qml-anchor

anchor用起来很方便，但是只有在parent对象下面或者同级兄弟对象之间才可以使用，否则报错如下：
QML Rectangle: Cannot anchor to an item that isn’t a parent or sibling.
见如下例子便很好了展示出这一问题。

import QtQuick 2.9
import QtQuick.Window 2.2

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

    Rectangle{
        id:rec1;
        x:100;
        y:100;
        width: 100;
        height: 100;
        color: "red"
        border.color: "black"
        Text {
            id: name1
            text: qsTr("1")
        }

        Component.onCompleted:
        {
            spliceTest();
            var arr=["t","t","s","t","s","t"];
            removeValue(arr,"s")
        }

        Rectangle{
            id:rec3;
            anchors.right: rec1.left;
            anchors.top: rec1.top;
            width: 100;
            height: 100;
            color: "red"
            border.color: "black"

            Text {
                id: name3
                text: qsTr("3")
            }
        }

    }

    Rectangle{
        id:rec2;
        anchors.left: rec1.right;
        anchors.top: rec1.top;
        width: 100;
        height: 100;
        color: "red"
        border.color: "black"

        Text {
            id: name2
            text: qsTr("2")
        }
    }


    Rectangle{
        id:rec4;
        anchors.left: rec3.right;
        anchors.top: rec3.top;
        width: 100;
        height: 100;
        color: "red"
        border.color: "black"

        Text {
            id: name4
            text: qsTr("4")
        }
    }

    function spliceTest() {
       var ar = ["t","t"];
       console.log(ar.length);
       ar.splice(-1,"s");
       console.log(ar)
       console.log(ar.length)
    }

    function removeValue(arr,val)
    {
        arr.splice(0, 0,"a")
        console.log(arr)
    }
}

运行结果: