How To – 스크롤 드로잉

w3.css

스크롤 드로잉

JavaScript와 SVG를 이용해 스크롤에 그리는 방법을 알아보자.

스크롤 드로잉 그리기

스크롤 시 삼각형을 그리기 위해 SVG와 JavaScript를 사용한다. <path> 요소여야 한다.

1단계) HTML 추가

<svg id="mySVG">
  <path fill="none" stroke="red" stroke-width="3" id="triangle" d="M150 0 L75 200 L225 200 Z"/>
</svg>

<script>
// Get the id of the <path> element and the length of <path>
var triangle = document.getElementById("triangle");
var length = triangle.getTotalLength();

// The start position of the drawing
triangle.style.strokeDasharray = length;

// Hide the triangle by offsetting dash. Remove this line to show the triangle before scroll draw
triangle.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() {
  var scrollpercent = (document.body.scrollTop + document.documentElement.scrollTop) / (document.documentElement.scrollHeight - document.documentElement.clientHeight);

  var draw = length * scrollpercent;

  // Reverse the drawing (when scrolling upwards)
  triangle.style.strokeDashoffset = length - draw;
}
</script>