itsm-pc-handle/assets/js/script/print/unitChange.js

//  px <-> mm  单位互相转换

/**
 * 获取DPI 每英寸像素点
 * @returns {Array}
 */
 let conversion_getDPI = function() {
    var DPI = 0;
    if (window.screen.deviceXDPI) {
      DPI = window.screen.deviceXDPI;
    } else {
      var tmpNode = document.createElement("DIV");
      tmpNode.style.cssText =
        "width:1in;height:1in;position:absolute;left:0px;top:0px;z-index:99;visibility:hidden";
      document.body.appendChild(tmpNode);
      DPI = parseInt(tmpNode.offsetWidth); 
      tmpNode.parentNode.removeChild(tmpNode);
    } 
    return DPI;
  };
  
  // 1 英寸=25.4 毫米
  
  /**
   * px转换为mm
   * @param value
   * @returns {number}
   */
  let px2mm = function(value) {
    var inch = value / conversion_getDPI();
    var c_value = inch * 25.4;
    //      console.log(c_value);
    return c_value;
  };
  
  /**
   * mm转换为px
   * @param value
   * @returns {number}
   */
  let mm2px = function(value) {
    var inch = value / 25.4;
    var c_value = inch * conversion_getDPI();
    //      console.log(c_value);
    return c_value;
  };
//   export default {
//       mm2px,
//       px2mm
//   };