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✂️ Generates an image from a DOM node using HTML5 canvas and SVG.

Fork fromdom-to-image with more maintainable code and some new features.

npm install --save html-to-image

/* ES6 */import*ashtmlToImagefrom'html-to-image';import{toPng,toJpeg,toBlob,toPixelData,toSvg}from'html-to-image';/* ES5 */varhtmlToImage=require('html-to-image');

All the top level functions accept DOM node and rendering options, and return a promise fulfilled with corresponding dataURL:

• toPng
• toSvg
• toJpeg
• toBlob
• toCanvas
• toPixelData

Go with the following examples.

Get a PNG image base64-encoded data URL and display it right away:

constnode=document.getElementById('my-node');htmlToImage.toPng(node).then((dataUrl)=>{constimg=newImage();img.src=dataUrl;document.body.appendChild(img);}).catch((err)=>{console.error('oops, something went wrong!',err);});

Get a PNG image base64-encoded data URL and download it (usingdownload):

htmlToImage.toPng(document.getElementById('my-node')).then((dataUrl)=>download(dataUrl,'my-node.png'));

Get an SVG data URL, but filter out all the<i> elements:

functionfilter(node){return(node.tagName!=='i');}htmlToImage.toSvg(document.getElementById('my-node'),{filter:filter}).then(function(dataUrl){/* do something */});

Save and download a compressed JPEG image:

htmlToImage.toJpeg(document.getElementById('my-node'),{quality:0.95}).then(function(dataUrl){varlink=document.createElement('a');link.download='my-image-name.jpeg';link.href=dataUrl;link.click();});

Get a PNG image blob and download it (usingFileSaver):

htmlToImage.toBlob(document.getElementById('my-node')).then(function(blob){if(window.saveAs){window.saveAs(blob,'my-node.png');}else{FileSaver.saveAs(blob,'my-node.png');}});

Get a HTMLCanvasElement, and display it right away:

htmlToImage.toCanvas(document.getElementById('my-node')).then(function(canvas){document.body.appendChild(canvas);});

Get the raw pixel data as aUint8Array with every 4 array elements representing the RGBA data of a pixel:

varnode=document.getElementById('my-node');htmlToImage.toPixelData(node).then(function(pixels){for(vary=0;y<node.scrollHeight;++y){for(varx=0;x<node.scrollWidth;++x){pixelAtXYOffset=(4*y*node.scrollHeight)+(4*x);/* pixelAtXY is a Uint8Array[4] containing RGBA values of the pixel at (x, y) in the range 0..255 */pixelAtXY=pixels.slice(pixelAtXYOffset,pixelAtXYOffset+4);}}});

importReact,{useCallback,useRef}from'react';import{toPng}from'html-to-image';constApp:React.FC=()=>{constref=useRef<HTMLDivElement>(null)constonButtonClick=useCallback(()=>{if(ref.current===null){return}toPng(ref.current,{cacheBust:true,}).then((dataUrl)=>{constlink=document.createElement('a')link.download='my-image-name.png'link.href=dataUrllink.click()}).catch((err)=>{console.log(err)})},[ref])return(<><divref={ref}>{/* DOM nodes you want to convert to PNG */}</div><buttononClick={onButtonClick}>Click me</button></>)}

(domNode:HTMLElement)=>boolean

A function taking DOM node as argument. Should return true if passed node should be included in the output. Excluding node means excluding it's children as well.

You can add filter to every image function. For example,

constfilter=(node:HTMLElement)=>{constexclusionClasses=['remove-me','secret-div'];return!exclusionClasses.some((classname)=>node.classList?.contains(classname));}htmlToImage.toJpeg(node,{quality:0.95,filter:filter});

or

htmlToImage.toPng(node,{filter:filter})

Not called on the root node.

A string value for the background color, any valid CSS color value.

Width and height in pixels to be applied to node before rendering.

Allows to scale the canva's size including the elements inside to a given width and height (in pixels).

An object whose properties to be copied to node's style before rendering. You might want to checkthis reference for JavaScript names of CSS properties.

A number between0 and1 indicating image quality (e.g.0.92 =>92%) of the JPEG image.

Defaults to1.0 (100%)

Set to true to append the current time as a query string to URL requests to enable cache busting.

Defaults tofalse

Set false to use all URL as cache key.If the value has falsy value, it will exclude query params from the provided URL.

Defaults tofalse

A data URL for a placeholder image that will be used when fetching an image fails.

Defaults to an empty string and will render empty areas for failed images.

The pixel ratio of the captured image. Default use the actual pixel ratio of the device. Set1 touse as initial-scale1 for the image.

The format required for font embedding. This is a useful optimisation when a webfont providerspecifies several different formats for fonts in the CSS, for example:

@font-face {name:'proxima-nova';src:url("...")format("woff2"),url("...")format("woff"),url("...")format("opentype");}

Instead of embedding each format, all formats other than the one specified will be discarded. Ifthis option is not specified then all formats will be downloaded and embedded.

When supplied, the library will skip the process of parsing and embedding webfont URLs in CSS,instead using this value. This is useful when combined withgetFontEmbedCSS() to only perform theembedding process a single time across multiple calls to library functions.

constfontEmbedCSS=awaithtmlToImage.getFontEmbedCSS(element1);html2Image.toSVG(element1,{ fontEmbedCSS});html2Image.toSVG(element2,{ fontEmbedCSS});

When supplied, the library will skip the process of scaling extra large doms into the canvas object.You may experience loss of parts of the image if set totrue and you are exporting a very large image.

Defaults tofalse

A string indicating the image format. The default type is image/png; that type is also used if the given type isn't supported.When supplied, the toCanvas function will return a blob matching the given image type and quality.

Defaults toimage/png

An array of style property names. Can be used to manually specify which style properties are included when cloning nodes. This can be useful for performance-critical scenarios.

Only standard lib is currently used, but make sure your browser supports:

• Promise
• SVG<foreignObject> tag

It's tested on latest Chrome, Firefox and Safari (49, 45 and 16 respectively at the time of writing), with Chrome performing significantly better on big DOM trees, possibly due to it's more performant SVG support, and the fact that it supportsCSSStyleDeclaration.cssText property.

Internet Explorer is not (and will not be) supported, as it does not support SVG<foreignObject> tag.

There might some day exist (or maybe already exists?) a simple and standard way of exporting parts of the HTML to image (and then this script can only serve as an evidence of all the hoops I had to jump through in order to get such obvious thing done) but I haven't found one so far.

This library uses a feature of SVG that allows having arbitrary HTML content inside of the<foreignObject> tag. So, in order to render that DOM node for you, following steps are taken:

1. Clone the original DOM node recursively
2. Compute the style for the node and each sub-node and copy it to corresponding clone
   • and don't forget to recreate pseudo-elements, as they are not cloned in any way, of course
3. Embed web fonts
   • find all the@font-face declarations that might represent web fonts
   • parse file URLs, download corresponding files
   • base64-encode and inline content as dataURLs
   • concatenate all the processed CSS rules and put them into one<style> element, then attach it to the clone
4. Embed images
   • embed image URLs in<img> elements
   • inline images used inbackground CSS property, in a fashion similar to fonts
5. Serialize the cloned node to XML
6. Wrap XML into the<foreignObject> tag, then into the SVG, then make it a data URL
7. Optionally, to get PNG content or raw pixel data as a Uint8Array, create an Image element with the SVG as a source, and render it on an off-screen canvas, that you have also created, then read the content from the canvas
8. Done!

• If the DOM node you want to render includes a<canvas> element with something drawn on it, it should be handled fine, unless the canvas istainted - in this case rendering will rather not succeed.
• Rendering will failed on huge DOM due to the dataURIlimit varies.

Please let us know how can we help. Do check outissues for bug reports or suggestions first.

To become a contributor, please follow ourcontributing guide.

The scripts and documentation in this project are released under theMIT License