canvas—基础篇

1，首先要画图，要先在页面上创建一个画布

  <canvas id="myCanvas"></canvas>

2，在js中获取到这个画布

  var canvas = document.getElementById("canvas");

3,內建html5对象

var context=canvas.getContext("2d");

4，设置颜色，可以参考手册,画出想要的，

 conrext.fillStyle = "red";

 例如：

var canvas = document.getElementById('canvas');
var context = canvas.getContext("2d");
canvas.weight = 1000;
canvas.height = 1000;
context.fillStyle = "#eeeeff";
context.fillRect(0,0,1000,1000);
for(var i=0;i<30;i++){
    context.beginPath();
    context.arc(i*35,i*35,i*10,0,Math.PI * 2,true);
    context.closePath();
    context.fillStyle = "rgba(255, 0, 0, 0.25)";
    context.fill();
}