我目前想在 HTML5 中使用 Canvas。我是画布的新手，想开始研究它。我正在使用easeljs 来实现画布。但是任何人都可以指定任何特定的 .js 文件来实现 Canvas。当我使用这个 .js 时，我收到错误：“ 0x800a1391 - Microsoft JScript 运行时错误：'Stage' 未定义如果有此异常的处理程序，程序可以安全地继续。 ”这是我的一段代码，我们得到上述指定的错误。我只从互联网上复制了这段代码：
<script>
//EaselJS Stage instance that wraps the Canvas element
var stage;
//EaselJS Shape instance that we will animate
var circle;
//radius of the circle Graphics that we will draw.
var CIRCLE_RADIUS = 10;
//x position that we will reset Shape to when it goes off
//screen
var circleXReset;
//EaselJS Rectangle instance we will use to store the bounds
//of the Canvas
var bounds;
//initialize function, called when page loads.
function init() {
//check and see if the canvas element is supported in
//the current browser
////http://diveintohtml5.org/detect.html#canvas
if (!(!!document.createElement('canvas').getContext)) {
var wrapper = document.getElementById("canvasWrapper");
wrapper.innerHTML = "Your browser does not appear to support " +
"the HTML5 Canvas element";
return;
}
//get a reference to the canvas element
var canvas = document.getElementById("stageCanvas");
//copy the canvas bounds to the bounds instance.
//Note, if we resize the canvas, we need to reset
//these bounds.
//bounds = new Rectangle();
//bounds.width = canvas.width;
//bounds.height = canvas.height;
//pass the canvas element to the EaselJS Stage instance
//The Stage class abstracts away the Canvas element and
//is the root level display container for display elements.
stage = new Stage(canvas);
//Create an EaselJS Graphics element to create the
//commands to draw a circle
var g = new Graphics();
//stroke of 1 px
g.setStrokeStyle(1);
//Set the stroke color, using the EaselJS
//Graphics.getRGB static method.
//This creates a white color, with an alpha
//of .7
g.beginStroke(Graphics.getRGB(255, 255, 255, .7));
//draw the circle
g.drawCircle(0, 0, CIRCLE_RADIUS);
//note that the circle has not been drawn yet.
//the Graphics instance just has the commands to
//draw the circle.
//It will be drawn when the stage needs to render it
//which is usually when we call stage.tick()
//create a new Shape instance. This is a DisplayObject
//which can be added directly to the stage (and rendered).
//Pass in the Graphics instance that we created, and that
//we want the Shape to draw.
circle = new Shape(g);
//set the initial x position, and the reset position
circle.x = circleXReset = -CIRCLE_RADIUS;
//set the y position
circle.y = canvas.height / 2;
//add the circle to the stage.
stage.addChild(circle);
//tell the stage to render to the canvas
stage.update();
Ticker.setFPS(24);
//Subscribe to the Tick class. This will call the tick
//method at a set interval (similar to ENTER_FRAME with
//the Flash Player)
Ticker.addListener(this);
}
//function called by the Tick instance at a set interval
function tick() {
//check and see if the Shape has gone of the right
//of the stage.
if (circle.x > bounds.width) {
//if it has, reset it.
circle.x = circleXReset;
}
//move the circle over 10 pixels
circle.x += 8;
//re-render the stage
stage.update();
}
</script>