ctx=canvas.getContext("2d");
ctx.font="60px microsoft yahei";
ctx.fillStyle = "rgba(255,255,255,0.5)";
ctx.fillText("aaaaaa",300,220);
ctx=canvas.getContext("2d");
ctx.font="60px microsoft yahei";
ctx.fillStyle = "rgba(255,255,255,0.5)";
ctx.fillText("aaaaaa",300,220);
ctx.rotate()