My program compiles and displays my push buttons correctly but for some reason its not displaying the QSpinBox's. I'm pretty new at C++ qt GUI so any input would be greatly appreciated. I also checked if the spinners were being overlapped by the buttons but they were not.
//
// mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtGui>
#include <QPushButton>
#include <QLabel>
#include <QSpinBox>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void clearx();
void equalsx();
void addx();
void subtractx();
void multiplyx();
void dividex();
void firstnumberx();
void secondnumberx();
private:
QLabel *label;
QPushButton *equal;
QPushButton *clear;
QPushButton *equals;
QPushButton *add;
QPushButton *subtract;
QPushButton *multiply;
QPushButton *divide;
QSpinBox *spinner;
QSpinBox *spinner2;
};
#endif // MAINWINDOW_H
//
// mainwindow.cpp
#include "mainwindow.h"
#include <QTCore/QCoreApplication>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
label = new QLabel("0,this");
label -> setGeometry(QRect(QPoint(75,75),QSize(50,200)));
clear = new QPushButton("Clear", this);
clear -> setGeometry(QRect(QPoint(80,300),QSize(50,50)));
connect(clear,SIGNAL(released()),this,SLOT(clearx()));
equal = new QPushButton("Equal", this);
equal -> setGeometry(QRect(QPoint(110,300),QSize(50,50)));
connect(equal,SIGNAL(released()),this,SLOT(equalx()));
add = new QPushButton("Add", this);
add -> setGeometry(QRect(QPoint(140,300),QSize(50,50)));
connect(add,SIGNAL(released()),this,SLOT(addx()));
subtract = new QPushButton("Subtract", this);
subtract -> setGeometry(QRect(QPoint(170,300),QSize(50,50)));
connect(subtract,SIGNAL(released()),this,SLOT(subtractx()));
multiply = new QPushButton("Multiply", this);
multiply -> setGeometry(QRect(QPoint(200,300),QSize(50,50)));
connect(multiply,SIGNAL(released()),this,SLOT(multiplyx()));
divide = new QPushButton("Divide", this);
divide -> setGeometry(QRect(QPoint(230,300),QSize(50,50)));
connect(divide,SIGNAL(released()),this,SLOT(dividex()));
spinner = new QSpinBox;
spinner -> setGeometry(QRect(QPoint(130,150),QSize(50,50)));
connect(divide,SIGNAL(released()),this,SLOT(firstnumberx()));
spinner->setRange(1,10);
spinner2 = new QSpinBox;
spinner2 -> setGeometry(QRect(QPoint(190,150),QSize(50,50)));
connect(divide,SIGNAL(released()),this,SLOT(secondnumberx()));
spinner2->setRange(1,10);
}
void MainWindow::clearx() {}
void MainWindow::equalsx() {}
void MainWindow::addx() {}
void MainWindow::subtractx() {}
void MainWindow::multiplyx() {}
void MainWindow::dividex() {}
void MainWindow::firstnumberx() {}
void MainWindow::secondnumberx() {}
MainWindow::~MainWindow() {}
In order for a widget to display inside another widget, you need to set up a parent-child relationship. The simplest way to do this is to pass a pointer to the parent to the child's constructor as an argument.
For your QSpinBox objects, this is done like so:
spinner = new QSpinBox(this);
spinner2 = new QSpinBox(this);
The rest of your code is very laden with hard-coded geometries. For small GUIs, this might not be a problem but can become a bit of a nightmare to maintain for larger ones. Have you considered using QtDesigner to design your GUI? You might also find the layout management classes helpful in making your GUI designs better maintenance of positions and sizing of child widgets.
Add this as parameter of QSpinBox constructor call.
Related
I am learning Qt using Qt 5.13 on MacOS.
First I define MyWidget inherited from QWidget. MyWidget has a QPushButton, but this button will be created in a slot function called 'fresh', not in constructor.
I add MyWidget in MainWindow (inherited from QMainWindow), and defined another button_2 to emit signal to callMyWidget's 'fresh' function to create button.
If I did not hide MyWidget in MainWindow first, MyWidget's button will not show. If I hide MyWidget first, everything seems OK.
I hope to know the reason. Thanks
I tried to repaint or update MyWidget in 'fresh' function, but did not help.
mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include<QPushButton>
class MyWidget : public QWidget
{
Q_OBJECT
public:
explicit MyWidget(QWidget *parent = nullptr);
~MyWidget();
public slots:
void fresh();
private:
QPushButton* myButton;
};
#endif // WIDGET_H
mywidget.cpp
#include "mywidget.h"
MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
}
MyWidget::~MyWidget()
{
}
void MyWidget::fresh()
{
myButton = new QPushButton(this);
myButton->setStyleSheet("QPushButton { background-color: green;}");
show();
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include"mywidget.h"
#include<QHBoxLayout>
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = nullptr);
signals:
public slots:
private:
MyWidget* myWidget;
};
#endif // MAINWINDOW_H
MainWindow.cpp
#include "mainwindow.h"
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{
QWidget* qwidget = new QWidget;
myWidget = new MyWidget(this);
QPushButton* button = new QPushButton("Show",this);
QHBoxLayout* mainLayout = new QHBoxLayout;
mainLayout->addWidget(myWidget);
mainLayout->addWidget(button);
qwidget->setLayout(mainLayout);
setCentralWidget(qwidget);
//myWidget->hide();
connect(button,&QPushButton::clicked,myWidget,&MyWidget::fresh);
}
main.cpp
#include "mywidget.h"
#include"mainwindow.h"
#include<QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
If I add myWidget->hide(); in mainwindow.cpp, it seems right.
If I remove it, the green button will not show, even if I repaint or update or show in fresh function.
'mywidget' is taking the whole space, if you want to know if it is taking all the space or not :
mywidget->setStyleSheet("* {border: 4px solid orange;}")
Since you are using a layout, you might want to determine the minimum size of a QPushButton. the QPushButton has a default horizontal size policy : "Minimum", by default. Maybe if you set the minimum width using this function : "setMinimumWidth(int width)", might fix your problem.
Also, don't forget to call this :
myButton->show();
Every object that inherits from QObject should be shown with this func ".show".
Here is all the flags for QSizePolicy will help you understand what is going on in layouts (layouts work a lot with QSizePlicy flags) : https://doc.qt.io/qt-5/qsizepolicy.html#Policy-enum .
Unless you don't want the layout, you have to specify the position and the size in this way :
mywidget->setGeometry(QPoint(x, y), QSize(width, height));
and the same thing for your buttons.
I have a parent-child window in my Qt application. Parent class is a QDialog named A and child class is QMainWindow named B. Now I want that whenever B is closed through the 'X' button a signal is to be emitted which can be caught by a slot in class A through which I want certain functionality to be implemented. Is there a predefined signal in Qt I can use?
I want something like this:
B *b=new B;
//some code
connect(b,SIGNAL(destroyed()),this,&A::doSomething);
B also has a QWidget which I can use to detect the destroyed signal. How do I implement this? Do I need to emit a custom signal from ~B() ?
Edit: I don't want to destroy the object b as this would require a reallocation when I want to recreate the window B from A and I want to keep the parameters of b.
Your solution would only work if you set a Qt::WA_DeleteOnClose attribute to your B widget:
b->setAttribute(Qt::WA_DeleteOnClose);
Another option would be to reimplement close event and emit a custom signal there.
Connect your object like this:
widget = new QWidget();
//widget->show(); //optional using
connect(widget, &QWidget::destroyed, this, &MainWindow::widgetDestroy);
widget->setAttribute(Qt::WA_DeleteOnClose);
.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;
}
void MainWindow::on_pushButtonNew_clicked()
{
widget = new QWidget();
widget->show();
connect(widget, &QWidget::destroyed, this, &MainWindow::widgetDestroy);
widget->setAttribute(Qt::WA_DeleteOnClose);
}
void MainWindow::on_pushButtonDel_clicked()
{
delete widget;
}
void MainWindow::widgetDestroy()
{
qDebug()<< "deleted."; //after destroy widget this function calling.
}
.h :
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QWidget>
#include <QDebug>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void widgetDestroy();
void on_pushButtonNew_clicked();
void on_pushButtonDel_clicked();
private:
Ui::MainWindow *ui;
QWidget *widget;
};
#endif // MAINWINDOW_H
.ui :
The following is the smallest example I could make to present the isuue.
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
QVBoxLayout *vLayout = new QVBoxLayout(this);
QGroupBox *gb = new QGroupBox;
// MyGroupBox *gb = new MyGroupBox;
vLayout->addWidget(gb);
QPushButton *btB = new QPushButton;
vLayout->addWidget(btB);
}
The code above produces the image above, it's just a group box and a button in vertical layout.
If I replace QGropBox by MyGroupBox then it doesn't show there anymore. The code below produces the image below.
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
QVBoxLayout *vLayout = new QVBoxLayout(this);
// QGroupBox *gb = new QGroupBox;
MyGroupBox *gb = new MyGroupBox;
vLayout->addWidget(gb);
QPushButton *btB = new QPushButton;
vLayout->addWidget(btB);
}
Where mygroupbox.h (the constructor body is empty in the .cpp file):
#include <QWidget>
class MyGroupBox : public QWidget
{
Q_OBJECT
public:
explicit MyGroupBox(QWidget *parent = 0);
signals:
public slots:
};
Why the group box isn't showing there? How to make it appear?
This is why it doesn't appear:
class MyGroupBox : public QWidget
Your "group box" is basically just a QWidget. Inherit from QGroupBox instead.
As an aside, a minimal example could look like the below. Not a single declaration/statement/expression can be removed. The button aids in visualizing the problem, so it should be left in. The use of a failure trigger variable highlights exactly what condition triggers the failure: the code self-documents and you almost need no narrative to explain it. The question could be as concise as the test case below and one sentence "Why is the group box's border not visible when fail is true?". Most likely, had you followed the minimization fully through, you'd realize yourself what the problem was - it becomes rather obvious. It's not so when MyGroupBox is declared in another file!
The technique of putting it all into a single main.cpp file is critical in spotting the problem: all of the code is physically next to each other, making it much easier to spot mistakes! When you minimize, usually the first things that have to go are separate files: cram it all into one file, and then relentlessly remove absolutely everything that's not directly needed in reproducing the issue.
#include <QtWidgets>
struct MyGroupBox : public QWidget {};
int main(int argc, char ** argv) {
bool fail = true;
QApplication app{argc, argv};
QWidget widget;
QVBoxLayout layout{&widget};
QGroupBox groupBox;
MyGroupBox myGroupBox;
QPushButton button;
layout.addWidget(fail ? static_cast<QWidget*>(&myGroupBox) : &groupBox);
layout.addWidget(&button);
widget.show();
return app.exec();
}
This concise style is not only for trivial test cases. In your real code, the Widget's header and implementation could look as follows:
// Widget.h
#include <QtWidgets>
#include "MyGroupBox.h"
class Widget : public QWidget {
Q_OBJECT
QVBoxLayout layout{this};
MyGroupBox groupBox;
QPushButton button{tr("Click Me!")};
public:
explicit Widget(QWidget * parent = nullptr);
};
// Widget.cpp
#include "Widget.h"
Widget::Widget(QWidget * parent) :
QWidget{parent} {
layout.addWidget(&groupBox);
layout.addWidget(&button);
}
If you insist on shielding the interface from implementation details, don't use pointers to widgets etc., use a PIMPL.
// Widget.h
#include <QWidget>
class WidgetPrivate;
class Widget : public QWidget {
Q_OBJECT
Q_DECLARE_PRIVATE(Widget)
QScopedPointer<WidgetPrivate> const d_ptr;
public:
explicit Widget(QWidget * parent = nullptr);
};
// Widget.cpp
#include "Widget.h" // should always come first!
#include "MyGroupBox.h"
class WidgetPrivate {
Q_DECLARE_PUBLIC(Widget)
Widget * const q_ptr;
public:
QVBoxLayout layout{q_func()};
QGroupBox groupBox;
MyGroupBox myGroupBox;
QPushButton button{"Click Me!"};
WidgetPrivate(Widget * q) : q_ptr(q) {
layout.addWidget(&groupBox);
layout.addWidget(&button);
}
};
Widget::Widget(QWidget * parent) :
QWidget{parent}, d_ptr{new WidgetPrivate{this}}
{}
Edit: I removed the destructor from the slot. But now I have memory leaking problems. Each new window that I open occupies some memory,and when I close it,the memory stays occupied
When I execute the program,and open new windows, they are opened normally. When I close any of them, the whole application crashes (not only that specific window),and I get the crash error.
What am I doing wrong?
mainWindow.h:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
class QHBoxLayout;
class QTextEdit;
class QWidget;
class QDialog;
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
public slots:
void closeWindow();
void newWindow();
private:
Ui::MainWindow *ui;
MainWindow *tempMainWindow;
QHBoxLayout * mainLyt;
QTextEdit *txtEdit;
QWidget *mainWidget;
};
#endif // MAINWINDOW_H
mainWindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QWidget>
#include <QHBoxLayout>
#include <QTextEdit>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
mainWidget=new QWidget();
mainLyt=new QHBoxLayout();
txtEdit=new QTextEdit();
mainLyt->addWidget(txtEdit);
mainWidget->setLayout(mainLyt);
setCentralWidget(mainWidget);
connect(ui->actionExit,SIGNAL(triggered()),this,SLOT(closeWindow()));
connect(ui->actionNew,SIGNAL(triggered()),this,SLOT(newWindow()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::closeWindow()
{
this->close();
delete txtEdit;
delete mainLyt;
delete mainWidget;
this->~MainWindow();
}
void MainWindow::newWindow()
{
tempMainWindow=new MainWindow(this);
tempMainWindow->show();
}
If you pass to QWidget(), QHBoxLayout() and QTextEdit() also this (which is the parent), at the delection of the MainWindow Qt will delete for you the ui and all the additional widgets yur defined in the construstor. In this way you can avoid to call closeWindow() method.
delete ui is also not necessary.
ui->setupUi(this);
mainWidget = new QWidget(this);
mainLyt = new QHBoxLayout(this);
txtEdit = new QTextEdit(this);
I'm trying to make basic text editor,and when New is triggered, it should open a new window for new text document. Is there some better way to do this?
Yes. It's called a factory, and it can be a static method as it doesn't operate on any object. You can call it from a slot, of course.
I imagine you'll need to pass a file name to the newly created window - that could be an argument to the factory method and the factory slot. If the "new" window is empty, then this is not an issue.
Other issues:
There is no reason to keep the mainWidget member: it is always available as centralWidget().
There's also no reason to have the members other than ui as pointers. It is actually a premature pessimization - it will waste a bit more heap memory.
You don't need a layout for the central widget if it has no child widgets. The QTextEdit instance itself can be the central widget.
The ui instance should be retained using a smart pointer. This makes the destructor completely compiler-generated (it has an empty body).
You don't need anything fancy in the closeWindow slot. Simply delete the instance!
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
static MainWindow * createWindow();
void setFileName(const QString & fileName);
public slots:
void closeWindow();
void newWindow();
private:
QScopedPointer<Ui::MainWindow> const ui;
QTextEdit m_txtEdit;
};
void MainWindow::newWindow() {
createWindow()->show();
}
void MainWindow::closeWindow() {
deleteLater();
}
MainWindow * MainWindow::createWindow(QWidget * parent) {
return new MainWindow(parent);
}
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
setCentralWidget(&m_txtEdit);
connect(ui->actionExit, SIGNAL(triggered()), SLOT(closeWindow()));
connect(ui->actionNew, SIGNAL(triggered()), SLOT(newWindow()));
}
MainWindow::~MainWindow()
{}
Let us see your code:
this->close();
delete txtEdit;
delete mainLyt;
delete mainWidget;
this->~MainWindow();
You are trying to destroy them and for the next open you allocate them almost the same way.
What you achieve here is basically performance penalty. I would suggest to hide, modify, and so on the unwanted items instead.
I have a subclassed QToolButton(in a toolbar added to mainwindow with addToolBar() ) that works as a "drag and drop button" dynamically generating subclassed QWidgets( which contain just 1 QTextEdit) on the central Widget of a QMainWindow which is a QWidget. The drag and drop works fine.
However unless the user accesses them in a very specific order, only one of the QTextEdit widgets stays accessible after which the others do not respond to mouse clicks and the whole central Widget is "stuck".
By that i mean any other widgets who are children of the central widget are unresponsive.
Why is that? Does it have something to do with focus policies possibly?
EDIT:
Thanks to SpongeBobs comment, where he suggested to test plain QTextEdit generating instead of a whole custom class, we know that the error is somewhere in the custom class ideafield. So how do I change it to get the appropriate behavior?
#ifndef IDEAFIELD_H
#define IDEAFIELD_H
#include <QWidget>
#include <QTextEdit>
#include <QFrame>
class IdeaField : public QWidget
{
Q_OBJECT
public:
explicit IdeaField(QWidget *parent = 0);
void move_all(int,int);
void move_all(QPoint);
QTextEdit *textField;
signals:
public slots:
};
code:
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
this->setStyleSheet("background-color: white;");
ideaPlane = new IdeaPlane(this);
setCentralWidget(ideaPlane);
MainWindow::createToolBars();
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::createToolBars()
{
QToolBar * topToolBar = addToolBar(tr("Title"));
dragIdeaButton = new dragButton(this);
topToolBar->addWidget(dragIdeaButton);
}
ideafield.cpp: subclassed QTextEdit:
#include "ideafield.h"
IdeaField::IdeaField(QWidget *parent):QWidget(parent)
{
textField = new QTextEdit(this);
textField->setFrameShape(QFrame::StyledPanel);
textField->setPlainText(tr("TEST TEXT\nHURRAY!"));
}
void IdeaField::move_all(int x,int y)
{
textField->move(x,y);
}
void IdeaField::move_all(QPoint point)
{
textField->move(point);
}