Transitions

Mount animations built on gpui's animation API — the same with_animation mechanism Loader uses, but one-shot instead of repeating.

gpui has no transform/scale on elements, so motion is expressed through opacity and margin offsets. A true height-collapsing Collapse would need a measured content height; the one here fades.

#Transition

Plays a one-shot entrance animation around its child. Give it a stable id so the animation has identity.

Transition::new("hero")
    .kind(TransitionKind::SlideUp)
    .duration_ms(220)
    .child(Card::new().child(content))

Methods: new(id), kind(TransitionKind) (default Fade), duration_ms(u64) (default 200), child(impl IntoElement).

TransitionKind is Fade | SlideUp | SlideDown | SlideLeft | SlideRight.

#Collapse

Reveals its child with a fade when open, renders nothing when closed. Useful for accordions, inline detail panels, and expanding sections.

Collapse::new("details")
    .open(self.expanded)
    .child(Text::new("Hidden detail").dimmed())

Methods: new(id), open(bool), duration_ms(u64) (default 180), child(impl IntoElement).