docs: function(ctx, x, y, width, height, radius) {
  		if (radius) {
  			var r = Math.min(radius, height / 2, width / 2);
  			var left = x + r;
  			var top = y + r;
  			var right = x + width - r;
  			var bottom = y + height - r;
  
  			ctx.moveTo(x, top);
  			if (left < right && top < bottom) {
  				ctx.arc(left, top, r, -PI, -HALF_PI);
  				ctx.arc(right, top, r, -HALF_PI, 0);
  				ctx.arc(right, bottom, r, 0, HALF_PI);
  				ctx.arc(left, bottom, r, HALF_PI, PI);
  			} else if (left < right) {
  				ctx.moveTo(left, y);
  				ctx.arc(right, top, r, -HALF_PI, HALF_PI);
  				ctx.arc(left, top, r, HALF_PI, PI + HALF_PI);
  			} else if (top < bottom) {
  				ctx.arc(left, top, r, -PI, 0);
  				ctx.arc(left, bottom, r, 0, PI);
  			} else {
  				ctx.arc(left, top, r, -PI, PI);
  			}
  			ctx.closePath();
  			ctx.moveTo(x, y);
  		} else {
  			ctx.rect(x, y, width, height);
  		}
  	}