I am building something called the "HTML Quiz". It's completely ran on JavaScript and it's pretty cool.
At the end, a results box pops up that says "Your Results:" and it shows how much time they took, what percentage they got, and how many questions they got right out of 10. I would like to have a button that says "Capture results" and have it somehow take a screenshot or something of the div, and then just show the image captured on the page where they can right click and "Save image as."
I really would love to do this so they can share their results with others. I don't want them to "copy" the results because they can easily change that. If they change what it says in the image, oh well.
Does anyone know a way to do this or something similar?
211 Answers
No, I don't know of a way to 'screenshot' an element, but what you could do, is draw the quiz results into a canvas element, then use the HTMLCanvasElement object's toDataURL function to get a data: URI with the image's contents.
When the quiz is finished, do this:
var c = document.getElementById('the_canvas_element_id');
var t = c.getContext('2d');
/* then use the canvas 2D drawing functions to add text, etc. for the result */When the user clicks "Capture", do this:
window.open('', document.getElementById('the_canvas_element_id').toDataURL());This will open a new tab or window with the 'screenshot', allowing the user to save it. There is no way to invoke a 'save as' dialog of sorts, so this is the best you can do in my opinion.
10This is an expansion of @Dathan's answer, using html2canvas and FileSaver.js.
$(function() { $("#btnSave").click(function() { html2canvas($("#widget"), { onrendered: function(canvas) { theCanvas = canvas; canvas.toBlob(function(blob) { saveAs(blob, "Dashboard.png"); }); } }); });
});This code block waits for the button with the id btnSave to be clicked. When it is, it converts the widget div to a canvas element and then uses the saveAs() FileSaver interface (via FileSaver.js in browsers that don't support it natively) to save the div as an image named "Dashboard.png".
An example of this working is available at this fiddle.
11After hours of research, I finally found a solution to take a screenshot of an element, even if the origin-clean FLAG is set (to prevent XSS), that´s why you can even capture for example Google Maps (in my case). I wrote a universal function to get a screenshot. The only thing you need in addition is the html2canvas library ().
Example:
getScreenshotOfElement($("div#toBeCaptured").get(0), 0, 0, 100, 100, function(data) { // in the data variable there is the base64 image // exmaple for displaying the image in an <img> $("img#captured").attr("src", "data:image/png;base64,"+data);
});Keep in mind console.log() and alert() won´t generate output if the size of the image is great.
Function:
function getScreenshotOfElement(element, posX, posY, width, height, callback) { html2canvas(element, { onrendered: function (canvas) { var context = canvas.getContext('2d'); var imageData = context.getImageData(posX, posY, width, height).data; var outputCanvas = document.createElement('canvas'); var outputContext = outputCanvas.getContext('2d'); outputCanvas.width = width; outputCanvas.height = height; var idata = outputContext.createImageData(width, height); idata.data.set(imageData); outputContext.putImageData(idata, 0, 0); callback(outputCanvas.toDataURL().replace("data:image/png;base64,", "")); }, width: width, height: height, useCORS: true, taintTest: false, allowTaint: false });
}If you wish to have "Save as" dialog, just pass image into php script, which adds appropriate headers
Example "all-in-one" script script.php
<?php if(isset($_GET['image'])): $image = $_GET['image']; if(preg_match('#^data:image/(.*);base64,(.*)$#s', $image, $match)){ $base64 = $match[2]; $imageBody = base64_decode($base64); $imageFormat = $match[1]; header('Content-type: application/octet-stream'); header("Pragma: public"); header("Expires: 0"); header("Cache-Control: must-revalidate, post-check=0, pre-check=0"); header("Cache-Control: private", false); // required for certain browsers header("Content-Disposition: attachment; filename=\"file.".$imageFormat."\";" ); //png is default for toDataURL header("Content-Transfer-Encoding: binary"); header("Content-Length: ".strlen($imageBody)); echo $imageBody; } exit();
endif;?>
<script type='text/javascript' src='
<canvas width="300" height="150"></canvas>
<button>Save</button>
<script> $(document).ready(function(){ var canvas = document.getElementById('canvas'); var oCtx = canvas.getContext("2d"); oCtx.beginPath(); oCtx.moveTo(0,0); oCtx.lineTo(300,150); oCtx.stroke(); $('#btn').on('click', function(){ // opens dialog but location doesnt change due to SaveAs Dialog document.location.href = '/script.php?image=' + canvas.toDataURL(); }); });
</script>Add this Script in your index.html
<script src=""></script>Use this function to get screenshot of div tag
getScreenShot(){ let c = this.elem.nativeElement.querySelector('.chartContainer'); // or document.getElementById('canvas'); html2canvas(c).then((canvas:any)=>{ var t = canvas.toDataURL().replace("data:image/png;base64,", ""); this.downloadBase64File('image/png',t,'image'); }) }
downloadBase64File(contentType:any, base64Data:any, fileName:any) { const linkSource = `data:${contentType};base64,${base64Data}`; const downloadLink = document.createElement("a"); downloadLink.href = linkSource; downloadLink.download = fileName; downloadLink.click();
}You can't take a screen-shot: it would be an irresponsible security risk to let you do so. However, you can:
- Do things server-side and generate an image
- Draw something similar to a Canvas and render that to an image (in a browser that supports it)
- Use some other drawing library to draw directly to the image (slow, but would work on any browser)
var shot1=imagify($('#widget')[0], (base64) => { $('img.screenshot').attr('src', base64);
});Take a look at htmlshot package , then, check deeply the client side section:
npm install htmlshot<script src="/assets/backend/js/html2canvas.min.js"></script>
<script> $("#download").on('click', function(){ html2canvas($("#printform"), { onrendered: function (canvas) { var url = canvas.toDataURL(); var triggerDownload = $("<a>").attr("href", url).attr("download", getNowFormatDate()+"电子签名详细信息.jpeg").appendTo("body"); triggerDownload[0].click(); triggerDownload.remove(); } }); })
</script>It's to simple you can use this code for capture the screenshot of particular area you have to define the div id in html2canvas. I'm using here 2 div-:
div
div id ="chartContainer"
if you want to capture only cars then use car i'm capture here car only you can change chartContainer for capture the graphhtml2canvas($('#car')copy and paste this code
<html> <head>
<script src=""></script>
<script src=""></script>
<script src=""></script>
<script src="" integrity="sha256-ZosEbRLbNQzLpnKIkEdrPv7lOy9C27hHQ+Xp8a4MxAQ=" crossorigin="anonymous"></script>
<script src=""></script>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="">
<link rel="stylesheet" href="" integrity="sha384-hWVjflwFxL6sNzntih27bfxkr27PmbbK/iSvJ+a4+0owXq79v+lsFkW54bOGbiDQ" crossorigin="anonymous">
<script> window.onload = function () { var chart = new CanvasJS.Chart("chartContainer", { animationEnabled: true, theme: "light2", title:{ text: "Simple Line Chart" }, axisY:{ includeZero: false }, data: [{ type: "line", dataPoints: [ { y: 450 }, { y: 414}, { y: 520, indexLabel: "highest",markerColor: "red", markerType: "triangle" }, { y: 460 }, { y: 450 }, { y: 500 }, { y: 480 }, { y: 480 }, { y: 410 , indexLabel: "lowest",markerColor: "DarkSlateGrey", markerType: "cross" }, { y: 500 }, { y: 480 }, { y: 510 } ] }] }); chart.render(); }
</script>
</head>
<body bgcolor="black">
<div>
<a href="javascript:genScreenshotgraph()"><button>Get Screenshot of Cars onl </button> </a>
<div align="center"> <i></i> <i></i> <i></i> <i></i> <i></i> <i></i> <i></i>
</div>
<br>
<div></div>
<script src=""></script>
<div>
</div>
</div>>
</body>
<script>
function genScreenshotgraph()
{ html2canvas($('#car'), { onrendered: function(canvas) { var imgData = canvas.toDataURL("image/jpeg"); var pdf = new jsPDF(); pdf.addImage(imgData, 'JPEG', 0, 0, -180, -180); pdf.save("download.pdf"); } });
}
</script>
</html>As far as I know you can't do that, I may be wrong. However I'd do this with php, generate a JPEG using php standard functions and then display the image, should not be a very hard job, however depends on how flashy the contents of the DIV are
2** This is an ~11 year old answer. Please ignore this answer and check other recent answers here ** As far as I know its not possible with javascript.
What you can do for every result create a screenshot, save it somewhere and point the user when clicked on save result. (I guess no of result is only 10 so not a big deal to create 10 jpeg image of results)
1
