In most distributions that come with KDE Software Compilation 4.3 and above, opening Dolphin for browsing the filesystem will give you this window:

The left circle shows the Preview Mode Button. We will expand on this option below.

On the right is the Information Panel, which in addition to showing info about the file (type, size, modified etc.),  will allow you to preview the majority of files (Text, Image, PDF, Open Document). This happens after you select a file or hover your mouse over it.

What’s more, the Information Panel enables playback of Video and Music files. A small media player will appear, with just a play/stop button and a bar, but it’s more than enough.

You can also add an extra information popup window that shows a preview and some information  about a file when you hover your mouse  over it. You can see it in the screenshot above and the ones following below. It displays similar information with the information panel.

In Dolphin go to Settings> Configure Dolphin> General. In the Behavior Tab enable “Show tooltips” like below:

How to show previews as icons:

Despite all these,  it isn’t possible for Dolphin to show the various files as thumbnails instead of icons as you browse the filesystem . For this to work, you must undergo the procedure described below:

For starters,  you need to select the Preview mode button in Dolphin, as shown in the screenshot at the beginning.

Now lets open Settings > Configure Dolphin.

Then go to General > Preview Tab.

Image, Txt and PDF files are supported by default.  You can also select previews for other file types and directories as well. Just click on the ones you wish.

Text Files

Supported but not enabled by default, this is what you should see if you enable preview:

Image Files (ie .png, .jpg)

By default enabled, you will be able to see thumbnails of the image files instead of the usual icons.

PDF files

This is supported but not enabled by default. In the Preview Tab select Postscript, PDF and DVI files to enable it. I think that this preview requires Okular to be installed to work.

Open Document files (ie .odt, .ods)

You will need to download the OpenDocument Thumbnail plugin.

Depending on your distribution, this package might not be in the repositories and you will have to compile it from source. Information on how to install the package can be found in the readme file after you extract the .tar.gz file. It’s quite easy!

After installing this package, just go back to Dolphin configuration and now you will have the ODF (OpenDocument Format) files selection. Here is what you get after enabling it:

Audio Files (ie. .flac, .mp3)

AudioThumbs allows Dolphin to preview cover arts embedded in audio file tags as thumbnails. Unfortunately it doesn’t support .ogg files currently. You can add images to your audio files, using Kid3. Thank you David for this tip.

Video files (ie .ogv, .avi)

This time we will need MplayerThumbs, it of course needs Mplayer installed to work.

Once again, depending on your distribution you will probably find this package in the repo’s, under a similar name. If not, information on how to install it can be found in the readme and install files after you download and extract the source package. You can run mplayerthumbsconfig to check that Mplayer is the selected backend.

As above, a new option will now be available in the Preview Tab in Dolphin Settings>General. Select Video Files (Mplayer thumbs) to enable it.

The preview of video files is rather slow on my PC, but it’s a very old one, so am guessing it runs smoother on newer systems.

Update: As suggested by MirzaD in a comment below, using kffmpegthumbnailer instead of mplayerthumbs will probably give you a better overall experience. According to it’s developer, it’s designed to be as fast and lightweight as possible.

I have tested this on my Chakra system, it should also work in other distributions that come with KDE SC 4.3  and above. What is your experience after enabling all these? Feedback and suggestions are welcomed!