feat(landing): slide showcase carousel horizontally

promo/landing/src/App.tsx

@@ -1,4 +1,4 @@
-import { useMemo, useRef, useState } from "react";
+import { useMemo, useRef, useState, type AnimationEvent } from "react";
 import logoUrl from "./assets/logo-universal.png";
 import ShowcaseVisual from "./ShowcaseVisual";
 
@@ -33,6 +33,13 @@ const slides = [
   },
 ];
 
+type SlideDirection = -1 | 1;
+
+type SlideTransition = {
+  from: number;
+  direction: SlideDirection;
+};
+
 function Logo() {
   return (
     <div className="brand" aria-label="SnapGo logo">
@@ -49,9 +56,40 @@ function Logo() {
 
 export default function App() {
   const [activeSlide, setActiveSlide] = useState(0);
+  const [slideTransition, setSlideTransition] = useState<SlideTransition | null>(null);
   const dragStartX = useRef<number | null>(null);
   const active = slides[activeSlide];
 
+  function getTransitionClass(role: "entering" | "exiting") {
+    if (!slideTransition) {
+      return "";
+    }
+
+    const edge = slideTransition.direction === 1 ? "right" : "left";
+    return `is-${role}-from-${edge}`;
+  }
+
+  function finishSlideTransition(event: AnimationEvent<HTMLElement>) {
+    if (event.target === event.currentTarget) {
+      setSlideTransition(null);
+    }
+  }
+
+  function selectSlide(nextSlide: number, direction: SlideDirection) {
+    if (slideTransition || nextSlide === activeSlide) {
+      return;
+    }
+
+    setSlideTransition({ from: activeSlide, direction });
+    setActiveSlide(nextSlide);
+  }
+
+  function selectDotSlide(nextSlide: number) {
+    const forwardDistance = (nextSlide - activeSlide + slides.length) % slides.length;
+    const backwardDistance = (activeSlide - nextSlide + slides.length) % slides.length;
+    selectSlide(nextSlide, forwardDistance <= backwardDistance ? 1 : -1);
+  }
+
   const accentDots = useMemo(
     () =>
       slides.map((slide, index) => (
@@ -60,14 +98,15 @@ export default function App() {
           className={`dot ${index === activeSlide ? "is-active" : ""}`}
           type="button"
           aria-label={`查看 ${slide.title}`}
-          onClick={() => setActiveSlide(index)}
+          onClick={() => selectDotSlide(index)}
         />
       )),
-    [activeSlide],
+    [activeSlide, slideTransition],
   );
 
-  function moveSlide(direction: -1 | 1) {
-    setActiveSlide((current) => (current + direction + slides.length) % slides.length);
+  function moveSlide(direction: SlideDirection) {
+    const nextSlide = (activeSlide + direction + slides.length) % slides.length;
+    selectSlide(nextSlide, direction);
   }
 
   function handlePointerEnd(clientX: number) {
@@ -148,13 +187,44 @@ export default function App() {
           </div>
 
           <div className="preview-stage">
-            <ShowcaseVisual key={active.eyebrow} activeIndex={activeSlide} />
+            {slideTransition && (
+              <div
+                key={`visual-${slideTransition.from}`}
+                className={`carousel-slide is-exiting ${getTransitionClass("exiting")}`}
+                aria-hidden="true"
+              >
+                <ShowcaseVisual activeIndex={slideTransition.from} />
+              </div>
+            )}
+            <div
+              key={`visual-${activeSlide}`}
+              className={`carousel-slide ${slideTransition ? `is-entering ${getTransitionClass("entering")}` : ""}`}
+              onAnimationEnd={finishSlideTransition}
+            >
+              <ShowcaseVisual activeIndex={activeSlide} />
+            </div>
           </div>
 
-          <div className="slide-panel" key={active.title}>
-            <p>{active.eyebrow}</p>
-            <h2>{active.title}</h2>
-            <span>{active.body}</span>
+          <div className="slide-panel-viewport">
+            {slideTransition && (
+              <div
+                key={`copy-${slideTransition.from}`}
+                className={`slide-panel is-exiting ${getTransitionClass("exiting")}`}
+                aria-hidden="true"
+              >
+                <p>{slides[slideTransition.from].eyebrow}</p>
+                <h2>{slides[slideTransition.from].title}</h2>
+                <span>{slides[slideTransition.from].body}</span>
+              </div>
+            )}
+            <div
+              key={`copy-${activeSlide}`}
+              className={`slide-panel ${slideTransition ? `is-entering ${getTransitionClass("entering")}` : ""}`}
+            >
+              <p>{active.eyebrow}</p>
+              <h2>{active.title}</h2>
+              <span>{active.body}</span>
+            </div>
           </div>
         </div>
 
@@ -164,9 +234,24 @@ export default function App() {
               <path d="m12 5-5 5 5 5" />
             </svg>
           </button>
-          <div className="slide-meta" aria-live="polite">
-            <strong>{active.metric}</strong>
-            <span>{active.feature}</span>
+          <div className="slide-meta-viewport" aria-live="polite">
+            {slideTransition && (
+              <div
+                key={`meta-${slideTransition.from}`}
+                className={`slide-meta is-exiting ${getTransitionClass("exiting")}`}
+                aria-hidden="true"
+              >
+                <strong>{slides[slideTransition.from].metric}</strong>
+                <span>{slides[slideTransition.from].feature}</span>
+              </div>
+            )}
+            <div
+              key={`meta-${activeSlide}`}
+              className={`slide-meta ${slideTransition ? `is-entering ${getTransitionClass("entering")}` : ""}`}
+            >
+              <strong>{active.metric}</strong>
+              <span>{active.feature}</span>
+            </div>
           </div>
           <div className="dots" aria-label="轮播分页">
             {accentDots}

promo/landing/src/index.css

@@ -339,8 +339,6 @@ h1 {
 .preview-stage {
   position: absolute;
   inset: 74px clamp(22px, 4vw, 52px) 154px;
-  display: grid;
-  place-items: center;
   overflow: hidden;
   border-radius: 34px;
   background:
@@ -350,6 +348,14 @@ h1 {
   background-size: 34px 34px, 34px 34px, auto;
 }
 
+.carousel-slide {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  will-change: transform;
+}
+
 .scene-parallax {
   position: relative;
   width: 100%;
@@ -361,7 +367,6 @@ h1 {
   inset: 0;
   overflow: hidden;
   color: #142033;
-  animation: scene-enter 360ms cubic-bezier(0.2, 0.8, 0.2, 1) both;
 }
 
 .visual-scene button {
@@ -1623,13 +1628,20 @@ h1 {
   box-shadow: 0 0 0 1px rgba(38, 52, 73, 0.12);
 }
 
-.slide-panel {
+.slide-panel-viewport {
   position: absolute;
   right: clamp(22px, 4vw, 52px);
   bottom: 34px;
   left: clamp(22px, 4vw, 52px);
+  display: grid;
   min-height: 92px;
-  animation: fade-slide 260ms ease both;
+  overflow: hidden;
+}
+
+.slide-panel {
+  position: relative;
+  grid-area: 1 / 1;
+  will-change: transform;
 }
 
 .slide-panel p {
@@ -1687,12 +1699,22 @@ h1 {
     background 180ms ease;
 }
 
+.slide-meta-viewport {
+  position: relative;
+  min-width: 0;
+  height: 28px;
+  overflow: hidden;
+}
+
 .slide-meta {
+  position: absolute;
+  inset: 0;
   display: flex;
   min-width: 0;
   align-items: baseline;
   gap: 10px;
   padding-left: 4px;
+  will-change: transform;
 }
 
 .slide-meta strong {
@@ -1733,15 +1755,59 @@ h1 {
   background: #0a84ff;
 }
 
-@keyframes scene-enter {
+.is-entering-from-right {
+  animation: carousel-enter-from-right 420ms cubic-bezier(0.22, 1, 0.36, 1) both;
+}
+
+.is-exiting-from-right {
+  animation: carousel-exit-to-left 420ms cubic-bezier(0.22, 1, 0.36, 1) both;
+}
+
+.is-entering-from-left {
+  animation: carousel-enter-from-left 420ms cubic-bezier(0.22, 1, 0.36, 1) both;
+}
+
+.is-exiting-from-left {
+  animation: carousel-exit-to-right 420ms cubic-bezier(0.22, 1, 0.36, 1) both;
+}
+
+@keyframes carousel-enter-from-right {
   from {
-    opacity: 0;
-    transform: translateY(9px) scale(0.985);
+    transform: translate3d(100%, 0, 0);
   }
 
   to {
-    opacity: 1;
-    transform: translateY(0) scale(1);
+    transform: translate3d(0, 0, 0);
+  }
+}
+
+@keyframes carousel-exit-to-left {
+  from {
+    transform: translate3d(0, 0, 0);
+  }
+
+  to {
+    transform: translate3d(-100%, 0, 0);
+  }
+}
+
+@keyframes carousel-enter-from-left {
+  from {
+    transform: translate3d(-100%, 0, 0);
+  }
+
+  to {
+    transform: translate3d(0, 0, 0);
+  }
+}
+
+@keyframes carousel-exit-to-right {
+  from {
+    transform: translate3d(0, 0, 0);
+  }
+
+  to {
+    transform: translate3d(100%, 0, 0);
   }
 }
 
@@ -2020,18 +2086,6 @@ h1 {
   }
 }
 
-@keyframes fade-slide {
-  from {
-    opacity: 0;
-    transform: translateY(8px);
-  }
-
-  to {
-    opacity: 1;
-    transform: translateY(0);
-  }
-}
-
 @media (max-width: 860px) {
   html,
   body,
@@ -2112,7 +2166,7 @@ h1 {
     border-radius: 24px;
   }
 
-  .slide-panel {
+  .slide-panel-viewport {
     right: 22px;
     bottom: 22px;
     left: 22px;
@@ -2535,6 +2589,10 @@ h1 {
     gap: 1px;
   }
 
+  .slide-meta-viewport {
+    height: 38px;
+  }
+
   .slide-meta strong {
     font-size: 16px;
   }