2020年新年大赛！

Question

Alexandr_TT

Asked:2020-02-11 22:46:51 +0000 UTC2020-02-11 22:46:51 +0000 UTC 2020-02-11 22:46:51 +0000 UTC

如何动画虚线箭头？

772

正如标题所示，我正在尝试为虚线箭头设置动画。
我希望它看起来尽可能接近，就像在这个网站上一样。

我能够制作一个箭头，虽然我不确定这是否是正确的方式。
我想我应该用 SVG 画这个。
而且动画看起来很奇怪，我不知道如何使它更流畅。

这是我的代码：

body {
  margin: 0;
  font-size: 16px;
  line-height: 1.528571429;
  padding: 0;
  height: 100%;
}
body #contact {
  height: calc(100vh - 40px);
  background-color: #ffffff;
}
body #contact .to-top-btn-wrapper {
  position: absolute;
  z-index: 999;
  left: 7%;
  bottom: 15%;
}
body #contact .to-top-btn-wrapper .btn-text-wrapper {
  margin: -35px auto;
}
body #contact .to-top-btn-wrapper .btn-text-wrapper .btn-text {
  font-size: 14px;
  letter-spacing: 0.25em;
  text-align: center;
  color: #676565;
  text-transform: uppercase;
}
body #contact .to-top-btn-wrapper .to-top-btn {
  position: absolute;
  top: 0;
  left: 35px;
  bottom: 25px;
  cursor: pointer;
}
body #contact .to-top-btn-wrapper .to-top-btn .line {
  border-right: 0.1rem dashed #676565;
  display: inline-block;
  animation: show 1000ms linear forwards infinite;
}
body #contact .to-top-btn-wrapper .to-top-btn .arrow {
  position: absolute;
  top: -0.3rem;
  bottom: 0;
  height: 1rem;
  border-right: 0.1rem solid #676565;
  display: inline-block;
}
body #contact .to-top-btn-wrapper .to-top-btn .right {
  left: 0.3rem;
  transform: rotate(-45deg);
}
body #contact .to-top-btn-wrapper .to-top-btn .left {
  right: 0.3rem;
  transform: rotate(45deg);
}
@keyframes show {
  0% {
    height: 5rem;
  }
  100% {
    height: 0rem;
  }
}

<section id="contact" class="container-fluid">
  <div class="to-top-btn-wrapper">
    <div class="btn-text-wrapper">
      <span class="btn-text">Scroll to top</span>
    </div>
    <div class="to-top-btn">
      <span class="arrow left"></span>
      <span class="line"></span>
      <span class="arrow right"></span>
    </div>
  </div>
</section>

_{问题的免费翻译如何为虚线箭头设置动画？来自成员 winde。}

4 个回答

Voted

user355286 · Answer 1 · 2020-02-11T23:32:37Z

仅适用于正常背景颜色。

:root {
  --arrow-color: white;
  --arrow-size: 3px;
  --bg: black;
}

body {
  margin: 0;
  height: 100vh;
  
  display: flex;
  align-items: center;
  justify-content: center;
  
  background: var(--bg);
  overflow: hidden;
}

.arrow {
  height: 40vh;
  width: 10vw;
  
  display: grid;
  grid-template-rows: 1fr auto;
  justify-items: center;
}

.line {
  grid-row: 1 / 2;
  grid-column: 1 / 2;
  
  width: var(--arrow-size);
  
  background-color: var(--arrow-color);
  background-image: repeating-linear-gradient(to bottom, transparent 0 8px, var(--bg) 8px 13px);
}

.bracket {
  box-sizing: border-box;
  grid-row: 2 / 3;
  grid-column: 1 / 2;

  width: 20px;
  height: 20px;
  
  border-left: var(--arrow-size) solid var(--arrow-color);
  border-bottom: var(--arrow-size) solid var(--arrow-color);
  
  transform: translateY(calc(-1 * var(--arrow-size))) rotate(-45deg);
}

.arrow::after {
  content: '';
  
  grid-row: 1 / 3;
  grid-column: 1 / 2;
  
  width: 100%;
  
  background-color: var(--bg);
  
  animation: xxx 2.4s cubic-bezier(0.76, 0.05, 0.34, 0.9) infinite;
}

@keyframes xxx {
  50% {
    transform: translateY(100%);
  }
  
  50.1% {
    transform: translateY(-100%);
  }
}

<div class="arrow">
  <div class="line"></div>
  <div class="bracket"></div>
</div>

因为动画是这样的：

:root {
  --arrow-color: white;
  --arrow-size: 3px;
  --bg: black;
}

body {
  margin: 0;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  overflow: hidden;
}

.arrow {
  height: 40vh;
  width: 10vw;
  
  display: grid;
  grid-template-rows: 1fr auto;
  justify-items: center;
}

.line {
  grid-row: 1 / 2;
  grid-column: 1 / 2;
  
  height: 100%;
  width: var(--arrow-size);
  
  background-color: var(--arrow-color);
  background-image: repeating-linear-gradient(to bottom, transparent 0 8px, var(--bg) 8px 13px);
}

.bracket {
  box-sizing: border-box;
  grid-row: 2 / 3;
  grid-column: 1 / 2;

  width: 20px;
  height: 20px;
  
  border-left: var(--arrow-size) solid var(--arrow-color);
  border-bottom: var(--arrow-size) solid var(--arrow-color);
  
  transform: translateY(calc(-1 * var(--arrow-size))) rotate(-45deg);
}

.arrow::after {
  content: '';
  grid-row: 1 / 3;
  grid-column: 1 / 2;
  width: 100%;
  height: 100%;
  background-color: #FFFF00;
  animation: xxx 2.4s cubic-bezier(0.76, 0.05, 0.34, 0.9) infinite;
}

@keyframes xxx {
  50% {
    transform: translateY(100%);
  }
  
  50.1% {
    transform: translateY(-100%);
  }
}

<div class="arrow">
  <div class="line"></div>
  <div class="bracket"></div>
</div>

Alexandr_TT · Answer 2 · 2020-02-11T22:58:11Z

翻译@Temani Afif对 EnSO 问题的回答如何为虚线箭头设置动画？

这可以通过动画clip-path和一些背景来完成：

.arrow {
  width: 20px;
  margin:10px;
  height: 150px; 
  display:inline-block;
  position: relative;
  padding-bottom:4px;
  color: #fff;
  background: linear-gradient(currentColor 50%, transparent 50%) top/2px 15px content-box repeat-y;
  clip-path:polygon(0 0,100% 0,100% 100%,0 100%);
  animation:hide infinite 2s linear;
}

.arrow:after {
  content: "";
  position: absolute;
  border-left: 2px solid;
  border-bottom: 2px solid;
  width: 80%;
  padding-top: 80%;
  bottom: 4px;
  left: 1px;
  transform: rotate(-45deg);
}

@keyframes hide {
  50% {
    clip-path:polygon(0 100%,100% 100%,100% 100%,0 100%);
  }
  50.1% {
    clip-path:polygon(0 0   ,100% 0   ,100% 0   ,0 0);
  }
}

body {
  background: #30203B;
}

<div class="arrow"></div>

<div class="arrow" style="transform:scaleY(-1)"></div>

使用面具的类似想法：

.arrow {
  width: 20px;
  margin:10px;
  height: 150px;
  padding-bottom:4px;
  display:inline-block;  
  position: relative;
  color: #fff;
  background: linear-gradient(currentColor 50%, transparent 50%) top/2px 15px content-box repeat-y;
  -webkit-mask:linear-gradient(#fff,#fff);
  -webkit-mask-size:100% 0%;
  -webkit-mask-repeat:no-repeat;
  mask:linear-gradient(#fff,#fff);
  mask-size:100% 0%;
  mask-repeat:no-repeat;
  animation:hide infinite 2s linear;
}

.arrow:after {
  content: "";
  position: absolute;
  border-left: 2px solid;
  border-bottom: 2px solid;
  width: 80%;
  padding-top: 80%;
  bottom: 4px;
  left: 1px;
  transform: rotate(-45deg);
}

@keyframes hide {
  50% {
     -webkit-mask-size:100% 100%; 
     -webkit-mask-position:top;  
     mask-size:100% 100%; 
     mask-position:top;      
  }
  50.1% {
     -webkit-mask-size:100% 100%; 
     -webkit-mask-position:bottom;
     mask-size:100% 100%; 
     mask-position:bottom;   
  }
  100% {
     -webkit-mask-position:bottom;
     mask-position:bottom;  
  }
}

body {
  background: #30203B;
}

<div class="arrow"></div>

<div class="arrow" style="transform:scaleY(-1)"></div>

这是一个background没有only 的解决方案clip-path：

.arrow {
  width: 20px;
  margin:10px;
  height: 150px; 
  display:inline-flex;
}
.arrow:before,
.arrow:after{
  content:"";
  width:50%;
  background: 
   linear-gradient(to bottom left, 
     transparent    calc(50% - 1px), 
     white        0 calc(50% + 1px),
     transparent  0) 
   bottom/100% 10px,
    
   repeating-linear-gradient(white 0 7px, transparent 0 15px) 
   right/1px 100%;
  background-repeat:no-repeat;
  background-clip:content-box;
  box-sizing:border-box;
  animation:hide infinite 2s linear;
}
.arrow:after {
  transform:scaleX(-1);
}
@keyframes hide {
  50% {
    padding:150px 0 0;
  }
  50.1% {
    padding:0 0 150px;
  }
}

body {
  background: #30203B;
}

<div class="arrow"></div>

<div class="arrow" style="transform:scaleY(-1)"></div>

另一个梯度较小的版本：

.arrow {
  width: 20px;
  margin:10px;
  height: 150px; 
  display:inline-flex;
}
.arrow:before,
.arrow:after{
  content:"";
  width:50%;
  background: 
   linear-gradient(to bottom left, 
     transparent    calc(50% - 1px), 
     white        0 calc(50% + 1px),
     transparent  0) 
   bottom/100% 10px,
    
   repeating-linear-gradient(white 0 7px, transparent 0 15px) 
   right/1px 100%;
  background-repeat:no-repeat;
  background-clip:content-box;
  box-sizing:border-box;
  animation:hide infinite 2s linear;
}
.arrow:after {
  transform:scaleX(-1);
}
@keyframes hide {
  50% {
    padding:150px 0 0;
  }
  50.1% {
    padding:0 0 150px;
  }
}

body {
  background: #30203B;
}

<div class="arrow"></div>

<div class="arrow" style="transform:scaleY(-1)"></div>

并使用 CSS 变量轻松控制一切：

.arrow {
  --h:150px;   /* height */
  --w:20px;    /* width */
  --b:7px;     /* width of the dash*/
  --g:8px;     /* gap between dashes*/
  width: var(--w);
  margin:10px;
  height: var(--h); 
  display:inline-flex;
}
.arrow:before,
.arrow:after{
  content:"";
  width:50%;
  background: 
   linear-gradient(to bottom left, 
     transparent    calc(50% - 1px), 
     white        0 calc(50% + 1px),
     transparent  0) 
   bottom/100% calc(var(--w)/2),
    
   repeating-linear-gradient(white 0 var(--b), transparent 0 calc(var(--b) + var(--g))) 
   right/1px 100%;
  background-repeat:no-repeat;
  background-clip:content-box;
  box-sizing:border-box;
  animation:hide infinite 2s linear;
}
.arrow:after {
  transform:scaleX(-1);
}
@keyframes hide {
  50% {
    padding:var(--h) 0 0;
  }
  50.1% {
    padding:0 0 var(--h);
  }
}

body {
  background: #30203B;
}

<div class="arrow"></div>
<div class="arrow" style="transform:scaleY(-1);--h:100px;--g:3px;"></div>
<div class="arrow" style="--h:120px;--b:3px;--w:30px"></div>
<div class="arrow" style="transform:scaleY(-1);--h:150px;--b:5px;--g:10px;--w:40px"></div>

_{来自成员 @Temani Afif的答案的松散翻译。}

NeedHate · Answer 3 · 2020-02-12T04:55:56Z

如何做到这一点很有趣，我使用 box-shadow 来绘制“破折号”+ css 动画“正如我所见”。没错，没有箭头本身，只是作为一个概念：

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  background: url(https://revolution.themepunch.com/wp-content/uploads/revslider/stark-header/stark_bg.jpg);
  display: -webkit-box;
  display: flex;
  -webkit-box-align: center;
          align-items: center;
  -webkit-box-pack: center;
          justify-content: center;
}

.wrapper .item {
  width: 100px;
  height: 100px;
  position: relative;
  overflow: hidden;
}
.wrapper .item:before {
  content: '';
  display: inline-block;
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  margin: 0 auto;
  background-color: transparent;
  width: 0;
  height: 0;
  -webkit-animation: show cubic-bezier(0.86, 0, 0.07, 1) 2s infinite;
          animation: show cubic-bezier(0.86, 0, 0.07, 1) 2s infinite;
  box-shadow: 2px 0 0 2px white,  2px 12px 0 2px white,  2px 24px 0 2px white,  2px 36px 0 2px white, 2px 48px 0 2px white, 2px 60px 0 2px white, 2px 72px 0 2px white, 2px 84px 0 2px white, 2px 96px 0 2px white;
}
@-webkit-keyframes show {
  0% {
    -webkit-transform: translatey(-100px);
            transform: translatey(-100px);
  }
  50% {
    -webkit-transform: translatey(0);
            transform: translatey(0);
  }
  100% {
    -webkit-transform: translatey(100px);
            transform: translatey(100px);
  }
}
@keyframes show {
  0% {
    -webkit-transform: translatey(-100px);
            transform: translatey(-100px);
  }
  50% {
    -webkit-transform: translatey(0);
            transform: translatey(0);
  }
  100% {
    -webkit-transform: translatey(100px);
            transform: translatey(100px);
  }
}

<div class="wrapper">
	<div class="item"></div>
</div>

Sevastopol' · Answer 4 · 2020-02-13T00:22:48Z

这是解决方案。从视觉上看，与问题中给出的网站上的箭头几乎没有区别。适用于任何背景颜色或图像，不依赖于背景。仅使用 CSS 来解决这个问题，使箭头元素不依赖于背景颜色，很可能是不可能的。所以我不得不求助于 JavaScript。

向下箭头：

function slide() {
  var $document = $(document);
  var $arrow = $('.box__show');
  var $arrowhide = $('.box__hide');
  $document.queue(function() {
    $arrow.slideDown(2000);
    setTimeout(function() {
      $arrowhide.css('top', 'auto').animate({
        'height': '0vh'
      }, 2000)
      $document.dequeue();
    }, 2000);
    setTimeout(function() {
      $arrow.hide()
      $arrowhide.css('top', '0').animate({
        'height': '50vh'
      }, 2000)
      $document.dequeue();
    }, 4000);
  });
}
setInterval(slide, 6000);
//дальше необязательно
setInterval(function() {
  document.getElementById("body").style.backgroundColor = '#' + ((1 << 24) * Math.random() | 0).toString(16)
}, 3000)
$('#button').click(function() {
  $('#body').toggle();
});
var timerBlock = $('.seconds');
var num = 5;
var timerId = setInterval(function() {
  timerBlock.html(--num);
}, 1000);
setTimeout(function() {
  clearInterval(timerId);
  $('#seconds').html('Поехали!');
  $('#seconds').delay(500).slideUp();
}, num * 1000);

body {
  background: url('https://i.imgur.com/TZ5ya3G.jpg');
  background-size: cover;
}

.box {
  position: relative;
  overflow: hidden;
  margin: 0 auto;
  width: 10vw;
  height: 50vh;
}

.box__show,
.box__hide {
  position: absolute;
  overflow: hidden;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: 0 auto;
  width: 10vw;
  height: 50vh;
}

.box__show {
  display: none;
}

.line {
  position: absolute;
  overflow: hidden;
  top: 0;
  left: 0;
  right: 0;
  bottom: 4px;
  border-bottom: 3px solid transparent;
}

.line::before {
  content: "";
  display: block;
  position: absolute;
  top: 0;
  bottom: 2px;
  left: 50%;
  width: 1px;
  height: calc(50vh - 2px);
  border-left: 1px dashed white;
  margin-left: -1px;
  margin-top: -2px;
}

.arrow {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 15px;
  width: 40px;
  margin: 0 auto;
}

.arrow::before {
  content: "";
  display: block;
  position: absolute;
  top: 10px;
  left: -1px;
  right: 0;
  margin: 0 auto;
  margin-top: -21px;
  width: 20px;
  height: 20px;
  border-bottom: 1px solid white;
  transform: rotate(-45deg);
}

.arrow::after {
  content: "";
  display: block;
  position: absolute;
  top: 10px;
  left: 0;
  right: -1px;
  margin: 0 auto;
  margin-top: -21px;
  width: 20px;
  height: 20px;
  border-bottom: 1px solid white;
  transform: rotate(45deg);
}


/*необязательно*/

#body {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100vh;
}

button {
  outline: none;
  cursor: pointer;
  position: fixed;
  top: 15px;
  left: 15px;
  padding: 5px;
  background: #f1f1f1;
  color: black;
  border: none;
  border-radius: 3px;
  font-size: 12px;
}

button:hover {
  background: #fff;
  color: dimgray;
}

#seconds {
  position: absolute;
  top: 5vh;
  left: 0;
  right: 0;
  width: 100%;
  margin: 0 auto;
  text-align: center;
  color: lightgray;
  font-size: 15px;
  font-family: monospace;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="body"></div>
<div id="seconds"><span class="seconds">5</span></div>
<button id="button">Поменять фон</button>
<div class="box">
  <div class="box__show">
    <div class="box__hide">
      <div class="line"></div>
      <div class="arrow"></div>
    </div>
  </div>
</div>

向上箭头：

function slide() {
  var $revealMe = $(".box__show");
  var originalHeight = $revealMe.height();
  var $document = $(document);
  var $arrow = $('.box__show');
  var $arrowhide = $('.box__hide');
  $document.queue(function() {
    $revealMe.css({
      position: "relative",
      top: originalHeight,
      height: 0
    }).show().animate({
      top: 0,
      height: originalHeight
    }, {
      duration: 2000,
      step: function(now, fx) {
        if (fx.prop == "top") {
          $(fx.elem).scrollTop(now);
        }
      }
    });
    setTimeout(function() {
      $arrowhide.css('top', 'auto').animate({
        'height': '0vh'
      }, 2000)
      $document.dequeue();
    }, 2000);
    setTimeout(function() {
      $arrow.hide()
      $arrowhide.css('top', '0').animate({
        'height': '50vh'
      }, 2000)
      $document.dequeue();
    }, 4000);
  });
}
setInterval(slide, 6000);
//дальше необязательно
setInterval(function() {
  document.getElementById("body").style.backgroundColor = '#' + ((1 << 24) * Math.random() | 0).toString(16)
}, 3000)
$('#button').click(function() {
  $('#body').toggle();
});
var timerBlock = $('.seconds');
var num = 5;
var timerId = setInterval(function() {
  timerBlock.html(--num);
}, 1000);
setTimeout(function() {
  clearInterval(timerId);
  $('#seconds').html('Поехали!');
  $('#seconds').delay(500).slideUp();
}, num * 1000);

body {
  background: url('https://i.imgur.com/TZ5ya3G.jpg');
  background-size: cover;
}

.box {
  position: relative;
  overflow: hidden;
  margin: 0 auto;
  margin-top: 45vh;
  width: 10vw;
  height: 50vh;
}

.box__show,
.box__hide {
  position: absolute;
  overflow: hidden;
  top: 0;
  left: 0;
  right: 0;
  margin: 0 auto;
  width: 10vw;
  height: 50vh;
}

.box__show {
  display: none;
}

.line {
  position: absolute;
  overflow: hidden;
  top: 4px;
  left: 0;
  right: 0;
  bottom: 0;
  border-top: 3px solid transparent;
}

.line::before {
  content: "";
  display: block;
  position: absolute;
  top: 2px;
  bottom: 0;
  left: 50%;
  width: 1px;
  height: calc(50vh - 2px);
  border-left: 1px dashed white;
  margin-left: -1px;
  margin-top: -2px;
}

.arrow {
  position: absolute;
  left: 0;
  right: 0;
  top: 15px;
  width: 40px;
  margin: 0 auto;
}

.arrow::before {
  content: "";
  display: block;
  position: absolute;
  bottom: 10px;
  left: 1px;
  right: 0;
  margin: 0 auto;
  margin-bottom: -21px;
  width: 20px;
  height: 20px;
  border-top: 1px solid white;
  transform: rotate(-45deg);
}

.arrow::after {
  content: "";
  display: block;
  position: absolute;
  bottom: 10px;
  left: 0;
  right: 1px;
  margin: 0 auto;
  margin-bottom: -21px;
  width: 20px;
  height: 20px;
  border-top: 1px solid white;
  transform: rotate(45deg);
}


/*необязательно*/

#body {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100vh;
}

button {
  outline: none;
  cursor: pointer;
  position: fixed;
  top: 15px;
  left: 15px;
  padding: 5px;
  background: #f1f1f1;
  color: black;
  border: none;
  border-radius: 3px;
  font-size: 12px;
}

button:hover {
  background: #fff;
  color: dimgray;
}

#seconds {
  position: absolute;
  bottom: 5vh;
  left: 0;
  right: 0;
  width: 100%;
  margin: 0 auto;
  text-align: center;
  color: lightgray;
  font-size: 15px;
  font-family: monospace;
}

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