元素变换在出现'相对'和'固定'之间的转换不平滑

问题描述 投票:0回答:1

我有一个横幅(.banner)和浮动元素(.float)的页面。

当用户在视图中滚动横幅时,我希望.float相对于横幅(垂直居中)出现,但是当用户滚过横幅时,它会粘在屏幕上。

实际上,浮点数的位置总是fixed,我使用Javascript来改变变换值,将其定位在我想要滚动的位置。

它几乎按照我的意愿工作,但我希望元素在位置之间“滑动”,我不能让这种行为按照我的意愿工作。没有CSS过渡,它会跳跃。通过CSS过渡,它会滑动,但是当我向后滚动时,它会在横幅的垂直中心上方滑动太远;一旦你滚动回横幅,我希望它能够“贴上”横幅。

任何帮助赞赏。 JSFiddle:http://jsfiddle.net/L452xf7h/12/

HTML:

<div class="container">
  <div class="banner"></div>
  <div class="float">Floating Element</div>
</div>

CSS:

body, html {
  margin: 0;
}

.container {
  background: orange;
  height: 2000px;
}

.banner {
  width: 100%;
  height: 400px;
  background: white;
}

.float {
  display: none;
  width: 50px;
  height: 50px;
  background: red;
  position: fixed;
  top: 100px;
  right: 100px;
  /* this transition makes float travel high in banner when scrolling up */
  /* transition: transform .3s linear; */
}

JS:

var float = document.querySelector('.float');

if (float) {
    // init position
  onScroll();
  // check on scroll
  window.addEventListener('scroll', onScroll);
}

function onScroll() {
var banner_height = 400;
var float_topCss = 100;
var float_height = 50;
  if (window.scrollY < banner_height) {
    position = 0;
    // center vertically in banner
    position += banner_height / 2;
    position -= float_height / 2;
    // account for current scroll
    position -= window.scrollY;
    // minus difference of top css value
    position -= float_topCss;
    float.style.transform = "translate3d(0,"+position+"px,0)";
  }
  else {
    float.style.transform = "translate3d(0,0,0)";
  }
  float.style.display = 'block';
}
javascript css position transform
1个回答
0
投票

这是你要找的结果吗?

    var float = document.querySelector('.float');

    if (float) {
   		// init position
      onScroll();
      // check on scroll
      window.addEventListener('scroll', onScroll);
    }

    function onScroll() {
    var banner_height = 400;
      if (window.scrollY < banner_height) {
        float.classList.remove('sticky');
      }
      else {
        float.classList.add('sticky');
      }
    }
    body, html {
      margin: 0;
    }

    .container {
      background: orange;
      height: 2000px;
      position: relative;
    }

    .banner {
      width: 100%;
      height: 400px;
      background: white;
    }

    .float {
      display: inline-block;
      width: 50px;
      height: 50px;
      background: red;
      position: absolute;
      top: 100px;
      right: 100px;
      float: right;
      transition: transform .3s linear;
    }

    .float.sticky {
      top: -50px;
      transform: translateY(150px);
      position: sticky;
    }
    
    <div class="container">
      <div class="banner"></div>
      <div class="float">Floating Element</div>
    </div>
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