QML鼠标拖动距离和速度

import QtQuick 2.12
import QtQuick.Window 2.12

Window {
    visible: true
     640
    height: 480
    title: qsTr("Hello World")

    Rectangle {
        height: 40
         parent.width
        color: "red"
        anchors.top: parent.top
    }

    MouseArea {
           id: mouseArea

           // 滑屏动画
           /*! 第一次点击y坐标 */
           property int pressY: 0
           /*! 拖动总距离 */
           property int dragTotalChangedY: 0
           /*! 每次拖动启始y坐标　*/
           property int dragStartY: 0
           /*! 每次拖动距离 */
           property int dragChangedY: 0
           property int distance: 40
           anchors.fill: parent
           enabled: true

           onPressed: {
               dragStartY = mouseY
               pressY = mouseY
               console.info("pressY = ", pressY, "Screen.height * 0.01 = ", Screen.height * 0.01)

           }

           onMouseYChanged: {
               // 边缘划入才拉起下拉面板，锁定及关机界面不唤起下拉面板
               if (pressY - distance > 0)
                   return

               dragChangedY = mouseY - dragStartY   // 每次拖动距离
               dragStartY = mouseY                      // 每次拖动启始坐标
               dragTotalChangedY = mouseY - pressY         // 拖动总距离
               console.info("onMouseYChanged dragChangedY = ", dragChangedY)
               console.info("onMouseYChanged dragTotalChangedY = ", dragTotalChangedY)
           }

           onReleased: {
               if (pressY - distance > 0)
                   return

               console.info("onReleased dragChangedY = ", dragChangedY)
               console.info("onReleased dragTotalChangedY = ", dragTotalChangedY)
               if (dragChangedY > Screen.height * 0.01) {
                   // 显示界面
                   console.info("111111111")
                   dragTotalChangedY = 0
               } else if (dragChangedY < -Screen.height * 0.01) {
                   // 隐藏界面
                   console.info("2222222")
                   dragTotalChangedY = -Screen.height
               } else {
                   // 超过屏幕一半显示，否则隐藏界面
                   dragTotalChangedY = (mouseY > (Screen.height / 2)) ? 0 : -Screen.height
               }

               if (0 === dragTotalChangedY) {
                   console.info("down")
               } else {
                   console.info("invalid")
               }

               // 清除历史数据
               dragChangedY = dragTotalChangedY = dragStartY = pressY = 0
           }
    }
}