Exporting dc.js chart from SVG to PNG - svg

Question

I have a dc.js chart and I want to export it as a PNG image, using exupero's saveSvgAsPng:
function save() {
var options = {};
options.backgroundColor = '#ffffff';
options.selectorRemap = function(s) { return s.replace(/\.dc-chart/g, ''); };
var chart = document.getElementById('chart').getElementsByTagName('svg')[0];
saveSvgAsPng(chart, 'chart.png', options)
}
var data = [
{day: 1, service: 'ABC', count: 100},
{day: 2, service: 'ABC', count: 80},
{day: 4, service: 'ABC', count: 10},
{day: 7, service: 'XYZ', count: 380},
{day: 8, service: 'XYZ', count: 400}
];
var ndx = crossfilter(data);
var dim = ndx.dimension(function(d){return [d.service, d.day];});
var grp = dim.group().reduceSum(function(d) { return d.count; });
grp = fillGroup(grp, d3.cross(['ABC', 'XYZ'], d3.range(1, 9)));
var chart= dc.seriesChart("#chart")
.width(500)
.height(180)
.chart(function(c) { return dc.lineChart(c).renderArea(true).curve(d3.curveCardinal); })
.dimension(dim)
.group(grp)
.brushOn(false)
.seriesAccessor(function(d) { return d.key[0]; })
.keyAccessor(function(d) { return d.key[1]; })
.valueAccessor(function(d) { return +d.value; })
.x(d3.scaleLinear())
.elasticX(true)
.y(d3.scaleLinear().domain([0, 450]))
.legend(dc.legend().horizontal(false).x(60).y(10))
.yAxisLabel("Count")
.render();
function fillGroup(grupo, rango) {
return {
all:function () {
var resultados = grupo.all().slice(0);
var encontrado = {};
resultados.forEach(function(d) {
encontrado[d.key] = true;
});
rango.forEach(function(d) {
if (!encontrado[d]) { resultados.push({key: d, value: 0}); }
});
return resultados;
}
};
}
/* Please ignore what follows - it's the minified SaveSvgAsPng library,
I haven't found any CDN for it... */
(function(){const out$=typeof exports!='undefined'&&exports||typeof define!='undefined'&&{}||this||window;if(typeof define!=='undefined')define(()=>out$);const xmlns='http://www.w3.org/2000/xmlns/';const doctype='<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd" [<!ENTITY nbsp " ">]>';const urlRegex=/url\(["']?(.+?)["']?\)/;const fontFormats={woff2:'font/woff2',woff:'font/woff',otf:'application/x-font-opentype',ttf:'application/x-font-ttf',eot:'application/vnd.ms-fontobject',sfnt:'application/font-sfnt',svg:'image/svg+xml'};const isElement=obj=>obj instanceof HTMLElement||obj instanceof SVGElement;const requireDomNode=el=>{if(!isElement(el))throw new Error(`an HTMLElement or SVGElement is required; got ${el}`)};const isExternal=url=>url&&url.lastIndexOf('http',0)===0&&url.lastIndexOf(window.location.host)===-1;const getFontMimeTypeFromUrl=fontUrl=>{const formats=Object.keys(fontFormats).filter(extension=>fontUrl.indexOf(`.${extension}`)>0).map(extension=>fontFormats[extension]);if(formats)return formats[0];console.error(`Unknown font format for ${fontUrl}. Fonts may not be working correctly.`);return'application/octet-stream'};const arrayBufferToBase64=buffer=>{let binary='';const bytes=new Uint8Array(buffer);for(let i=0;i<bytes.byteLength;i++)binary+=String.fromCharCode(bytes[i]);return window.btoa(binary)}
const getDimension=(el,clone,dim)=>{const v=(el.viewBox&&el.viewBox.baseVal&&el.viewBox.baseVal[dim])||(clone.getAttribute(dim)!==null&&!clone.getAttribute(dim).match(/%$/)&&parseInt(clone.getAttribute(dim)))||el.getBoundingClientRect()[dim]||parseInt(clone.style[dim])||parseInt(window.getComputedStyle(el).getPropertyValue(dim));return typeof v==='undefined'||v===null||isNaN(parseFloat(v))?0:v};const getDimensions=(el,clone,width,height)=>{if(el.tagName==='svg')return{width:width||getDimension(el,clone,'width'),height:height||getDimension(el,clone,'height')};else if(el.getBBox){const{x,y,width,height}=el.getBBox();return{width:x+width,height:y+height}}};const reEncode=data=>decodeURIComponent(encodeURIComponent(data).replace(/%([0-9A-F]{2})/g,(match,p1)=>{const c=String.fromCharCode(`0x${p1}`);return c==='%'?'%25':c}));const uriToBlob=uri=>{const byteString=window.atob(uri.split(',')[1]);const mimeString=uri.split(',')[0].split(':')[1].split(';')[0]
const buffer=new ArrayBuffer(byteString.length);const intArray=new Uint8Array(buffer);for(let i=0;i<byteString.length;i++){intArray[i]=byteString.charCodeAt(i)}
return new Blob([buffer],{type:mimeString})};const query=(el,selector)=>{if(!selector)return;try{return el.querySelector(selector)||el.parentNode&&el.parentNode.querySelector(selector)}catch(err){console.warn(`Invalid CSS selector "${selector}"`,err)}};const detectCssFont=rule=>{const match=rule.cssText.match(urlRegex);const url=(match&&match[1])||'';if(!url||url.match(/^data:/)||url==='about:blank')return;const fullUrl=url.startsWith('../')?`${rule.href}/../${url}`:url.startsWith('./')?`${rule.href}/.${url}`:url;return{text:rule.cssText,format:getFontMimeTypeFromUrl(fullUrl),url:fullUrl}};const inlineImages=el=>Promise.all(Array.from(el.querySelectorAll('image')).map(image=>{let href=image.getAttributeNS('http://www.w3.org/1999/xlink','href')||image.getAttribute('href');if(!href)return Promise.resolve(null);if(isExternal(href)){href+=(href.indexOf('?')===-1?'?':'&')+'t='+new Date().valueOf()}
return new Promise((resolve,reject)=>{const canvas=document.createElement('canvas');const img=new Image();img.crossOrigin='anonymous';img.src=href;img.onerror=()=>reject(new Error(`Could not load ${href}`));img.onload=()=>{canvas.width=img.width;canvas.height=img.height;canvas.getContext('2d').drawImage(img,0,0);image.setAttributeNS('http://www.w3.org/1999/xlink','href',canvas.toDataURL('image/png'));resolve(!0)}})}));const cachedFonts={};const inlineFonts=fonts=>Promise.all(fonts.map(font=>new Promise((resolve,reject)=>{if(cachedFonts[font.url])return resolve(cachedFonts[font.url]);const req=new XMLHttpRequest();req.addEventListener('load',()=>{const fontInBase64=arrayBufferToBase64(req.response);const fontUri=font.text.replace(urlRegex,`url("data:${font.format};base64,${fontInBase64}")`)+'\n';cachedFonts[font.url]=fontUri;resolve(fontUri)});req.addEventListener('error',e=>{console.warn(`Failed to load font from: ${font.url}`,e);cachedFonts[font.url]=null;resolve(null)});req.addEventListener('abort',e=>{console.warn(`Aborted loading font from: ${font.url}`,e);resolve(null)});req.open('GET',font.url);req.responseType='arraybuffer';req.send()}))).then(fontCss=>fontCss.filter(x=>x).join(''));let cachedRules=null;const styleSheetRules=()=>{if(cachedRules)return cachedRules;return cachedRules=Array.from(document.styleSheets).map(sheet=>{try{return sheet.cssRules}catch(e){console.warn(`Stylesheet could not be loaded: ${sheet.href}`)}})};const inlineCss=(el,options)=>{const{selectorRemap,modifyStyle,modifyCss,fonts}=options||{};const generateCss=modifyCss||((selector,properties)=>{const sel=selectorRemap?selectorRemap(selector):selector;const props=modifyStyle?modifyStyle(properties):properties;return `${sel}{${props}}\n`});const css=[];const detectFonts=typeof fonts==='undefined';const fontList=fonts||[];styleSheetRules().forEach(rules=>{if(!rules)return;Array.from(rules).forEach(rule=>{if(typeof rule.style!='undefined'){if(query(el,rule.selectorText))css.push(generateCss(rule.selectorText,rule.style.cssText));else if(detectFonts&&rule.cssText.match(/^#font-face/)){const font=detectCssFont(rule);if(font)fontList.push(font)}else css.push(rule.cssText)}})});return inlineFonts(fontList).then(fontCss=>css.join('\n')+fontCss)};out$.prepareSvg=(el,options,done)=>{requireDomNode(el);const{left=0,top=0,width:w,height:h,scale=1,responsive=!1,}=options||{};return inlineImages(el).then(()=>{let clone=el.cloneNode(!0);const{width,height}=getDimensions(el,clone,w,h);if(el.tagName!=='svg'){if(el.getBBox){clone.setAttribute('transform',clone.getAttribute('transform').replace(/translate\(.*?\)/,''));const svg=document.createElementNS('http://www.w3.org/2000/svg','svg');svg.appendChild(clone);clone=svg}else{console.error('Attempted to render non-SVG element',el);return}}
clone.setAttribute('version','1.1');clone.setAttribute('viewBox',[left,top,width,height].join(' '));if(!clone.getAttribute('xmlns'))clone.setAttributeNS(xmlns,'xmlns','http://www.w3.org/2000/svg');if(!clone.getAttribute('xmlns:xlink'))clone.setAttributeNS(xmlns,'xmlns:xlink','http://www.w3.org/1999/xlink');if(responsive){clone.removeAttribute('width');clone.removeAttribute('height');clone.setAttribute('preserveAspectRatio','xMinYMin meet')}else{clone.setAttribute('width',width*scale);clone.setAttribute('height',height*scale)}
Array.from(clone.querySelectorAll('foreignObject > *')).forEach(foreignObject=>{if(!foreignObject.getAttribute('xmlns'))
foreignObject.setAttributeNS(xmlns,'xmlns','http://www.w3.org/1999/xhtml')});return inlineCss(el,options).then(css=>{const style=document.createElement('style');style.setAttribute('type','text/css');style.innerHTML=`<![CDATA[\n${css}\n]]>`;const defs=document.createElement('defs');defs.appendChild(style);clone.insertBefore(defs,clone.firstChild);const outer=document.createElement('div');outer.appendChild(clone);const src=outer.innerHTML.replace(/NS\d+:href/gi,'xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href');if(typeof done==='function')done(src,width,height);else return{src,width,height}})})};out$.svgAsDataUri=(el,options,done)=>{requireDomNode(el);const result=out$.prepareSvg(el,options).then(({src})=>`data:image/svg+xml;base64,${window.btoa(reEncode(doctype+src))}`);if(typeof done==='function')return result.then(done);return result};out$.svgAsPngUri=(el,options,done)=>{requireDomNode(el);const{encoderType='image/png',encoderOptions=0.8,backgroundColor,canvg}=options||{};const convertToPng=({src,width,height})=>{const canvas=document.createElement('canvas');const context=canvas.getContext('2d');const pixelRatio=window.devicePixelRatio||1;canvas.width=width*pixelRatio;canvas.height=height*pixelRatio;canvas.style.width=`${canvas.width}px`;canvas.style.height=`${canvas.height}px`;context.setTransform(pixelRatio,0,0,pixelRatio,0,0);if(canvg)canvg(canvas,src);else context.drawImage(src,0,0);if(backgroundColor){context.globalCompositeOperation='destination-over';context.fillStyle=backgroundColor;context.fillRect(0,0,canvas.width,canvas.height)}
let png;try{png=canvas.toDataURL(encoderType,encoderOptions)}catch(e){if((typeof SecurityError!=='undefined'&&e instanceof SecurityError)||e.name==='SecurityError'){console.error('Rendered SVG images cannot be downloaded in this browser.');return}else throw e}
if(typeof done==='function')done(png);return Promise.resolve(png)}
if(canvg)return out$.prepareSvg(el,options).then(convertToPng);else return out$.svgAsDataUri(el,options).then(uri=>{return new Promise((resolve,reject)=>{const image=new Image();image.onload=()=>resolve(convertToPng({src:image,width:image.width,height:image.height}));image.onerror=()=>{reject(`There was an error loading the data URI as an image on the following SVG\n${window.atob(uri.slice(26))}Open the following link to see browser's diagnosis\n${uri}`)}
image.src=uri})})};out$.download=(name,uri)=>{if(navigator.msSaveOrOpenBlob)navigator.msSaveOrOpenBlob(uriToBlob(uri),name);else{const saveLink=document.createElement('a');if('download' in saveLink){saveLink.download=name;saveLink.style.display='none';document.body.appendChild(saveLink);try{const blob=uriToBlob(uri);const url=URL.createObjectURL(blob);saveLink.href=url;saveLink.onclick=()=>requestAnimationFrame(()=>URL.revokeObjectURL(url))}catch(e){console.warn('This browser does not support object URLs. Falling back to string URL.');saveLink.href=uri}
saveLink.click();document.body.removeChild(saveLink)}
else{window.open(uri,'_temp','menubar=no,toolbar=no,status=no')}}};out$.saveSvg=(el,name,options)=>{requireDomNode(el);out$.svgAsDataUri(el,options||{},uri=>out$.download(name,uri))};out$.saveSvgAsPng=(el,name,options)=>{requireDomNode(el);out$.svgAsPngUri(el,options||{},uri=>out$.download(name,uri))}})()
circle.dot { fill-opacity:0.5 !important; }
/* Please ignore what follows - it's the minified version of
https://cdnjs.cloudflare.com/ajax/libs/dc/3.0.4/dc.css, I had to include it here
because if it's stored in a different domain, SaveSvgAsPng can't load it */
.dc-chart path.dc-symbol,.dc-legend g.dc-legend-item.fadeout{fill-opacity:.5;stroke-opacity:.5}div.dc-chart{float:left}.dc-chart rect.bar{stroke:none;cursor:pointer}.dc-chart rect.bar:hover{fill-opacity:.5}.dc-chart rect.deselected{stroke:none;fill:#ccc}.dc-chart .pie-slice{fill:#fff;font-size:12px;cursor:pointer}.dc-chart .pie-slice.external{fill:#000}.dc-chart .pie-slice :hover,.dc-chart .pie-slice.highlight{fill-opacity:.8}.dc-chart .pie-path{fill:none;stroke-width:2px;stroke:#000;opacity:.4}.dc-chart .selected path,.dc-chart .selected circle{stroke-width:3;stroke:#ccc;fill-opacity:1}.dc-chart .deselected path,.dc-chart .deselected circle{stroke:none;fill-opacity:.5;fill:#ccc}.dc-chart .axis path,.dc-chart .axis line{fill:none;stroke:#000;shape-rendering:crispEdges}.dc-chart .axis text{font:10px sans-serif}.dc-chart .grid-line,.dc-chart .axis .grid-line,.dc-chart .grid-line line,.dc-chart .axis .grid-line line{fill:none;stroke:#ccc;opacity:.5;shape-rendering:crispEdges}.dc-chart .brush rect.selection{fill:#4682b4;fill-opacity:.125}.dc-chart .brush .custom-brush-handle{fill:#eee;stroke:#666;cursor:ew-resize}.dc-chart path.line{fill:none;stroke-width:1.5px}.dc-chart path.area{fill-opacity:.3;stroke:none}.dc-chart path.highlight{stroke-width:3;fill-opacity:1;stroke-opacity:1}.dc-chart g.state{cursor:pointer}.dc-chart g.state :hover{fill-opacity:.8}.dc-chart g.state path{stroke:#fff}.dc-chart g.deselected path{fill:gray}.dc-chart g.deselected text{display:none}.dc-chart g.row rect{fill-opacity:.8;cursor:pointer}.dc-chart g.row rect:hover{fill-opacity:.6}.dc-chart g.row text{fill:#fff;font-size:12px;cursor:pointer}.dc-chart g.dc-tooltip path{fill:none;stroke:gray;stroke-opacity:.8}.dc-chart g.county path{stroke:#fff;fill:none}.dc-chart g.debug rect{fill:#00f;fill-opacity:.2}.dc-chart g.axis text{-webkit-touch-callout:none;-webkit-user-select:none;-khtml-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;pointer-events:none}.dc-chart .node{font-size:.7em;cursor:pointer}.dc-chart .node :hover{fill-opacity:.8}.dc-chart .bubble{stroke:none;fill-opacity:.6}.dc-chart .highlight{fill-opacity:1;stroke-opacity:1}.dc-chart .fadeout{fill-opacity:.2;stroke-opacity:.2}.dc-chart .box text{font:10px sans-serif;-webkit-touch-callout:none;-webkit-user-select:none;-khtml-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;pointer-events:none}.dc-chart .box line{fill:#fff}.dc-chart .box rect,.dc-chart .box line,.dc-chart .box circle{stroke:#000;stroke-width:1.5px}.dc-chart .box .center{stroke-dasharray:3,3}.dc-chart .box .data{stroke:none;stroke-width:0}.dc-chart .box .outlier{fill:none;stroke:#ccc}.dc-chart .box .outlierBold{fill:red;stroke:none}.dc-chart .box.deselected{opacity:.5}.dc-chart .box.deselected .box{fill:#ccc}.dc-chart .symbol{stroke:none}.dc-chart .heatmap .box-group.deselected rect{stroke:none;fill-opacity:.5;fill:#ccc}.dc-chart .heatmap g.axis text{pointer-events:all;cursor:pointer}.dc-chart .empty-chart .pie-slice{cursor:default}.dc-chart .empty-chart .pie-slice path{fill:#fee;cursor:default}.dc-chart circle.dot{stroke:none}.dc-data-count{float:right;margin-top:15px;margin-right:15px}.dc-data-count .filter-count,.dc-data-count .total-count{color:#3182bd;font-weight:700}.dc-legend{font-size:11px}.dc-legend .dc-legend-item{cursor:pointer}.dc-hard .number-display{float:none}div.dc-html-legend{overflow-y:auto;overflow-x:hidden;height:inherit;float:right;padding-right:2px}div.dc-html-legend .dc-legend-item-horizontal{display:inline-block;margin-left:5px;margin-right:5px;cursor:pointer}div.dc-html-legend .dc-legend-item-horizontal.selected{background-color:#3182bd;color:white}div.dc-html-legend .dc-legend-item-vertical{display:block;margin-top:5px;padding-top:1px;padding-bottom:1px;cursor:pointer}div.dc-html-legend .dc-legend-item-vertical.selected{background-color:#3182bd;color:white}div.dc-html-legend .dc-legend-item-color{display:table-cell;width:12px;height:12px}div.dc-html-legend .dc-legend-item-label{line-height:12px;display:table-cell;vertical-align:middle;padding-left:3px;padding-right:3px;font-size:.75em}.dc-html-legend-container{height:inherit}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crossfilter/1.3.12/crossfilter.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.13.0/d3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/dc/3.0.4/dc.min.js"></script>
<div id="chart"></div>
<button id="export" onclick="save()">Export as PNG</button>
Basically, I just get the SVG DOM element, and pass it to the saveSvgAsPng function:
var chart = document.getElementById('chart').getElementsByTagName('svg')[0];
saveSvgAsPng(chart, 'chart.png', options);
This is how the dc.js chart looks like:
And this is how the exported PNG looks:
Why does it show lines/areas/circles under the X axis (and beyond the horizontal limits too)? How can I fix it?
The <defs><clipPath /></defs> section is present within the SVG element, and I guess it's properly defined (right?).

Answer 1

I haven't tried saveSvgAsPng, so this is just a guess, but you could try
chart.select('g.chart-body').attr('clip-path',
chart.select('g.chart-body').attr('clip-path').replace(/.*#/, 'url(#'))
Reasoning: dc.js uses an obscure form of the clip-path attribute with an absolute URL. It's looking for the URL of the current page using window.location.href and that could go wrong, or saveSvgAsPng might not expect an absolute URL.
It does this for Angular compatibility but I can see why this would confuse a library.
The code above will remove the base URL, leaving only the relative hash part.
If this helps, we can add an option for this behavior.

Answer 2

I'm not self-answering, I just want to add a side note, which might be helpful for other SaveSvgAsPng users:
For the exported PNG to have the same look as the SVG, SaveSvgAsPng needs to properly apply the CSS styles. Otherwise, it would look like this:
If you run into this problem, please note that:
The stylesheets need to be stored in the same domain as the javascript code, otherwise the library won't be able to load them (for security reasons).
Most dc.js' styles are applied to the .dc-chart class or its children. This CSS class is applied to the parent DIV, not to the SVG element, which is what SaveSvgAsPng exports. Therefore, you will have to remove the selector from the CSS rules. The easiest way to do so is using the selectorRemap option, like this:
var options = {
selectorRemap: function(s) { return s.replace(/\.dc-chart/g, ''); }
};
var chart = document.getElementById('chart').getElementsByTagName('svg')[0];
saveSvgAsPng(chart, 'chart.png', options);

Answer 3

I'm not familiar with saveSvgAsPng, it might be that it's already using canvas. If It's the case, please downvote my question, probably not going to be useful ;)
Did you try using the svg->canvas->png path? I did use it with other d3 projects and worked fine.
This is a snippet lifted from another answer on that question:
var btn = document.querySelector('button');
var svg = document.querySelector('svg');
var canvas = document.querySelector('canvas');
function triggerDownload (imgURI) {
var evt = new MouseEvent('click', {
view: window,
bubbles: false,
cancelable: true
});
var a = document.createElement('a');
a.setAttribute('download', 'MY_COOL_IMAGE.png');
a.setAttribute('href', imgURI);
a.setAttribute('target', '_blank');
a.dispatchEvent(evt);
}
btn.addEventListener('click', function () {
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var data = (new XMLSerializer()).serializeToString(svg);
var DOMURL = window.URL || window.webkitURL || window;
var img = new Image();
var svgBlob = new Blob([data], {type: 'image/svg+xml;charset=utf-8'});
var url = DOMURL.createObjectURL(svgBlob);
img.onload = function () {
ctx.drawImage(img, 0, 0);
DOMURL.revokeObjectURL(url);
var imgURI = canvas
.toDataURL('image/png')
.replace('image/png', 'image/octet-stream');
triggerDownload(imgURI);
};
img.src = url;
});
<button>svg to png</button>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="200" height="200">
<rect x="10" y="10" width="50" height="50" />
<text x="0" y="100">Look, i'm cool</text>
</svg>
<canvas id="canvas"></canvas>