# DOM to Image [![Build Status](https://travis-ci.org/tsayen/dom-to-image.svg?branch=master)](https://travis-ci.org/tsayen/dom-to-image) ## What is it **dom-to-image** is a library which can turn arbitrary DOM node into a vector (SVG) or raster (PNG or JPEG) image, written in JavaScript. It's based on [domvas by Paul Bakaus](https://github.com/pbakaus/domvas) and has been completely rewritten, with some bugs fixed and some new features (like web font and image support) added. ## Installation ### NPM `npm install dom-to-image` Then load ```javascript /* in ES 6 */ import domtoimage from 'dom-to-image'; /* in ES 5 */ var domtoimage = require('dom-to-image'); ``` ### Bower `bower install dom-to-image` Include either `src/dom-to-image.js` or `dist/dom-to-image.min.js` in your page and it will make the `domtoimage` variable available in the global scope. ```html ``` ## Usage All the top level functions accept DOM node and rendering options, and return promises, which are fulfilled with corresponding data URLs. Get a PNG image base64-encoded data URL and display right away: ```javascript var node = document.getElementById('my-node'); domtoimage.toPng(node) .then(function (dataUrl) { var img = new Image(); img.src = dataUrl; document.body.appendChild(img); }) .catch(function (error) { console.error('oops, something went wrong!', error); }); ``` Get a PNG image blob and download it (using [FileSaver](https://github.com/eligrey/FileSaver.js/), for example): ```javascript domtoimage.toBlob(document.getElementById('my-node')) .then(function (blob) { window.saveAs(blob, 'my-node.png'); }); ``` Save and download a compressed JPEG image: ```javascript domtoimage.toJpeg(document.getElementById('my-node'), { quality: 0.95 }) .then(function (dataUrl) { var link = document.createElement('a'); link.download = 'my-image-name.jpeg'; link.href = dataUrl; link.click(); }); ``` Get an SVG data URL, but filter out all the `` elements: ```javascript function filter (node) { return (node.tagName !== 'i'); } domtoimage.toSvg(document.getElementById('my-node'), {filter: filter}) .then(function (dataUrl) { /* do something */ }); ``` Get the raw pixel data as a [Uint8Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) with every 4 array elements representing the RGBA data of a pixel: ```javascript var node = document.getElementById('my-node'); domtoimage.toPixelData(node) .then(function (pixels) { for (var y = 0; y < node.scrollHeight; ++y) { for (var x = 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); } } }); ``` * * * _All the functions under `impl` are not public API and are exposed only for unit testing._ * * * ### Rendering options #### filter 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). Not called on the root node. #### bgcolor A string value for the background color, any valid CSS color value. #### height, width Height and width in pixels to be applied to node before rendering. #### style An object whose properties to be copied to node's style before rendering. You might want to check [this reference](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Properties_Reference) for JavaScript names of CSS properties. #### quality A number between 0 and 1 indicating image quality (e.g. 0.92 => 92%) of the JPEG image. Defaults to 1.0 (100%) #### cacheBust Set to true to append the current time as a query string to URL requests to enable cache busting. Defaults to false #### imagePlaceholder A data URL for a placeholder image that will be used when fetching an image fails. Defaults to undefined and will throw an error on failed images ## Browsers It's tested on latest Chrome and Firefox (49 and 45 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 supports `CSSStyleDeclaration.cssText` property. _Internet Explorer is not (and will not be) supported, as it does not support SVG `` tag_ _Safari [is not supported](https://github.com/tsayen/dom-to-image/issues/27), as it uses a stricter security model on ` tag. Suggested workaround is to use `toSvg` and render on the server._` ## Dependencies ### Source Only standard lib is currently used, but make sure your browser supports: - [Promise](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise) - SVG `` tag ### Tests Most importantly, tests depend on: - [js-imagediff](https://github.com/HumbleSoftware/js-imagediff), to compare rendered and control images - [ocrad.js](https://github.com/antimatter15/ocrad.js), for the parts when you can't compare images (due to the browser rendering differences) and just have to test whether the text is rendered ## How it works 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 `` 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 `data:` URLs - concatenate all the processed CSS rules and put them into one `

Package	Téléchargements	Stars	Taille	Issues	Publication	Licence

dom-to-image	228,702	10,611	-	331	il y a 8 ans	MIT