oCanvas changes the way you work with the canvas element. With the native canvas API you are drawing pixels onto the canvas. But when building something, you tend to think more in terms of objects than actual pixels. This is what oCanvas is made to do — create a bridge between the native API and the way you want to work. If you would want to access the native API, that is also possible.
http://ocanvas.org/docs
例子代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>oCanvas Demo</title>
<script src="ocanvas-2.7.4.min.js"></script>
<style type="text/css">
</style>
</head>
<body>
<canvas id="c1" width="1000" height="600"></canvas>
<script type="text/javascript">
// 创建一个Canvas画布对象
var canvas = oCanvas.create({
canvas:"#c1",
background:'#000000'
});
// Center planet
var center = canvas.display.ellipse({
x:canvas.width/2,
y:canvas.height/2,
radius:canvas.width/20,
fill:'#fff'
}).add();
// Prototype objects that will be used to instantiate the others
var satelliteProto = canvas.display.ellipse({
fill:'#eee'
});
var pathProto = canvas.display.ellipse({
stroke:'1px #999'
});
// Set up data
var satellites=[];depth=3;
var satelliteColors=["#FF0000","#00BC22","#00659D"];
var pathColors=["#6C6868","#EF1919","#20208F"];
// Create seven satellites and paths. Definition is further down.
for (var i = 0,l=7; i <l; i++) {
createSatellite({
parent:center,
depth:1,
distance:(i+1)*canvas.width/6,
radius:canvas.width/100,
speed:1
})
};
// Set up a tick function that will move all satellites each time
canvas.setLoop(function () {
for (var i = 0; i < satellites.length; i++) {
satellites[i].rotation+=satellites[i].speed;
};
});
// Definition for a satellite and its corresponding path
function createSatellite (options) {
// Create the path that the satellite will follow
var path = pathProto.clone({
radius: options.distance,
x: options.x || 0, y: options.y || 0,
strokeColor: pathColors[options.depth - 1]
});
options.parent.addChild(path);
// Create a new satellite
var satellite = satelliteProto.clone({
origin: {
x: 0,
y: options.distance * (Math.round(Math.random()) ? 1 : -1)
},
speed: Math.random() * (2 * Math.random() - 0.5) + 0.5,
radius: options.radius,
x: options.x || 0, y: options.y || 0,
fill: satelliteColors[options.depth - 1],
rotation: Math.random() * 360
});
options.parent.addChild(satellite);
satellites.push(satellite);
// Create another satellite that will circle around this satellite
if (options.depth < depth) {
createSatellite({
parent: satellite, depth: options.depth + 1,
distance: options.radius * 7,
radius: options.radius / 1.5,
x: satellite.origin.x * -1, y: satellite.origin.y * -1,
speed: 10
});
}
}
canvas.timeline.start();
</script>
</body>
</html>
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