I'm new to C++ and Qt, and I'm having a bit of trouble getting off the ground. I'd really appreciate some help. I want to add a menubar that will remain constant for all app screens. If I add this to the main function, the menubar shows up fine, but I know this shouldn't be in my main function:
#include <QtGui/QApplication>
#include "mainwindow.h"
#include "form.h"
#include "menu.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
QMenuBar *menu = new QMenuBar(0);
QMenu* menu1 = new QMenu("MENU1");
menu1->addMenu(new QMenu("menu1_SubMenu"));
QMenu* menu2 = new QMenu("MENU2");
menu2->addMenu(new QMenu("menu2_SubMenu"));
menu->addMenu(menu1);
menu->addMenu(menu2);
w.show();
return a.exec();
}
If I create a class for the menu bar, it does not appear. The only difference is that I've put the menu code in the constructor of the menu class and then instantiated the menu class from main.cpp:
main.cpp
#include <QtGui/QApplication>
#include "mainwindow.h"
#include "form.h"
#include "menu.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
Menu m;
m.show();
w.show();
return a.exec();
}
menu.h
#ifndef MENU_H
#define MENU_H
#include <QMenuBar>
class Menu : public QMenuBar
{
Q_OBJECT
public:
Menu(QMenuBar *parent = 0);
};
#endif // MENU_H
menu.cpp
#include "menu.h"
Menu::Menu(QMenuBar *parent)
{
QMenuBar *menu = new QMenuBar(0);
QMenu* menu1 = new QMenu("MENU1");
menu1->addMenu(new QMenu("menu1_SubMenu"));
QMenu* menu2 = new QMenu("MENU2");
menu2->addMenu(new QMenu("menu2_SubMenu"));
menu->addMenu(menu1);
menu->addMenu(menu2);
}
What am I doing wrong?
Your Menu class is derived from QMenuBar, but you don't call any methods on it except show(). All addMenu() calls are made for the local variable menu in the constructor, which are allocated and then forgotten. You should call them on this instead:
#include "menu.h"
Menu::Menu(QMenuBar *parent)
{
QMenu* menu1 = new QMenu("MENU1");
menu1->addMenu(new QMenu("menu1_SubMenu"));
QMenu* menu2 = new QMenu("MENU2");
menu2->addMenu(new QMenu("menu2_SubMenu"));
this->addMenu(menu1);
this->addMenu(menu2);
}
Related
I have a QTreeView and I can't find a way of making it fill the whole dialog window and resize with the window when it is resized.
Something like this:
#include <QApplication>
#include <QDialog>
#include <QHBoxLayout>
#include <QTreeView>
class MyDialog: public QDialog
{
public:
MyDialog()
{
QHBoxLayout* l = new QHBoxLayout(this);
setLayout(l);
QTreeView* v = new QTreeView(this);
l->addWidget(v);
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MyDialog d;
d.exec();
return a.exec();
}
I'd like to show and then close a dialog after 5 seconds. The dialog needs to be automatically resized (horizontally and vertically) based on the content of a label. Here is my code:
#include <QApplication>
#include <QDialog>
#include <QLabel>
#include <QTimer>
void notify (int intTime=1000)
{
QDialog notify;
notify.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
notify.setWindowFlag(Qt::FramelessWindowHint);
QLabel *lbl = new QLabel(¬ify);
lbl->setText("This is a test This is a test This is a test This is a test This is a test This is a test This is a test");
QApplication::processEvents();
notify.adjustSize();
QTimer::singleShot(intTime, ¬ify, SLOT(close()));
notify.exec();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
notify(5000);
exit(0);
// return a.exec();
}
It does not not expand the dialog based on the label size. Here is how it looks:
How can I fix it? (Please also let me know if there is better way of doing this.)
I am using Qt5 in Linux.
Since you have not used a QLayout the QLabel will be displayed as large as you can, a possible request is to change the size of QDialog to the recommended size of QLabel with sizeHint():
#include <QApplication>
#include <QDialog>
#include <QLabel>
#include <QTimer>
void notify (int intTime=1000)
{
QDialog notify;
notify.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
notify.setWindowFlag(Qt::FramelessWindowHint);
QLabel *lbl = new QLabel(¬ify);
lbl->setText("This is a test This is a test This is a test This is a test This is a test This is a test This is a test");
QApplication::processEvents();
notify.resize(lbl->sizeHint());
QTimer::singleShot(intTime, ¬ify, SLOT(close()));
notify.exec();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
notify(5000);
exit(0);
// return a.exec();
}
The other possible solution is to use a QLayout:
#include <QApplication>
#include <QDialog>
#include <QLabel>
#include <QTimer>
#include <QVBoxLayout>
void notify (int intTime=1000)
{
QDialog notify;
QVBoxLayout *lay = new QVBoxLayout(¬ify);
//notify.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
notify.setWindowFlag(Qt::FramelessWindowHint);
QLabel *lbl = new QLabel;
lay->addWidget(lbl);
lbl->setText("This is a test This is a test This is a test This is a test This is a test This is a test This is a test");
QApplication::processEvents();
QTimer::singleShot(intTime, ¬ify, SLOT(close()));
notify.exec();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
notify(5000);
exit(0);
// return a.exec();
}
I want to use layout in qt5, but In Visual Studio 2015 the layout does not work?
Here is my code:
layout.h code
#ifndef LAYOUT_H
#define LAYOUT_H
#include <QtWidgets/QMainWindow>
#include "ui_layout.h"
class layout : public QMainWindow
{
Q_OBJECT
public:
layout(QWidget *parent = 0);
~layout();
private:
Ui::layoutClass ui;
};
#endif // LAYOUT_H
main.cpp
#include "layout.h"
#include <QtWidgets/QApplication>
#include <QtWidgets/QPushButton>
#include <QtWidgets/QHBoxLayout>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
layout w;
QHBoxLayout hb;
QPushButton b("button 0");
QPushButton b1("button 1");
hb.addWidget(&b);
hb.addWidget(&b1);
w.setLayout(&hb);
w.show();
return a.exec();
}
Here is my result:
How to fix this problem?
QMainWindow is a special widget since it has default widgets like QStatusbar, QMenuBar, etc. When working with this widget we must place the new elements in the centralWidget.
So we must assign a widget that will be our centralWidget, and then to this we add the layouts as shown below:
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
layout w;
w.setCentralWidget(new QWidget);
QHBoxLayout hb;
QPushButton b("button 0");
QPushButton b1("button 1");
hb.addWidget(&b);
hb.addWidget(&b1);
w.centralWidget()->setLayout(&hb);
w.show();
return a.exec();
}
Alright so is there any way to make this program randomly change the variables x and y every time the button is clicked i am new to programming...
#include <QtGui/QApplication>
#include "mainwindow.h"
#include <QtGUI>
#include <QWidget>
#include <cstdlib>
#include <ctime>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget *window = new QWidget;
srand(time(0));
int x = 1+(rand()%900);
int y = 1+(rand()%400);
QPushButton *MainInter = new QPushButton("Push me!",window);
QPropertyAnimation *animation = new QPropertyAnimation(MainInter, "pos");
animation->setDuration(0);
animation->setEndValue(QPoint(x,y));
Object::connect(MainInter,SIGNAL(released()),animation,SLOT(start()));
window->resize(900,500);
window->show();
return a.exec();
}
What you can do is, instead of connecting the released() signal of your button directly to your animations start() SLOT, you would create your own custom SLOT. Then you connect the button to it, handle the action, and call the animation.
First read up on how to create a custom QWidget, instead of creating top level object in your main(). Simple example here
A custom widget might look like this:
widget.h
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
class QPushButton;
class QPropertyAnimation;
class MyWidget : public QWidget
{
Q_OBJECT
public:
MyWidget(QWidget *parent = 0);
private:
QPushButton *button;
QPropertyAnimation *animation;
public slots:
void randomizeAnim();
};
#endif // WIDGET_H
widget.cpp
#include "widget.h"
#include <QPushButton>
#include <QPropertyAnimation>
#include <ctime>
MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
button = new QPushButton("Push me!", this);
animation = new QPropertyAnimation(button, "pos");
animation->setDuration(0);
QObject::connect(button, SIGNAL(released()), this, SLOT(randomizeAnim()));
}
void MyWidget::randomizeAnim()
{
srand(time(0));
int x = 1+(rand()%900);
int y = 1+(rand()%400);
animation->setEndValue(QPoint(x,y));
animation->start();
}
And now your main.cpp can be reduced to the boilerplate code:
#include <QApplication>
#include "widget.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget *window = new MyWidget;
window->resize(900,500);
window->show();
return a.exec();
}
Every time you click, your custom slot will handle the action and do the animation.
I am getting an error while trying to run this Application ... the error message is:
main.cpp(11): error: expression must have class type
int r = dialog.exec(); and I am not sure why!!!
I am using qmake to generate the make file... I have added the necessary files to the *.pro file since Dialog is inherited from QDialog I should have access to the function exec!
#include <QtGui>
#include <QDialog>
#include <QtUtil.h>
#include <Mathematics.h>
#include <Pair.h>
#include "View.h"
class QMesseageBox;
class QAction;
class QDialogButtonBox;
class QLabel;
class QLineEdit;
class QPushButton;
class QTextEdit;
class Dialog : public QDialog {
Q_OBJECT
public:
Dialog() {
QHBoxLayout *layout = new QHBoxLayout;
// prevent left vertical box from growing when main window resized
layout->addStretch(1);
QLabel* lab_Layers = new QLabel(tr("Layers"));
d_inline = new QLineEdit;
d_inline->setText("50");
scene = new QGraphicsScene(0, 0, 500, 500);
view = new View;
layout->addWidget(view);
view->setScene(scene);
QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addLayout(layout);
setLayout(mainLayout);
setWindowTitle(tr("VI Smooth 0.4"));
}
private slots:
// scroll the "after" window when "before" one is scrolled (so they
// remain in sync)
private:
QAction* exitAction;
QtUtil qt;
QLineEdit* d_inline;
QGraphicsScene* scene;
QGraphicsView* view;
};
main class
#include <QApplication>
#include <QMessageBox>
#include "Dialog.h"
int
main(int argc, char **argv) {
QApplication app(argc, argv);
argv++;
Dialog dialog();
// dialog.showMaximized();
int r = dialog.exec();
return 0;
}
It should look something like this. If you create a Dialog object, you need to call show(). And you also need to return app.exec() in main().
#include <QApplication>
#include <QMessageBox>
#include "Dialog.h"
int
main(int argc, char **argv) {
QApplication app(argc, argv);
argv++;
Dialog dialog;
dialog.show()
return app.exec(argc, argv);
}