qt - QML 将信号连接到函数

Question

我正在熟悉 QT5 中的 QML。所以我试图从以下视频中编写代码:video

在此视频中使用了代码:send.connect(target.receive());。但这部分不起作用。我收到错误:

qrc:/Receiver.qml:8: Error: Cannot assign [undefined] to QString

此方法是否已弃用或者我做错了什么？

ma​​in.qml

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

Background {
    id: background
    anchors.fill: parent
    target: sender

    Sender {
        id: sender
        y: 145
        displayText: "Sender"
        anchors.verticalCenter: parent.verticalCenter
        anchors.left: parent.left
        anchors.leftMargin: 50
        target: receiver
    }

    Receiver {
        id: receiver
        x: 376
        y: 158
        displayText: "Receiver"
        anchors.verticalCenter: parent.verticalCenter
        anchors.right: parent.right
        anchors.rightMargin: 50
        width: sender.width
    }
}
}

接收器.qml

Cirkel {
id: receiveButton

function receive(value)
{
    displayText = value
    clicknotify.running = true
}

SequentialAnimation on buttonColor
{
    id: clicknotify
    running: false

    ColorAnimation {
        from: "#afc4cb"
        to: "red"
        duration: 200
    }

    ColorAnimation {
        from: "red"
        to: "#afc4cb"
        duration: 200
    }
}
}

发件人.qml

Cirkel {
id: sendButton

property int counter: 0
property Receiver target: null

signal send(string value)

onTargetChanged: {
    send.connect(target.receive());
}

MouseArea {
    anchors.fill: parent

    onClicked: {
        counter++
        parent.send(counter)
        displayText = counter
    }

    onPressed: parent.buttonColor = "green"
    onReleased: parent.buttonColor = "#afc4cb"
}
}

问题: 如何将信号从一个 qml 链接到另一个 qml 函数？

Answer 1

你写:

send.connect(target.receive());

在其中调用 target.receive() 并尝试将其返回值连接到 send。

你想要的是:

send.connect(target.receive);

将 send 连接到函数 receive 本身的位置。

---

建议:

Also try the declarative way, using a Connection-object.