js css3 drag rotation

FIG direct effects on:
Then the code:
A total of two ways:
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
  <style>
    .box {
      width: 200px;
      height:100px;
      background: #cccccc;
      position: absolute;
      top: 30%;
      left: 40%;
      transform-origin: 50% 50% 0;
    }
  </style>
</head>
<body>
  <div id="box" class="box"></div>

  <script>

    // 第一种
    var isMove = false;
    $('#box').mousedown(function (event) {
      const element = event.target;
      const rect = element.getBoundingClientRect();
      element.dataset.centerX = rect.left + rect.width / 2;
      element.dataset.centerY = rect.top + rect.height / 2;
      element.dataset.angle = getDragAngle(event);
      isMove = true;
    });

    $('#box').mousemove(function (event) {
      if (isMove) {
        var angle = getDragAngle(event);
        event.target.style.transform = 'rotate(' + angle + 'rad)';
      }
    });

    $('#box').mouseup(function (event) {
      isMove = false;
      event.target.dataset.angle = getDragAngle(event);
    });

    function getDragAngle(event) {
      var element = event.target;
      var startAngle = parseFloat(element.dataset.angle) || 0;
      var center = {
        x: parseFloat(element.dataset.centerX) || 0,
        y: parseFloat(element.dataset.centerY) || 0,
      };
      var angle =Math.atan2 (center.y - event.clientY, center.x - event.clientX);
       return angle - startAngle; 
    } 
//      second 
//      $ (Document) .on ( 'mouseMove', function (E) { 
//        var X = e.clientX; 
//        var Y = e.clientY; 
//        var Origin = {X: 950, Y: 190} // to manually specify the current center point, may be left in accordance with the current element + width to x top + height / 2 give the value of y / 2 

//        // calculate the current mouse coordinates of the element with respect to the center point 
//        x = x - origin.x; // since x is greater than the y-axis origin.x to the right, directly on the line Save 
@        y = origin.y - y; y // if you want, but the x-axis direction, which is smaller than the origin.y, so there needs to turn 

//         // calculation is then it 
@       var ele = document.getElementById('box')
//       var deg = Math.atan2(y, x) / Math.PI * 180;
//       ele.style.transform = 'rotate('+ -deg +'deg)'
// });

    </script>

</body>
</html>
js css3 drag rotation

Guess you like
