<Canvas> 使用canvas画图并充当背景图片，但出现奇怪效果_html/css_WEB-ITnose
这是初始的样子，我想要的效果是这颗心不随滚动条滚动
当我拖动滚动条的时候，这颗心跟着移动了，但原位置固定了另一颗心。
继续拖动滚动条，
由此可见，初始页面的心会随着滚动条移动，但同时有另一个心被固定在中间。
我只想要让这个心被固定在中心。不会因为滚动条的移动而出现另一颗心。
我通过JS建立canvas并将画设为背景图，JS代码如下：
var canvas = document.createElement('canvas');
var canvas_width = $("body").css("width").split("p")[0];
var canvas_height = $("body").css("height").split("p")[0];
document.body.appendChild(canvas);
canvas.id='homePageCanvas';
canvas.width = canvas_width;
canvas.height = canvas_height;
//canvas.style.backgroundColor = '#F9D1D4';
drawHeartCurve(); //画出了一个心
document.body.style.background = "url('"+homePageCanvas.toDataURL()+"')";
document.body.style['background-attachment']='fixed';
HTML/CSS只有一个很高的div让滚动条出现。
回复讨论(解决方案)
document.body.appendChild(canvas);这行删除
document.body.appendChild(canvas);这行删除
不行，这样子画出来的东西就没了。
建议加个alart调试看看， 会不会是代码重复执行了。
建议加个alart调试看看， 会不会是代码重复执行了。
我在画心的函数里加了alert（1），只弹出一次1....
你引用元素时不要用id “homePageCanvas”，直接用 var canvas = document.createElement('canvas');这行定义的 canvas变量就可以了
<!doctype html><html lang="en"><head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" /> <title> 页面名称 </title><style type="text/css">html,body { height: 100%;}</style></head><body><div id="a" style="width:100px;height:3000px;background:yellow;position:absolute;"></div><script type="text/javascript"> var canvas = document.createElement('canvas'); var canvas_width = document.body.offsetWidth; var canvas_height = document.body.offsetHeight; canvas.id='homePageCanvas'; canvas.width = canvas_width; canvas.height = canvas_height; var context = canvas.getContext("2d"); context.arc(400,400,100,0,2*Math.PI,true); context.fill(); document.body.style.background = "url('"+canvas.toDataURL()+"')"; document.body.style['background-attachment']='fixed';</script></body></html> 已解决。
要增添下列语句：
canvas.style.display="none";
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