精通 CSS 动画范围：现代网页设计中基于滚动的动画控制

            

  

    
Animate Me!
  
  

    
Lots of content here to make the container scrollable...
    
  


            

              
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.scroll-container {
  height: 500px; /* Adjust as needed */
  overflow-y: scroll;
  position: relative;
}

.animated-element {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0; /* Initially hidden */
  transition: opacity 0.5s ease;
}

.animated-element.active {
  opacity: 1; /* Visible when active */
}

.content {
  padding: 20px;
}

            

              
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const scrollContainer = document.querySelector('.scroll-container');
const animatedElement = document.querySelector('.animated-element');

function isInViewport(element) {
  const rect = element.getBoundingClientRect();
  return (
    rect.top >= 0 &&
    rect.left >= 0 &&
    rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
    rect.right <= (window.innerWidth || document.documentElement.clientWidth)
  );
}

function handleScroll() {
  if (isInViewport(animatedElement)) {
    animatedElement.classList.add('active');
  } else {
    animatedElement.classList.remove('active');
  }
}

scrollContainer.addEventListener('scroll', handleScroll);

// Initial check on page load
handleScroll();

            

              
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.animated-element {
  /* ... other styles ... */
  transform: translate(-50%, -50%) scale(0.5);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.animated-element.active {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
}

            

              
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const animatedElement = document.querySelector('.animated-element');

const observer = new IntersectionObserver(entries => {
  entries.forEach(entry => {
    if (entry.isIntersecting) {
      animatedElement.classList.add('active');
    } else {
      animatedElement.classList.remove('active');
    }
  });
});

observer.observe(animatedElement);

            

              
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const scrollContainer = document.querySelector('.scroll-container');
const animatedElement = document.querySelector('.animated-element');

scrollContainer.addEventListener('scroll', () => {
  const scrollHeight = scrollContainer.scrollHeight - scrollContainer.clientHeight;
  const scrollPosition = scrollContainer.scrollTop;
  const scrollPercentage = scrollPosition / scrollHeight;

  // Map scroll percentage to animation progress (0 to 1)
  const animationProgress = scrollPercentage;

  // Apply the animation based on the progress
  animatedElement.style.transform = `translateX(${animationProgress * 100}px)`;
  animatedElement.style.opacity = animationProgress;
});

            

              
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function debounce(func, delay) {
  let timeout;
  return function(...args) {
    const context = this;
    clearTimeout(timeout);
    timeout = setTimeout(() => func.apply(context, args), delay);
  };
}

const scrollContainer = document.querySelector('.scroll-container');
const animatedElement = document.querySelector('.animated-element');

const handleScroll = () => {
  // ... animation logic ...
};

scrollContainer.addEventListener('scroll', debounce(handleScroll, 20));

            

              
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@scroll-timeline my-timeline {
  source: element(body);
  orientation: vertical;
  scroll-offsets: 0, 100vh;
}

.animated-element {
  animation: fade-in 1s linear;
  animation-timeline: my-timeline;
  animation-range: entry 0, exit 100%;
}

@keyframes fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

            

              
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