polygon.js—多边形52

//建立这样一个对象，每次绘制时可以加入到一个缓存中，以后可以实现拖动等操作
var Point = function (x, y) {
   this.x = x;
   this.y = y;
};

var Polygon = function (centerX, centerY, radius, sides, startAngle, strokeStyle, fillStyle, filled) {
   this.x = centerX;
   this.y = centerY;
   this.radius = radius;
   this.sides = sides;
   this.startAngle = startAngle;
   this.strokeStyle = strokeStyle;
   this.fillStyle = fillStyle;
   this.filled = filled;
};

Polygon.prototype = {
   getPoints: function () {//保存多边形的点的数组，根据多边形的边来绘制的，是一个规则的图形
      var points = [],
          angle = this.startAngle || 0;

      for (var i=0; i