Remove hidden text from a word processing document

  • Articolo

This topic shows how to use the classes in the Open XML SDK for Office to programmatically remove hidden text from a word processing document.

Getting a WordprocessingDocument Object

To open an existing document, you instantiate the WordprocessingDocument class as shown in the following using statement. In the same statement, you open the word processing file with the specified fileName by using the Open method, with the Boolean parameter set to true in order to enable editing the document.

    using (WordprocessingDocument doc = 
        WordprocessingDocument.Open(fileName, true))
    {
       // Insert other code here. 
    }

The using statement provides a recommended alternative to the typical .Create, .Save, .Close sequence. It ensures that the Dispose method (internal method used by the Open XML SDK to clean up resources) is automatically called when the closing brace is reached. The block that follows the using statement establishes a scope for the object that is created or named in the using statement, in this case doc. Because the WordprocessingDocument class in the Open XML SDK automatically saves and closes the object as part of its System.IDisposable implementation, and because Dispose is automatically called when you exit the block, you do not have to explicitly call Save and Close─as long as you use using.

Structure of a WordProcessingML Document

The basic document structure of a WordProcessingML document consists of the document and body elements, followed by one or more block level elements such as p, which represents a paragraph. A paragraph contains one or more r elements. The r stands for run, which is a region of text with a common set of properties, such as formatting. A run contains one or more t elements. The t element contains a range of text. The following code example shows the WordprocessingML markup for a document that contains the text "Example text."

    <w:document xmlns:w="https://schemas.openxmlformats.org/wordprocessingml/2006/main">
      <w:body>
        <w:p>
          <w:r>
            <w:t>Example text.</w:t>
          </w:r>
        </w:p>
      </w:body>
    </w:document>

Using the Open XML SDK, you can create document structure and content using strongly-typed classes that correspond to WordprocessingML elements. You will find these classes in the DocumentFormat.OpenXml.Wordprocessing namespace. The following table lists the class names of the classes that correspond to the document, body, p, r, and t elements.

WordprocessingML Element Open XML SDK Class Description
document Document The root element for the main document part.
body Body The container for the block level structures such as paragraphs, tables, annotations and others specified in the ISO/IEC 29500 specification.
p Paragraph A paragraph.
r Run A run.
t Text A range of text.

Structure of the Vanish Element

The vanish element plays an important role in hiding the text in a Word file. The Hidden formatting property is a toggle property, which means that its behavior differs between using it within a style definition and using it as direct formatting. When used as part of a style definition, setting this property toggles its current state. Setting it to false (or an equivalent) results in keeping the current setting unchanged. However, when used as direct formatting, setting it to true or false sets the absolute state of the resulting property.

The following information from the ISO/IEC 29500 specification introduces the vanish element.

vanish (Hidden Text)

This element specifies whether the contents of this run shall be hidden from display at display time in a document. [Note: The setting should affect the normal display of text, but an application can have settings to force hidden text to be displayed. end note]

This formatting property is a toggle property (§17.7.3).

If this element is not present, the default value is to leave the formatting applied at previous level in the style hierarchy .If this element is never applied in the style hierarchy, then this text shall not be hidden when displayed in a document.

[Example: Consider a run of text which shall have the hidden text property turned on for the contents of the run. This constraint is specified using the following WordprocessingML:

    <w:rPr>
      <w:vanish />
    </w:rPr>

This run declares that the vanish property is set for the contents of this run, so the contents of this run will be hidden when the document contents are displayed. end example]

© ISO/IEC29500: 2008.

The following XML schema segment defines the contents of this element.

    <complexType name="CT_OnOff">
       <attribute name="val" type="ST_OnOff"/>
    </complexType>

The val property in the code above is a binary value that can be turned on or off. If given a value of on, 1, or true the property is turned on. If given the value off, 0, or false the property is turned off.

Sample Code

The following code example shows how to remove all of the hidden text from a document. You can call the method, WDDeleteHiddenText, by using the following call as an example to delete the hidden text from a file named "Word14.docx."

    string docName = @"C:\Users\Public\Documents\Word14.docx";
    WDDeleteHiddenText(docName);

Note

This example assumes that the file Word14.docx contains some hidden text. In order to hide part of the file text, select it, and click CTRL+D to show the Font dialog box. Select the Hidden box and click OK.

Following is the complete sample code in both C# and Visual Basic.

using DocumentFormat.OpenXml.Packaging;
using System;
using System.IO;
using System.Xml;

WDDeleteHiddenText(args[0]);

static void WDDeleteHiddenText(string docName)
{
    // Given a document name, delete all the hidden text.
    const string wordmlNamespace = "https://schemas.openxmlformats.org/wordprocessingml/2006/main";

    using (WordprocessingDocument wdDoc = WordprocessingDocument.Open(docName, true))
    {
        // Manage namespaces to perform XPath queries.
        NameTable nt = new NameTable();
        XmlNamespaceManager nsManager = new XmlNamespaceManager(nt);
        nsManager.AddNamespace("w", wordmlNamespace);

        if (wdDoc.MainDocumentPart is null || wdDoc.MainDocumentPart.Document.Body is null)
        {
            throw new ArgumentNullException("MainDocumentPart and/or Body is null.");
        }

        // Get the document part from the package.
        // Load the XML in the document part into an XmlDocument instance.
        XmlDocument xdoc = new XmlDocument(nt);
        using (Stream stream = wdDoc.MainDocumentPart.GetStream())
        {
            xdoc.Load(stream);
            XmlNodeList? hiddenNodes = xdoc.SelectNodes("//w:vanish", nsManager);

            if (hiddenNodes is null)
            {
                return;  // No hidden text.
            }

            foreach (System.Xml.XmlNode hiddenNode in hiddenNodes)
            {
                if (hiddenNode.ParentNode is null || hiddenNode.ParentNode.ParentNode is null || hiddenNode.ParentNode.ParentNode.ParentNode is null)
                {
                    continue;
                }

                XmlNode topNode = hiddenNode.ParentNode.ParentNode;
                XmlNode topParentNode = topNode.ParentNode;
                topParentNode.RemoveChild(topNode);

                if (topParentNode.ParentNode is null)
                {
                    continue;
                }

                if (!topParentNode.HasChildNodes)
                {
                    topParentNode.ParentNode.RemoveChild(topParentNode);
                }
            }
        }

        using (Stream stream2 = wdDoc.MainDocumentPart.GetStream(FileMode.Create, FileAccess.Write))
        {
            // Save the document XML back to its document part.
            xdoc.Save(stream2);
        }
    }
}

See also