69 lines
1.9 KiB
Markdown
69 lines
1.9 KiB
Markdown
---
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title: Mouse cursor gradient tracking
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tags: visual,interactivity
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expertise: advanced
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cover: blog_images/tram-car.jpg
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firstSeen: 2018-02-25T15:14:39+02:00
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lastUpdated: 2021-01-07T23:52:15+02:00
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---
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A hover effect where the gradient follows the mouse cursor.
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- Declare two CSS variables, `--x` and `--y`, used to track the position of the mouse on the button.
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- Declare a CSS variable, `--size`, used to modify the gradient's dimensions.
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- Use `background: radial-gradient(circle closest-side, pink, transparent)` to create the gradient at the correct position.
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- Use `Document.querySelector()` and `EventTarget.addEventListener()` to register a handler for the `'mousemove'` event.
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- Use `Element.getBoundingClientRect()` and `CSSStyleDeclaration.setProperty()` to update the values of the `--x` and `--y` CSS variables.
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```html
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<button class="mouse-cursor-gradient-tracking">
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<span>Hover me</span>
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</button>
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```
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```css
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.mouse-cursor-gradient-tracking {
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position: relative;
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background: #7983ff;
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padding: 0.5rem 1rem;
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font-size: 1.2rem;
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border: none;
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color: white;
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cursor: pointer;
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outline: none;
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overflow: hidden;
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}
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.mouse-cursor-gradient-tracking span {
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position: relative;
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}
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.mouse-cursor-gradient-tracking:before {
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--size: 0;
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content: '';
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position: absolute;
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left: var(--x);
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top: var(--y);
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width: var(--size);
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height: var(--size);
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background: radial-gradient(circle closest-side, pink, transparent);
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transform: translate(-50%, -50%);
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transition: width 0.2s ease, height 0.2s ease;
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}
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.mouse-cursor-gradient-tracking:hover:before {
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--size: 200px;
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}
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```
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```js
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let btn = document.querySelector('.mouse-cursor-gradient-tracking');
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btn.addEventListener('mousemove', e => {
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let rect = e.target.getBoundingClientRect();
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let x = e.clientX - rect.left;
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let y = e.clientY - rect.top;
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btn.style.setProperty('--x', x + 'px');
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btn.style.setProperty('--y', y + 'px');
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});
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```
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