Xml Editor Control


If you have a Windows Forms application that involves Xml editing or viewing, you can use this control to save yourself the effort of formatting the Xml content. For now, only syntax highlighting is implemented. I expect to add more features in the future like spacing, grouping, intellisense, etc…

Usage

Simply add the files (XmlToken.cs, XmlTokenizer.cs, XmlEditor.cs, XmlEditor.designer.cs) to your project then drag and drop the XmlEditor control from the Toolbox into your Windows Form.

The XmlEditor control currently has three public properties. Use AllowXmlFormatting to enable or disable formatting on the Xml content in the editor. The ReadOnly property tells whether or not to allow the user to change the text. The Text property sets or gets the text of the Xml editor.

Here is how the control looks like when AllowXmlFormatting = true and ReadOnly = false (default values):

Implementation

To color the Xml string, we have to split it into multiple tokens, then color each token based on its type. I have identified the following token types (based on syntax highlighting behavior in Visual Studio 2008):

  • A “Value” is anything between double quotes
  • A “Comment” is anything that starts with <!– and ends with –> (or starts with <!– and is never closed with –>)
  • An “Element” is any letter or digit that falls between < and a space or >
  • An “Attribute” is any letter or digit that falls after a < followed by space and not closed by >
  • An “Escape” is anything that starts with & and ends with ; (For example &quote;)
  • A “SpecialChar” is any character that is not a letter or a digit
  • A “None” is anything else

The Tokenize() public static method of the XmlTokenizer class does the job of splitting a string into Xml tokens.

An XmlToken object is a representation of an Xml token with details about the exact text of that token, its location in the string and its type.

Here is the code in the XmlEditor control that does the syntax highlighting:

List<XmlToken> tokens = XmlTokenizer.Tokenize(xmlEditor.Text);

foreach (XmlToken token in tokens)
{
    xmlEditor.Select(token.Index, token.Text.Length);

    switch (token.Type)
    {
        case XmlTokenType.Attribute:
            xmlEditor.SelectionColor = Color.Red;
            break;
        case XmlTokenType.Comment:
            xmlEditor.SelectionColor = Color.DarkGreen;
            break;

        //  and so on for the other token types
    }
}

Download source and exe.

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    • maria judi
    • November 15th, 2010

    thak u_______

    ths is very useful for my project

  1. Glad it is..

    • Marco van Tintelen
    • January 10th, 2011

    Very nice!

    • rishi
    • February 9th, 2011

    intellisense: do you have support for that ? If not can you tell me how can I implement it. thanks in advance.

  2. Nice work! Are you okay if I start with this and extend it or is this “as-is” only?

    Thank you!

    Colby

  3. Sure… Please share the final version that you come up with.

    If you are planning to distribute it, it’s OK as long as you keep reference that it was originally created by me and link to this post in the source code…

    • Joseph Gordon
    • August 17th, 2011

    Great work here. Small performance tip: you have a re-entry issue in your FormatXml method, where changing the selectionColor fires the textbox_changed event, causing another call to FormatXml.

    • W
    • February 17th, 2012

    Thanks. This is really helpful.

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