QLineEdit lostFocus problem

[TheCipo76]

Hi,
i've to create an App to calculate tools data for CNC Machine
Now for Desktop and later for Android.

i have to know when LineEdit lost Focus in order to do some operations
(using numeric keyboard i have to insert to the MyLineEdit who lost focus and ...)

to do this i've subclassed QLineEdit class:

class MyLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    MyLineEdit(QWidget *parent = nullptr) : QLineEdit(parent){}
protected:
    void focusOutEvent(QFocusEvent *event)
    {
       QLineEdit::focusOutEvent(event);
       QWidget * widgetName = qApp->focusWidget();
       Target = widgetName->objectName(); //<- to identify MyLineEdit who lost focus 
        if(!hasAcceptableInput())
        {
            setFocus();
        }

    }
signals:
};

my problem is when i try to add MyLineEdit to QGridLayout:

 QGridLayout *mainLayout = new QGridLayout;
    //mainLayout->setAlignment(Qt::AlignCenter);
    mainLayout->addWidget(LFresatura, 0, 0, 1, 2);
    mainLayout->setSizeConstraint(QLayout::SetFixedSize);
    mainLayout->addWidget(LDiametro, 1, 0);
    mainLayout->addWidget(Diametro, 1, 1);
    mainLayout->addWidget(LVelTaglio, 2, 0);
    mainLayout->addWidget(VelTaglio, 2, 1);
    mainLayout->addWidget(LGiriMandrino, 3, 0);
    mainLayout->addWidget(GiriMandrino, 3, 1);
    mainLayout->addWidget(LNDenti, 4, 0);
    mainLayout->addWidget(NDenti, 4, 1);
    mainLayout->addWidget(LAvDente, 5, 0);
    mainLayout->addWidget(AvDente, 5, 1);
    mainLayout->addWidget(LAvanzamento, 6, 0);
    mainLayout->addWidget(Avanzamento, 6, 1);
    this->setLayout(mainLayout);

Application crashes..
I can't understand why.. Someone can help me please??

I suppose that no initialization can give problem but if i try to initialize with "0"
give me this error :

error: cannot initialize a variable of type 'MyLineEdit *' with an lvalue of type 'const char [1]'

this is declaration of Diametro:

MyLineEdit *Diametro;

[J.Hilk]

@thecipo76

if this
MyLineEdit *Diametro;

if everything in your code, than you only have a pointer but no instance.

MyLineEdit *Diametro = new MyLineEdit();

[TheCipo76]

@j-hilk said in QLineEdit lostFocus problem:

MyLineEdit *Diametro = new MyLineEdit()

i've tried but gave me this:

symbol(s) not found for architecture x86_64
linker command failed with exit code 1 (use -v to see invocation)

[J.Hilk]

@thecipo76
that's a bit difficult to debug with just that information.

a couple of things to check:

• did you include MyLineEdit.h
• as a header only class do you still have a .cpp file in your project
• switch to the compiler output tab, the error there should provide more information

[TheCipo76]

@j-hilk i've put MyLineEdit class directly in .cpp file
to keep Target value

this is Compile Output

Undefined symbols for architecture x86_64:
"vtable for MyLineEdit", referenced from:
MyLineEdit::MyLineEdit(QWidget*) in fresatura.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [CNCMaster.app/Contents/MacOS/CNCMaster] Error 1
13:25:08: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project CNCMaster (kit: Desktop Qt 5.13.0 clang 64bit)
When executing step "Make"

[TheCipo76]

@j-hilk i've tried to put MyLineEdit class to .h file like explained here

https://lizardo.wordpress.com/2009/04/24/undefined-reference-to-vtable-for-errors-in-qt-derived-classes/

but

i have this:

use of undeclared identifier qApp

on this line

QWidget * widgetName = qApp->focusWidget();

[Eddy]

did you
#include <QApplication>

[TheCipo76]

@eddy said in QLineEdit lostFocus problem:

#include <QApplication>

you're right .. i forgot it

but now i have this:

duplicate symbol _Target in:
fresatura.o
mainwindow.o
duplicate symbol _Target in:
fresatura.o
moc_fresatura.o
ld: 2 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [CNCMaster.app/Contents/MacOS/CNCMaster] Error 1
14:06:25: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project CNCMaster (kit: Desktop Qt 5.13.0 clang 64bit)
When executing step "Make"

[Eddy]

search your project for "Target"
the compiler tells you you have defined it twice

EDIT: look in the pro file also

[TheCipo76]

@eddy

EDIT: can TARGET in pro file give duplicate??
it's better change name??

[Eddy]

I would not expect it.

But anyway is it possible to upload a small compilable example. We're guessing all the time what could be wrong in your application.

[TheCipo76]

@eddy
main.cpp

#include "mainwindow.h"
#include <QApplication>
#include <QFont>



int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    QFont V = QFont ("Verdana", 16);
    QApplication::setFont(V);
    w.showMaximized();



    return a.exec();
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "fresatura.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

}

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

void MainWindow::on_pushButton_Esci_clicked()
{
    close();
}

void MainWindow::on_pushButton_Fresatura_clicked()
{
    //FRESATURA
    fresatura Fresatura;
    Fresatura.setModal(true);
    Fresatura.exec();

}

fresatura.h

#ifndef FRESATURA_H
#define FRESATURA_H

#include <QDialog>
#include <QLineEdit>
#include <QLabel>
#include <QPushButton>
#include <QWidget>
#include <QApplication>

QString Target;

class MyLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    MyLineEdit(QWidget *parent = nullptr) : QLineEdit(parent){}
protected:
    void focusOutEvent(QFocusEvent *event)
    {
       QLineEdit::focusOutEvent(event);
       QWidget * widgetName = qApp->focusWidget();
       Target = widgetName->objectName();

        if(!hasAcceptableInput())
        {
            setFocus();
        }

    }
signals:
};

namespace Ui {
class fresatura;
}

class fresatura : public QDialog
{
    Q_OBJECT

public:
    explicit fresatura(QWidget *parent = nullptr);
    ~fresatura();

private slots:


private:
    //Label
    QLabel *LFresatura;
    QLabel *LDiametro;
    QLabel *LVelTaglio;
    QLabel *LGiriMandrino;
    QLabel *LNDenti;
    QLabel *LAvDente;
    QLabel *LAvanzamento;
    //LineEdit
    //QLineEdit *Diametro;
    QLineEdit *VelTaglio;
    QLineEdit *GiriMandrino;
    QLineEdit *NDenti;
    QLineEdit *AvDente;
    QLineEdit *Avanzamento;
    //PushButton
    QPushButton *Zero;
    QPushButton *Uno;
    QPushButton *Due;
    QPushButton *Tre;
    QPushButton *Quattro;
    QPushButton *Cinque;
    QPushButton *Sei;
    QPushButton *Sette;
    QPushButton *Otto;
    QPushButton *Nove;
    //QPushButton *BS;
    //QPushButton *Punto;

    QPushButton *Esci;

    Ui::fresatura *ui;
};

#endif // FRESATURA_H

fresatura.cpp

#include "fresatura.h"
#include "ui_fresatura.h"
#include <QIntValidator>
#include <QDoubleValidator>
#include <QGridLayout>
#include <QFont>
#include <QMessageBox>


fresatura::fresatura(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::fresatura)
{
    ui->setupUi(this);

    this->showMaximized();
    this->setFixedSize(1080, 1920);
    QFont V16 = QFont ("Verdana", 16);
    QFont VT = QFont ("Verdana", 34);
    this->setFont(V16);

    LFresatura = new QLabel(" F  R  E  S  A  T  U  R  A");
    LFresatura->setFont(VT);

    LDiametro = new QLabel("Diametro Fresa:");
    LVelTaglio = new QLabel("Velocità di Taglio:");
    LGiriMandrino = new QLabel("Giri Mandrino:");
    LNDenti = new QLabel("N. Denti Fresa:");
    LAvDente = new QLabel("Avanzam./Dente:");
    LAvanzamento = new QLabel("Avanzam. mm/min:");

    MyLineEdit *Diametro = new MyLineEdit();
    Diametro->setAlignment(Qt::AlignRight);
    Diametro->setValidator(new QIntValidator(1, 100, this));

    VelTaglio = new QLineEdit("");
    VelTaglio->setAlignment(Qt::AlignRight);
    VelTaglio->setValidator(new QIntValidator(1, 300, this));

    GiriMandrino = new QLineEdit("");
    GiriMandrino->setAlignment(Qt::AlignRight);
    GiriMandrino->setReadOnly(true);

    NDenti = new QLineEdit("");
    NDenti->setAlignment(Qt::AlignRight);
    NDenti->setValidator(new QIntValidator(1, 10, this));

    AvDente = new QLineEdit("");
    AvDente->setAlignment(Qt::AlignRight);
    AvDente->setValidator(new QDoubleValidator(0, 10, 2, this));

    Avanzamento = new QLineEdit("");
    Avanzamento->setAlignment(Qt::AlignRight);
    Avanzamento->setReadOnly(true);

    //KeyBoard
    Zero = new QPushButton;
    Zero->setText("0");
    Uno = new QPushButton;
    Uno->setText("1");
    Due = new QPushButton;
    Due->setText("2");
    Tre = new QPushButton;
    Tre->setText("3");
    Quattro = new QPushButton;
    Quattro->setText("4");
    Cinque = new QPushButton;
    Cinque->setText("5");
    Sei = new QPushButton;
    Sei->setText("6");
    Sette = new QPushButton;
    Sette->setText("7");
    Otto = new QPushButton;
    Otto->setText("8");
    Nove= new QPushButton;
    Nove->setText("9");
    QGridLayout *mainLayout = new QGridLayout;
    //mainLayout->setAlignment(Qt::AlignCenter);
    mainLayout->addWidget(LFresatura, 0, 0, 1, 2);
    mainLayout->setSizeConstraint(QLayout::SetFixedSize);
    mainLayout->addWidget(LDiametro, 1, 0);
    mainLayout->addWidget(Diametro, 1, 1);
    mainLayout->addWidget(LVelTaglio, 2, 0);
    mainLayout->addWidget(VelTaglio, 2, 1);
    mainLayout->addWidget(LGiriMandrino, 3, 0);
    mainLayout->addWidget(GiriMandrino, 3, 1);
    mainLayout->addWidget(LNDenti, 4, 0);
    mainLayout->addWidget(NDenti, 4, 1);
    mainLayout->addWidget(LAvDente, 5, 0);
    mainLayout->addWidget(AvDente, 5, 1);
    mainLayout->addWidget(LAvanzamento, 6, 0);
    mainLayout->addWidget(Avanzamento, 6, 1);

    mainLayout->addWidget(Uno, 7, 0);
    mainLayout->addWidget(Due, 7, 1);
    mainLayout->addWidget(Tre, 7, 2);
    mainLayout->addWidget(Quattro, 8, 0);
    mainLayout->addWidget(Cinque, 8, 1);
    mainLayout->addWidget(Sei, 8, 2);
    mainLayout->addWidget(Sette, 9, 0);
    mainLayout->addWidget(Otto, 9, 1);
    mainLayout->addWidget(Nove, 9, 2);
    this->setLayout(mainLayout);

}



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

Pro File:

#-------------------------------------------------
#
# Project created by QtCreator 2019-08-08T13:35:11
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = CNCMaster
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += \
        fresatura.cpp \
        main.cpp \
        mainwindow.cpp

HEADERS += \
        fresatura.h \
        mainwindow.h

FORMS += \
        fresatura.ui \
        mainwindow.ui

CONFIG += mobility
MOBILITY = 


# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
    resource.qrc

[Eddy]

at first glance I can see in your pro file:
MOBILITY =

[TheCipo76]

@eddy said in QLineEdit lostFocus problem:

at first glance I can see in your pro file

yes because i will try it as for Desktop and Android too

[Eddy]

You cannot put a line without putting something behind MOBILITY
like
MOBILITY += sensors
What is it you want to do here?

I recommend when looking at your code to make it work first on desktop before even thinking on using it on Android.
Comment that line for now and look in Qt Creator at all the lines with errors. Solve one at a time...you cannot let lines open or ignore warnings from the compiler.

[TheCipo76]

@eddy I've started to load it to my smartphone (Android) then i've decided to try before on my mac..

i haven't put this lines:

CONFIG += mobility
MOBILITY =

in the pro file..

now i've comment it with #

the only errors i can see is in Compile Output:

duplicate symbol _Target in:
fresatura.o
mainwindow.o
duplicate symbol _Target in:
fresatura.o
moc_fresatura.o
ld: 2 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [CNCMaster.app/Contents/MacOS/CNCMaster] Error 1
15:10:04: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project CNCMaster (kit: Desktop Qt 5.13.0 clang 64bit)
When executing step "Make"
15:10:04: Elapsed time: 00:03.

i've searched in the project but i can't find duplicate

[Pl45m4]

@thecipo76

It may cause trouble, because you define two QObject - derived classes in one header file. Put your custom LineEdit in a separate headerfile (and .cpp) and include it in your dialog. Then try to compile it again :)

[TheCipo76]

@pl45m4
i've definded it in a separate file

mylineedit.h

#ifndef MYLINEEDIT_H
#define MYLINEEDIT_H

#include <QApplication>
#include <QLineEdit>

extern QString Target;

class MyLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    MyLineEdit(QWidget *parent = nullptr) : QLineEdit(parent){}
protected:
    void focusOutEvent(QFocusEvent *event)
    {
       QLineEdit::focusOutEvent(event);
       QWidget * widgetName = qApp->focusWidget();
       Target = widgetName->objectName();

        if(!hasAcceptableInput())
        {
            setFocus();
        }

    }
signals:
};

#endif // MYLINEEDIT_H

and i've #included it in fresatura.cpp

#include "mylineedit.h"

but no way..

Undefined symbols for architecture x86_64:
"_Target", referenced from:
MyLineEdit::focusOutEvent(QFocusEvent*) in moc_mylineedit.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [CNCMaster.app/Contents/MacOS/CNCMaster] Error 1
15:32:58: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project CNCMaster (kit: Desktop Qt 5.13.0 clang 64bit)
When executing step "Make"
15:32:58: Elapsed time: 00:02.

[mrjj]

@thecipo76 said in QLineEdit lostFocus problem:
extern QString Target;

and then in the mylineedit.CPP file you also have

QString Target;

so its actually defined ?

[TheCipo76]

@mrjj ok i've defined it in .cpp file and works..
but i've lost Target value