popmotion/lib/animations/inertia.js

The animator's toolbox

import { __assign } from "tslib";
import { animate } from ".";
import { velocityPerSecond } from "../utils/velocity-per-second";
import { getFrameData } from "framesync";
export function inertia(_a) {
    var _b = _a.from, from = _b === void 0 ? 0 : _b, _c = _a.velocity, velocity = _c === void 0 ? 0 : _c, min = _a.min, max = _a.max, _d = _a.power, power = _d === void 0 ? 0.8 : _d, _e = _a.timeConstant, timeConstant = _e === void 0 ? 750 : _e, _f = _a.bounceStiffness, bounceStiffness = _f === void 0 ? 500 : _f, _g = _a.bounceDamping, bounceDamping = _g === void 0 ? 10 : _g, _h = _a.restDelta, restDelta = _h === void 0 ? 1 : _h, modifyTarget = _a.modifyTarget, driver = _a.driver, onUpdate = _a.onUpdate, onComplete = _a.onComplete;
    var currentAnimation;
    function isOutOfBounds(v) {
        return (min !== undefined && v < min) || (max !== undefined && v > max);
    }
    function boundaryNearest(v) {
        if (min === undefined)
            return max;
        if (max === undefined)
            return min;
        return Math.abs(min - v) < Math.abs(max - v) ? min : max;
    }
    function startAnimation(options) {
        currentAnimation === null || currentAnimation === void 0 ? void 0 : currentAnimation.stop();
        currentAnimation = animate(__assign(__assign({}, options), { driver: driver, onUpdate: function (v) {
                var _a;
                onUpdate === null || onUpdate === void 0 ? void 0 : onUpdate(v);
                (_a = options.onUpdate) === null || _a === void 0 ? void 0 : _a.call(options, v);
            }, onComplete: onComplete }));
    }
    function startSpring(options) {
        startAnimation(__assign({ type: "spring", stiffness: bounceStiffness, damping: bounceDamping, restDelta: restDelta }, options));
    }
    if (isOutOfBounds(from)) {
        startSpring({ from: from, velocity: velocity, to: boundaryNearest(from) });
    }
    else {
        var target = power * velocity + from;
        if (typeof modifyTarget !== "undefined")
            target = modifyTarget(target);
        var boundary_1 = boundaryNearest(target);
        var heading_1 = boundary_1 === min ? -1 : 1;
        var prev_1;
        var current_1;
        var checkBoundary = function (v) {
            prev_1 = current_1;
            current_1 = v;
            velocity = velocityPerSecond(v - prev_1, getFrameData().delta);
            if ((heading_1 === 1 && v > boundary_1) ||
                (heading_1 === -1 && v < boundary_1)) {
                startSpring({ from: v, to: boundary_1, velocity: velocity });
            }
        };
        startAnimation({
            type: "decay",
            from: from,
            velocity: velocity,
            timeConstant: timeConstant,
            power: power,
            restDelta: restDelta,
            modifyTarget: modifyTarget,
            onUpdate: isOutOfBounds(target) ? checkBoundary : undefined,
        });
    }
    return {
        stop: function () { return currentAnimation === null || currentAnimation === void 0 ? void 0 : currentAnimation.stop(); },
    };
}
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