paper.js/src/color/GradientColor.js

/*
 * Paper.js
 *
 * This file is part of Paper.js, a JavaScript Vector Graphics Library,
 * based on Scriptographer.org and designed to be largely API compatible.
 * http://paperjs.org/
 * http://scriptographer.org/
 *
 * Distributed under the MIT license. See LICENSE file for details.
 *
 * Copyright (c) 2011, Juerg Lehni & Jonathan Puckey
 * http://lehni.org/ & http://jonathanpuckey.com/
 *
 * All rights reserved.
 */

var GradientColor = this.GradientColor = Color.extend({
	beans: true,

	initialize: function(gradient, origin, destination, hilite) {
		this.gradient = gradient || new Gradient();
		this.setOrigin(origin);
		this.setDestination(destination);
		if (hilite)
			this.setHilite(hilite);
	},

	getOrigin: function() {
		return this._origin;
	},

	setOrigin: function(origin) {
		origin = Point.read(arguments);
		this._origin = origin;
		if (this._destination)
			this._radius = this._destination.getDistance(this._origin);
		return this;
	},

	getDestination: function() {
		return this._destination;
	},

	setDestination: function(destination) {
		destination = Point.read(arguments);
		this._destination = destination;
		this._radius = this._destination.getDistance(this._origin);
		return this;
	},

	getHilite: function() {
		return this._hilite;
	},

	setHilite: function(hilite) {
		hilite = Point.read(arguments);
		var vector = hilite.subtract(this._origin);
		if (vector.getLength() > this._radius) {
			this._hilite = this._origin.add(vector.normalize(
					this._radius - 0.1));
		} else {
			this._hilite = hilite;
		}
		return this;
	},

	getCanvasStyle: function(ctx) {
		var gradient;
		if (this.gradient.type === 'linear') {
			gradient = ctx.createLinearGradient(this._origin.x, this._origin.y,
				this.destination.x, this.destination.y);
		} else {
			var origin = this._hilite || this._origin;
			gradient = ctx.createRadialGradient(origin.x, origin.y,
				0, this._origin.x, this._origin.y, this._radius);
		}
		for (var i = 0, l = this.gradient._stops.length; i < l; i++) {
			var stop = this.gradient._stops[i];
			gradient.addColorStop(stop._rampPoint, stop.color.toCssString());
		}
		return gradient;
	}
});