使滚动增长 <path>到虚线 [英] Make the on scroll growing <path> to dashed line

问题描述

这是我目前在 stackoverfow 本身的朋友的帮助下所做的.

This what I have done so far with the help from friends from stackoverfow itself.

效果很好，但我想做一个对我来说有点复杂的动画.

It works fine but I want to do an animation which is little much complicated for me.

// Get the id of the <path> element and the length of <path>
var myline = document.getElementById("myline");
var length = myline.getTotalLength();
circle = document.getElementById("circle");
// The start position of the drawing
myline.style.strokeDasharray = length;

// Hide the triangle by offsetting dash. Remove this line to show the triangle before scroll draw
myline.style.strokeDashoffset = length;

// Find scroll percentage on scroll (using cross-browser properties), and offset dash same amount as percentage scrolled
window.addEventListener("scroll", myFunction);

function myFunction() {
  // What % down is it?
  var scrollpercent = (document.body.scrollTop + document.documentElement.scrollTop) / (document.documentElement.scrollHeight - document.documentElement.clientHeight);
  // Length to offset the dashes
  var draw = length * scrollpercent;

  // Reverse the drawing (when scrolling upwards)
  myline.style.strokeDashoffset = length - draw;

  //get point at length
  endPoint = myline.getPointAtLength(draw);
  circle.setAttribute("cx", endPoint.x);
  circle.setAttribute("cy", endPoint.y);

}

body {
  height: 2000px;
  background: #f1f1f1;
}

#circle {
  fill: red;
}

#mySVG {
  position: fixed;
  top: 15%;
  width: 100vw;
  height: 100vh;
  margin-left: -50px;
}

.st0 {
  fill: none;
  stroke-dashoffset: 3px;
  stroke: red;
  stroke-width: 5;
  stroke-miterlimit: 10;
  stroke-dasharray: 20;
}

<h2>Scroll down this window to draw my path.</h2>
<p>Scroll back up to reverse the drawing.</p>

<svg id="mySVG" viewBox="0 0 60 55" preserveAspectRatio="xMidYMin slice" style="width: 6%; padding-bottom: 42%; height: 1px; overflow: visible">
  <circle id="circle" cx="10" cy="10" r="10"/>
  <path id="myline" class="st0" stroke-dasharray="10,9" d="M 20 0 v 20 a 30 30 0 0 0 30 30 h 600 a 40 40 0 0 1 0 80 h -140 a 30 30 0 0 0 0 60 h 200 a 40 40 0 0 1 0 80 h -100 a 30 30 0 0 0 -30 30 v 20" /> Sorry, your browser does not support inline SVG.
</svg>

我的问题是我们可以把这条线变成虚线吗?

我知道路径正在使用 strokeDasharray 增长.但是，有没有办法实现我正在寻找的东西?如果不是，那么请建议另一种方式.我不是在寻找在您要绘制的线上放置一条虚线并为其指定背景颜色".

I know the path is growing using the strokeDasharray. But still, is there a way to attain what am looking for? If no, then please do suggest another way. I am not looking for "to place a dashed line over the line you want to draw and give it the colour of your background".

推荐答案

有 一种方法可以做到.您可以使用虚线作为动画线的蒙版.

There is a way to do it. You can use a dashed line as a mask for the animated line.

// Get the id of the <path> element and the length of <path>
var myline = document.getElementById("myline");
var length = myline.getTotalLength();
circle = document.getElementById("circle");
// The start position of the drawing
myline.style.strokeDasharray = length;

// Hide the triangle by offsetting dash. Remove this line to show the triangle before scroll draw
myline.style.strokeDashoffset = length;

// Find scroll percentage on scroll (using cross-browser properties), and offset dash same amount as percentage scrolled
window.addEventListener("scroll", myFunction);

function myFunction() {
  // What % down is it?
  var scrollpercent = (document.body.scrollTop + document.documentElement.scrollTop) / (document.documentElement.scrollHeight - document.documentElement.clientHeight);
  // Length to offset the dashes
  var draw = length * scrollpercent;

  // Reverse the drawing (when scrolling upwards)
  myline.style.strokeDashoffset = length - draw;

  //get point at length
  endPoint = myline.getPointAtLength(draw);
  circle.setAttribute("cx", endPoint.x);
  circle.setAttribute("cy", endPoint.y);

}

body {
  height: 2000px;
  background: #f1f1f1;
}

#circle {
  fill: red;
}

#mySVG {
  position: fixed;
  top: 15%;
  width: 100vw;
  height: 100vh;
  margin-left: -50px;
}

.st0 {
  fill: none;
  stroke-dashoffset: 3px;
  stroke: red;
  stroke-width: 5;
  stroke-miterlimit: 10;
  stroke-dasharray: 20;
}

.mask-style {
  stroke: white;
  stroke-width: 7;
}

<h2>Scroll down this window to draw my path.</h2>
<p>Scroll back up to reverse the drawing.</p>

<svg id="mySVG" viewBox="0 0 60 55" preserveAspectRatio="xMidYMin slice" style="width: 6%; padding-bottom: 42%; height: 1px; overflow: visible">
  <defs>
    <mask id="dash-mask">
      <path class="st0 mask-style" stroke-dasharray="10,9" d="M 20 0 v 20 a 30 30 0 0 0 30 30 h 600 a 40 40 0 0 1 0 80 h -140 a 30 30 0 0 0 0 60 h 200 a 40 40 0 0 1 0 80 h -100 a 30 30 0 0 0 -30 30 v 20" />
    </mask>
  </defs>
  <circle id="circle" cx="10" cy="10" r="10"/>
  <path id="myline" class="st0" stroke-dasharray="10,9" d="M 20 0 v 20 a 30 30 0 0 0 30 30 h 600 a 40 40 0 0 1 0 80 h -140 a 30 30 0 0 0 0 60 h 200 a 40 40 0 0 1 0 80 h -100 a 30 30 0 0 0 -30 30 v 20" mask="url(#dash-mask)"/>
  Sorry, your browser does not support inline SVG.
</svg>

这篇关于使滚动增长 <path>到虚线的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！