这与先前的here有关。但是，我认为这是一项艰巨的任务。所以我将其分解为较小的块。
我制作了一个简单的SVG图像，其中包含一个“路径”和一个“矩形”元素。用户可以通过上下滚动页面(向下滚动页面，上下滚动页面以关闭/“取消绘制”)在窗口上和窗口上绘制线条，但是，两个元素同时“绘制” /动画。我想做的是，当用户向下滚动页面时，画出行路径，然后绘制“rect”元素(之后)，因此更加流畅和按时间顺序排列。
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>the single line</title>
<link rel="stylesheet" type="text/css" href="line.css">
<style>
svg {
position: fixed;
margin: auto;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 50%;
}
/*.line{
stroke-dashoffset:850;
stroke-dasharray: 850;
}
.box {
stroke-dashoffset:1852;
stroke-dasharray: 1852;
}*/
.all{
stroke-dashoffset:2702;
stroke-dasharray: 2702;
}
.straightLine {
height: 3000px;
position: relative;
width: 360px;
margin: 40vh auto 0 auto;
}
</style>
</head>
<body>
<main role="article" title="line">
<div class="straightLine">
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 1280 800" style="enable-background:new 0 0 1280 800;" xml:space="preserve">
<style type="text/css">
.st0{fill:none;stroke:#000000;stroke-width:8;stroke-miterlimit:10;}
</style>
<g class="all">
<path class="st0" d="M54,178h509.6c49.9,0,90.4,40.5,90.4,90.4V428"/>
<rect x="498" y="428" class="st0" width="308" height="162"/>
</g>
</svg>
</div>
</main>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script src="line.js"></script>
<script>
$(document).ready(function() {
//variable for the 'stroke-dashoffset' unit
var $dashOffset = $(".all").css("stroke-dashoffset");
//on a scroll event - execute function
$(window).scroll(function() {
//calculate how far down the page the user is
var $percentageComplete = (($(window).scrollTop() / ($("html").height() - $(window).height())) * 100);
//convert dashoffset pixel value to interger
var $newUnit = parseInt($dashOffset, 10);
//get the value to be subtracted from the 'stroke-dashoffset'
var $offsetUnit = $percentageComplete * ($newUnit / 100);
//set the new value of the dashoffset to create the drawing effect
$(".all").css("stroke-dashoffset", $newUnit - $offsetUnit);
});
});
</script>
</body>
</html>
最佳答案
这怎么样？您可以通过在startPct数组中设置endPct和scrollBehaviour百分比值来控制每个路径何时开始和结束绘制。
注意:此代码假定您仅使用路径和矩形。如果您开始使用其他元素，则必须更新calcPathLength()函数。
var scrollBehaviour = [
{id: 'line1', startPct: 0, endPct: 30},
{id: 'rect1', startPct: 30, endPct: 60},
{id: 'line2', startPct: 60, endPct: 80},
{id: 'circ1', startPct: 80, endPct: 100}
];
$(document).ready(function() {
// On a scroll event - execute function
$(window).scroll(scrollEventHandler);
// Call the scroll event handler once at the start to initialise the dash offsets
scrollEventHandler();
});
function scrollEventHandler()
{
// Calculate how far down the page the user is
var percentOfScroll = (($(window).scrollTop() / ($("html").height() - $(window).height())) * 100);
// For each lement that is getting drawn...
for (var i=0; i<scrollBehaviour.length; i++)
{
var data = scrollBehaviour[i];
var elem = document.getElementById(data.id);
// Get the length of this elements path
var dashLen = calcPathLength(elem);
// Calculate where the current scroll position falls relative to our path
var fractionThroughThisElem = (percentOfScroll - data.startPct) / (data.endPct - data.startPct);
// Clamp the fraction value to within this path (0 .. 1)
fractionThroughThisElem = Math.max(fractionThroughThisElem, 0);
fractionThroughThisElem = Math.min(fractionThroughThisElem, 1);
var dashOffset = dashLen * (1 - fractionThroughThisElem);
elem.setAttribute("stroke-dasharray", dashLen);
elem.setAttribute("stroke-dashoffset", dashOffset);
}
}
function calcPathLength(elem)
{
if (elem.getTotalLength)
{
// It's a path
return elem.getTotalLength();
}
else if (elem.tagName === "rect")
{
// Handle rect elements: perimeter length = w + w + h + h
return (elem.width.baseVal.value + elem.height.baseVal.value) * 2;
}
else if (elem.tagName === "circle")
{
// Handle circle elements: perimeter length = 2 * r * PI
return elem.r.baseVal.value * 2 * Math.PI;
}
else if (elem.tagName === "line")
{
// Handle line elements: use pythagoras' theorem
var dx = elem.x2.baseVal.value - elem.x1.baseVal.value;
var dy = elem.y2.baseVal.value - elem.y1.baseVal.value;
return Math.sqrt(dx * dx + dy * dy);
}
// If you use other elem types, you will have to add support for them here.
}svg {
position: fixed;
margin: auto;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 50%;
}
/*.line{
stroke-dashoffset:850;
stroke-dasharray: 850;
}
.box {
stroke-dashoffset:1852;
stroke-dasharray: 1852;
}
.all{
stroke-dashoffset:2702;
stroke-dasharray: 2702;
}*/
.straightLine {
height: 3000px;
position: relative;
width: 360px;
margin: 40vh auto 0 auto;
}<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<main role="article" title="line">
<div class="straightLine">
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 1280 1000" style="enable-background:new 0 0 1280 800;" xml:space="preserve">
<style type="text/css">
.st0{fill:none;stroke:#000000;stroke-width:8;stroke-miterlimit:10;}
</style>
<g class="all">
<path id="line1" class="st0" d="M54,178h509.6c49.9,0,90.4,40.5,90.4,90.4V428"/>
<rect id="rect1" x="498" y="428" class="st0" width="308" height="162"/>
<line id="line2" x1="652" y1="590" x2="652" y2="790" class="st0"/>
<circle id="circ1" cx="652" cy="890" r="100" class="st0"/>
</g>
</svg>
</div>
</main>