// detectZoom.js
window.onload = function () {
  // fun2();
  // init();
};
function fun1() {
  var keyCodeMap = {
    // 91: true, // command
    61: true,
    107: true, // 数字键盘 +
    109: true, // 数字键盘 -
    173: true, // 火狐 - 号
    187: true, // +
    189: true, // -
  };
  // 覆盖ctrl||command + ‘+’/‘-’
  document.onkeydown = function (event) {
    var e = event || window.event;
    var ctrlKey = e.ctrlKey || e.metaKey;
    if (ctrlKey && keyCodeMap[e.keyCode]) {
      e.preventDefault();
    } else if (e.detail) {
      // Firefox
      event.returnValue = false;
    }
  };
  // 覆盖鼠标滑动
  document.body.addEventListener(
    "wheel",
    (e) => {
      if (e.ctrlKey) {
        if (e.deltaY < 0) {
          e.preventDefault();
          return false;
        }
        if (e.deltaY > 0) {
          e.preventDefault();
          return false;
        }
      }
    },
    { passive: false }
  );
}
function _getSystem() {
  let flag = false;
  var agent = navigator.userAgent.toLowerCase();
  //现只针对windows处理，其它系统暂无该情况，如有，继续在此添加
  if (agent.indexOf("windows") >= 0) {
    return true;
  }
}
//获取页面缩放比例
//    _getDevicePixelRatio() {
//        let t = this;
//    }
//监听方法兼容写法
function _addHandler(element, type, handler) {
  if (element.addEventListener) {
    element.addEventListener(type, handler, false);
  } else if (element.attachEvent) {
    element.attachEvent("on" + type, handler);
  } else {
    element["on" + type] = handler;
  }
}
//校正浏览器缩放比例
function _correct() {
  let t = this;
  //页面devicePixelRatio（设备像素比例）变化后，计算页面body标签zoom修改其大小，来抵消devicePixelRatio带来的变化。
  document.getElementsByTagName("body")[0].style.zoom =
    1 / window.devicePixelRatio;
}
//监听页面缩放
function _watch() {
  let t = this;
  t._addHandler(window, "resize", function () {
    //注意这个方法是解决全局有两个window.resize
    //重新校正
    t._correct();
  });
}
//初始化页面比例
function init() {
  let t = this;
  if (t._getSystem()) {
    //判断设备，目前只在windows系统下校正浏览器缩放比例
    //初始化页面校正浏览器缩放比例
    t._correct();
    //开启监听页面缩放
    t._watch();
  }
}
function fun2() {
  let ratio = 0,
    screen = window.screen,
    ua = navigator.userAgent.toLowerCase();
  if (window.devicePixelRatio !== undefined) {
    ratio = window.devicePixelRatio;
  } else if (~ua.indexOf("msie")) {
    if (screen.deviceXDPI && screen.logicalXDPI) {
      ratio = screen.deviceXDPI / screen.logicalXDPI;
    }
  } else if (
    window.outerWidth !== undefined &&
    window.innerWidth !== undefined
  ) {
    ratio = window.outerWidth / window.innerWidth;
  }
  if (ratio) {
    ratio = Math.round(ratio * 100);
  }

  document.body.style.zoom = 100 / Number(ratio);
}