Javascript JS热图画布下载(尽管热图正在显示,但画布是空的)
我想下载使用我自己点的设置数据创建的JS热图。热图正在显示,但当我下载画布时,得到的是一张空图片Javascript JS热图画布下载(尽管热图正在显示,但画布是空的),javascript,html,canvas,heatmap,Javascript,Html,Canvas,Heatmap,我想下载使用我自己点的设置数据创建的JS热图。热图正在显示,但当我下载画布时,得到的是一张空图片 <!doctype html> <html> <head> <meta charset="utf-8"> <title>Heatmap Test Code</title> <script src='http://www.patrick- wied.at/static/heatmapjs/assets/js/heatmap
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Heatmap Test Code</title>
<script src='http://www.patrick-
wied.at/static/heatmapjs/assets/js/heatmap.min.js'></script>
</head>
<body>
<div id="heatMap" style="height:740px">
<canvas id="myCanvas" width="1024" height="540"
style="position:absolute; left: 0; top: 0"></canvas>
</div>
<a id="download" download="triangle.jpeg"><button type="button"
onClick="download()">Download</button></a>
<img id="myImage">
</body>
<script>
var heatmapInstance = h337.create({
container: document.getElementById('heatMap')
});
var testData = {
min: 0,
max: 100,
data: [{x: 807, y: 583, value: 500},{x: 770, y: 583, value: 500},{x:
750, y: 583, value: 500},{x: 750, y: 583, value: 500},{x: 200, y: 583,
value: 500},{x: 750, y: 583, value: 500}, {x: 597, y: 285, value: 51}, {x:
217, y: 449, value: 73}, {x: 377, y: 656, value: 58}, {x: 467, y: 509,
value: 47}, {x: 487, y: 164, value: 46}, {x: 247, y: 194, value: 35}]
};
heatmapInstance.setData(testData);
function download(){
var download = document.getElementById("download");
var image =
document.getElementById("myCanvas").toDataURL("image/png")
.replace("image/png", "image/octet-stream");
download.setAttribute("href", image);
}
</script>
</html>
热图测试代码
下载
var heatmapInstance=h337.create({
容器:document.getElementById('heatMap')
});
var testData={
分:0,,
最高:100,
数据:[{x:807,y:583,值:500},{x:770,y:583,值:500},{x:
750,y:583,value:500},{x:750,y:583,value:500},{x:200,y:583,
值:500},{x:750,y:583,值:500},{x:597,y:285,值:51},{x:
217,y:449,value:73},{x:377,y:656,value:58},{x:467,y:509,
数值:47},{x:487,y:164,数值:46},{x:247,y:194,数值:35}]
};
heatmaInstance.setData(testData);
函数下载(){
var download=document.getElementById(“下载”);
变量图像=
document.getElementById(“myCanvas”).toDataURL(“image/png”)
.replace(“图像/png”、“图像/octet流”);
下载.setAttribute(“href”,图像);
}
当您关闭时,将Href设置为图像,然后触发下载:
link.href = document.getElementById("myCanvas").toDataURL();
link.download = 'image_name.png';
我明白了,H337没有使用你的画布。您正在提供容器,它正在该div中创建画布
var heatmapInstance = h337.create({
container: document.getElementById('heatMap')
});
如果您运行页面并检查热图,您将看到该分区中有两个画布元素。删除您的元素并按类选择热图:
这是我的完整调整(上面添加了offwhite备注)和工作代码,用于根据一组具有各自值的点绘制JS热图,如果有人需要工作代码,则将该热图作为PNG下载
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Heatmap Test Code</title>
<script src='http://www.patrick-
wied.at/static/heatmapjs/assets/js/heatmap.min.js'></script>
<script>
function load(){
renderCanvas();
// add listener to the download button
document.getElementById('download').addEventListener(
'click',
function() {download(this)},
false
);
}
// draw your heatmap here
function renderCanvas(){
var heatmapInstance = h337.create({
container: document.getElementById('heatMap')
});
var testData = {
min: 0,
max: 100,
data: [{x: 807, y: 583, value: 500},{x: 770, y: 583, value: 500},{x:
750, y: 583, value: 500},{x: 750, y: 583, value: 500},{x: 200, y: 583,
value: 500},{x: 750, y: 583, value: 500}, {x: 597, y: 285, value: 51}, {x:
217, y: 449, value: 73}, {x: 377, y: 656, value: 58}, {x: 467, y: 509,
value: 47}, {x: 487, y: 164, value: 46}, {x: 247, y: 194, value: 35}]
};
heatmapInstance.setData(testData);
}
function download(link){
link.href =
(document.getElementById("heatMap").childNodes[1]).toDataURL();
// console.log(document.getElementById("heatMap").childNodes[1]);
link.download = 'image_name.png';
}
</script>
</head>
<body onload="load()">
<div id="heatMap" style="height:740px" >
</div>
<a id="download" href="#">Download as image</a>
</body>
</html>
热图测试代码
函数加载(){
renderCanvas();
//将侦听器添加到下载按钮
document.getElementById('download').addEventListener(
“点击”,
函数(){download(this)},
假的
);
}
//在这里画你的热图
函数renderCanvas(){
var heatmapInstance=h337.create({
容器:document.getElementById('heatMap')
});
var testData={
分:0,,
最高:100,
数据:[{x:807,y:583,值:500},{x:770,y:583,值:500},{x:
750,y:583,value:500},{x:750,y:583,value:500},{x:200,y:583,
值:500},{x:750,y:583,值:500},{x:597,y:285,值:51},{x:
217,y:449,value:73},{x:377,y:656,value:58},{x:467,y:509,
数值:47},{x:487,y:164,数值:46},{x:247,y:194,数值:35}]
};
heatmaInstance.setData(testData);
}
功能下载(链接){
link.href=
(document.getElementById(“heatMap”).childNodes[1]).toDataURL();
//log(document.getElementById(“heatMap”).childNodes[1]);
link.download='image_name.png';
}
感谢您提供了正确的下载方法。我用普通的简单画布进行了尝试,效果不错,但我的问题是它仍然下载空图片,我猜我的问题是在画布部分绘制的热图,我仍然想不出来。我希望能得到任何帮助。谢谢你,我刚刚意识到,在检查元素并提取画布的URI(URL)时,通过访问div的子级创建的地图成功了!