prime8dev

commit 492c102c8e36d8970cc69a94527a7eed505a6519
parent ac6a01a5d715d47344e34f897e6803f987818b72
Author: Damian Myrda <damian@prime8.dev>
Date:   Wed, 21 Oct 2026 01:57:18 +0000

feat(web): line-by-line reveal on tab switch and project detail

After an htmx swap of the content or project detail, visible lines
appear one after another within a ~450ms budget, like output being
printed. Skipped under prefers-reduced-motion.

Diffstat:
M
internal/web/scripts/app.js
 | 
5
+++++
A
internal/web/scripts/modules/reveal.js
 | 
72
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
internal/web/styles/layout.css
 | 
7
+++++++

3 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/internal/web/scripts/app.js b/internal/web/scripts/app.js
@@ -5,6 +5,7 @@ import { initHelp } from "./modules/help.js";
 import { initLayout } from "./modules/layout.js";
 import { initLightbox } from "./modules/lightbox.js";
 import { initProjects } from "./modules/projects.js";
+import { revealLines } from "./modules/reveal.js";
 
 function initApp() {
   initHeader();
@@ -25,8 +26,12 @@ function initApp() {
 
     switch (e.target.id) {
       case "content":
+        initDynamicContent();
+        revealLines(e.target);
+        break;
       case "project-detail":
         initDynamicContent();
+        revealLines(e.target);
         break;
       default:
         break;
diff --git a/internal/web/scripts/modules/reveal.js b/internal/web/scripts/modules/reveal.js
@@ -0,0 +1,72 @@
+const SKIP = new Set(["STYLE", "SCRIPT", "TEMPLATE", "NOSCRIPT"]);
+const ATOMIC = new Set(["PRE", "IMG", "SVG", "VIDEO", "CANVAS", "IFRAME", "TABLE"]);
+const BLOCKISH = /^(block|flex|grid|list-item|table|flow-root)$/;
+const BUDGET_MS = 450;
+const MAX_STEP_MS = 14;
+
+const pending = new Map();
+
+export function revealLines(root) {
+  if (!root || window.matchMedia("(prefers-reduced-motion: reduce)").matches) return;
+
+  for (const [r] of pending) {
+    if (r === root || r.contains(root) || root.contains(r)) cleanup(r);
+  }
+
+  const lines = collectLines(root).filter(onScreen);
+  if (lines.length === 0) return;
+
+  const step = Math.min(MAX_STEP_MS, BUDGET_MS / lines.length);
+  root.style.setProperty("--line-ms", `${step}ms`);
+  lines.forEach((el, i) => {
+    el.style.setProperty("--line", String(i));
+    el.classList.add("line-in");
+  });
+
+  const timer = window.setTimeout(() => cleanup(root), step * lines.length + 50);
+  pending.set(root, { lines, timer });
+}
+
+function cleanup(root) {
+  const entry = pending.get(root);
+  if (!entry) return;
+  pending.delete(root);
+  window.clearTimeout(entry.timer);
+  root.style.removeProperty("--line-ms");
+  for (const el of entry.lines) {
+    el.classList.remove("line-in");
+    el.style.removeProperty("--line");
+  }
+}
+
+function onScreen(el) {
+  const r = el.getBoundingClientRect();
+  return r.bottom > 0 && r.top < window.innerHeight && r.width > 0;
+}
+
+function collectLines(root) {
+  const lines = [];
+  const walk = (el) => {
+    for (const child of el.children) {
+      if (SKIP.has(child.tagName)) continue;
+      if (getComputedStyle(child).display === "none") continue;
+      if (isLine(child)) {
+        lines.push(child);
+      } else {
+        walk(child);
+      }
+    }
+  };
+  walk(root);
+  return lines;
+}
+
+function isLine(el) {
+  if (ATOMIC.has(el.tagName.toUpperCase())) return true;
+  if (el.classList.contains("tags") || el.classList.contains("tag")) return true;
+  for (const child of el.children) {
+    if (SKIP.has(child.tagName)) continue;
+    if (BLOCKISH.test(getComputedStyle(child).display)) return false;
+  }
+  return true;
+}
diff --git a/internal/web/styles/layout.css b/internal/web/styles/layout.css
@@ -324,3 +324,10 @@ a:hover {
     min-width: 260px;
   }
 }
+
+/* line-by-line reveal on tab switch */
+.line-in {
+  animation: lineIn 0s steps(1) both;
+  animation-delay: calc(var(--line) * var(--line-ms));
+}
+@keyframes lineIn { from { visibility: hidden; } }