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// Copyright 2010 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Factories for common path types.
* @author nicksantos@google.com (Nick Santos)
*/
goog.provide('goog.graphics.paths');
goog.require('goog.graphics.Path');
goog.require('goog.math.Coordinate');
/**
* Defines a regular n-gon by specifing the center, a vertex, and the total
* number of vertices.
* @param {goog.math.Coordinate} center The center point.
* @param {goog.math.Coordinate} vertex The vertex, which implicitly defines
* a radius as well.
* @param {number} n The number of vertices.
* @return {!goog.graphics.Path} The path.
*/
goog.graphics.paths.createRegularNGon = function(center, vertex, n) {
var path = new goog.graphics.Path();
path.moveTo(vertex.x, vertex.y);
var startAngle = Math.atan2(vertex.y - center.y, vertex.x - center.x);
var radius = goog.math.Coordinate.distance(center, vertex);
for (var i = 1; i < n; i++) {
var angle = startAngle + 2 * Math.PI * (i / n);
path.lineTo(center.x + radius * Math.cos(angle),
center.y + radius * Math.sin(angle));
}
path.close();
return path;
};
/**
* Defines an arrow.
* @param {goog.math.Coordinate} a Point A.
* @param {goog.math.Coordinate} b Point B.
* @param {?number} aHead The size of the arrow head at point A.
* 0 omits the head.
* @param {?number} bHead The size of the arrow head at point B.
* 0 omits the head.
* @return {!goog.graphics.Path} The path.
*/
goog.graphics.paths.createArrow = function(a, b, aHead, bHead) {
var path = new goog.graphics.Path();
path.moveTo(a.x, a.y);
path.lineTo(b.x, b.y);
var angle = Math.atan2(b.y - a.y, b.x - a.x);
if (aHead) {
path.appendPath(
goog.graphics.paths.createRegularNGon(
new goog.math.Coordinate(
a.x + aHead * Math.cos(angle),
a.y + aHead * Math.sin(angle)),
a, 3));
}
if (bHead) {
path.appendPath(
goog.graphics.paths.createRegularNGon(
new goog.math.Coordinate(
b.x + bHead * Math.cos(angle + Math.PI),
b.y + bHead * Math.sin(angle + Math.PI)),
b, 3));
}
return path;
};
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