Syntax Highlight Quicklook

This application offers a quicklook extension for MacOS 10.15 Catalina or later for previewing source files. Inside it uses Highlight to render source code with syntax highlighting. The application is distributed with a version of the highlight. If you want you can use a different version customizing the preferences.

Starting from MacOS 10.15.0 Catalina the qlgenerator APIs are deprecated. Moreover a .qlgenerator package inside Library/QuickLook must be notarized on 10.15.0 to work. In version 10.15.1 it seems that notarization is no longer required.

This project consists of these components:

• a standalone app that can view source files and provide the interface for the preferences;
• a quicklook system extension to preview the source files;
• an XPC service that generate the preview of source file and pass the formatted data to the app or the quicklook extension.

MacOS 10.15 Catalina require sandboxed extension that prevent the execution of external processes (like shell script). To work around this problem, it is possible to use an XPC service that may have different security policies than the application / extension that invokes it. In this case the XPC service is not sandboxed.

The XPC service is executed automatically when requested by the application or the quicklook extension. After closing the quicklook preview the process is automatically closed after some seconds releasing the resources.

The app and quicklook extension can preview files showing the formatted code as html, inside a WKWebView, or as rtf inside a NSTextView. The suggested mode is rtf.

To use the quicklook preview you must launch the application at least once. In this way the quicklook extension will be discovered by the system. After the first execution, the quicklook extension will be available among those present in the System preferences/Extensions.