[solved]Call class function in another cpp file

TheHawk

Hi,

Sorry for this very simple question but I am failing horribly at it.

So I have a function in my MainWindow.cpp; void test().

void MainWindow::test()
{
    progressBar->setEnabled(true);
    progressBar->setVisible(true);
    progressBar->setValue(50);
    ui->dockWidget->setWindowTitle("TEST");
}

The function is declared in mainwindow.h

In jsfunctions.cpp I have mainwindow.h included and I try to call test(); . However, I have to make an object because otherwise I cant call it. The result of this is that the changes in UI that are made in the test() function are not visible, they are in a new object. I do not want this, I want to change the current UI that is visible (and I would like to avoid creating a new UI). I tried static (which gave errors) and tried to make signal/slot connections.

I am sure its something very simple, but I just don't see it. Help would be greatly appreciated.

JohanSolo

Well, as you discovered, you need an object to call a method. Then the most obvious solution would be to give a pointer on your MainWindow object to the function which tries to call MainWindow::test().

One solution would be to emit a signal in your jsfunction,cpp (about which you don't give information) which would trigger the call to MainWindow::test() (which would need to be a slot). But without knowing what the content of jsfunction.cpp it's hard to tell.

Give us more information on how you want to call MainWindow::test() and we'll be able to help.

jsulm

You should not call MainWindow methods somewhere else. Your jsfunction should emit a signal instead of calling test(), you connect that signal to a slot in MainWindow. This way jsfunction do not need to know anything about MainWindow.

TheHawk

@JohanSolo @jsulm

Currently I am working in 2 windows. 1 window is the MainWindow, the application launches with only this. The second window opens when requested and gives the functionality to parse a script (using QJSEngine). This window is called CustomCode.

In the script I want to call functions which I have in my project. Currently I am only trying to call test() to understand the principle and continue from that.

According to this stackoverflow, I had to use QObjects. That is where jsfunctions came in, this is a QObject class which I integrate into the QJSEngine.

So my QS Script looks like this: jsfunction.call_test();

CustomCode.h:

#ifndef CUSTOMCODE_H
#define CUSTOMCODE_H

#include <QMainWindow>

namespace Ui {
class CustomCode;
}

class CustomCode : public QMainWindow
{
    Q_OBJECT

public:
    explicit CustomCode(QWidget *parent = 0);
    ~CustomCode();

private:
    Ui::CustomCode *ui;

private slots:
    void on_button_clicked();
};

#endif // CUSTOMCODE_H

CustomCode.cpp:

#include "customcode.h"
#include "ui_customcode.h"
#include "jsfunctions.h"
#include <QtWidgets>
#include <QJSEngine>
#include <QFile>

CustomCode::CustomCode(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::CustomCode)
{
    ui->setupUi(this);
    QPushButton *button = new QPushButton("Test");
    ui->verticalLayout->addWidget(button);
    connect(button,SIGNAL(pressed()),SLOT(on_button_clicked()));

}

CustomCode::~CustomCode()
{
    delete ui;
}

void CustomCode::on_button_clicked()
{
    QLabel *tb = new QLabel;
    ui->verticalLayout->addWidget(tb);
    QJSEngine myEngine;
    QJSValue scripttb = myEngine.newQObject(tb);
    jsfunctions jsfunction;
    QJSValue jsfunctionObj = myEngine.newQObject(&jsfunction);
    myEngine.globalObject().setProperty("jsfunction",jsfunctionObj);
    myEngine.globalObject().setProperty("tb",scripttb);

    QString fileName = "customlogic.qs";
    QFile scriptFile(fileName);
    if (!scriptFile.open(QIODevice::ReadOnly))
    {
    }// handle error

    QTextStream stream(&scriptFile);
    QString contents = stream.readAll();
    scriptFile.close();
    QJSValue result = myEngine.evaluate(contents, fileName);
    //QJSValue result = myEngine.evaluate("jsfunction.call_test();");
    if (result.isError())
    {
        qDebug() << "result: " << result.property("lineNumber").toInt() << ":" << result.toString();
    }
}

jsfunctions.h:

#ifndef JSFUNCTIONS_H
#define JSFUNCTIONS_H

#include <QObject>
#include <QWidget>
#include <mainwindow.h>

class jsfunctions : public QObject
{
    Q_OBJECT
public:
    explicit jsfunctions(QObject *parent = 0);
    void call_test()
    {
        emit send_test();
    }


signals:
    void send_test();

public slots:

};

#endif // JSFUNCTIONS_H

jsfunctions.cpp:

#include "jsfunctions.h"
#include "mainwindow.h"


jsfunctions::jsfunctions(QObject *parent) : QObject(parent)
{

}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtCore>
#include <QtGui>
#include <QProgressBar>
#include <QGridLayout>
#include <QScrollArea>
#include "vprParam.h"
#include "customcode.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    CustomCode *codewindow;
    ~MainWindow();

public slots:
    void test();

private:
    QStandardItemModel *model;
    QWidget *box;
    QGridLayout *grid;
    void build_UI(vprParam_Inst_t* pInst, std::string profile);

private slots:
    void on_actionOpen_CSV_triggered();
    void on_actionIP_List_toggled(bool arg1);

    void on_treeView_doubleClicked(const QModelIndex &index);

    void on_actionSave_triggered();

    void on_profile_clicked(int index);

    void on_actionAdd_custom_logic_triggered();

private:
    Ui::MainWindow *ui;
    QProgressBar *progressBar;
    QWidget *central;
    QGridLayout *layout;
};

void loadcsv(QString IP, QString SUBIP);
void SetValueInDb(QString name, int value);

#endif // MAINWINDOW_H

mainwindow.cpp (only the relevant code)

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "vprParam.h"
#include <string>
#include <vector>
#include <QFileDialog>
#include <QtWidgets>
#include <QComboBox>
#include <QLabel>
#include "paramblock.h"

struct readips
{
};

struct create_db
{
};

struct memory
{
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    progressBar = new QProgressBar;
    ui->statusBar->addPermanentWidget(progressBar);
    progressBar->setVisible(false);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_actionOpen_CSV_triggered()
{
}


void loadcsv(QString IP,QString SUBIP)
{

}

void MainWindow::on_actionIP_List_toggled(bool arg1)
{
}


void MainWindow::on_treeView_doubleClicked(const QModelIndex &index)
{
    
}

void MainWindow::on_profile_clicked(int index)
{
}

void MainWindow::build_UI(vprParam_Inst_t* pInst, std::string profile)
{
}

void MainWindow::on_actionAdd_custom_logic_triggered()
{
    codewindow = new CustomCode;
    codewindow->show();
}

void MainWindow::test()
{
    progressBar->setEnabled(true);
    progressBar->setVisible(true);
    progressBar->setValue(50);
    ui->dockWidget->setWindowTitle("TEST");
}

I already tried to make it with signal/slots but I failed at this, I always ended up with having to create a new object for mainwindow, I would like to see how to do it properly.
Also, sorry for any messy/confusing code, I am new to c++ and Qt and a rookie programmer overall.

Thanks!

JohanSolo

OK, according to what I understood from your design, MainWindow spawns a CustomCode instance when requested. Therefore when constructing the CustomCode instance you know which MainWindow instance you have to connect to. If I were you I'd use the calling MainWindow instance as parent of the CustomCode instance. This would allow to connect the send_test() signal to the test() slot of your MainWindow instance.

TheHawk

How could I do that?

If I do this in mainwindow.cpp:

    codewindow = new CustomCode;
    codewindow->setParent(this);
    connect(codewindow,SIGNAL(send_test()),SLOT(test()));
    codewindow->show();

This makes it compile but instead of a seperate window the current mainwindow gets overwritten with the codewindow and the send_test() is in jsfunctions.h, not in CustomCode.h. Would I have to make a function that calls another function that calls the signal? Or am I missing it here? Sorry

Edit:

Succes!

I used : (in mainwindow.cpp)

void MainWindow::on_actionAdd_custom_logic_triggered()
{
    codewindow = new CustomCode;
    QObject::connect(&jsfunction,SIGNAL(send_test()),this,SLOT(test()));
    codewindow->show();
}

added extern jsfunctions jsfunction; to mainwindow.h and customcode.h
added jsfunctions jsfunction; in jsfunctions.cpp

and changed jsfunctions.h to

signals:
    void send_test();

public slots:
    void call_test()
    {
        emit send_test();
    }

Now it works! test() gets properly called and my UI actually changes. Many thanks! :)

PS: How do I change the topic to solved?

JohanSolo

I don't think it is necessary to have a static instance of jsfunctions to do this. Why did you add it? As far as I understand, the jsfunctions instance was meant to be used in the CustomCode instance? Assuming my hypothesis is correct, I would do the connect in the CustomCode, where both the MainWindow and jsfunctions instance are used:

void MainWindow::on_actionAdd_custom_logic_triggered()
{
    codewindow = new CustomCode( this );
    codewindow->show();
}

CustomCode::CustomCode( QObject* parent )
    : QMainWindow(parent)
    , ui(new Ui::CustomCode)
    , jsfunction( new jsfunctions() )
{
    connect( jsfunction, SIGNAL( send_test() ), parent, SLOT( test() ) );
}

@TheHawk said:
> PS: How do I change the topic to solved?

You can simply edit the topic title (IIRC by editing your first post),

TheHawk

I have no particular reason why I chose it to be static, I did it because after googling some errors it was suggested to use static.

Anyhow, your code indeed works as well and your assumption was correct! :)
I do have a little issue now. Calling codewindow = new CustomCode( this ); makes the new window always on top. I previously called codewindow = new CustomCode;, this made the 2 windows independant (if you clicked the one in the back it came to front). I don't really see an option how to fix this behavior besides using signals and slots at a click to bring a window up and lower the other one. Am I missing the obvious here?

thanks!

JohanSolo

I think you can tune this behaviour with the correct window flag, which is the second argument of the QMainWindow constructor.

Edit:
As another way to do it, you can pass a null pointer to the QMainWindow constructor in the CustomCode constructor, but still use the parent pointer in the connect statement.

TheHawk

I tried all the window flag settings without succes, it always stays on top.

How would I pass a null pointer to the QMainWindow constructor in the CustomCode constructor? Can't really get my head around it. Changing the call to:
codewindow = new CustomCode(0); or codewindow = new CustomCode; creates the desired effect but makes me unable to call the function (since no parent exists I think?).

Am I even calling the windowflag correctly?

void MainWindow::on_actionAdd_custom_logic_triggered()
{
    CustomCode *codewindow;
    codewindow = new CustomCode(0);
    //QObject::connect(&jsfunction,SIGNAL(send_test()),this,SLOT(test()));
    codewindow->setWindowFlags(Qt::Window);
    codewindow->show();

}

JohanSolo

I was thinking about

CustomCode::CustomCode( QObject* parent )
    : QMainWindow( 0 )
    , ui( new Ui::CustomCode )
    , jsfunction( new jsfunctions() )
{
    connect( jsfunction, SIGNAL( send_test() ), parent, SLOT( test() ) );
}

TheHawk

@JohanSolo

Ah yes, seems so obvious now. Works like a charm!

Thanks :)

JohanSolo

You're welcome! I'm glad I could help.

TheHawk

@JohanSolo

I got a question though (kinda off-topic). Would it be possible to create a signal from the MainWindow to a slot (or function) inside the javascript script that I evaluate inside CustomCode? So for example:

I want to plot a graph using the javascript script. I want that graph to use actual, changing values from mainwindow. So I would like to create a signal that triggers upon a value change and then call a function inside the javascript script to update the graph with the new values.

JohanSolo

@TheHawk said:

I got a question though (kinda off-topic). Would it be possible to create a signal from the MainWindow to a slot (or function) inside the javascript script that I evaluate inside CustomCode? So for example:

Better ask a new question in a new thread, for the future, it helps when looking for a problem on the forum.

You are free to define any signal / slot you want, so the short answer is yes.
You can emit a signal in MainWindowwhen the data needs to be reprocessed by the js script managed by CustomCode.

TheHawk

My apologies, I will create a new thread. Thanks for all your help! (and putting up with my stuff :) )