Scroll on line <path> on dashed line
This is what I have done so far with the help of friends from stackoverfow .
It works great, but I want to make an animation which is a bit tricky 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>
My question is Can I make the line dotted?
I know the path grows with help strokeDasharray
. But still, is there a way to achieve what I am looking for? If not, please suggest another way. I'm not looking for "to put the dotted line along the line you want to draw and give it your background color."
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1 answer
There is a way to do this. You can use the dotted 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>
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