MediaWiki:Gadget-AnimatedCursorFollower.js

Note: After publishing, you may have to bypass your browser's cache to see the changes.

• Firefox / Safari: Hold Shift while clicking Reload, or press either Ctrl-F5 or Ctrl-R (⌘-R on a Mac)
• Google Chrome: Press Ctrl-Shift-R (⌘-Shift-R on a Mac)
• Edge: Hold Ctrl while clicking Refresh, or press Ctrl-F5.

/**
 * Animated Cursor Follower
 * Clones a WalkScape sprite and makes it follow the mouse.
 */

(function () {
	'use strict';

	const CONFIG = {
		scale: 1.5,
		speed: 0.5,
		offsetX: 30,
		offsetY: 30
	};

	const state = {
		targetX: window.innerWidth / 2,
		targetY: window.innerHeight / 2,
		currentX: window.innerWidth / 2,
		currentY: window.innerHeight / 2,
		facingRight: true,
		reqId: null
	};

	let mounted = false;
	let centerOffset = 36;

	function mountPet(sourceNode) {
		if (mounted) return;
		mounted = true;

		const wrapper = document.createElement('span');
		const pet = sourceNode.cloneNode(true);
		const styles = window.getComputedStyle(sourceNode);
		const frameSize = parseInt(styles.getPropertyValue('--frame'), 10) || 48;

		centerOffset = (frameSize * CONFIG.scale) / 2;

		wrapper.className = 'animated-cursor-follower-wrapper';

		Object.assign(wrapper.style, {
			position: 'fixed',
			top: '0',
			left: '0',
			pointerEvents: 'none',
			zIndex: '99999',
			margin: '0',
			willChange: 'transform',
			transition: 'none'
		});

		// Let the existing ws-sprite CSS/JS handle sprite rendering.
		pet.removeAttribute('style');
		pet.className = sourceNode.className;
		pet.style.setProperty('--scale', String(CONFIG.scale));
		pet.style.display = 'inline-block';

		wrapper.appendChild(pet);
		document.body.appendChild(wrapper);

		document.addEventListener('mousemove', function (e) {
			state.targetX = e.clientX + CONFIG.offsetX;
			state.targetY = e.clientY + CONFIG.offsetY;
		}, { passive: true });

		document.addEventListener('mouseleave', function () {
			if (state.reqId) {
				cancelAnimationFrame(state.reqId);
				state.reqId = null;
			}
		});

		document.addEventListener('mouseenter', function () {
			if (!state.reqId) {
				render();
			}
		});

		function render() {
			state.currentX += (state.targetX - state.currentX) * CONFIG.speed;
			state.currentY += (state.targetY - state.currentY) * CONFIG.speed;

			if (state.targetX > state.currentX + 1) {
				state.facingRight = true;
			} else if (state.targetX < state.currentX - 1) {
				state.facingRight = false;
			}

			const scaleX = state.facingRight ? 1 : -1;

			wrapper.style.transform =
				`translate3d(${state.currentX - centerOffset}px, ` +
				`${state.currentY - centerOffset}px, 0) scaleX(${scaleX})`;

			state.reqId = requestAnimationFrame(render);
		}

		render();
	}

	function init() {
		const sprite = document.querySelector(
			'span.ws-sprite:not(.animated-cursor-follower-wrapper span.ws-sprite)'
		);

		if (!sprite) {
			setTimeout(init, 500);
			return;
		}

		mountPet(sprite);
	}

	$(init);

}());