Set the font for a text run
This topic shows how to use the classes in the Open XML SDK for Office to set the font for a portion of text within a word processing document programmatically.
Packages and Document Parts
An Open XML document is stored as a package, whose format is defined by ISO/IEC 29500-2. The package can have multiple parts with relationships between them. The relationship between parts controls the category of the document. A document can be defined as a word-processing document if its package-relationship item contains a relationship to a main document part. If its package-relationship item contains a relationship to a presentation part it can be defined as a presentation document. If its package-relationship item contains a relationship to a workbook part, it is defined as a spreadsheet document. In this how-to topic, you will use a word-processing document package.
Create a WordprocessingDocument Object
The code example opens a word processing document package by passing a file name as an argument to one of the overloaded Open() methods of the WordprocessingDocument class that takes a string and a Boolean value that specifies whether the file should be opened in read/write mode or not. In this case, the Boolean value is true specifying that the file should be opened in read/write mode.
// Open a Wordprocessing document for editing.
using (WordprocessingDocument package = 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 bracket 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 package. Because the WordprocessingDocument class in the Open XML SDK automatically saves and closes the object as part of its System.IDisposable implementation, and because the Dispose method 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 the Run Fonts Element
The following text from the ISO/IEC 29500 specification can be useful when working with rFonts element.
This element specifies the fonts which shall be used to display the text contents of this run. Within a single run, there may be up to four types of content present which shall each be allowed to use a unique font:
ASCII
High ANSI
Complex Script
East Asian
The use of each of these fonts shall be determined by the Unicode character values of the run content, unless manually overridden via use of the cs element.
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 the text shall be displayed in any default font which supports each type of content.
Consider a single text run with both Arabic and English text, as follows:
English العربية
This content may be expressed in a single WordprocessingML run:
<w:r>
<w:t>English العربية</w:t>
</w:r>
Although it is in the same run, the contents are in different font faces by specifying a different font for ASCII and CS characters in the run:
<w:r>
<w:rPr>
<w:rFonts w:ascii="Courier New" w:cs="Times New Roman" />
</w:rPr>
<w:t>English العربية</w:t>
</w:r>
This text run shall therefore use the Courier New font for all characters in the ASCII range, and shall use the Times New Roman font for all characters in the Complex Script range.
© ISO/IEC29500: 2008.
How the Sample Code Works
After opening the package file for read/write, the code creates a RunProperties object that contains a RunFonts object that has its Ascii property set to "Arial". RunProperties and RunFonts objects represent run properties (<rPr>) elements and run fonts elements (<rFont>), respectively, in the Open XML Wordprocessing schema. Use a RunProperties object to specify the properties of a given text run. In this case, to set the font of the run to Arial, the code creates a RunFonts object and then sets the Ascii value to "Arial".
// Use an object initializer for RunProperties and rPr.
RunProperties rPr = new RunProperties(
new RunFonts()
{
Ascii = "Arial"
});
The code then creates a Run object that represents the first text run of the document. The code instantiates a Run and sets it to the first text run of the document. The code then adds the RunProperties object to the Run object using the PrependChild<T>(T) method. The PrependChild method adds an element as the first child element to the specified element in the in-memory XML structure. In this case, running the code sample produces an in-memory XML structure where the RunProperties element is added as the first child element of the Run element. It then saves the changes back to the Save(MainDocumentPart) object. Calling the Save method of the WordprocessingDocument object commits changes made to the in-memory representation of the MainDocumentPart part back into the XML file for the MainDocumentPart (the document.xml file in the Wordprocessing package).
Run r = package.MainDocumentPart.Document.Descendants<Run>().First();
r.PrependChild<RunProperties>(rPr);
// Save changes to the MainDocumentPart part.
package.MainDocumentPart.Document.Save();
Sample Code
The following is the code you can use to change the font of the first paragraph of a Word-processing document. For instance, you can invoke the SetRunFont method in your program to change the font in the file "myPkg9.docx" by using the following call.
string fileName = @"C:\Users\Public\Documents\MyPkg9.docx";
SetRunFont(fileName);
After running the program check your file "MyPkg9.docx" to see the changed font.
Note
This code example assumes that the test word processing document (MyPakg9.docx) contains at least one text run.
The following is the complete sample code in both C# and Visual Basic.
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
using System;
using System.Linq;
SetRunFont(args[0]);
// Set the font for a text run.
static void SetRunFont(string fileName)
{
// Open a Wordprocessing document for editing.
using (WordprocessingDocument package = WordprocessingDocument.Open(fileName, true))
{
// Set the font to Arial to the first Run.
// Use an object initializer for RunProperties and rPr.
RunProperties rPr = new RunProperties(
new RunFonts()
{
Ascii = "Arial"
});
if (package.MainDocumentPart is null)
{
throw new ArgumentNullException("MainDocumentPart is null.");
}
Run r = package.MainDocumentPart.Document.Descendants<Run>().First();
r.PrependChild<RunProperties>(rPr);
// Save changes to the MainDocumentPart part.
package.MainDocumentPart.Document.Save();
}
}