komorebi/docs/linux/usage/animation.md

Animation

komorebi can have a window slide to its new place when the layout changes, instead of jumping there. It does not animate anything itself: a KWin effect, Geometry Change, animates a window that a program or a script moves or resizes, and komorebi tells it how long the animation lasts and how it eases. Animation is off by default.

Installing the effect

The effect is not part of KWin, and KWin finds effects when it starts: log out and in again after installing it. On NixOS the flake's module installs it with komorebi, which is what services.komorebi.effects.animation.enable does (it is on by default); the effect is built so that KWin does not load it until komorebi asks. installation.md has the module's options.

komorebi loads the effect when animation is turned on, and unloads it when it is turned off or komorebi exits. A machine that does not have the effect has no animation: komorebi says so once in its log, and windows jump to their places.

Turning it on, and how long it lasts

komorebic animation turns animation on or off, and komorebic animation-duration sets how long it lasts, in milliseconds: 250 by default.

komorebic animation enable
komorebic animation-duration 400
komorebic animation disable

Both take --animation-type movement to set the animation of windows going to their places apart from the global setting, which is how the settings of one kind of animation win over the global ones. Movement is the only kind there is. A global setting takes the settings of the kinds away.

komorebic animation enable --animation-type movement
komorebic animation-duration 600 --animation-type movement

komorebic animation-fps is accepted and does nothing: KWin animates at the refresh rate of the screen.

Easing

komorebic animation-style sets the curve a window follows to its place: linear by default, or one of the easings by name (ease-out-expo, ease-in-out-sine, ease-out-bounce, ...; komorebic animation-style --help lists them). They are Qt's easing curves, and a style is Qt's name for the curve with the "Ease" taken off (EaseInOutSine is InOutSine). Like the others, it takes --animation-type movement.

komorebic animation-style --style ease-out-expo
komorebic animation-style --style ease-in-out-sine --animation-type movement

The stock Geometry Change always eases out exponentially. The build the flake installs also reads the curve, which is what lets a style other than that one take effect; with the stock effect every style looks like an ease out. A cubic Bézier, which only a configuration can name, is not one of Qt's curves and is drawn as an ease out too.

In komorebi.json

The animation key of komorebi.json has the same settings: enabled, duration and style, each either one value for every kind of animation or a value for each kind ({ "movement": true }), and fps.

{
  "animation": {
    "enabled": true,
    "duration": 400,
    "style": "EaseOutExpo"
  }
}

The file sets them when the daemon starts and when the file changes. A file without the key leaves the settings as they are, and one with it that leaves out duration or style leaves that one as it is.

What is animated

What is painted moves; the window does not. The frame KWin reports for a window, and so the frame komorebi reads back, is the final one from the start of the animation, so komorebi never waits for an animation to end. The window is not cross-faded as it changes size: it is a move and a resize, not a change of what the window shows. An interactive move or resize by the user is not animated. While the effect is loaded, windows that other programs move are animated too.

What is put back

The effect keeps its settings in the user's kwinrc, in the group [Effect-kwin4_effect_geometry_change]. komorebi writes them when it asks for the animation, and when it exits or animation is turned off it puts back what the user had there.