利用画布，绘制随机大小，颜色，位置 方框
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>H5-canvas</title>
<style type="text/css">
canvas{background: #f1aaa3; margin: 80px auto; display: block;}
</style>
</head>
<body >
<canvas id="canvas" width="900px" height="468px">
</canvas>
</body>
<script type="text/javascript">
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var width = canvas.width;
var height = canvas.height;
// context.fillStyle = "#008ce1"; //填充色
// context.strokeStyle = "#515151"; //描边色
// context.globalAlpha = 0.5; // 透明度
// context.fillRect(10,20,100,100); //x,y,w,h 方形
// context.strokeRect(10,150,88,88); //描边
// context.clearRect(20,30,50,50); //橡皮擦
//随机颜色函数
function randomColor(){
var r = Math.floor(Math.random()*256);
var g = Math.floor(Math.random()*256);
var b = Math.floor(Math.random()*256);
var color = 'rgb('+r+','+g+','+b+')';
console.log(color);
return color;
}
//canvas内随机位置大小方框函数
function randomSize(){
var x = Math.random()*width;
var y = Math.random()*height;
var w = Math.random()*(width-x);
var h = Math.random()*(height-y);
var data = [x,y,w,h];
console.log(data);
return data;
}
//canvas内随机位置出现随机大小颜色方框
function randomRect(){
context.strokeStyle = randomColor();
var data = randomSize();
context.strokeRect(data[0],data[1],data[2],data[3]);
//递归每隔0.5秒执行一次当前函数
setTimeout(randomRect,500);
}
randomRect();
</script>
</html>
