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/*
oktransition.add({
obj: el.style,
units: "px",
from: { left: 0 },
to: { left: 100 },
duration: 1000,
easing: oktransition.easing.circ_out,
update: function(obj){
console.log(obj.left)
}
finished: function(){
console.log("done")
}
})
*/
const oktransition = {};
let transitions = [];
let last_t = 0;
let id = 0;
const lerp = (n, a, b) => (b - a) * n + a;
oktransition.speed = 1;
oktransition.add = (transition) => {
transition.id = id++;
transition.obj = transition.obj || {};
if (transition.easing) {
if (typeof transition.easing === "string") {
transition.easing = oktransition.easing[transition.easing];
}
} else {
transition.easing = oktransition.easing.linear;
}
if (!("from" in transition) && !("to" in transition)) {
transition.keys = [];
} else if (!("from" in transition)) {
transition.from = {};
transition.keys = Object.keys(transition.to);
transition.keys.forEach(function (prop) {
transition.from[prop] = parseFloat(transition.obj[prop]);
});
} else {
transition.keys = Object.keys(transition.from);
}
transition.delay = transition.delay || 0;
transition.start = last_t + transition.delay;
transition.done = false;
transition.after = transition.after || [];
transition.then = (fn) => {
transition.after.push(fn);
return transition;
};
transition.tick = 0;
transition.skip = transition.skip || 1;
transition.dt = 0;
transition.cancel = () =>
(transitions = transitions.filter((item) => item !== transition));
transitions.push(transition);
return transition;
};
oktransition.update = (t) => {
let done = false;
requestAnimationFrame(oktransition.update);
last_t = t * oktransition.speed;
if (transitions.length === 0) return;
transitions.forEach((transition, i) => {
const dt = Math.min(1.0, (t - transition.start) / transition.duration);
transition.tick++;
if (
dt < 0 ||
(dt < 1 && transition.tick % transition.skip != 0) ||
transition.done
)
return;
const ddt = transition.easing(dt);
transition.dt = ddt;
transition.keys.forEach((prop) => {
let val = lerp(ddt, transition.from[prop], transition.to[prop]);
if (transition.round) val = Math.round(val);
if (transition.units) val = Math.round(val) + transition.units;
transition.obj[prop] = val;
});
if (transition.update) {
transition.update(transition.obj, dt);
}
if (dt === 1) {
if (transition.finished) {
transition.finished(transition);
}
if (transition.after.length) {
const twn = transition.after.shift();
twn.obj = twn.obj || transition.obj;
twn.after = transition.after;
oktransition.add(twn);
}
if (transition.loop) {
transition.start = t + transition.delay;
} else {
done = true;
transition.done = true;
}
}
});
if (done) {
transitions = transitions.filter((transition) => !transition.done);
}
};
requestAnimationFrame(oktransition.update);
oktransition.easing = {
linear: (t) => {
return t;
},
circ_out: (t) => {
return Math.sqrt(1 - (t = t - 1) * t);
},
circ_in: (t) => {
return -(Math.sqrt(1 - t * t) - 1);
},
circ_in_out: (t) => {
return (t *= 2) < 1
? -0.5 * (Math.sqrt(1 - t * t) - 1)
: 0.5 * (Math.sqrt(1 - (t -= 2) * t) + 1);
},
quad_in: (n) => {
return Math.pow(n, 2);
},
quad_out: (n) => {
return n * (n - 2) * -1;
},
quad_in_out: (n) => {
n = n * 2;
if (n < 1) {
return Math.pow(n, 2) / 2;
}
return (-1 * (--n * (n - 2) - 1)) / 2;
},
cubic_bezier: (mX1, mY1, mX2, mY2) => {
function A(aA1, aA2) {
return 1.0 - 3.0 * aA2 + 3.0 * aA1;
}
function B(aA1, aA2) {
return 3.0 * aA2 - 6.0 * aA1;
}
function C(aA1) {
return 3.0 * aA1;
}
// Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
function CalcBezier(aT, aA1, aA2) {
return ((A(aA1, aA2) * aT + B(aA1, aA2)) * aT + C(aA1)) * aT;
}
// Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
function GetSlope(aT, aA1, aA2) {
return 3.0 * A(aA1, aA2) * aT * aT + 2.0 * B(aA1, aA2) * aT + C(aA1);
}
function GetTForX(aX) {
// Newton raphson iteration
let aGuessT = aX;
for (let i = 0; i < 10; ++i) {
const currentSlope = GetSlope(aGuessT, mX1, mX2);
if (currentSlope == 0.0) return aGuessT;
const currentX = CalcBezier(aGuessT, mX1, mX2) - aX;
aGuessT -= currentX / currentSlope;
}
return aGuessT;
}
return function (aX) {
if (mX1 == mY1 && mX2 == mY2) return aX; // linear
return CalcBezier(aX, mY1, mY2);
};
},
};
export default oktransition;
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