From 17fbfc50229ca773e4d45f6ca423a0f975520146 Mon Sep 17 00:00:00 2001
From: Tim Kainz <tikaiz@gmx.at>
Date: Thu, 16 Apr 2026 20:01:54 +0200
Subject: [PATCH] constant auto-scrolling

---
 .../tech-stack-carousel.css                   |  4 +
 .../tech-stack-carousel.html                  | 10 ++-
 .../tech-stack-carousel.ts                    | 79 ++++++++++++++-----
 3 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/src/components/tech-stack-carousel/tech-stack-carousel.css b/src/components/tech-stack-carousel/tech-stack-carousel.css
index d20294d..fd7e591 100644
--- a/src/components/tech-stack-carousel/tech-stack-carousel.css
+++ b/src/components/tech-stack-carousel/tech-stack-carousel.css
@@ -50,6 +50,10 @@ h2 {
   scrollbar-color: rgba(88, 166, 255, 0.45) rgba(33, 38, 45, 0.65);
 }
 
+.stack-carousel.is-auto-scrolling {
+  scroll-snap-type: none;
+}
+
 .stack-slide {
   flex: 0 0 min(320px, calc(100% - 0.2rem));
   scroll-snap-align: start;
diff --git a/src/components/tech-stack-carousel/tech-stack-carousel.html b/src/components/tech-stack-carousel/tech-stack-carousel.html
index db5e4e4..8f69ecc 100644
--- a/src/components/tech-stack-carousel/tech-stack-carousel.html
+++ b/src/components/tech-stack-carousel/tech-stack-carousel.html
@@ -18,8 +18,14 @@
     </button>
 
     <div class="stack-carousel-column">
-      <div class="stack-carousel" #stackCarousel role="region" aria-label="Tech stack carousel">
-        @for (skill of skills; track skill.name) {
+      <div
+        class="stack-carousel"
+        [class.is-auto-scrolling]="isAutoScrolling"
+        #stackCarousel
+        role="region"
+        aria-label="Tech stack carousel"
+      >
+        @for (skill of renderedSkills; track $index) {
           <app-card cardClass="skill-card stack-slide">
             <div class="skill-heading">
               <span class="skill-icon" role="img" [attr.aria-label]="skill.name + ' logo'">
diff --git a/src/components/tech-stack-carousel/tech-stack-carousel.ts b/src/components/tech-stack-carousel/tech-stack-carousel.ts
index 3c5a62a..c7b5949 100644
--- a/src/components/tech-stack-carousel/tech-stack-carousel.ts
+++ b/src/components/tech-stack-carousel/tech-stack-carousel.ts
@@ -17,7 +17,12 @@ interface Skill {
 })
 export class TechStackCarousel implements AfterViewInit, OnDestroy {
   @ViewChild('stackCarousel') private readonly stackCarousel?: ElementRef<HTMLElement>;
-  private autoScrollTimer: ReturnType<typeof setInterval> | null = null;
+  private autoScrollFrameId: number | null = null;
+  private startAutoScrollTimeout: ReturnType<typeof setTimeout> | null = null;
+  private lastAutoScrollTime = 0;
+  private virtualScrollLeft = 0;
+  private readonly autoScrollSpeedPxPerSecond = 72;
+  isAutoScrolling = false;
 
   readonly skills: Skill[] = [
     { name: 'Angular', category: 'Frontend', level: 'Advanced', logoUrl: '/tech-logos/angular.svg', fallbackLabel: 'NG' },
@@ -34,6 +39,8 @@ export class TechStackCarousel implements AfterViewInit, OnDestroy {
     { name: 'Flutter', category: 'Mobile', level: 'Advanced', logoUrl: '/tech-logos/flutter.svg', fallbackLabel: 'FL' },
   ];
 
+  readonly renderedSkills: Skill[] = [...this.skills, ...this.skills];
+
   ngAfterViewInit(): void {
     const prefersReducedMotion =
       typeof window.matchMedia === 'function' && window.matchMedia('(prefers-reduced-motion: reduce)').matches;
@@ -42,11 +49,21 @@ export class TechStackCarousel implements AfterViewInit, OnDestroy {
       return;
     }
 
-    this.resumeAutoScroll();
+    // Defer start to the next task to avoid NG0100 in dev mode.
+    this.startAutoScrollTimeout = setTimeout(() => {
+      this.startAutoScrollTimeout = null;
+      this.resumeAutoScroll();
+    }, 0);
   }
 
   ngOnDestroy(): void {
+    if (this.startAutoScrollTimeout !== null) {
+      clearTimeout(this.startAutoScrollTimeout);
+      this.startAutoScrollTimeout = null;
+    }
+
     this.pauseAutoScroll();
+    this.isAutoScrolling = false;
   }
 
   scrollStack(direction: -1 | 1): void {
@@ -59,22 +76,45 @@ export class TechStackCarousel implements AfterViewInit, OnDestroy {
   }
 
   pauseAutoScroll(): void {
-    if (!this.autoScrollTimer) {
+    if (this.autoScrollFrameId === null) {
       return;
     }
 
-    clearInterval(this.autoScrollTimer);
-    this.autoScrollTimer = null;
+    cancelAnimationFrame(this.autoScrollFrameId);
+    this.autoScrollFrameId = null;
+    this.lastAutoScrollTime = 0;
   }
 
   resumeAutoScroll(): void {
-    if (this.autoScrollTimer) {
+    if (this.autoScrollFrameId !== null) {
       return;
     }
 
-    this.autoScrollTimer = setInterval(() => {
-      this.autoAdvanceStack();
-    }, 3200);
+    this.isAutoScrolling = true;
+
+    const step = (timestamp: number) => {
+      const carousel = this.stackCarousel?.nativeElement;
+      if (!carousel) {
+        this.autoScrollFrameId = null;
+        this.lastAutoScrollTime = 0;
+        this.virtualScrollLeft = 0;
+        this.isAutoScrolling = false;
+        return;
+      }
+
+      if (this.lastAutoScrollTime === 0) {
+        const loopWidth = this.getLoopWidth(carousel);
+        this.virtualScrollLeft = loopWidth > 0 ? carousel.scrollLeft % loopWidth : 0;
+      }
+
+      const deltaMs = this.lastAutoScrollTime > 0 ? Math.min(timestamp - this.lastAutoScrollTime, 40) : 16;
+      this.lastAutoScrollTime = timestamp;
+
+      this.autoAdvanceStack(carousel, deltaMs);
+      this.autoScrollFrameId = requestAnimationFrame(step);
+    };
+
+    this.autoScrollFrameId = requestAnimationFrame(step);
   }
 
   onCarouselFocusOut(event: FocusEvent): void {
@@ -92,23 +132,22 @@ export class TechStackCarousel implements AfterViewInit, OnDestroy {
     wrapper?.classList.add('is-fallback');
   }
 
-  private autoAdvanceStack(): void {
-    const carousel = this.stackCarousel?.nativeElement;
-    if (!carousel) {
+  private autoAdvanceStack(carousel: HTMLElement, deltaMs: number): void {
+    const loopWidth = this.getLoopWidth(carousel);
+    if (loopWidth <= 0) {
       return;
     }
 
-    const maxScroll = carousel.scrollWidth - carousel.clientWidth;
-    if (maxScroll <= 0) {
-      return;
+    this.virtualScrollLeft += (this.autoScrollSpeedPxPerSecond * deltaMs) / 1000;
+    if (this.virtualScrollLeft >= loopWidth) {
+      this.virtualScrollLeft %= loopWidth;
     }
 
-    if (carousel.scrollLeft >= maxScroll - 4) {
-      carousel.scrollTo({ left: 0, behavior: 'smooth' });
-      return;
-    }
+    carousel.scrollLeft = this.virtualScrollLeft;
+  }
 
-    carousel.scrollBy({ left: this.getScrollStep(carousel), behavior: 'smooth' });
+  private getLoopWidth(carousel: HTMLElement): number {
+    return carousel.scrollWidth / 2;
   }
 
   private getScrollStep(carousel: HTMLElement): number {