KDE Breeze is undoubtedly one of the most beautiful widget style for Qt based applications.
While using KDE Plasma desktop you can change the color schema and widget style of Qt based applications easily via the Systemsettings application.
However that's not always possible, like if you're running LXQt desktop, or Gnome Shell and don't want to install whole bunch of KDE related software packages.
In this situation you can use the Plasma Theme Switcher command line utility to change the widget style and color schema of any Qt5 based application without KDE Systemsettings.
Note: - plasma-theme is not part of KDE, it's developed independently, here's the Github repo.
Installing Plasma Theme Switcher
There's two option to install, either download the pre-compiled binary or download the source code and compile it yourself.
The first option is pretty straight forward, just download it, the make the file executable with
chmod +x and start using it.
To compile, you need to install some development libraries, here's the example for Ubuntu or Debian.
sudo apt install build-essential qt5-default qt5-qmake qtchooser qtbase5-dev libqt5svg5-dev libpng12-dev qtbase5-dev-tools qttools5-dev-tools qtbase5-private-dev libqt5x11extras5-dev libkf5config-dev libqt5dbus5
Depending on your system, these above development libraries may not be enough, you've to install the missing ones.
Next clone the git repository.
cd ~ git clone https://github.com/maldoinc/plasma-theme-switcher.git
Go to the directory and and start building.
cd ~/plasma-theme-switcher/ ./build-release
This will take some time to compile, aftter finishing, you can run the binary from the cmake-build-release directory.
The help message is pretty self explainatory.
Changing KDE plasma theme or color schema from command line
You can install copy the compiled plasma-theme binary to /usr/local/bin directory for easier access, otherwise use as you like.
plasma-theme -c ~/kde/Arc.colors
The above example is to change color schema. generally the KDE plasma color schemes are stored inside the
However you can store then wherever you want and use as needed.
To change the widget style to Breeze or Kavntum, use it like below.
plasma-theme -w kvantum
Then use the Kvantum Manager to configure the themes.
This application specially useful while running a minimal LXQt desktop, and you don't want to install whole lot of KDE libraries and utilities.