# DOM to Image [![Version](https://img.shields.io/npm/v/dom-to-image-more.svg?style=flat-square)](https://npmjs.com/package/dom-to-image-more) [![Bundle Size](https://img.shields.io/bundlephobia/minzip/dom-to-image-more?style=flat-square)](https://bundlephobia.com/result?p=dom-to-image-more) [![Open Issues](https://img.shields.io/github/issues/1904labs/dom-to-image-more?style=flat-square)](https://github.com/1904labs/dom-to-image-more/issues) [![GitHub Repo stars](https://img.shields.io/github/stars/1904labs/dom-to-image-more?style=social)](https://github.com/1904labs/dom-to-image-more) [![Twitter](https://img.shields.io/twitter/follow/idisposable.svg?style=social&label=Follow)](https://www.twitter.com/idisposable) ## Breaking Change Notice The 3.x release branch included some breaking changes in the very infrequently used ability to configure some utility methods used in this internal processing of dom-to-image-more. As browsers have matured, many of the hacks we're accumulated over the years are not needed, or better ways have been found to handle some edge-cases. With the help of folks like @meche-gh, in #99 we're stripping out the following members: - `.mimes` - was the not-very-comprehensive list of mime types used to handle inlining things - `.parseExtension` - was a method to extract the extension from a filename, used to guess mime types - `.mimeType` - was a method to map file extensions to mime types - `.dataAsUrl` - was a method to reassemble a `data:` URI from a Base64 representation and mime type The 3.x release branch should also fix more node compatibility and `iframe` issues. ## What is it **dom-to-image-more** is a library which can turn arbitrary DOM node, including same origin and blob iframes, into a vector (SVG) or raster (PNG or JPEG) image, written in JavaScript. This fork of [dom-to-image by Anatolii Saienko (tsayen)](https://github.com/tsayen/dom-to-image) with some important fixes merged. We are eternally grateful for his starting point. Anatolii's version was 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. Moved to [1904labs organization](https://github.com/1904labs/) from my repositories 2019-02-06 as of version 2.7.3 ## Installation ### NPM `npm install dom-to-image-more` Then load ```javascript /* in ES 6 */ import domtoimage from 'dom-to-image-more'; /* in ES 5 */ var domtoimage = require('dom-to-image-more'); ``` ## 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); } } }); ``` Get a canvas object: ```javascript domtoimage.toCanvas(document.getElementById('my-node')).then(function (canvas) { console.log('canvas', canvas.width, canvas.height); }); ``` Adjust cloned nodes before/after children are cloned [sample fiddle](https://jsfiddle.net/IDisposable/grLtjwe5/12/) ```javascript const adjustClone = (node, clone, after) => { if (!after && clone.id === 'element') { clone.style.transform = 'translateY(100px)'; } return clone; }; const wrapper = document.getElementById('wrapper'); const blob = domtoimage.toBlob(wrapper, { adjustClonedNode: adjustClone }); ``` --- _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. #### filterStyles A function taking style propertie name as argument. Should return true if passed propertie should be included in the output Sample use: ```javascript filterStyles(node, propertyName) { return !propertyName.startssWith('--'); // to filter out CSS variables } ``` #### adjustClonedNode A function that will be invoked on each node as they are cloned. Useful to adjust nodes in any way needed before the conversion. Note that this be invoked before the onclone callback. The handler gets the original node, the cloned node, and a boolean that says if we've cloned the children already (so you can handle either before or after) Sample use: ```javascript const adjustClone = (node, clone, after) => { if (!after && clone.id === 'element') { clone.style.transform = 'translateY(100px)'; } return clone; } ``` const wrapper = document.getElementById('wrapper'); const blob = domtoimage.toBlob(wrapper, { adjustClonedNode: adjustClone}); #### onclone A function taking the cloned and modified DOM node as argument. It allows to make final adjustements to the elements before rendering, on the whole clone, after all elements have been individually cloned. Note that this will be invoked after all the onclone callbacks have been fired. The cloned DOM might differ a lot from the original DOM, for example canvas will be replaced with image tags, some class might have changed, the style are inlined. It can be useful to log the clone to get a better senses of the transformations. #### 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 #### copyDefaultStyles Set to true to enable the copying of the default styles of elements. This will make the process faster. Try disabling it if seeing extra padding and using resetting / normalizing in CSS. Defaults to true. #### useCredentialFeatures Allows optionally setting the `useCredentials` option if the resource matches a pattern in the `useCredentialFilters` array. #### scale Scale value to be applied on canvas's `ctx.scale()` on both x and y axis. Can be used to increase the image quality with higher image size. ### Alternative Solutions to CORS Policy Issue Are you facing a [CORS policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) issue in your app? Don't worry, there are alternative solutions to this problem that you can explore. Here are some options to consider: 1. **Use the option.corsImg support by passing images** With this option, you can setup a proxy service that will process the requests in a safe CORS context. 2. **Use third-party services like [allOrigins](https://allorigins.win/).** With this service, you can fetch the source code or an image in base64 format from any website. However, this method can be a bit slow. 3. **Set up your own API service.** Compared to third-party services like [allOrigins](https://allorigins.win/), this method can be faster, but you'll need to convert the image URL to base64 format. You can use the "[image-to-base64](https://github.com/renanbastos93/image-to-base64)" package for this purpose. 4. **Utilize [server-side functions](https://nextjs.org/docs/basic-features/data-fetching/get-server-side-props) features of frameworks like [Next.js](https://nextjs.org/).** This is the easiest and most convenient method, where you can directly fetch a URL source within [server-side functions](https://nextjs.org/docs/basic-features/data-fetching/get-server-side-props) and convert it to base64 format if needed. By exploring these alternative solutions, you can overcome [the CORS policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) issue in your app and ensure that your images are accessible to everyone. ## 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 Uses Object.hasOwn() so needs at least Chrome/Edge 93, Firefox 92, Opera 79. Safari 15.4 or Node 16.9.0 ### 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 As of this v3 branch chain, the testing jig is taking advantage of the `onclone` hook to insert the clone-output into the testing page. This should make it a tiny bit easier to track down where exactly the inlining of CSS styles against the DOM nodes is wrong. Most importantly, tests **only** depend on: - [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 1. 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 1. 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 `

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