PreviewQt v4.0

Published: 6th of March, 2025

It has been a little while since the last release of PreviewQt, so it's about time for some updates and a bunch of new features.

The biggest addition is the support for text files of all kinds, including syntax highlighting (using KSyntaxHighlighting) and a search feature. Note that it is not possible to edit files through PreviewQt as it simply serves as viewer. For editing, pass the file on to your editor of choice using the built-in 'open in external app' feature. Some basic additional settings are available for text files, including an adjustable font size, line wrap, and case senstivity of searching for substrings. Certain files can also be processed before they are shown. This is currently available for:

JSON files: beautify the structure of JSON files
HTML files: show the parsed HTML instead of the source
Markdown files: show the processed markdown instead of the syntax

The processing is never done automatically, but is accessible (for supported files) via a button with a 'magic wand' that will show up next to the settings button in the bottom right corner. It is also possible to trigger that action with the Ctrl+R shortcut.

In addition to all this, the user interface was slightly tweaked to be easier to use by adding tooltips for the various buttons (including their respective shortcuts) and context menus, including a general context menu listing all possible actions. In addition, the empty area in the top row can be used to move the window around through click-and-drag.

Some other smaller changes and improvements include:

Better detection of file type by balancing the file ending with the mime type of any given file.
Improved plugins for LibArchive, libvips, and for Qt.
The color scheme of all sub-parts of the interface now follow the global desktop theme.
The number of supported file formats is listed in the config information accessible through a click on the logo in the About window.
PreviewQt is now available as portable application for Windows, and (very soon) also available in the Windows store and through winget.

Going forward, the plugin system in PreviewQt is planned to be standardized and in doing so be made more flexible, including the ability to detect and load plugins at runtime. This will allow for a more selective process for which plugins you want to have support for (as some might be a little heavier), it will lead to a cleaner separation between the basic functionality and the plugins, and it will make it possible for custom plugins to be added to further extend PreviewQt.

You want to help out? Why not join the translation team for PreviewQt over on Crowdin. If your language is missing you can simply request it directly on Crowdin or send me an email/message and I will add it to the project.

If you are considering supporting PhotoQt by donation, please consider donating to the humanitarian relief in Ukraine instead, for example to the Ukrainian Red Cross, or to the United24 fund by the Ukranian government (wikipedia article).

Enjoy PreviewQt,

Lukas

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