我正在尝试创建一个脚本,其中Qml代码可以将数据发送到c ++脚本,然后相应地执行一个函数。这部分工作正常,但我也希望将执行函数的反馈发送回Qml。
我有以下代码(这是一个精简的示例,用于测试从 Receiver.cpp 向Qml发送数据)
Main.cpp的
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "receiver.h"
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
Receiver receiver;
QQmlContext* ctx = engine.rootContext();
ctx->setContextProperty("receiver", &receiver);
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
return app.exec();
}
Reciever.cpp (注意:我也试图从这段代码中发送数据。我猜这就是出错的地方)
#include "receiver.h"
#include <QDebug>
#include <QQmlApplicationEngine> //For sending to QML
#include <QQmlContext> //For sending to QML
Receiver::Receiver(QObject *parent) :
QObject(parent)
{
}
int counter = 0;
void Receiver::receiveFromQml(int count) {
qDebug() << "Received in C++ from QML:" << count;
//For sending to QML start
QQmlApplicationEngine engine;
Receiver receiver;
QQmlContext* ctx = engine.rootContext();
ctx->setContextProperty("receiver", &receiver);
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
//For sending to QML end
receiver.sendToQml(counter); //Send to the QML
counter++;
}
Reciever.h
#ifndef RECEIVER_H
#define RECEIVER_H
#include <QObject>
class Receiver : public QObject
{
Q_OBJECT
public:
explicit Receiver(QObject *parent = 0);
signals:
void sendToQml(int count);
public slots:
void receiveFromQml(int count);
};
#endif // RECEIVER_H
Main.qml
import QtQuick 2.2
import QtQuick.Window 2.1
Window {
id: test
visible: true
width: 500
height: 500
property variant globalForJs: 10;
Item {
Timer {
interval: 1000; running: true; repeat: true
onTriggered: console.log("Real text value:", text1.text, " Global for JS:", globalForJs);
}
}
MouseArea {
anchors.fill: parent
onClicked: {
receiver.receiveFromQml(42);
}
Text {
id: text1
x: 193
y: 329
text: globalForJs
font.pixelSize: 12
}
}
Text {
text: qsTr("Press me to send a signal to C++")
anchors.centerIn: parent
}
Connections {
target: receiver
onSendToQml: {
console.log("Received in QML from C++: " + count);
globalForJs = count;
console.log(text1.text);
console.log("Real text value:2", text1.text, " Global for JS:", globalForJs);
}
}
}
我正在使用计时器来显示 text1 的真实值以及我试图制作的全局变量 GlobalForJs 但是它没有用。在 Connections 部分内部,它显示文本实际上发生了变化。但是在 Connections 之外它不会改变。
我最好的猜测是,这是因为我在 receiver.cpp
中创建了一个“新”连接。因此,在简短的总结中,我的问题是:如何将 receiver.cpp (以及将来的其他cpp文件)中的数据发送到Qml文件并显示它?
答案 0 :(得分:1)
以下是很多解决方案:
在C++
代码中创建一个信号并在qml
中连接到该信号,以便能够从C ++方法获得结果。
插槽不仅可以void
,还可以实际返回值。但在这种情况下,它会阻止你的线程并导致“冻结”。
导出可与之完全交互的对象。这是做这些事情最合适的方式。