Draw Manually 手工绘制

With the draw() method, you can draw on the canvas using native canvas methods (or any method, for that matter). To do this, write your code inside a function
用draw()方法，你可以使用本地画布方法（或其它方法）来在画布上绘图。为了做到这点，要将你的代码写进一个函数当中。

$('canvas').draw({
  fn: function(ctx) {
    ctx.fillStyle = '#333';
    ctx.fillRect(50, 50, 100, 100);
  }
});

Draw Anything 画任意东西

The draw() method can be used to draw any other jCanvas drawing (although usually this is not necessary).
draw()方法可以用来绘制任何其它jCanvas的绘制过程（尽管通常情况下不必要这么做）。

$('canvas').draw({
  type: 'rectangle',
  fillStyle: '#c33',
  x: 100, y: 100,
  width: 100, height: 80
});

The above code is equivalent to the following:
上边的代码等效于下边的：

$('canvas').drawRect({
  fillStyle: '#c33',
  x: 100, y: 100,
  width: 100, height: 80
});

Notes 注意

The this keyword in the callback function refers to the canvas DOM element.
回调函数中的关键字this，指向的是画布的DOM元素。