Optimize Output Of HTML2Canvas
I created a chart with amchart. I will later have to export it as PDF. As suggested here, I need to convert the chart first into SVG with html2canvas. It works, but the chart looks
Solution 1:
I have tried a lot of solution, but the most i have found is to use a script for convert SVG (Thanks @Kaiido) and use html2canvas plugin.
I generated your chart and onclick event i assign ID to the SVG tag created.
After click on the button the SVG transform this to Canvas. Now you can just make what you want with this.
Please try bellow in full screen mode for show your label totally
$(document).ready(function(){
var chart = AmCharts.makeChart("chartdiv1", {
"type": "serial",
"theme": "light",
"dataProvider": [{
"country": "USA",
"visits": 2025
}, {
"country": "China",
"visits": 1882
}, {
"country": "Japan",
"visits": 1809
}, {
"country": "Germany",
"visits": 1322
}, {
"country": "UK",
"visits": 1122
}, {
"country": "France",
"visits": 1114
}, {
"country": "India",
"visits": 984
}, {
"country": "Spain",
"visits": 711
}, {
"country": "Netherlands",
"visits": 665
}, {
"country": "Russia",
"visits": 580
}, {
"country": "South Korea",
"visits": 443
}, {
"country": "Canada",
"visits": 441
}, {
"country": "Brazil",
"visits": 395
}],
"valueAxes": [{
"gridColor": "#FFFFFF",
"gridAlpha": 0.2,
"dashLength": 0
}],
"gridAboveGraphs": true,
"startDuration": 1,
"graphs": [{
"balloonText": "[[category]]: <b>[[value]]</b>",
"fillAlphas": 0.8,
"lineAlpha": 0.2,
"type": "column",
"valueField": "visits"
}],
"chartCursor": {
"categoryBalloonEnabled": false,
"cursorAlpha": 0,
"zoomable": false
},
"categoryField": "country",
"categoryAxis": {
"gridPosition": "start",
"gridAlpha": 0,
"tickPosition": "start",
"tickLength": 20
},
"export": {
"enabled": true
}
});
$('#cmd').click(function() {
$("svg").attr("id","svg") //Assign ID to SCG tag
// without converting the svg to png
html2canvas(chartdiv1, { // chartdiv1 is your div
onrendered: function(can) {
//dirty.appendChild(can);
}
});
// first convert your svg to png
exportInlineSVG(svg, function(data, canvas) {
svg.parentNode.replaceChild(canvas, svg);
// then call html2canvas
html2canvas(chartdiv1, { // chartdiv1 is your div
onrendered: function(can) {
can.id = 'canvas';
// clean.appendChild(can);
}
});
})
function exportInlineSVG(svg, receiver, params, quality) {
if (!svg || !svg.nodeName || svg.nodeName !== 'svg') {
console.error('Wrong arguments : should be \n exportSVG(SVGElement, function([dataURL],[canvasElement]) || IMGElement || CanvasElement [, String_toDataURL_Params, Float_Params_quality])')
return;
}
var xlinkNS = "http://www.w3.org/1999/xlink";
var clone;
// This will convert an external image to a dataURL
var toDataURL = function(image) {
var img = new Image();
// CORS workaround, this won't work in IE<11
// If you are sure you don't need it, remove the next line and the double onerror handler
// First try with crossorigin set, it should fire an error if not needed
img.crossOrigin = 'Anonymous';
img.onload = function() {
// we should now be able to draw it without tainting the canvas
var canvas = document.createElement('canvas');
var bbox = image.getBBox();
canvas.width = bbox.width;
canvas.height = bbox.height;
// draw the loaded image
canvas.getContext('2d').drawImage(this, 0, 0, bbox.width, bbox.height);
// set our original <image>'s href attribute to the dataURL of our canvas
image.setAttributeNS(xlinkNS, 'href', canvas.toDataURL());
// that was the last one
if (++encoded === total) exportDoc()
}
// No CORS set in the response
img.onerror = function() {
// save the src
var oldSrc = this.src;
// there is an other problem
this.onerror = function() {
console.warn('failed to load an image at : ', this.src);
if (--total === encoded && encoded > 0) exportDoc();
}
// remove the crossorigin attribute
this.removeAttribute('crossorigin');
// retry
this.src = '';
this.src = oldSrc;
}
// load our external image into our img
img.src = image.getAttributeNS(xlinkNS, 'href');
}
// The final function that will export our svgNode to our receiver
var exportDoc = function() {
// check if our svgNode has width and height properties set to absolute values
// otherwise, canvas won't be able to draw it
var bbox = svg.getBBox();
// avoid modifying the original one
clone = svg.cloneNode(true);
if (svg.width.baseVal.unitType !== 1) clone.setAttribute('width', bbox.width);
if (svg.height.baseVal.unitType !== 1) clone.setAttribute('height', bbox.height);
parseStyles();
// serialize our node
var svgData = (new XMLSerializer()).serializeToString(clone);
// remember to encode special chars
var svgURL = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(svgData);
var svgImg = new Image();
svgImg.onload = function() {
// if we set a canvas as receiver, then use it
// otherwise create a new one
var canvas = (receiver && receiver.nodeName === 'CANVAS') ? receiver : document.createElement('canvas');
// IE11 doesn't set a width on svg images...
canvas.width = this.width || bbox.width;
canvas.height = this.height || bbox.height;
canvas.getContext('2d').drawImage(this, 0, 0, canvas.width, canvas.height);
// try to catch IE
try {
// if we set an <img> as receiver
if (receiver.nodeName === 'IMG') {
// make the img looks like the svg
receiver.setAttribute('style', getSVGStyles(receiver));
receiver.src = canvas.toDataURL(params, quality);
} else {
// make the canvas looks like the canvas
canvas.setAttribute('style', getSVGStyles(canvas));
// a container element
if (receiver.appendChild && receiver !== canvas)
receiver.appendChild(canvas);
// if we set a function
else if (typeof receiver === 'function')
receiver(canvas.toDataURL(params, quality), canvas);
}
} catch (ie) {
console.warn("Your ~browser~ has tainted the canvas.\n The canvas is returned");
if (receiver.nodeName === 'IMG') receiver.parentNode.replaceChild(canvas, receiver);
else receiver(null, canvas);
}
}
svgImg.onerror = function(e) {
if (svg._cleanedNS) {
console.error("Couldn't export svg, please check that the svgElement passed is a valid svg document.");
return;
}
// Some non-standard NameSpaces can cause this issues
// This will remove them all
function cleanNS(el) {
var attr = el.attributes;
for (var i = 0; i < attr.length; i++) {
if (attr[i].name.indexOf(':') > -1) el.removeAttribute(attr[i].name)
}
}
cleanNS(svg);
for (var i = 0; i < svg.children.length; i++)
cleanNS(svg.children[i]);
svg._cleanedNS = true;
// retry the export
exportDoc();
}
svgImg.src = svgURL;
}
// ToDo : find a way to get only usefull rules
var parseStyles = function() {
var styleS = [],i;
// transform the live StyleSheetList to an array to avoid endless loop
for (i = 0; i < document.styleSheets.length; i++)
styleS.push(document.styleSheets[i]);
// Do we have a `<defs>` element already ?
var defs = clone.querySelector('defs') || document.createElementNS('http://www.w3.org/2000/svg', 'defs');
if (!defs.parentNode)
clone.insertBefore(defs, clone.firstElementChild);
// iterate through all document's stylesheets
for (i = 0; i < styleS.length; i++) {
var style = document.createElement('style');
var rules = styleS[i].cssRules,
l = rules.length;
for (var j = 0; j < l; j++)
style.innerHTML += rules[j].cssText + '\n';
defs.appendChild(style);
}
// small hack to avoid border and margins being applied inside the <img>
var s = clone.style;
s.border = s.padding = s.margin = 0;
s.transform = 'initial';
}
var getSVGStyles = function(node) {
var dest = node.cloneNode(true);
svg.parentNode.insertBefore(dest, svg);
var dest_comp = getComputedStyle(dest);
var svg_comp = getComputedStyle(svg);
var mods = "";
for (var i = 0; i < svg_comp.length; i++) {
if (svg_comp[svg_comp[i]] !== dest_comp[svg_comp[i]])
mods += svg_comp[i] + ':' + svg_comp[svg_comp[i]] + ';';
}
svg.parentNode.removeChild(dest);
return mods;
}
var images = svg.querySelectorAll('image'),
total = images.length,
encoded = 0;
// Loop through all our <images> elements
for (var i = 0; i < images.length; i++) {
// check if the image is external
if (images[i].getAttributeNS(xlinkNS, 'href').indexOf('data:image') < 0)
toDataURL(images[i]);
// else increment our counter
else if (++encoded === total) exportDoc()
}
// if there were no <image> element
if (total === 0) exportDoc();
}
})
})#chartdiv1 {
width: 100%;
height: 500px;
}
.amcharts-export-menu {
display:none;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://www.amcharts.com/lib/3/amcharts.js"></script>
<script src="https://www.amcharts.com/lib/3/serial.js"></script>
<script src="https://www.amcharts.com/lib/3/themes/light.js"></script>
<script src="https://www.amcharts.com/lib/3/plugins/export/export.min.js"></script>
<script src="https://github.com/niklasvh/html2canvas/releases/download/0.5.0-alpha1/html2canvas.js"></script>
<button id="cmd">HTML2Canvas</button>
<div id="output">
<div id="chartdiv1">
</div>
</div>Solution 2:
On click of html2Canvas button add jQuery code to add height and width as attribute to your svg element (add as attribute and not in style) and it will export in exact format
Solution 3:
I have tried the same, and fix this by changing the SVG width and height. Here is the code used to fix the issue.
function printOptions(type = 'before') {
var svg = chart.div.querySelector('svg');
if (svg) {
if (type == 'after') { // remove the attributes after generating canvas
svg.removeAttribute('width');
svg.removeAttribute('height');
} else { // set width and height according to parent container
svg.setAttribute('width', chart.div.clientWidth);
svg.setAttribute('height', chart.div.clientHeight);
}
chart.validateNow(); // validating am chart again.
}
}
// code for download image
downloadImage() {
printOptions();
html2canvas(document.getElementById('chart-div')).then(canvas => {
printOptions('after');
let a = document.createElement('a');
a.href = canvas.toDataURL("image/png")
a.download = 'Report.png';
a.click();
});
}
Working Demo, you can comment printOption before converting the image for the exported image changes.
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