How to Add Syntax Highlights for Codeblocks in the Output

Syntax Highlighting makes it easier to read the semantics of the structured content by displaying each type of code (language) in different colors and fonts. The application provides the ability to add syntax highlights in codeblocks for DITA to PDF or HTML-based output through the use of the @outputclass attribute and a variety of predefined values are available.

To provide syntax highlighting in the codeblocks that appear in the output, add the @outputclass attribute on the <codeblock> element and set its value to one of the predefined language values. The Content Completion Assistant offers a list of the possible values when adding the @outputclass attribute in Text mode but there are also two simple ways to set the value in Author mode:

Select the <codeblock> element in the editor and in the Attributes view, click on the Value cell for the @outputclass attribute and select one of the predefined values (for example, language-xml).
Select the <codeblock> element in the editor and use the Alt + Enter keyboard shortcut to open the in-place attributes editor window. Then select one of the predefined values from the Value drop-down menu.

The predefined values that can be selected are:

language-json
language-yaml
language-xml
language-bourne
language-c
language-cmd
language-cpp
language-csharp
language-css
language-dtd
language-ini
language-java
language-javascript
language-lua
language-perl
language-powershell
language-php
language-python
language-ruby
language-sql
language-xquery

Attention: It is recommended that you do not add inline elements in the codeblocks when using this @outputclass attribute, as it may lead to improper highlighting.

Tip: Starting with version 24.0, the language values can also be set without using the language- prefix.

Example:

The following codeblock with the @outputclass set as language-css:

<codeblock outputclass="language-css" id="codeblock_1">@page preface-page {
	background-color:silver;
	@top-center{
		content: "Custom Preface Header";
	}
}
*[class ~= "topic/topic"][@topicrefclass ~= "bookmap/preface"] {
	page: preface-page;
}</codeblock>

would like this in WebHelp output:

@page preface-page {
	background-color:silver;
	@top-center{
		content: "Custom Preface Header";
	}
}
*[class ~= "topic/topic"][@topicrefclass ~= "bookmap/preface"] {
	page: preface-page;
}