double vw::animate(std::string_view id, double target, const vw::AnimationOptions& options = {});
std::optional<vw::Easing> vw::parse_easing(std::string_view name);
void vw::request_animation_continuation();
bool vw::animations_active();
void vw::begin_animation_frame();AnimationOptions
| Field | Default | Meaning |
|---|---|---|
duration |
0.28 | seconds; 0 jumps to the target |
initial |
target | starting value the first time id is seen |
easing |
out_cubic |
see below |
bezier |
{0.25, 0.1, 0.25, 1} |
control points for Easing::bezier |
mass, stiffness, damping |
1, 180, 18 | spring parameters |
min, max |
±∞ | clamp |
Easing
linear, in_out_cubic, out_cubic, out_quint, out_expo, out_back (overshoots), bezier (CSS-style cubic), spring (physical, keeps velocity when retargeted).
parse_easing accepts the same names as strings.
Frame semantics
vw::App calls begin_animation_frame() before each build and reads animations_active() after it: a build in which any tween is still moving (or that called request_animation_continuation()) asks for another frame. Tweens live for the program’s lifetime and are keyed only by id, so ids should be stable for one logical value and fresh for one-shot effects.