NativeScript/packages/core/ui/styling/linear-gradient.ts

import { CoreTypes } from '../../core-types';
import { Color } from '../../color';
import { LinearGradient as CSSLinearGradient } from '../../css/parser';

export interface ColorStop {
	color: Color;
	offset?: CoreTypes.LengthPercentUnit;
}

export class LinearGradient {
	public angle: number;
	public colorStops: ColorStop[];

	public static parse(value: CSSLinearGradient): LinearGradient {
		const result = new LinearGradient();
		result.angle = value.angle;
		result.colorStops = value.colors.map((color) => {
			const offset = color.offset || null;
			let offsetUnit: CoreTypes.LengthPercentUnit;

			if (offset && offset.unit === '%') {
				offsetUnit = {
					unit: '%',
					value: offset.value,
				};
			}

			return {
				color: color.color,
				offset: offsetUnit,
			};
		});

		return result;
	}

	public static equals(first: LinearGradient, second: LinearGradient): boolean {
		if (!first && !second) {
			return true;
		} else if (!first || !second) {
			return false;
		}

		if (first.angle !== second.angle) {
			return false;
		}

		if (first.colorStops.length !== second.colorStops.length) {
			return false;
		}

		for (let i = 0; i < first.colorStops.length; i++) {
			const firstStop = first.colorStops[i];
			const secondStop = second.colorStops[i];
			if (firstStop.offset !== secondStop.offset) {
				return false;
			}
			if (!Color.equals(firstStop.color, secondStop.color)) {
				return false;
			}
		}

		return true;
	}
}