text that you want to add to your markup controls before sending it to the control. Right now I'm using this function and it has been working (although I don't know if the list is exhaustive, so I'd appreciate any input if there are bugs):

Public Function xamlEncodePlaintext(ByVal pPlainText As String) As String
   ' Convert illegal characters to XAML entities
   pPlainText = Replace$(pPlainText, "&", "&amp;")
   pPlainText = Replace$(pPlainText, "<", "&lt;")
   pPlainText = Replace$(pPlainText, ">", "&gt;")
   pPlainText = Replace$(pPlainText, "'", "&apos;")
   pPlainText = Replace$(pPlainText, """", "&quot;")
   ' Expand VB newline characters to XAML <LineBreak/> tags
   pPlainText = Replace$(pPlainText, vbNewLine, "<LineBreak/>")

   xamlEncodePlaintext = pPlainText
End Function

I've also added (as a convenience) the conversion of VB NewLines to <LineBreak/> elements to preserve line spacing.

To use it (for this example, put a TextBox (Text1) and a CJ Label (Label1) on your form):

Private Sub Form_Load

Me.Text1.Text = "<This is a test of plain-text XAML entity encoding & markup>" & vbNewline & vbNewline & "You shouldn't see any XAML in your label caption!"

With Me.Label1   ' CJ label
    .EnableMarkup = True
    .Caption = "<TextBlock>" & xamlEncodePlaintext(Me.Text1.Text) & "</TextBlock>"
End With

End Sub

Pretty simple & straight-forward, but hopefully it will be of some use to someone!