哪位大神告诉我一下，html5的变换矩阵为什么得出下面的结果？
context.setTransform(1, 0, 0, 1, 0, 0);

var xScale = Math.cos(Math.PI/4);

var ySkew = -Math.sin(Math.PI/4);

var xSkew = Math.sin(Math.PI/4);

var yScale = Math.cos(Math.PI/4);

var xTrans = 200;

var yTrans = 200;

context.transform(xScale, ySkew, xSkew, yScale, xTrans, yTrans);

context.fillRect(-50, -50, 100, 100)


[解决办法]
x’=x*cosθ-y*sinθ
y’=x*sinθ+y*cosθ
矩阵变换 由x,y绕转θ得到x'和y'
Math.PI/4即为45度角

//初始化为正立
context.setTransform(1, 0, 0, 1, 0, 0);

//下面四个参数说明旋转45度
 var xScale = Math.cos(Math.PI/4);

 var ySkew  = -Math.sin(Math.PI/4);

 var xSkew  = Math.sin(Math.PI/4);

 var yScale = Math.cos(Math.PI/4);

//绕行坐标点
 var xTrans = 200;

 var yTrans = 200;

//进行旋转
 context.transform(xScale, ySkew, xSkew, yScale, xTrans, yTrans);
//填充颜色 参数分别为 x坐标 y坐标 长 宽
 context.fillRect(-50, -50, 100, 100)