When I try to add any new widget to layout my program crashes. What could be the problem?
I have a pointer to QLabel as a data member of MainWindow. In constructor I allocate memory for it and that try to add it to layout. I really don't know what is the problem, cause I did this method before and it worked.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QLabel>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow {
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private:
QLabel* tempLabel;
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) {
tempLabel = new QLabel("QLabel 2");
ui->widget->layout()->addWidget(tempLabel);
ui->setupUi(this);
}
MainWindow::~MainWindow() {
delete ui;
}
Error msg
Related
I've been trying to create a frame to be shown as a tooltip, but be functionally different. It's got to be shown at a certain point, floating, to be called from a delegate.
Now, if I don't pass a parent it's seen but yeah, it's detached.
And I want it to be windowless.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "./ui_mainwindow.h"
#include <QDebug>
#include <QFrame>
MainWindow::MainWindow(QWidget* parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
QSize size { 350, 550 };
QPoint topLeft { 550, 550 };
auto* frame = new QFrame(this); // this is a QWidget
frame->setGeometry({ topLeft, size });
frame->show();
frame->activateWindow();
frame->raise();
qInfo() << frame->isVisible(); // returns true
}
MainWindow::~MainWindow()
{
delete ui;
}
Any suggestions?
Welcome, I have a question about Qt's windows operations. I have a simple app which contains 2 windows:
MainWindow - includes push button, can't be resizeable,
AdminWindow - includes label, can be resizeable.
When I click push button, it should open AdminWindow and hide MainWindow. I made the app and it seems to work but when I open the AdminWindow, the application icon which is located in windows's bottom bar is missing. How can I fix it?
Icon is showed when MainWindow is opened:
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "adminwindow.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_pushButtonOpenAdmin_clicked();
private:
Ui::MainWindow *ui;
AdminWindow *adminWindow;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
// hides MainWindow and show AdminWindow
void MainWindow::on_pushButtonOpenAdmin_clicked()
{
hide();
adminWindow = new AdminWindow(this);
adminWindow->show();
}
adminwindow.h
#ifndef ADMINWINDOW_H
#define ADMINWINDOW_H
#include <QMainWindow>
namespace Ui {
class AdminWindow;
}
class AdminWindow : public QMainWindow
{
Q_OBJECT
public:
explicit AdminWindow(QWidget *parent = 0);
~AdminWindow();
private:
Ui::AdminWindow *ui;
};
#endif // ADMINWINDOW_H
adminwindow.cpp
#include "adminwindow.h"
#include "ui_adminwindow.h"
AdminWindow::AdminWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::AdminWindow)
{
ui->setupUi(this);
}
AdminWindow::~AdminWindow()
{
delete ui;
}
I don't get it.
loginview.h
#ifndef LOGINVIEW_H
#define LOGINVIEW_H
#include <QMainWindow>
#include <QDebug>
#include <QPushButton>
class LoginView : public QWidget
{
public:
QWidget *LoginViewSetup(QWidget * wdgMain);
public slots:
virtual void LogInUser();
virtual void CreateUser();
public:
QPushButton *logInBtn;
QPushButton *createBtn;
};
#endif // LOGINVIEW_H
loginview.cpp
#include "loginview.h"
QWidget *LoginView::LoginViewSetup(QWidget * wdgMain)
{
//some code
return wdgCenter;
}
void LoginView::LogInUser()
{
//some code
}
void LoginView::CreateUser()
{
//some code
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QDebug>
#include <loginview.h>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
QWidget * wdgMain;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
wdgMain = new QWidget(this);
LoginView LoginViewObj;
QWidget *wdgCenter = LoginViewObj.LoginViewSetup(wdgMain);
setCentralWidget( wdgMain );
connect(LoginViewObj.createBtn, SIGNAL (released()), &LoginViewObj, SLOT (CreateUser()));
}
MainWindow::~MainWindow()
{
delete ui;
}
Problem:
QObject::connect: No such slot QWidget::CreateUser() in
../proj/mainwindow.cpp:16
I tried to add Q_OBJECT to the loginview.h and then rebuild project with QMAKE. After that there is no warning about slot, but buttons still not active. Program don't jump to handle of the button in debug mode.
Please, help me to understand what's wrong? I have an object of another class LoginView and I pass this object as a reciever for a slot. Why it passes through my class and searches slot in QWidget?
I am trying to connect a signal from a second QMainWindow to the mainwindow. It doesn't say anything about a problem connection when the program is launched, but It doesn't work. I am not very familiar with C++ and Qt so maybe is something simple.
My code consists on a Mainwindow used as a SCADA with Start, stop, On, off buttons. In the second qmainwindow I created a terminal where you can type, start,stop... There, I would like to emit a signal to my MainWindow which is in charge of controlling the multiple threads and windows. The problem is that I cannot connect to my slot. I present here a simple overview of this two pieces of code.
Terminal. h
#ifndef TERMINAL__H
#define TERMINAL__H
#include <QMainWindow>
#include <QTextEdit>
#include <QLineEdit>
#include <QObject>
namespace Ui {
class Terminal_;
}
class Terminal_ : public QMainWindow
{
Q_OBJECT
public:
explicit Terminal_(QWidget *parent = 0);
~Terminal_();
signals:
void turnonPLC_terminal();
public slots:
void newline();
private:
Ui::Terminal_ *ui;
QTextEdit* mTerminal;
QLineEdit* mInput;
};
#endif // TERMINAL__H
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "terminal_.h"
#include "terminal_help.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
Terminal_ *terminal;
public slots:
void turnon_terminal();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
Mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "terminal_.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
terminal = new Terminal_(this);
connect(terminal, SIGNAL(turnonPLC_terminal()), this, SLOT(turnon_terminal()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::turnon_terminal(){
turnonPLC=1;
}
terminal_.cpp
#include "terminal_.h"
#include "ui_terminal_.h"
#include <QDockWidget>
#include <QWidget>
#include <QLineEdit>
QString on=("on");
Terminal_::Terminal_(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::Terminal_)
{
ui->setupUi(this);
mTerminal = new QTextEdit();
setCentralWidget(mTerminal);
mInput = new QLineEdit();
QDockWidget* qdw = new QDockWidget;
qdw->setWidget(mInput);
addDockWidget(Qt::BottomDockWidgetArea, qdw);
connect (mInput, SIGNAL(returnPressed()),
this, SLOT(newline()));
}
Terminal_::~Terminal_()
{
delete ui;
}
void Terminal_::newline(){
QString command = mInput->text();
if (command==on){
emit turnonPLC_terminal();
}
}
Thanks
The signal-slots part in the code works perfectly. (compiled and tested with some small modifications)
After entering "on" (not On as written in question)
Terminal_::newline() slot called, turnonPLC_terminal() is fired and finally
void MainWindow::turnon_terminal() is called.
However, there are some small details the header file is called terminal_.h, not Terminal.h turnonPLC is not defined. terminal is created by not displayed (no show-call).
I guess, there are simply some many small logic errors. Try to use debugger or trace the chain of expected calls with qDebug.
I am currently learning Qt and I seem to have run into a problem.
In my practice project I have 2 classes: MainWindow and Dialog.
MainWindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include "dialog.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_pushButtonDialog_clicked();
private:
Ui::MainWindow *ui;
Dialog *dialogInstance;
};
#endif // MAINWINDOW_H
MainWindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
dialogInstance = new Dialog(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButtonDialog_clicked()
{
dialogInstance->show();
}
Dialog.h
#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
namespace Ui {
class Dialog;
}
class Dialog : public QDialog
{
Q_OBJECT
public:
explicit Dialog(QWidget *parent = 0);
~Dialog();
private:
Ui::Dialog *ui;
};
#endif // DIALOG_H
Dialog.cpp
#include "dialog.h"
#include "ui_dialog.h"
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
}
Dialog::~Dialog()
{
delete ui;
}
My goal is to input a value using the Dialog window, then have the value of that input shown on the MainWindow, I know how to pass variables around within the class using widgets, but I am not sure how to transfer variables between unrelated objects.
Any input would be of great help.
Try this:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
connect(ui->pushButtonDialog, SIGNAL(clicked()), this, SLOT(on_pushButtonDialog_clicked()));
dialogInstance = new Dialog(this);
}
// ...