多个图像未加载到画布上

我使用arc创建了Circle,如下所示.

var startAngle = 0;
var arc = Math.PI / 6;
var ctx;

var leftValue=275;
var topValue=300;	
	   
var wheelImg = ["http://i.stack.imgur.com/wwXlF.png","http://i.stack.imgur.com/wwXlF.png","cat.png","cock.png",
				"croco.png","dog.png","eagle.png","elephant.png","lion.png",
				"monkey.png","rabbit.png","sheep.png"];

function drawWheelImg()
{
	var canvas = document.getElementById("canvas");
  	if(canvas.getContext)
	{
		var outsideRadius = 260;
		var textRadius = 217;
		var insideRadius = 202;

		ctx = canvas.getContext("2d");	

		for(var i = 0; i < 12; i++)
		{
			var angle = startAngle + i * arc;

			ctx.beginPath();
			ctx.arc(leftValue, topValue, outsideRadius, angle, angle + arc, false);
			ctx.arc(leftValue, topValue, insideRadius, angle + arc, angle, true);
			ctx.fill();
			ctx.closePath();
			ctx.beginPath();
			ctx.arc(leftValue, topValue, outsideRadius, angle, angle + arc, false);
			ctx.shadowBlur=3;
			ctx.shadowColor="#A47C15";
			ctx.stroke();
			ctx.closePath();
			
			ctx.save();
			ctx.translate(leftValue + Math.cos(angle + arc / 2) * textRadius,
						topValue + Math.sin(angle + arc / 2) * textRadius);
			ctx.rotate(angle + arc / 2 + Math.PI / 2);
			var img = new Image();
			
			img.src = wheelImg[i];
			ctx.drawImage(img,-44, -25,50,40);
			ctx.restore();
		}
  	}
}	



function spin()
{
	drawWheelImg();
}

drawWheelImg();

Spin