Step-by-Step Guide to Setting a Folder Thumbnail in Dolphin File Manager

This post is specifically for dolphin file manager in KDE. So my goal was to achieve following:

• have a image inside some folders with name folder.jpg
• and display it as thumbnail of the folder

For this I used keneric.

• Install keneric. This will create a shared library file keneric.so in /usr/lib/x86_64-linux-gnu/qt5/plugins
• Now create a desktop file kenericfolder.desktop in one of the location given by command kf5-config --path services. For me it was ~/.local/share/kservices5 and /usr/share/kseervices5. Content of kenericfolder.desktop:

[Desktop Entry]
Type=Service
Name=Folder (Keneric)
Name[x-test]=xxFolder (Keneric)xx

X-KDE-ServiceTypes=ThumbCreator
MimeType=inode/directory;

X-KDE-Library=keneric
CacheThumbnail=true

• Now create a script stripPicture in one of the locations in your $PATH variable. Contents of stripPicture:

#!/bin/sh
# Usage: stripPicture fullname mime exportPicture

fullname="$1"
mime="$2"
exportPicture="$3"

# thumbnail options by mime type
case "$mime" in
    inode/directory)
        cp "$fullname"/folder.jpg "$exportPicture"
        cp "$fullname"/Cover.png "$exportPicture"
        cp "$fullname"/Poster.jpg "$exportPicture"
        cp "$fullname"/Front.jpg "$exportPicture"
    exit
    ;;

    *)
        # case trap
    exit
esac

• Now open dolphin -> open Configure Dolphin... window.
• Inside General category, in the Previews tab disable the Folder preview and enable Folders only one image (Keneric) option.

References

• https://forum.kde.org/viewtopic.php?f=224&t=156241