When turning Dark off (Dark -> Light transition), the NEW layer is Light.
Previously we tried shrinking the OLD layer (Dark) over it, but if the
root snapshot captured a transparent html, revealing the transparent layer
produced no visual change.
Now we:
1. Always keep the NEW layer on top (z-index: 2).
2. Always animate the NEW layer expanding from 0 to max radius.
3. Explicitly set background-color on html in input.css to ensure the
VT root snapshots are fully opaque, avoiding transparent captures that
make expansions invisible.
4. Add background: var(--color-paper-theme) directly to ::view-transition-new
just to be absolutely certain it's painted opaque.
Adopt a fully CSS-driven strategy for the theme transition:
- Use CSS variables (--tt-x, --tt-y, --tt-r) injected onto documentElement
- Define static @keyframes in style.css using these variables
- Key logic: the Dark layer is ALWAYS placed on top (z-index: 2).
- Light -> Dark: NEW layer is Dark, so NEW expands from circle(0) to cover OLD.
- Dark -> Light: OLD layer is Dark, so OLD shrinks to circle(0) to reveal NEW.
This completely eliminates reliance on Web Animations API (which had bugs
with clip-path when animation:none is set) and eliminates dynamic <style>
injection (which caused timing gaps and style residue).
The result is perfectly symmetrical and bug-free in both directions.
Chrome does not allow WAAPI clip-path animations on ::view-transition-new
when animation:none !important is set via CSS. This caused dark→light
transitions to have no visible animation.
Replace with opacity:1 !important to neutralize the UA fade-in/out
animations: the UA animations still 'run' but cannot change opacity
because !important author declarations override CSS animation values.
WAAPI clip-path is no longer blocked.
Gray expanding circle was caused by UA default animations (fade-in/out)
and mix-blend-mode: plus-lighter not being fully overridden by WAAPI
opacity animations alone.
Fix: use CSS with !important to hard-lock the VT pseudo-elements:
- animation: none !important — kills UA fade-in/out
- opacity: 1 !important — both layers stay fully opaque
- mix-blend-mode: normal !important — no color addition
WAAPI now only controls clip-path on ::view-transition-new(root),
which doesn't conflict with any CSS property (no CSS clip-path exists).
This cleanly separates concerns: CSS handles static properties,
WAAPI handles the dynamic circle expansion.
Replace dynamic <style> injection (@keyframes + pseudo-element rules)
with document.documentElement.animate({ pseudoElement }) calls.
Previous approach accumulated <style> elements across transitions,
causing subsequent dark→light animations to be invisible. The Web
Animations API:
- Creates per-call Animation objects with no DOM residue
- Has higher composite priority than CSS animations, naturally
overriding UA default fade-in/out without !important
- Eliminates style element lifecycle management entirely
Static CSS now only sets mix-blend-mode: normal (not animatable via
WAAPI) and the is-theme-transitioning transition suppression.
Previous approach injected ::view-transition-new animation in vt.ready,
creating a timing gap where the NEW layer had no clip-path and was fully
visible, making dark→light transitions invisible.
Now:
- Inject <style> with @keyframes + VT pseudo-element rules BEFORE
calling startViewTransition, so styles are ready when pseudo-elements
are created.
- Force synchronous getComputedStyle() in VT callback to ensure the
NEW snapshot captures final background-color, not a mid-transition
value.
The static CSS rule 'animation: none' on ::view-transition-new(root)
caused the new (light) screenshot to be fully visible before the JS-
injected clip-path @keyframes kicked in. This meant the light layer
was already covering the dark layer, making the expanding circle
invisible.
Fix: move all VT pseudo-element styles (animation, mix-blend-mode)
into the dynamically injected <style> block in vt.ready, so they
apply atomically with the clip-path keyframes.
Also:
- Add transition:none !important during VT to prevent body's
background-color 0.3s transition from producing a stale capture.
- Restore Dioxus theme.set() that was disabled for debugging, so
the toggle icon and localStorage persist correctly.
- Use !important on injected animation to reliably override any
UA default VT animations.
body 有 transition: background-color .3s,VT 在 toggle dark class
后下一帧拍 NEW 快照时背景色才走了 ~5%,新旧快照几乎一样,
圆形展开看不出颜色差。修复:回调里加 vt-freeze 类禁用所有
过渡,让 NEW 快照立即拿到新主题配色;动画结束(finished)后
移除。补 1 个测试覆盖 freeze 生命周期。
