QML中的SmoothedAnimation动画

SmoothedAnimation：一个特定的NumberAnimation类型，当目标值改变时会在动画中提供一个平滑过渡的过渡效果。

import QtQuick 2.9
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600
    title: qsTr("Hello World")

      Rectangle {
          anchors.fill: parent
          width: 800; height: 600
          color: "blue"

          Rectangle {
              width: 60; height: 60
              x: rect1.x - 5; y: rect1.y - 5
              color: "green"

              Behavior on x { SmoothedAnimation { velocity: 200 } }
              Behavior on y { SmoothedAnimation { velocity: 200 } }
          }

          Rectangle {
              id: rect1
              width: 50; height: 50
              color: "red"
          }

          focus: true
          Keys.onRightPressed: rect1.x = rect1.x + 100
          Keys.onLeftPressed: rect1.x = rect1.x - 100
          Keys.onUpPressed: rect1.y = rect1.y - 100
          Keys.onDownPressed: rect1.y = rect1.y + 100
      }
}

运行效果：

鼠标左右键控制红色矩形的位置，绿色矩形会自动跟随。
还在网上看到一篇跟随鼠标的例子：
https://blog.youkuaiyun.com/xuancailinggan/article/details/50894032?locationNum=16&fps=1