Text State Swap

<!--
  Text State Swap - transitions.dev-inspired primitive for HyperFrames.

  Paste the markup, CSS and script into a composition. Use the timeline
  integration note at the bottom as the starting point for deterministic GSAP
  animation.

  Variables. The script reads each one, falls back to the declared default on
  anything missing or unrecognised, and writes the result into the markup or
  into a custom property the CSS above consumes. The timeline recipe below is
  untouched by them: it keeps driving one offset and one blur, and these decide
  what that offset means on screen.

    - from-text (string, default "Saving draft"): the outgoing label, on screen
      before the swap. Blank falls back to the default.
    - to-text (string, default "Saved"): the incoming label, on screen after the
      swap. It rests at zero opacity, so it only shows once the timeline reveals
      it. Blank falls back to the default.
    - distance (close | standard | far, default standard): scales the vertical
      offset the timeline drives, so the outgoing label leaves further and the
      incoming label starts further below, in the same time. Both labels rest at
      their settled position on every setting, so this only changes the middle
      of the swap.
    - tone (ink | paper | accent, default ink): label colour for both states.
      ink is near-black for light frames, paper near-white for dark ones, accent
      rides --brand.

  On every default the result is identical to the original: near-black
  "Saving draft" lifts 18px through an 8px blur while "Saved" rises into place.
-->

<div
  class="hf-transition-text-state-swap"
  data-composition-variables='[
    {"id": "from-text", "type": "string", "role": "content", "label": "From text", "description": "The outgoing label, on screen before the swap.", "default": "Saving draft"},
    {"id": "to-text", "type": "string", "role": "content", "label": "To text", "description": "The incoming label, on screen after the swap. It rests hidden until the timeline reveals it.", "default": "Saved"},
    {"id": "distance", "type": "enum", "role": "motion", "label": "Distance", "description": "Scales the vertical offset the timeline drives, so each label covers a shorter or longer run in the same time.", "default": "standard", "options": [{"value": "close", "label": "Close"}, {"value": "standard", "label": "Standard"}, {"value": "far", "label": "Far"}]},
    {"id": "tone", "type": "enum", "role": "style", "label": "Tone", "description": "Label colour: ink for light frames, paper for dark ones, accent rides --brand.", "default": "ink", "options": [{"value": "ink", "label": "Ink"}, {"value": "paper", "label": "Paper"}, {"value": "accent", "label": "Accent"}]}
  ]'
>
  <span class="from">Saving draft</span><span class="to">Saved</span>
</div>

<style>
  .hf-transition-text-state-swap {
    position: relative;
    width: 250px;
    height: 36px;
    color: var(--hf-text-color, #18181b);
    font:
      900 28px/1 Inter,
      system-ui,
      sans-serif;
  }
  .hf-transition-text-state-swap span {
    position: absolute;
    left: 0;
    top: 0;
    filter: blur(var(--hf-text-blur, 0px));
    transform: translateY(calc(var(--hf-text-y, 0px) * var(--hf-text-reach, 1)));
    will-change: transform, filter, opacity;
  }
  .hf-transition-text-state-swap .to {
    opacity: 0;
  }
</style>

<script>
  (function () {
    "use strict";

    var vars =
      window.__hyperframes && window.__hyperframes.getVariables
        ? window.__hyperframes.getVariables()
        : {};

    // Unrecognised overrides return to their declared defaults.
    var reaches = { close: 0.5, standard: 1, far: 1.85 };
    var tones = {
      ink: "#18181b",
      paper: "#fafafa",
      accent: "var(--brand, #34d399)",
    };

    function pick(table, value, fallback) {
      return Object.prototype.hasOwnProperty.call(table, value) ? value : fallback;
    }

    function text(value, fallback) {
      var resolved = value == null ? "" : String(value).trim();
      return resolved.length > 0 ? resolved : fallback;
    }

    var fromText = text(vars["from-text"], "Saving draft");
    var toText = text(vars["to-text"], "Saved");
    var reach = reaches[pick(reaches, vars.distance, "standard")];
    var tone = tones[pick(tones, vars.tone, "ink")];

    var roots = document.querySelectorAll(".hf-transition-text-state-swap");
    for (var i = 0; i < roots.length; i += 1) {
      var root = roots[i];
      root.style.setProperty("--hf-text-reach", String(reach));
      root.style.setProperty("--hf-text-color", tone);
      root.querySelector(".from").textContent = fromText;
      root.querySelector(".to").textContent = toText;
    }
  })();
</script>

<!--
  Timeline integration:
  tl.to('.hf-transition-text-state-swap .from', { opacity: 0, '--hf-text-y': '-18px', '--hf-text-blur': '8px', duration: 0.18, ease: 'power2.in' }, startTime); tl.fromTo('.hf-transition-text-state-swap .to', { opacity: 0, '--hf-text-y': '18px', '--hf-text-blur': '8px' }, { opacity: 1, '--hf-text-y': '0px', '--hf-text-blur': '0px', duration: 0.26, ease: 'power2.out' }, startTime + 0.12);
-->