Instantiating gui object issue

[Dn588]

When I do that I get an error saying QWidget is not a direct base type of ordergui...

Also why was that not done in this example?

http://qt-project.org/doc/qt-4.8/mainwindows-application.html

[SGaist]

I've updated the wording of my last post (was a bit tired)

Since you have that error, it means that ordergui doesn't inherit from QWidget. It should inherit from QMainWindow.

Since you don't see anything do you call show somewhere in you main.cpp ?

[Dn588]

Yes I call show from main.cpp but for some reason I don't get any output, any idea what i'm doing wrong?

main.cpp:

@
#include <QtGui>
#include <QApplication>
#include "ordergui.h"

int main(int argc, char *argv[]) {
QApplication app(argc, argv);
ordergui order;

order.show();
return app.exec();

}
@

[mranger90]

could it be becuase you orderForm is created on the stack before being sent to setCentralWidget ? It then goes out of scope and is not available.
You should allocate it off the heap with "new".

[Dn588]

I just tried that but still no luck...

[A Former User]

Just wondering, how can you even call setCentralWidget without a pointer to QWidget? :)
@
void QMainWindow::setCentralWidget(QWidget * widget)
@
you should get a compile error here:
@
orderForm obj;
setCentralWidget(obj);
@

[Dn588]

Hi Xander. Sorry yes I changed it to OrderForm* obj but for some reason there's no output. Also when I try to close the running program I have to force quit

[A Former User]

[quote author="Dn588" date="1397930234"]Hi Xander. Sorry yes I changed it to OrderForm* obj but for some reason there's no output. Also when I try to close the running program I have to force quit[/quote]
Then you have most like created another (invisible) top level windows, if you have to "kill" the app.
you can try setting the parent of your central widget, I though the setCentralWidget would reparent it, but maybe not:
@
setCentralWidget(new orderForm(this));
@
maybe that works.

[Dn588]

No still no visible output and I still have to force quit...

[A Former User]

Is it possible that you can upload your whole project code somewhere? I don't know if you can publish your code or how large your codebase is beside what you already posted, but an logic error like this is hard to debug over the forums.. :/

[Dn588]

My Code:

@
order.h

#ifndef ORDER_H
#define ORDER_H

#include <QString>
#include <QDate>

class Order {

public:
//getters
QString name() const {return m_name;}
QDate dateAdded() const { return m_added; }
int quantity() const {return m_quantity; }
double price() const {return m_price;}

//return a string representation of an order
QString toString() const;

//setters
void setName(const QString &name) {m_name = name;}
void setDateAdded(const QDate &added) {m_added = added;}
void setQuantity(int qty) {m_quantity = qty;}
void setPrice(double unitPrice) {m_price = unitPrice;}

private:
//data members
QString m_name;
QDate m_added;
int m_quantity;
double m_price;

};

#endif // #ifndef ORDER_H

order.cpp

#include "order.h"
#include <QString>

//returns the string representation of an order
QString Order::toString() const {
return QString("%1 %2 (%3)at $ %4 total: %5").arg(m_name)
.arg(m_added.toString("yyyyMMdd")).arg(m_quantity)
.arg(m_price).arg(m_quantity*m_price);
}

OrderForm.h
#ifndef ORDERFORM_H
#define ORDERFORM_H

#include <QtGui>
#include "order.h"

class OrderForm : public QWidget {
Q_OBJECT

public:
//constructor
OrderForm(QWidget* parent);
//view a given order
void setOrder(Order prod);

private slots:
//create a new order
void submit();
//calculate the cost of an order
void calculateCost();

private:
//private data members
QLineEdit* m_nameEdit;
QDateEdit* m_dateEdit;
QSpinBox* m_quantitySpin;
QDoubleSpinBox* m_priceSpin;
QLineEdit* m_totalEdit;
QPushButton* m_submitButton;
QPushButton* m_cancelButton;

Order m_Order;

//to view an order
void viewOrder();
//sets up the GUI
void setUpGui();

};

#endif // #ifndef ORDERFORM_H

OrderForm.cpp

#include "orderform.h"
#include "order.h"
#include <QFormLayout>

//constructor
OrderForm::OrderForm(QWidget *parent) : QWidget(parent) {
setUpGui();
}

//sets up the GUI
void OrderForm::setUpGui(){
m_nameEdit = new QLineEdit();
m_dateEdit = new QDateEdit();
m_quantitySpin = new QSpinBox();
m_quantitySpin->setRange(1,1000);
m_priceSpin = new QDoubleSpinBox();
m_priceSpin->setRange(1.0,1000.00);
m_totalEdit = new QLineEdit();
m_totalEdit->setReadOnly(true);
m_submitButton = new QPushButton("OK");
m_cancelButton = new QPushButton("Cancel");

QGridLayout* gridLayout = new QGridLayout();
gridLayout->addWidget(m_submitButton,0,0);
gridLayout->addWidget(m_cancelButton,0,1);

QFormLayout *formLayout = new QFormLayout();
formLayout->addRow(tr("&Name"), m_nameEdit);
formLayout->addRow(tr("&Date Added"), m_dateEdit);
formLayout->addRow(tr("&Quantity"), m_quantitySpin);
formLayout->addRow(tr("&Unit Price"), m_priceSpin);
formLayout->addRow(tr("&Total Price"), m_totalEdit);
formLayout->addRow(gridLayout);

connect(m_submitButton, SIGNAL(clicked()), this, SLOT(submit()));
connect(m_cancelButton, SIGNAL(clicked()), this, SLOT(close()));
connect(m_quantitySpin, SIGNAL(editingFinished()), this, SLOT(calculateCost()));
connect(m_priceSpin, SIGNAL(editingFinished()), this, SLOT(calculateCost()));

this->setLayout(formLayout);
this->setWindowTitle("Manual Order Form");

}

// sets an order
void OrderForm::setOrder(Order prod){
m_Order = prod;
viewOrder();
}

//create a new order
void OrderForm::submit(){
m_Order.setName(m_nameEdit->text());
m_Order.setDateAdded(m_dateEdit->date());
m_Order.setQuantity(m_quantitySpin->value());
m_Order.setPrice(m_priceSpin->value());
}

//view an order
void OrderForm::viewOrder(){
m_nameEdit->setText(m_Order.name());
m_dateEdit->setDate(m_Order.dateAdded());
m_quantitySpin->setValue(m_Order.quantity());
m_priceSpin->setValue(m_Order.price());
calculateCost();
}
//calculate the cost of an order
void OrderForm::calculateCost(){
double total = double(m_quantitySpin->value()* m_priceSpin->value());
m_totalEdit->setText(QString::number(total, 'f', 2));
}

ordergui.h

#ifndef ORDERGUI_H
#define ORDERGUI_H
#include <QMainWindow>
#include <QTextEdit>

class ordergui : public QMainWindow {
Q_OBJECT
public:
ordergui();
public slots:
void add_order_clicked();
void view_orders_clicked();
private:
void createMenu();
void createActions();
QTextEdit* m_text;
QMenu* orderMenu;
QAction* add_order;
QAction* view_orders;
};

#endif // ORDERGUI_H

ordergui.cpp

#include <QTGui>
#include "ordergui.h"
#include "OrderForm.h"

ordergui::ordergui() {
m_text = new QTextEdit;
setCentralWidget(m_text);
createActions();
createMenu();
}

void ordergui::createActions() {
add_order = new QAction(("Add Order"), this);
connect(add_order, SIGNAL(triggered()), this, SLOT(add_order_clicked()));

view_orders = new QAction(("View Order"), this);
connect(view_orders, SIGNAL(triggered()), this, SLOT(view_orders_clicked()));

}

void ordergui::createMenu() {
orderMenu = menuBar()->addMenu("Order");
orderMenu->addAction(add_order);
orderMenu->addAction(view_orders);
orderMenu->exec();
}

void ordergui::add_order_clicked() {
//OrderForm* obj = new OrderForm;
setCentralWidget(new OrderForm(this));
}

void ordergui::view_orders_clicked() {
setCentralWidget(m_text);
}

main.cpp

#include <QtGui>
#include <QApplication>
#include "ordergui.h"

int main(int argc, char *argv[]) {
QApplication app(argc, argv);
ordergui order1;

order1.show();
return app.exec();

}

@

[edit: modified the code to allow proper tagging SGaist]

[A Former User]

HI, sorry I tried to copy your messed up code here but it's almost impossible because it puts everything into one line and the quotations are also messed up etc.

If you put it in proper code tags or just zip and upload your project somewhere I will try finding your error, but not like this if I have to cleanup all the code just to recreate your whole project. :D

[Dn588]

Hi Xander thanks for taking a look
I uploaded it to dropbox, hope that's ok?

download link:

https://www.dropbox.com/s/i2hz6per5o78lry/Order-exercise.rar

[A Former User]

Ok i had to add some stuff to the pro file and include QtWidgets in OrderForm.h to compile the project, I think you are using Qt 4 or why don't you need that?

Anyway I didn't change the code and it works!? lol
maybe a little weird to start the app with a menu only, but when i click on "Add Order" i see this:
!http://i.imgur.com/2ADRudL.png(order form)!
isn't that what you want, I am a little confused now because it seems to work or what is not working!?

I noticed some other bugs, but i'm waiting for your response on this first.

[Dn588]

Yes I am using QT 4

[Dn588]

no idea why it's not working for me... it is a little strange yes i'm busy working through "Design patterns in C++ with QT" and this is a varient of one of the exercises...

[Dn588]

I just tried to run it from command prompt but still nothing. A process gets created under windows processes but nothing happens...

[A Former User]

are you sure your slot is working? how are you compiling your project?
because I had to modify your project file to get it to work :D

also if you start learning Qt now and have the choice you should use Qt5 and not the old version, or is there any other reason you use Qt4?

maybe put a debug line in your slot to see if it's called, if you compile the project without qmake your signals and slots are not working I think.
@
void ordergui::add_order_clicked() {
qDebug("add_order_clicked");
//OrderForm* obj = new OrderForm;
setCentralWidget(new OrderForm(this));
}
@
I have the feeling your slot is never called..

also the other bug in your slot:
@
void ordergui::view_orders_clicked() {
setCentralWidget(m_text);
}
@
that will crash the app because m_text has been deleted, check the doc of "setCentralWidget":http://qt-project.org/doc/qt-5/qmainwindow.html#setCentralWidget (Note: QMainWindow takes ownership of the widget pointer and deletes it at the appropriate time.)
that means if you set your ordner form as central widget it will delete the previous widget (your text)..

[Dn588]

i'm currently busy with a university course that uses QT 4 which is why I am using it. I just commented out the slots but still not getting a main window... I created a new project and added the order and OrderForm files to it and it ran with no issues... So i'm guessing there's also something wrong with my main window's constructor?

[A Former User]

Oh yeah I thought it was supposed to be like that, that's why I said it is a little weird your app starts with a menu and not the main window, so that is a bug too?

comment out this line
@
orderMenu->exec();
@
in your ordergui::createMenu() function.
you should sometimes read the Qt doc, it tells you that QMenu::exec() "Executes this menu synchronously." which means it will block the thread until you close the menu (click an item) and only after that display the window. if you don't call "exec" it will just show the main window with your menu and your text widget (like it should?).