从QML访问C ++函数 [英] Access C++ function from QML

问题描述

我试图用Qt做一个小程序。我有一个 main.cpp 以下代码：

  #include < QtGui / QApplication的> 
 #includeqmlapplicationviewer.h
 
 Q_DECL_EXPORT int main（int argc，char * argv []）
 {
 QScopedPointer< QApplication> app（createApplication（argc，argv））; 
 
 QmlApplicationViewer查看器; 
 viewer.setOrientation（QmlApplicationViewer :: ScreenOrientationAuto）; 
 viewer.setMainQmlFile（QLatin1String（qml / tw_looptijden_berekenen / main.qml））; 
 viewer.showExpanded（）; 
 
 return app-> exec（）; 
} 
 
 int reken_tijden_uit（）{
 return true; 
} 
  

我有一个 .qml $ b

  import QtQuick 1.1 
 
矩形{
 
 width：360 
 height：360 
 Text {
 text：qsTr（Hello World）
 anchors.centerIn：parent 
} 
 MouseArea {
 anchors.fill：parent 
 onClicked：{
 Qt.quit（）; 
} 
} 
} 
  

现在，当我点击 MouseArea ，程序退出。我想要的是它在 main.cpp 文件中调用函数 reken_tijden_uit 。

我搜索了很多，并在本网站上搜索到。我发现了一些答案，但我没有得到一个工作。

那么我要放哪些代码，以便我可以调用函数 reken_tijden_uit in C ++？

预先感谢。 b

头文件如下所示：

  #ifndef EIGEN_FUNCTION_HEADER_H 
 #define EIGEN_FUNCTION_HEADER_H 
 
 class MyObject：public QObject {
 Q_OBJECT $ b $ public：
显式MyObject（QObject * parent = 0）：QObject（parent）{} 
 Q_INVOKABLE int reken_tijden_uit（）{
 return 1; 
} 
}; 
 
 #endif // EIGEN_FUNCTION_HEADER_H 
  

main。 cpp ：

  #include< QtGui / QApplication> 
 #includeqmlapplicationviewer.h
 #includeeigen_function_header.h
 
 QScopedPointer< QApplication> app（createApplication（argc，argv））; 
 
 qmlRegisterType< MyObject>（com.myself，1,0，MyObject）; 
 
 Q_DECL_EXPORT int main（int argc，char * argv []）
 {
 QScopedPointer< QApplication> app（createApplication（argc，argv））; 
 
 QmlApplicationViewer查看器; 
 viewer.setOrientation（QmlApplicationViewer :: ScreenOrientationAuto）; 
 viewer.setMainQmlFile（QLatin1String（qml / tw_looptijden_berekenen / main.qml））; 
 viewer.showExpanded（）; 
 
 return app-> exec（）; 
} 
  

和QML文件：

  import QtQuick 1.1 
 import com.myself 1.0 
 
矩形{
宽度：360 
高度：360 
 Text {
 text：qsTr（Hello World）
 anchors.centerIn：parent 
} 
 MyObject {
 id：myobject 
} 
 MouseArea {
 anchors.fill：parent 
 onClicked：{
 myobject.reken_tijden_uit（）
} 
} 
} 
  

错误如下：

  D：\ * \ main.cpp：6：错误：'argc'未在此范围内声明
 D：\ * \ main.cpp：6：error：' argv'未在此范围内声明
 D：\ * \ main.cpp：8：错误：预期的构造函数，析构函数或'<'令牌之前的类型转换
  
         对于任何C + +代码从QML调用，它必须驻留在 QObject 中。
 
 
 
你需要做的是创建使用你的函数一个 QObject 后代类，把它注册到QML，在你的QML中实例化它并调用函数。 
还要注意你必须用 Q_INVOKABLE 来标记你的函数。
 
 
 
代码：
  
 
 
  #ifndef EIGEN_FUNCTION_HEADER_H 
 #define EIGEN_FUNCTION_HEADER_H 
 
 #include< QObject> 
 
 class MyObject：public QObject {
 Q_OBJECT $ b $ public：
 explicit MyObject（QObject * parent = 0）：QObject（parent）{} 
 Q_INVOKABLE int reken_tijden_uit（）{
 return 1; 
} 
}; 
 
 #endif // EIGEN_FUNCTION_HEADER_H 
  
 main.cpp：
 
  #include< QtGui / QApplication> 
 #include< QtDeclarative> 
 
 #includeqmlapplicationviewer.h
 #includeeigen_function_header.h
 
 Q_DECL_EXPORT int main（int argc，char * argv []）
 {
 QScopedPointer< QApplication> app（createApplication（argc，argv））; 
 qmlRegisterType< MyObject>（com.myself，1,0，MyObject）; 
 
 QmlApplicationViewer查看器; 
 viewer.setOrientation（QmlApplicationViewer :: ScreenOrientationAuto）; 
 viewer.setMainQmlFile（QLatin1String（qml / tw_looptijden_berekenen / main.qml））; 
 viewer.showExpanded（）; 
 
 return app-> exec（）; 
} 
  
 QML： 
 
 
  import QtQuick 1.1 
 import com.myself 1.0 
 
 Rectangle {
 
 width：360 
 height：360 
 Text {
 text：qsTr（Hello World）
 anchors.centerIn：parent 
} 
 MyObject {
 id：myobject 
 } 
 $ b MouseArea {
 anchors.fill：parent 
 onClicked：{
 console.log（myobject.reken_tijden_uit（））
} 
 } 
} 
  
 
I'm trying to make a little program with Qt. I have a main.cpp with the following code:
#include <QtGui/QApplication>
#include "qmlapplicationviewer.h"

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));

    QmlApplicationViewer viewer;
    viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
    viewer.setMainQmlFile(QLatin1String("qml/tw_looptijden_berekenen/main.qml"));
    viewer.showExpanded();

    return app->exec();
}

int reken_tijden_uit(){
    return true;
}
and I have a .qml file:
import QtQuick 1.1

Rectangle {

width: 360
height: 360
Text {
    text: qsTr("Hello World")
    anchors.centerIn: parent
}
MouseArea {
    anchors.fill: parent
    onClicked: {
        Qt.quit();
    }
}
}
Now, when I click on the MouseArea, the program quits. What I want is that it calls the function reken_tijden_uit in the main.cpp file.


I've googled a lot, and searched on this site to. I've found a couple of answers, but I didn't get one working.

So what code do I put where so I can call the function reken_tijden_uit in C++?

Thanks in advance.



The header file looks like this:
#ifndef EIGEN_FUNCTION_HEADER_H
#define EIGEN_FUNCTION_HEADER_H

class MyObject : public QObject{
   Q_OBJECT
public:
    explicit MyObject (QObject* parent = 0) : QObject(parent) {}
    Q_INVOKABLE int reken_tijden_uit(){
    return 1;
    }
};

#endif // EIGEN_FUNCTION_HEADER_H
main.cpp:
#include <QtGui/QApplication>
#include "qmlapplicationviewer.h"
#include "eigen_function_header.h"

QScopedPointer<QApplication> app(createApplication(argc, argv));

qmlRegisterType<MyObject>("com.myself", 1, 0, "MyObject");

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));

    QmlApplicationViewer viewer;
    viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
    viewer.setMainQmlFile(QLatin1String("qml/tw_looptijden_berekenen/main.qml"));
    viewer.showExpanded();

    return app->exec();
}
and the QML file:
import QtQuick 1.1
import com.myself 1.0

Rectangle {
    width: 360
    height: 360
    Text {
        text: qsTr("Hello World")
        anchors.centerIn: parent
    }
    MyObject {
        id: myobject
    }
    MouseArea {
        anchors.fill: parent
        onClicked: {
            myobject.reken_tijden_uit()
        }
    }
}
And the errors are as follow:
D:\*\main.cpp:6: error: 'argc' was not declared in this scope
D:\*\main.cpp:6: error: 'argv' was not declared in this scope
D:\*\main.cpp:8: error: expected constructor, destructor, or type conversion before '<' token
So what did I do wrong?
解决方案
For any C++ code to be called from QML, it must reside inside a QObject.

What you need to do is create a QObject descended class with your function, register it to QML, instantiate it in your QML and call the function.
Note also that you have to mark your function with Q_INVOKABLE.

Code:
#ifndef EIGEN_FUNCTION_HEADER_H
#define EIGEN_FUNCTION_HEADER_H

#include <QObject>

class MyObject : public QObject{
   Q_OBJECT
public:
    explicit MyObject (QObject* parent = 0) : QObject(parent) {}
    Q_INVOKABLE int reken_tijden_uit(){
    return 1;
    }
};

#endif // EIGEN_FUNCTION_HEADER_H
main.cpp:
#include <QtGui/QApplication>
#include <QtDeclarative>

#include "qmlapplicationviewer.h"
#include "eigen_function_header.h"

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));
    qmlRegisterType<MyObject>("com.myself", 1, 0, "MyObject");

    QmlApplicationViewer viewer;
    viewer.setOrientation(QmlApplicationViewer::ScreenOrientationAuto);
    viewer.setMainQmlFile(QLatin1String("qml/tw_looptijden_berekenen/main.qml"));
    viewer.showExpanded();

    return app->exec();
}
QML:
import QtQuick 1.1
import com.myself 1.0

Rectangle {

    width: 360
    height: 360
    Text {
        text: qsTr("Hello World")
        anchors.centerIn: parent
    }
    MyObject {
       id: myobject
    }

    MouseArea {
        anchors.fill: parent
        onClicked: {
            console.log(myobject.reken_tijden_uit())
        }
    }
}


                        
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