a PWA to transform raster pictures to SVG vector graphics


SVGcode is a Progressive Web App that allows you to convert raster pictures like JPG, PNG, GIF, WebP, AVIF, and so forth. to vector graphics in SVG format. It makes use of the File System Access API, the Async Clipboard API, the File Handling API, and Window Controls Overlay customization.

Thomas Steiner
(If you favor watching over studying, this text can also be out there as a video.)

From raster to vector #

Have you ever scaled a picture and the consequence was pixelated and unsatisfactory? If so, you could have in all probability handled a raster picture format comparable to WebP, PNG, or JPG.

Scaling up a raster picture makes it look pixelated.

In distinction, vector graphics are pictures which can be outlined by factors in a coordinate system. These factors are linked by traces and curves to kind polygons and different shapes. Vector graphics have a bonus over raster graphics in that they could be scaled up or all the way down to any decision with out pixelation.

Scaling up a vector picture with no lack of high quality.

Introducing SVGcode #

I’ve constructed a PWA known as SVGcode that may enable you convert raster pictures to vectors. Credit the place credit score is due: I did not invent this. With SVGcode, I simply stand on the shoulders of a command line software known as Potrace by Peter Selinger that I’ve transformed to Web Assembly, so it may be utilized in a Web app.

SVGcode application screenshot.
The SVGcode app.

Using SVGcode #

First, I need to present you how you can use the app. I begin with the teaser picture for Chrome Dev Summit that I downloaded from the ChromiumDev Twitter channel. This is a PNG raster picture that I then drag onto the SVGcode app. When I drop the file, the app traces the picture coloration by coloration, till a vectorized model of the enter seems. I can now zoom into the picture, and as you’ll be able to see, the sides keep sharp. But zooming in on the Chrome emblem, you’ll be able to see that the tracing wasn’t excellent, and particularly the outlines of the emblem look a bit speckled. I can enhance the consequence by de-speckling the tracing by suppressing speckles of as much as, say, 5 pixels.

Converting a dropped picture to SVG.

Posterization in SVGcode #

An necessary step for vectorization, particularly for photographic pictures, is posterizing the enter picture to scale back the variety of colours. SVGcode permits me to do that per coloration channel, and see the ensuing SVG as I make modifications. When I’m proud of the consequence, I can save the SVG to my onerous disk and use it wherever I like.

Posterizing a picture to scale back the variety of colours.

APIs utilized in SVGcode #

Now that you’ve got seen what the app is able to, let me present you among the APIs that assist make the magic occur.

Progressive Web App #

SVGcode is an installable Progressive Web App and subsequently absolutely offline enabled. The app relies on the Vanilla JS template for Vite.js and makes use of the favored Vite plugin PWA, which creates a service employee that makes use of Workbox.js underneath the hood. Workbox is a set of libraries that may energy a production-ready service employee for Progressive Web Apps, This sample might not essentially work for all apps, however for SVGcode’s use case it is nice.

Window Controls Overlay #

To maximize the out there display screen actual property, SVGcode makes use of Window Controls Overlay customization by transferring its major menu up into the titlebar space. You can see this get activated on the finish of the set up move.

Installing SVGcode and activating the Window Controls Overlay customization.

File System Access API #

To open enter picture recordsdata and save the ensuing SVGs, I take advantage of the File System Access API. This permits me to maintain a reference to beforehand opened recordsdata and to proceed the place I left off, even after an app reload. Whenever a picture will get saved, it’s optimized through the svgo library, which can take a second, relying on the complexity of the SVG. Showing the file save dialog requires a consumer gesture. It is subsequently necessary to acquire the file deal with earlier than the SVG optimization occurs, so the consumer gesture is just not invalidated by the point the optimized SVG is prepared.

attempt {
let svg = svgOutput.innerHTML;
let deal with = null;
if (supported) {
deal with = await showSaveFilePicker({
varieties: [{description: 'SVG file', accept: {'image/svg+xml': ['.svg']}}],
});
}
presentToast(i18n.t('optimizingSVG'), Infinity);
svg = await optimizeSVG(svg);
presentToast(i18n.t('savedSVG'));
const blob = new Blob([svg], {sort: 'picture/svg+xml'});
await fileSave(blob, {description: 'SVG file'}, deal with);
} catch (err) {
console.error(err.identify, err.message);
presentToast(err.message);
}

Drag an drop #

For opening an enter picture, I can both use the file open function, or, as you could have seen above, simply drag and drop a picture file onto the app. The file open function is fairly simple, extra attention-grabbing is the drag and drop case. What’s notably good about that is that you would be able to get a file system deal with from the information switch merchandise through the getAsFileSystemDeal with() methodology. As talked about earlier than, I can persist this deal with, so it is prepared when the app will get reloaded.

doc.addEventListener('drop', async (occasion) => {
occasion.preventDefault();
dropContainer.classList.take away('dropenter');
const merchandise = occasion.dataTransfer.objects[0];
if (merchandise.sort === 'file') {
inputImage.addEventListener(
'load',
() => {
URL.revokeObjectURL(blobURL);
},
{as soon as: true},
);
const deal with = await merchandise.getAsFileSystemDeal with();
if (deal with.sort !== 'file') {
return;
}
const file = await deal with.getFile();
const blobURL = URL.createObjectURL(file);
inputImage.src = blobURL;
await set(FILE_HANDLE, deal with);
}
});

For extra particulars, take a look at the article on the File System Access API and, should you’re , examine the SVGcode supply code in src/js/filesystem.js.

Async Clipboard API #

SVGcode can also be absolutely built-in with the working system’s clipboard through the Async Clipboard API. You can paste pictures from the working system’s file explorer into the app both by clicking the paste picture button or by urgent command or management plus v in your keyboard.

Pasting a picture from the file explorer into SVGcode.

The Async Clipboard API has just lately gained the power to take care of SVG pictures as nicely, so you may as well copy an SVG picture and paste it into one other utility for additional processing.

Copying a picture from SVGcode into SVGOMG.

copyButton.addEventListener('click on', async () => {
let svg = svgOutput.innerHTML;
presentToast(i18n.t('optimizingSVG'), Infinity);
svg = await optimizeSVG(svg);
const textual contentBlob = new Blob([svg], {sort: 'textual content/plain'});
const svgBlob = new Blob([svg], {sort: 'picture/svg+xml'});
navigator.clipboard.write([
new ClipboardItem({
[svgBlob.type]: svgBlob,
[textBlob.type]: textual contentBlob,
}),
]);
presentToast(i18n.t('copiedSVG'));
});

To be taught extra, learn the Async Clipboard article, or see the file src/js/clipboard.js.

File Handling #

One of my favourite options of SVGcode is how nicely it blends in with the working system. As an put in PWA, it might turn into a file handler, and even the default file handler, for picture recordsdata. This implies that when I’m within the Finder on my macOS machine, I can right-click a picture and open it with SVGcode. This function is named File Handling and works primarily based on the file_handlers property within the Web App Manifest and the launch queue, which permits the app to eat the handed file.

Opening a file from the desktop with put in SVGcode app.

window.launchQueue.setConsumer(async (launchParams) => {
if (!launchParams.recordsdata.size) {
return;
}
for (const deal with of launchParams.recordsdata) {
const file = await deal with.getFile();
if (file.sort.beginsWith('picture/')) {
const blobURL = URL.createObjectURL(file);
inputImage.addEventListener(
'load',
() => {
URL.revokeObjectURL(blobURL);
},
{as soon as: true},
);
inputImage.src = blobURL;
await set(FILE_HANDLE, deal with);
return;
}
}
});

For extra data, see Let put in internet purposes be file handlers, and consider the supply code in src/js/filehandling.js.

Conclusion #

Alright, this was a fast tour by means of among the superior app options in SVGcode. I hope this app can turn into a necessary software in your picture processing wants alongside different wonderful apps like Squoosh or SVGOMG.

SVGcode is on the market at svgco.de. See what I did there? You can overview its supply code on GitHub. Note that since Potrace is GPL-licensed, so is SVGcode. And with that, blissful vectorizing! I hope SVGcode can be helpful, and a few of its options can encourage your subsequent app.

Acknowledgements #

This article was reviewed by Joe Medley.

Last up to date: Improve article

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