自定义信号

import QtQuick 2.6
import QtQuick.Window 2.2
import QtQuick.Controls 1.4
Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Text {
        id: text;
        text: qsTr("text");
        anchors.centerIn: parent;
        font.pixelSize: 20;
        color:"black";
    }
    Component{
        id:btnComponent;
        Rectangle{
            id:colorPicker;
            width: 50;
            height: 30;
            signal colorPicked(color clr);
            MouseArea{
                anchors.fill: parent;
                onPressed: colorPicker.colorPicked(colorPicker.color);
            }
        }
    }

    Loader{
        id:loader1;
        anchors.left: parent.left;
        anchors.bottom: parent.bottom;
        anchors.leftMargin: 10;
        anchors.bottomMargin: 10;
        sourceComponent: btnComponent;
        onLoaded: {
            item.color = "red";
        }
    }

    Connections{
        target: loader1.item;//这里为什么是item?
        onColorPicked: {
            text.color = clr;
        }
    }
}