我目前正在尝试将 QML 信号连接到 C++ 插槽,但未成功。
我刚刚看了几个其他的例子,但我想我不明白如何获取 qml 文档的根对象...
我的问题是,信号似乎是从 qml 文件发送的,但没有在 cpp 文件中接收到。执行此代码时没有错误。
//Counter.h
#ifndef COUNTER_H
#define COUNTER_H
#include <QObject>
class Counter : public QObject
{
Q_OBJECT
private:
int counter;
public:
explicit Counter(QObject *parent = 0);
signals:
void counterHasChanged(int);
public slots:
void click();
};
#endif // COUNTER_H
//counter.cpp
#include "counter.h"
#include <QDebug>
Counter::Counter(QObject *parent) :
QObject(parent)
{
this->counter = 0;
qDebug() << "Class Counter created";
}
void Counter::click() {
this->counter++;
qDebug() << "clickRegistered() - emit counterHasChanged()";
emit counterHasChanged(counter);
}
//main.cpp
#include <QtGui/QGuiApplication>
#include "qtquick2applicationviewer.h"
#include "counter.h"
#include <QObject>
#include <QtQuick>
#include <QDebug>
#include <QQuickItem>
#include <QQmlContext>
#include <QtCore>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QtQuick2ApplicationViewer viewer;
viewer.setMainQmlFile(QStringLiteral("qml/StatesTest2/main.qml"));
viewer.showExpanded();
QQuickView view;
view.setSource(QUrl::fromLocalFile("qml/StatesTest2/main.qml"));
QObject *item = view.rootObject();
Counter counter;
QObject::connect(item, SIGNAL(click()), &counter, SLOT(click()));
return app.exec();
}
//main.qml
import QtQuick 2.0
Rectangle {
id: root
width: 360
height: 360
signal click
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
MouseArea {
anchors.fill: parent
onClicked: {
root.click
console.log("click() qml")
}
}
Text {
text: "clicks: "
x: 30
y: 250
}
Text {
id: counter
text: "0"
x: 75
y: 250
}
}
我知道有很多这样的话题.. 出于某种原因,没有其他解决方案对我有用..也许我应该改变我的 IDE :D
最佳答案
我建议您将计数器添加为上下文属性。这需要进行以下更改。
//Counter.h
#ifndef COUNTER_H
#define COUNTER_H
#include <QObject>
class Counter : public QObject
{
Q_OBJECT
private:
int counter;
public:
explicit Counter(QObject *parent = 0);
signals:
void counterHasChanged(int Value);
public slots:
void click();
};
#endif // COUNTER_H
Counter.cpp 文件
//counter.cpp
#include "counter.h"
#include <QDebug>
Counter::Counter(QObject *parent) :
QObject(parent)
{
this->counter = 0;
qDebug() << "Class Counter created";
}
void Counter::click() {
this->counter++;
qDebug() << "clickRegistered() - emit counterHasChanged()";
emit counterHasChanged(counter);
}
main.cpp文件
//main.cpp
#include <QtGui/QGuiApplication>
#include "qtquick2applicationviewer.h"
#include "counter.h"
#include <QObject>
#include <QtQuick>
#include <QDebug>
#include <QQuickItem>
#include <QQmlContext>
#include <QtCore>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
Counter counter;
QtQuick2ApplicationViewer viewer;
viewer.rootContext()->setContextProperty("counterObj",&counter);
viewer.setMainQmlFile(QStringLiteral("qml/SO_QMLCPPCommunication/main.qml"));
viewer.showExpanded();
return app.exec();
}
并且在qml文件中,可以通过引用counterObj来访问Counter对象的slot。
//main.qml
import QtQuick 2.0
Rectangle {
id: root
width: 360
height: 360
signal click
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
MouseArea {
anchors.fill: parent
onClicked: {
counterObj.click()
console.log("click() qml")
}
}
Text {
text: "clicks: "
x: 30
y: 250
}
Text {
id: counter
text: "0"
x: 75
y: 250
}
Connections
{
id:cppConnection
target:counterObj
ignoreUnknownSignals : true
onCounterHasChanged:{
//To access signal parameter,please name the parameter.
console.debug("Counter value changed")
counter.text = Value
}
}
}
关于c++ - Qt 信号和插槽 - 没有任何反应,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22605257/