NativeScript/nativescript-core/ui/styling/converters.ts

import { AnimationCurve } from "../enums";

const STYLE_CURVE_MAP = Object.freeze({
	ease: AnimationCurve.ease,
	linear: AnimationCurve.linear,
	"ease-in": AnimationCurve.easeIn,
	"ease-out": AnimationCurve.easeOut,
	"ease-in-out": AnimationCurve.easeInOut,
	spring: AnimationCurve.spring,
});

export function timeConverter(value: string): number {
	let result = parseFloat(value);
	if (value.indexOf("ms") === -1) {
		result = result * 1000;
	}

	return Math.max(0.0, result);
}

export function animationTimingFunctionConverter(value: string): any {
	return value
		? STYLE_CURVE_MAP[value] || parseCubicBezierCurve(value)
		: AnimationCurve.ease;
}

function parseCubicBezierCurve(value: string) {
	const coordsString = /\((.*?)\)/.exec(value);
	const coords =
		coordsString && coordsString[1].split(",").map(stringToBezieCoords);

	if (
		value.startsWith("cubic-bezier") &&
		coordsString &&
		coords.length === 4
	) {
		const [x1, x2, y1, y2] = [...coords];

		return AnimationCurve.cubicBezier(x1, x2, y1, y2);
	} else {
		throw new Error(`Invalid value for animation: ${value}`);
	}
}

function stringToBezieCoords(value: string): number {
	let result = parseFloat(value);
	if (result < 0) {
		return 0;
	} else if (result > 1) {
		return 1;
	}

	return result;
}