在剪切路径中使用时重新计算滚动 div 的位置

Question

我正在使用剪切路径根据背景颜色更改我的徽标颜色。

除此之外，徽标会根据用户在页面上的垂直位置从上到下滚动。页面顶部 = 顶部徽标，页面底部 = 底部徽标等。

不幸的是，当我添加剪切路径时，徽标失去了滚动位置，在第一个之后，根本不起作用。

有没有办法解决这个问题？此外，徽标位置开始时有点偏离，所以如果有任何方法可以同时解决这个问题。

您可以在此处查看原始问题： div position based on scroll position

我已经尝试过了，但我似乎无法让它工作。

Scroll position lost when hiding div

我正在使用高级自定义字段，并且 PHP 文件的每个部分在标题中都有这个作为剪切路径的一部分，相应地使用白色或深色版本的徽标。其父级相对定位，其子级绝对定位。

div class="logo-scroll">
        <div class="scroll-text">
                    <a href="/home"><img width="53px" height="260px" src="/wp-content/uploads/2019/07/sheree-walker-web-design-edinburgh-vertical-01.svg"/></a>
       </div>
</div>  

Javascript

const docHeight = Math.max(document.documentElement.scrollHeight, document.body.scrollHeight);
const logo = document.querySelector('.scroll-text');
const logoHeight = logo.offsetHeight;
// to get the pseudoelement's '#page::before' top we use getComputedStyle method
const barTopMargin = parseInt(getComputedStyle(document.querySelector('#page'), '::before').top);

let viewportHeight, barHeight, maxScrollDist, currentScrollPos, scrollFraction;

logo.style.top = barTopMargin + 'px';

window.addEventListener('load', update);
window.addEventListener('resize', setSizes);
document.addEventListener('scroll', update);

setSizes();


function update() {
    currentScrollPos = Math.max(document.documentElement.scrollTop, document.body.scrollTop);
    scrollFraction = currentScrollPos / (docHeight - viewportHeight);

    logo.style.top = barTopMargin + (scrollFraction * maxScrollDist) + 'px';
}

function setSizes() {
    viewportHeight = window.innerHeight;
    // to get the pseudoelement's '#page::before' height we use getComputedStyle method
    barHeight = parseInt(getComputedStyle(document.querySelector('#page'), '::before').height); 
    maxScrollDist = barHeight - logoHeight;
    update();
}

CSS

.logo-scroll .scroll-text img {
    padding: 0 6px 0 17px;
}


#page::before {
    content: "";
    position: fixed;
    top: 30px;
    bottom: 30px;
    left: 30px;
    right: 30px;
    border: 2px solid white;
    pointer-events: none;
    -webkit-transition: all 2s; /* Safari prior 6.1 */
    transition: all 2s;
}

.logo-scroll {
    position: fixed;
    left: 30px;
    top: 30px;
    bottom: 30px;
    border-right: 2px solid white;
    width: 75px;
    z-index: 10;
}

.scroll-text {
    position: fixed;
}

Answer 1

let logos, logoHeight, barTopMargin;
let viewportHeight;

window.addEventListener('load', init);
window.addEventListener('resize', setSizes);
document.addEventListener('scroll', update);


function init(lockUpdate) {
    logos = document.querySelectorAll('.scroll-text');
    setSizes(lockUpdate);
}

function update() {
    // ensure initialization and prevent recursive call
    if (!logos) init(true);
    //*************************************************

    /**************************************************
        THIS LINE MUST BE HERE.
    **************************************************/
    let maxScrollDist  = document.documentElement.scrollHeight - viewportHeight;
    //*************************************************

    let currentScrollPos = document.documentElement.scrollTop;
    let newTop;

    let middle = currentScrollPos + viewportHeight/2;
    let middleY = maxScrollDist/2;

    if (middle >= (maxScrollDist+viewportHeight)/2) {
        let p = (middleY - Math.floor(middle - (maxScrollDist+viewportHeight)/2))*100/middleY;

        newTop = viewportHeight/2 - logoHeight/2;
        newTop += (100-p)*(viewportHeight/2)/100;
        newTop -= (100-p)*(barTopMargin +logoHeight/2)/100;
        newTop = Math.max(newTop, viewportHeight/2 - logoHeight/2); /*fix*/
    } else {
        let p = (middleY - Math.floor(-middle + (maxScrollDist+viewportHeight)/2))*100/middleY;
        newTop = barTopMargin*(100-p)/100+(viewportHeight/2 - (logoHeight/2)*p/100 )*p/100;
        newTop = Math.min(newTop, viewportHeight/2 - logoHeight/2); /*fix*/
    }

    logos.forEach(function(el) {
        el.style.top = newTop + "px";
    });
}

function setSizes(lockUpdate) {
    logoHeight     = logos[0].offsetHeight;
    barTopMargin   = parseInt(getComputedStyle(document.querySelector('#page'), '::before').top);
    viewportHeight = window.innerHeight;
    if (lockUpdate === true) return;
    update();
}

更新和测试。

要检查它，请将此代码放入您的控制台：

document.removeEventListener('scroll', update);
document.onscroll = function() {
    let _logoHeight     = logos[0].offsetHeight;
    let _barTopMargin   = parseInt(getComputedStyle(document.querySelector('#page'), '::before').top);
    let _viewportHeight = window.innerHeight;
    let _maxScrollDist  = document.documentElement.scrollHeight - _viewportHeight;

    let currentScrollPos = document.documentElement.scrollTop;
    let percent100 = currentScrollPos + _viewportHeight;

    let scrolledPercent = currentScrollPos * 100/_maxScrollDist;

    let newTop = ((_viewportHeight - _logoHeight/2)*scrolledPercent/100);

    let middle = currentScrollPos + _viewportHeight/2;
    let middleY = _maxScrollDist/2; // 100

    if (middle >= (_maxScrollDist+_viewportHeight)/2) {
        let y1 = middleY - Math.floor(middle - (_maxScrollDist+_viewportHeight)/2);
        let p = y1*100/middleY;

        newTop = _viewportHeight/2 - _logoHeight/2;
        newTop += (100-p)*(_viewportHeight/2)/100;
        newTop -= (100-p)*(30 +_logoHeight/2)/100;

        newTop = Math.max(newTop, _viewportHeight/2 - _logoHeight/2); /*fix*/

    } else {
        let y2 = middleY - Math.floor(-middle + (_maxScrollDist+_viewportHeight)/2);
        let p = y2*100/middleY;
        newTop = 30*(100-p)/100+(_viewportHeight/2 - (_logoHeight/2)*p/100 )*p/100;

        newTop = Math.min(newTop, _viewportHeight/2 - _logoHeight/2); /*fix*/
    }

    logos.forEach(function(el) {
        el.style.top = newTop + "px";
    });
}

---

CSS 修复： custom.css :: 第 767 行

@media (max-width: 1000px)...
.scroll-text {
    padding-left: 13px;
    /*width: 27px;*/
}
.scroll-text img {
    /* remove it. but if necessary move it to .scroll-text rule above
    width: 27px; */
}

custom.css :: 第 839 行

@media (max-width: 599px)...
.logo-scroll {
    /*display: none; why! remove it*/
}

custom.css :: 第 268 行

.scroll-text {
    position: fixed;
    /* height: 280px; remove it*/
    padding-left: 20px;
}

看到这个capture

---

最后，祝你有美好的一天，再见。

Answer 2

您只选择了第一个“logo-text”。而不是：

const logo = document.querySelector('.scroll-text');

你应该使用querySelectorAll:

const logos = document.querySelectorAll('.scroll-text');

然后，在您的滚动处理程序中，您应该将它们全部移动。

因此，您可以用遍历所有徽标元素的循环替换每个徽标使用实例：

logos.forEach(logo => logo.style.top = ...);

请注意，您在滚动处理程序中执行了相当昂贵的操作，这对渲染性能不利。您可能还想使用requestAnimationFrame 来提高渲染性能。查看reference page on MDN。 实际上，我很快就使用requestAnimationFrame 制作了一个版本，但没有明显的性能改进。这可能是因为显然 rAF 以与scroll 事件大致相同的速率触发。无论如何，我将其删除以避免混淆。如果您发现性能问题，请告诉我。

不过，我建议您使用 transform: translate() 而不是 top 移动徽标。在这里你有一个完整的解决方案。我在 Chrome 中尝试过。

const docHeight = Math.max(document.documentElement.scrollHeight, document.body.scrollHeight);
const logos = document.querySelectorAll('.scroll-text');
const logoHeight = logos[0].offsetHeight;
// to get the pseudoelement's '#page::before' top we use getComputedStyle method
const barTopMargin = parseInt(getComputedStyle(document.querySelector('#page'), '::before').top);

let viewportHeight, barHeight, maxScrollDist, currentScrollPos, scrollFraction;

window.addEventListener('load', update);
window.addEventListener('resize', setSizes);
document.addEventListener('scroll', update);

setSizes();

function update() {
  currentScrollPos = Math.max(document.documentElement.scrollTop, document.body.scrollTop);
  scrollFraction = currentScrollPos / (docHeight - viewportHeight);
  const translateDelta = barTopMargin + (scrollFraction * maxScrollDist);

  logos.forEach(logo => logo.style.transform = `translateY(${translateDelta}px)`);
}

function setSizes() {
  viewportHeight = window.innerHeight;
  // to get the pseudoelement's '#page::before' height we use getComputedStyle method
  barHeight = parseInt(getComputedStyle(document.querySelector('#page'), '::before').height);
  maxScrollDist = barHeight - logoHeight;
  update();
}