QuickLook: preview files in Windows Explorer
QuickLook is a relatively new program for Microsoft Windows PCs that enables you to preview files in Explorer with a tap on Space.
Windows Explorer -- File Explorer on Windows 10 -- ships with its own preview functionality, but it is limited to select file types only. The preview feature adds a third column to Explorer that displays previews of the selected file if supported. If you highlight an image for instance, you get a preview of the image there in that column.
Downside is that it works only for select file types. If a file type is not supported, the whole interface shows a "no preview available" message but nothing else.
QuickLook is a port of the Mac OS X feature. It enables you to tap on space to preview files in Explorer. This works with many file types, but not all of them. While you can preview most media files, plain text documents, HTML files, PDF files or zip archives, you will run into issues when you try to preview executable files, Office documents (without Office installation), audio files, or other binary file formats.
Note: QuickLook is not the first program to add support for that functionality. Check out Seer for instance which offers something similar.
QuickLook runs silently in the background for the most part once you run it. The application adds a system tray icon but its functionality is limited. You can right-click on it to enable "run at startup", and to run a manual check for updates.
The preview window looks different depending on the file that you are previewing. Plain text files are displayed right away, and you may scroll them as you see fit. Archives are shown with their folder and file structure, and you may navigate them using mouse or keyboard.
Media is displayed directly, or played when it is a video file or animated gif. Not all media file types are supported though. While you can play mp4 or flv files for instance using QuickLook, avi or wmv files won't play.
You can navigate to the next or previous file in line with a tap on the up or down arrow key on the keyboard,. Holding down the Ctrl-key and using the mouse wheel zooms in or out of files.
There is no indication whether a file will show up as a preview when you hit space, so it is always a trial and error thing at first to find out about that. An option to display the list of supported file types would be useful. You find the list of supported file types on the project's homepage on GitHub.
QuickLook supports plugins, and can be extended with plugins to support additional file types. Information on how that is done is provided on the project's home as well.
QuickLook is a handy program for Windows. One downside to using it is that it can be quite the CPU and memory hog. CPU usage shot up to about 50% at times, and memory usage to more than 350 Megabytes on a Windows 10 Pro system. That's quite a lot for the functionality that QuickLook provides, and a primary reason that is keeping it from achieving a better review score.