AtlasSpringAnimation

The Atlas spring for spatial movement: standard (no overshoot, settles quickly) or expressive (a small overshoot, for the signature moments only; see AtlasStyle). Use it in a Behavior on x, y, width, height or scale, never on colour or opacity. Under reduced motion, turn the Behavior off so the value jumps, and fade with an opacity animation where a jump would look abrupt.

AtlasSpringAnimation is a Qt Quick SpringAnimation; its inherited properties work as usual.

Example

Rectangle {
    id: indicator
    Behavior on x {
        enabled: !AtlasStyle.reducedMotion
        AtlasSpringAnimation { expressive: true }
    }
}

Properties

Timing

Measured in Qt 6.11 for a 100 px move, within 1 px of the target:

The spring stops once it is within epsilon of the target, 0.25 by default, which suits pixels. For a value that moves less than about 2 units, set fine: true, or the spring ends in one frame:

Behavior on scale { AtlasSpringAnimation { expressive: true; fine: true } }

A fine spring keeps stepping a little longer (a 0.04 scale move: standard about 210 ms, expressive about 340 ms; a 100 px move about 510 ms and 1 s), and the extra frames are sub-pixel.

Qt steps the spring once per 16 ms frame. It is a damped oscillator of unit mass, so a shell can match it: