Squircle CSS Houdini

A tiny CSS Houdini module that allows adding a squircle shape to HTML elements.

---

🎻  Demo on GitHub Pages

👾  Codepen examples

📦  NPM package

🗞  Medium article

---

🚀 Usage

Add the script

In order to use the module, you need to add the script to your HTML file. But it's not a usual JS module that you can import.

// Vanilla JS and Create React App
// Add the script to the index.html file

<script>
  if ("paintWorklet" in CSS) {
    CSS.paintWorklet.addModule(
      "https://www.unpkg.com/css-houdini-squircle/squircle.min.js"
    );
  }
</script>

// NextJS for TSX files
// Add the script to the _app.js file (or any other file that is loaded on every page)

React.useEffect(() => {
  (CSS as any).paintWorklet.addModule("squircle.min.js");
}, []);

Add the styles

/* use mask */
.squircle {
  width: 200px;
  height: 200px;
  background: linear-gradient(45deg, yellow, blue);
  --squircle-smooth: 1;
  --squircle-radius: 10px;
  mask-image: paint(squircle);
}

/* use background */
.squircle {
  width: 200px;
  height: 200px;
  background: paint(squircle);
  --squircle-smooth: 1;
  --squircle-radius: 10px;
  --squircle-fill: #f45;
}

👉 codepen example

---

🎛  Custom CSS Properties

--squircle-radius property

The property controls the roundness of the corners. You can provide 1, 2, 3 or 4 values, similar to padding/margin in CSS. The order is clockwise: top left, top right, bottom right, bottom left

• Syntax: <px> OR <px px> OR <px px px> OR <px px px px>
• Defaul value: 8px (if no radius at all is defined) OR: 0 (if only some radii are defined)
• Min/Max values: — (the radii are capped at half of the shorter side of width/ height)

--squircle-radius-top-left, --squircle-radius-top-right, --squircle-radius-bottom-right, --squircle-radius-bottom-left

Set radii for the corners individually

/* Usage */

.squircle {
  /* other properties */
  width: 200px;
  height: 200px;
  background: paint(squircle);
  /* the property */
  --squircle-radius: 20px;
}

---

individual border radius

The property controls the roundness of the corners individually.

/* Usage */

.squircle {
  /* other properties */
  width: 200px;
  height: 200px;
  background: paint(squircle);
  /* the property */
  --squircle-radius-top-left: 0px;
  --squircle-radius-top-right: 15px;
  --squircle-radius-bottom-right: 30px;
  --squircle-radius-bottom-left: 40px;
}

---

--squircle-smooth property

The property controls the length of bezier guide lines. Could be defined by --squircle-ratio.

• Syntax: <number>
• Defaul value: 1
• Min/Max values: 0.1 / 1

/* Usage */

.squircle {
  /* other properties */
  width: 200px;
  height: 200px;
  background: paint(squircle);
  --squircle-radius: 20px;
  /* the property */
  --squircle-smooth: 0.5;
}

---

--squircle-outline property

The property controls squircle outline. There are two methods how too use it with background-mask and mask+:pseudo-element. to find out more check codepen examples.

• Syntax: <px>
• Defaul value: —
• Min/Max values: —

/* Usage */

.squircle {
  /* other properties */
  width: 200px;
  height: 200px;
  background: paint(squircle);
  --squircle-radius: 20px;
  /* the property */
  --squircle-outline: 5px;
}

---

--squircle-fill property

The property accepts any color, including variables.

⚠️ Work only with background: paint(squircle);. For mask-image: paint(squircle); use background property.

• Syntax: <color>
• Defaul value: #f45
• Min/Max values: —

/* Usage */

.squircle {
  /* other properties */
  width: 200px;
  height: 200px;
  background: paint(squircle);
  --squircle-radius: 20px;
  /* the property */
  --squircle-fill: #f45;
}

---

🕹  How to install particular version

// latest version
<script>
  if ("paintWorklet" in CSS) {
    CSS.paintWorklet.addModule(
      "https://www.unpkg.com/css-houdini-squircle/squircle.min.js"
    );
  }
</script>

// or particular version
<script>
  if ("paintWorklet" in CSS) {
    CSS.paintWorklet.addModule(
      "https://www.unpkg.com/css-houdini-squircle@0.3.0/squircle.min.js"
    );
  }
</script>

Install via NPM

npm i css-houdini-squircle

Download

You can download the min version of the module from UNPKG

// latest version
https://www.unpkg.com/browse/css-houdini-squircle/squircle.min.js

---

✨  Use css-paint-polyfill

In order to get the module work on other browsers, you can use Paint Worklets polyfill.

⚠️ Check for artefacts before deploying.

// use with polifill example
<script>
  (async function () {
    if (!("paintWorklet" in CSS)) {
      await import("css-paint-polyfill");
    }

    CSS.paintWorklet.addModule(
      `https://www.unpkg.com/css-houdini-squircle/squircle.min.js`
    );
  })();
</script>

---

Contributing and testing

If you have any ideas, just open an issue and tell what you think.

If you'd like to contribute, please fork the repository. Pull requests are warmly welcome.

The project structure is separated into nextJS app and lib folder. The lib folder contains the script itself. The nextJS app is used for the demo. The lib folder is a separate NPM package.

📁 root
  📁 lib
    - package.json
    - squircle.js
  📁 … other nextJS folders

In order to test the script locally:

1. you need to run npm run dev in the root folder. It will start the NextJS app.
2. Then you need to run npm run watch:build in the lib folder. It will start the watcher for the script. It will build the script every time you change it and create squircle.min.js file in the lib folder and in the public folder of the NextJS app.
3. In the index.tsx file of the NextJS app, you can uncomment the line with test section un comment other in order to ease the development process.

---

Change log (v0.3.0)

• Removed --squircle-ratio property. It's now fixed to 1.8. It's still possible to change the ratio by changing --squircle-smooth property.
• Moved the demo to NextJS
• Added --squircle-radius-top-left, --squircle-radius-top-right, --squircle-radius-bottom-right, --squircle-radius-bottom-left properties
• Added separate lib folder only for the script