html5 canvas 像素随机百分之十显示

时间：2024-12-19 20:36:20
<!doctype html>

<html>

<head>

<meta charset="utf-8">

<title>无标题文档</title>

<script>

window.onload = function ()

{

    var oc = document.getElementById('c1');

    var ogc = oc.getContext('2d');

    var ali = document.getElementsByTagName('li');

    for(var i = 0; i < ali.length; i++)

    {

        ali[i].onclick = function ()

        {

            var str = this.innerHTML;

            var h = 180;

            ogc.clearRect(0,0,oc.width,oc.height);

            ogc.font = h + 'px impact';

            ogc.fillStyle = 'red';

            ogc.textBaseline = 'top';

            var w = ogc.measureText(str).width;

            ogc.fillText(str,(oc.width - w)/2,(oc.height - h)/2);

            var oimg = ogc.getImageData((oc.width - w)/2,(oc.height - h)/2,w,h);

            ogc.clearRect(0,0,oc.width,oc.height);

            var arr = randnum(w*h,w*h/10);

            var newimg = ogc.createImageData(w,h)

            for(var i = 0; i <arr.length; i++)

            {

                newimg.data[arr[i]*4] = oimg.data[arr[i]*4];

                newimg.data[arr[i]*4 + 1] = oimg.data[arr[i]*4 + 1];

                newimg.data[arr[i]*4 + 2 ] = oimg.data[arr[i]*4 + 2];

                newimg.data[arr[i]*4 + 3] = oimg.data[arr[i]*4 + 3];

            }

            ogc.putImageData(newimg,(oc.width - w)/2,(oc.height - h)/2);

        }

    }

    function randnum( iall,inow)

    {

        var arr = [];

        var newarr = [];

        for(var i = 0; i < iall; i++)

        {

            arr.push(i);

        }

        for(var i = 0; i< inow; i++)

        {

            newarr.push(arr.splice(Math.floor(Math.random()*arr.length),1));

        }

        return newarr

    }

}

</script>

<style>

body{

    background:pink;

    }

#c1{

    background:white;

    }

</style>

</head>

<body>

<canvas id="c1" width="400" height="400"></canvas>

<ul style="float:left;font-size:30px;">

    <li>新</li>

    <li>年</li>

    <li>快</li>

    <li>乐</li>

</ul>

</body>

</html>

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