robmc.github.io/custom_slider.html at master · robmc/robmc.github.io · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Spiral Tap</title>
    <style>
        :root {
            --primary: #04AA6D;
            --bg: #ddd;
            --dial-size: 200px;
        }

        body {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            height: 100vh;
            background: #f4f4f4;
            font-family: sans-serif;
            margin: 0;
        }

        .dial-wrapper {
            position: relative;
            width: var(--dial-size);
            height: var(--dial-size);
            user-select: none;
        }

        /* The Numbers positioned around the dial */
        .label {
            position: absolute;
            width: 24px;
            height: 24px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: bold;
            color: #666;
            font-size: 14px;
            transform: translate(-50%, -50%);
            pointer-events: none; /* Let clicks pass through to the dial */
        }

        /* The Rotating Knob */
        #knob {
            position: absolute;
            top: 25px;
            left: 25px;
            width: 150px;
            height: 150px;
            background: white;
            border-radius: 50%;
            box-shadow: 0 10px 20px rgba(0,0,0,0.15), inset 0 2px 5px white;
            cursor: pointer;
            z-index: 2;
            transition: outline 0.1s ease;
        }

        /* Accessibility Focus Style */
        #knob:focus {
            outline: 3px solid var(--primary);
            outline-offset: 5px;
        }

        /* The Pointer Dot */
        #pointer {
            position: absolute;
            top: 15px;
            left: 50%;
            width: 12px;
            height: 12px;
            background: var(--primary);
            border-radius: 50%;
            transform: translateX(-50%);
        }

        h1 { margin-bottom: 40px; }
        #status { margin-top: 40px; font-size: 1.5rem; color: var(--primary); font-weight: bold; }
    </style>
</head>
<body>

    <h1>This slider goes to 11...</h1>

    <div class="dial-wrapper" id="container">
        <div id="knob"
             tabindex="0"
             role="slider"
             aria-label="Volume"
             aria-valuemin="0"
             aria-valuemax="11"
             aria-valuenow="0">
            <div id="pointer"></div>
        </div>
    </div>

    <div id="status">Volume: 0</div>
		<footer style="margin-top: 50px;">
			<a href="http://robertjmccaffery.com/examples.html">Back to Examples</a> | <a href="http://robertjmccaffery.com/">Home</a>
		</footer>
    <script>
        const container = document.getElementById('container');
        const knob = document.getElementById('knob');
        const status = document.getElementById('status');

        const totalValues = 12; // 0 through 11
        const step = 360 / totalValues;
        const radius = 90; // Distance of labels from center
        let currentVal = 0;

        // 1. GENERATE LABELS
        for (let i = 0; i < totalValues; i++) {
            const label = document.createElement('div');
            label.className = 'label';
            label.innerText = i;

            // Calculate position: (i / 12) * 360 degrees, adjusted by -90 so 0 is at top
            const angle = (i * step - 90) * (Math.PI / 180);
            const x = 100 + radius * Math.cos(angle);
            const y = 100 + radius * Math.sin(angle);

            label.style.left = `${x}px`;
            label.style.top = `${y}px`;
            container.appendChild(label);
        }

        // 2. CORE UPDATE LOGIC
        function setVolume(val) {
            if (val < 0) val = 0;
            if (val > 11) val = 11;

            currentVal = val;

            // Apply rotation and update text
            knob.style.transform = `rotate(${val * step}deg)`;
            status.innerText = `Volume: ${val}`;

            // Update ARIA for accessibility
            knob.setAttribute('aria-valuenow', val);
        }

        // 3. KEYBOARD INTERACTION
        knob.addEventListener('keydown', (e) => {
            if (e.key === 'ArrowUp' || e.key === 'ArrowRight') {
                e.preventDefault();
                setVolume(currentVal + 1);
            } else if (e.key === 'ArrowDown' || e.key === 'ArrowLeft') {
                e.preventDefault();
                setVolume(currentVal - 1);
            } else if (e.key === 'Home') {
                setVolume(0);
            } else if (e.key === 'End') {
                setVolume(11);
            }
        });

        // 4. MOUSE & TOUCH INTERACTION
        let isDragging = false;

        const updateFromPointer = (e) => {
            if (!isDragging) return;

            const rect = container.getBoundingClientRect();
            const centerX = rect.left + rect.width / 2;
            const centerY = rect.top + rect.height / 2;

            const clientX = e.touches ? e.touches[0].clientX : e.clientX;
            const clientY = e.touches ? e.touches[0].clientY : e.clientY;

            const mouseX = clientX - centerX;
            const mouseY = clientY - centerY;

            // atan2 gives angle in radians, convert to degrees and adjust offset
            let deg = Math.atan2(mouseY, mouseX) * (180 / Math.PI) + 90;
            if (deg < 0) deg += 360;

            const val = Math.round(deg / step) % totalValues;
            setVolume(val);
        };

        // Event Bindings
        knob.addEventListener('mousedown', () => isDragging = true);
        window.addEventListener('mouseup', () => isDragging = false);
        window.addEventListener('mousemove', updateFromPointer);

        knob.addEventListener('touchstart', (e) => { e.preventDefault(); isDragging = true; });
        window.addEventListener('touchend', () => isDragging = false);
        window.addEventListener('touchmove', updateFromPointer);

    </script>
</body>

</html>