[Qt Qml] 一个可以拖拽的小球

import QtQuick 2.0

Item
{
    id: root;
    width: 800;
    height: 480;

    Rectangle{
        anchors.fill: parent
        color: "grey"
    }

    Rectangle{
        id:spreadBtn
        width: 80
        height: 80
        radius: 40
        color: "red"
        opacity: dragArea.pressed ? 0.5 : 1
        x: 20
        y: 200

        Drag.active: dragArea.drag.active

        MouseArea
        {
            id: dragArea
            anchors.fill: parent
            drag.target: parent

            drag.minimumY: 0;
            drag.maximumY: 400;
            drag.minimumX: 0;
            drag.maximumX: 720;
        }
    }
}