| 1 |
(function () { |
| 2 |
'use strict'; |
| 3 |
|
| 4 |
function reducedMotion() { |
| 5 |
return window.matchMedia && window.matchMedia('(prefers-reduced-motion: reduce)').matches; |
| 6 |
} |
| 7 |
|
| 8 |
function initStickyScroll(wrap) { |
| 9 |
if (wrap.dataset.activate !== '1') return; |
| 10 |
|
| 11 |
var panels = Array.prototype.slice.call(wrap.querySelectorAll('.bkss-panel')); |
| 12 |
var imageWrap = wrap.querySelector('.bkss-image-wrap'); |
| 13 |
|
| 14 |
if (!panels.length || !imageWrap) return; |
| 15 |
|
| 16 |
// Reduced motion: keep all panels fully visible, skip crossfade |
| 17 |
if (reducedMotion()) { |
| 18 |
panels.forEach(function (p) { p.classList.add('bkss-active'); }); |
| 19 |
return; |
| 20 |
} |
| 21 |
|
| 22 |
var activeIdx = 0; |
| 23 |
|
| 24 |
function setActive(idx) { |
| 25 |
if (idx === activeIdx) return; |
| 26 |
activeIdx = idx; |
| 27 |
panels.forEach(function (p, i) { |
| 28 |
p.classList.toggle('bkss-active', i === idx); |
| 29 |
}); |
| 30 |
|
| 31 |
// Swap pinned image (crossfade) |
| 32 |
var newUrl = panels[idx].dataset.image || ''; |
| 33 |
var existing = imageWrap.querySelector('img, .bkss-placeholder'); |
| 34 |
if (!newUrl) { |
| 35 |
if (existing && existing.tagName === 'IMG') { |
| 36 |
existing.style.opacity = '0.4'; |
| 37 |
} |
| 38 |
return; |
| 39 |
} |
| 40 |
|
| 41 |
// Check if same image |
| 42 |
if (existing && existing.tagName === 'IMG' && existing.src === newUrl) { |
| 43 |
existing.style.opacity = '1'; |
| 44 |
return; |
| 45 |
} |
| 46 |
|
| 47 |
// Build new image, fade in |
| 48 |
var img = document.createElement('img'); |
| 49 |
img.src = newUrl; |
| 50 |
img.alt = ''; |
| 51 |
img.style.width = '100%'; |
| 52 |
img.style.display = 'block'; |
| 53 |
img.style.opacity = '0'; |
| 54 |
img.style.transition = 'opacity 0.35s ease'; |
| 55 |
|
| 56 |
// Copy border-radius from existing image |
| 57 |
if (existing) { |
| 58 |
img.style.borderRadius = getComputedStyle(existing).borderRadius; |
| 59 |
img.style.boxShadow = getComputedStyle(existing).boxShadow; |
| 60 |
} |
| 61 |
|
| 62 |
img.onload = function () { |
| 63 |
// Fade out old, fade in new |
| 64 |
if (existing) { |
| 65 |
existing.style.transition = 'opacity 0.2s ease'; |
| 66 |
existing.style.opacity = '0'; |
| 67 |
setTimeout(function () { |
| 68 |
if (existing.parentNode) existing.parentNode.removeChild(existing); |
| 69 |
}, 220); |
| 70 |
} |
| 71 |
imageWrap.appendChild(img); |
| 72 |
requestAnimationFrame(function () { |
| 73 |
img.style.opacity = '1'; |
| 74 |
}); |
| 75 |
}; |
| 76 |
} |
| 77 |
|
| 78 |
// IntersectionObserver — each panel triggers when it crosses center of viewport |
| 79 |
var observers = []; |
| 80 |
|
| 81 |
panels.forEach(function (panel, idx) { |
| 82 |
var obs = new IntersectionObserver(function (entries) { |
| 83 |
entries.forEach(function (entry) { |
| 84 |
if (entry.isIntersecting) { |
| 85 |
setActive(idx); |
| 86 |
} |
| 87 |
}); |
| 88 |
}, { threshold: 0.5, rootMargin: '-20% 0px -20% 0px' }); |
| 89 |
|
| 90 |
obs.observe(panel); |
| 91 |
observers.push(obs); |
| 92 |
}); |
| 93 |
|
| 94 |
// Initialise with first panel active |
| 95 |
panels[0] && panels[0].classList.add('bkss-active'); |
| 96 |
} |
| 97 |
|
| 98 |
function init() { |
| 99 |
document.querySelectorAll('.bkss-wrap').forEach(initStickyScroll); |
| 100 |
} |
| 101 |
|
| 102 |
if (typeof IntersectionObserver === 'undefined') { |
| 103 |
// Fallback: show all panels fully |
| 104 |
document.querySelectorAll('.bkss-panel').forEach(function (p) { |
| 105 |
p.style.opacity = '1'; |
| 106 |
}); |
| 107 |
return; |
| 108 |
} |
| 109 |
|
| 110 |
if (document.readyState === 'loading') { |
| 111 |
document.addEventListener('DOMContentLoaded', init); |
| 112 |
} else { |
| 113 |
init(); |
| 114 |
} |
| 115 |
|
| 116 |
}()); |
| 117 |
|
