计算鼠标和 DOM 元素边缘之间的距离

Question

我想计算鼠标和给定元素边缘之间的距离。所以当鼠标碰到元素的边缘时，值应该是0px；

https://codepen.io/nishaljohn/pen/BVmGbz

var mX, mY, distance,
    $distance = $('#distance_text p'),
    $element  = $('.div1');

function calculateDistance(elem, mouseX, mouseY) {
    return Math.floor(Math.sqrt(Math.pow(mouseX - (elem.offset().left+(elem.width()/2)), 2) + Math.pow(mouseY - (elem.offset().top+(elem.height()/2)), 2)));
}

$(document).mousemove(function(e) {  
    mX = e.pageX;
    mY = e.pageY;
    distance = calculateDistance($element, mX, mY);
    $distance.text(distance);         
});

这会考虑到元素的中心，只有当你到达绝对中心时才会读取 0px。

一个 JQuery 插件也可以。

Answer 1

对于任何尺寸的元素，我都使用了我在另一个示例中找到的代码：

var mX = e.pageX;
var mY = e.pageY;
var from = {x:mX, y:mY};
var $n=your_Element;
var off = $n.offset(),
  nx1 = off.left,
  ny1 = off.top,
  nx2 = nx1 + $n.outerWidth(),
  ny2 = ny1 + $n.outerHeight(),
  maxX1 = Math.max(mX, nx1),
  minX2 = Math.min(mX, nx2),
  maxY1 = Math.max(mY, ny1),
  minY2 = Math.min(mY, ny2),
  intersectX = minX2 >= maxX1,
  intersectY = minY2 >= maxY1,
  to = {
    x: intersectX ? mX : nx2 < mX ? nx2 : nx1,
    y: intersectY ? mY : ny2 < mY ? ny2 : ny1
  };
var distX = to.x - from.x,
  distY = to.y - from.y,
  hypot = Math.sqrt(distX * distX + distY * distY);
console.log(hypot);//this will output 0 when next to your element.

Answer 2

好的，解决方案只是纯数学。刚好要去掉容器的宽高- elem.width()/2和- elem.height()/2

(function() {
    
    var mX, mY, distance,
        $distance = $('#distance span'),
        $element  = $('#element');

    function calculateDistance(elem, mouseX, mouseY) {
        return Math.floor(Math.sqrt(Math.pow(mouseX - (elem.offset().left+(elem.width()/2)), 2) - elem.width()/2 + Math.pow(mouseY - (elem.offset().top+(elem.height()/2)), 2) ) -elem.height()/2);
    }

    $(document).mousemove(function(e) {  
        mX = e.pageX;
        mY = e.pageY;
        distance = calculateDistance($element, mX, mY);
        if(distance > 0)
        	$distance.text(distance);
        else{
        $distance.text(0);
        }
    });

})();

body {
    font: 11px helvetica, arial, sans-serif;
    text-align: center;    
}

#distance {
    font-size: 16px;
    font-weight: bold; 
    margin-top: 10px; 
}

#element {
    background: #000;
    color: #fff;
    height: 50px;
    left: 50%;
    margin: -25px 0 0 -25px;
    position: absolute;
    top: 50%;
    width: 50px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p>Move your mouse to calculate distance between the center of the element and the mouse cursor.</p>

<p id="distance">Distance: <span>0</span>px</p>

<div id="element"></div>

这是解决方案吗？