KirinCode/packages/ui/src/components/text-reveal.css

/*
 * TextReveal — mask-position wipe animation
 *
 * Instead of sliding text through a fixed mask (odometer style),
 * the mask itself sweeps across each span to reveal/hide text.
 *
 * Direction: top-to-bottom. New text drops in from above, old text exits downward.
 *
 * Entering: gradient reveals top-to-bottom (top of text appears first).
 *   gradient(to bottom, white 33%, transparent 33%+edge)
 *   pos 0 100% = transparent covers element = hidden
 *   pos 0 0%   = white covers element       = visible
 *
 * Leaving: gradient hides top-to-bottom (top of text disappears first).
 *   gradient(to top, white 33%, transparent 33%+edge)
 *   pos 0 100% = white covers element       = visible
 *   pos 0 0%   = transparent covers element = hidden
 *
 * Both transition from 0 100% (swap) → 0 0% (settled).
 */

[data-component="text-reveal"] {
  --_edge: var(--text-reveal-edge, 17%);
  --_dur: var(--text-reveal-duration, 450ms);
  --_spring: var(--text-reveal-spring, cubic-bezier(0.34, 1.08, 0.64, 1));
  --_spring-soft: var(--text-reveal-spring-soft, cubic-bezier(0.34, 1, 0.64, 1));
  --_travel: var(--text-reveal-travel, 0px);

  display: inline-flex;
  align-items: center;
  min-width: 0;
  overflow: visible;

  [data-slot="text-reveal-track"] {
    display: grid;
    min-height: 20px;
    line-height: 20px;
    justify-items: start;
    align-items: center;
    overflow: visible;
    transition: width var(--_dur) var(--_spring-soft);
  }

  [data-slot="text-reveal-entering"],
  [data-slot="text-reveal-leaving"] {
    grid-area: 1 / 1;
    line-height: 20px;
    white-space: nowrap;
    justify-self: start;
    text-align: start;
    mask-size: 100% 300%;
    -webkit-mask-size: 100% 300%;
    mask-repeat: no-repeat;
    -webkit-mask-repeat: no-repeat;
    transition-duration: var(--_dur);
    transition-timing-function: var(--_spring);
  }

  /* ── entering: reveal top-to-bottom ──
   * Gradient(to top): white at bottom, transparent at top of mask.
   * Settled pos 0 100% = white covers element   = visible
   * Swap    pos 0 0%   = transparent covers      = hidden
   * Slides from above: translateY(-travel) → translateY(0)
   */
  [data-slot="text-reveal-entering"] {
    mask-image: linear-gradient(to top, white 33%, transparent calc(33% + var(--_edge)));
    -webkit-mask-image: linear-gradient(to top, white 33%, transparent calc(33% + var(--_edge)));
    mask-position: 0 100%;
    -webkit-mask-position: 0 100%;
    transition-property:
      mask-position,
      -webkit-mask-position,
      transform;
    transform: translateY(0);
  }

  /* ── leaving: hide top-to-bottom + slide downward ──
   * Gradient(to bottom): white at top, transparent at bottom of mask.
   * Swap    pos 0 0%   = white covers element   = visible
   * Settled pos 0 100% = transparent covers      = hidden
   * Slides down: translateY(0) → translateY(travel)
   */
  [data-slot="text-reveal-leaving"] {
    mask-image: linear-gradient(to bottom, white 33%, transparent calc(33% + var(--_edge)));
    -webkit-mask-image: linear-gradient(to bottom, white 33%, transparent calc(33% + var(--_edge)));
    mask-position: 0 100%;
    -webkit-mask-position: 0 100%;
    transition-property:
      mask-position,
      -webkit-mask-position,
      transform;
    transform: translateY(var(--_travel));
  }

  /* ── swapping: instant reset ──
   * Snap entering to hidden (above), leaving to visible (center).
   */
  &[data-swapping="true"] [data-slot="text-reveal-entering"] {
    mask-position: 0 0%;
    -webkit-mask-position: 0 0%;
    transform: translateY(calc(var(--_travel) * -1));
    transition-duration: 0ms !important;
  }

  &[data-swapping="true"] [data-slot="text-reveal-leaving"] {
    mask-position: 0 0%;
    -webkit-mask-position: 0 0%;
    transform: translateY(0);
    transition-duration: 0ms !important;
  }

  /* ── not ready: kill all transitions ── */
  &[data-ready="false"] [data-slot="text-reveal-track"] {
    transition-duration: 0ms !important;
  }

  &[data-ready="false"] [data-slot="text-reveal-entering"],
  &[data-ready="false"] [data-slot="text-reveal-leaving"] {
    transition-duration: 0ms !important;
  }

  &[data-truncate="true"] {
    width: 100%;
  }

  &[data-truncate="true"] [data-slot="text-reveal-track"] {
    width: 100%;
    min-width: 0;
    overflow: hidden;
  }

  &[data-truncate="true"] [data-slot="text-reveal-entering"],
  &[data-truncate="true"] [data-slot="text-reveal-leaving"] {
    min-width: 0;
    width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
  }
}

@media (prefers-reduced-motion: reduce) {
  [data-component="text-reveal"] [data-slot="text-reveal-track"] {
    transition-duration: 0ms !important;
  }

  [data-component="text-reveal"] [data-slot="text-reveal-entering"],
  [data-component="text-reveal"] [data-slot="text-reveal-leaving"] {
    transition-duration: 0ms !important;
  }
}