I'm trying to write application's menu for my text editor, but I don't understand why signal triggered does not working. It should open a QFileDialog::getOpenFileName, but it does not happen. Why?
main.cpp
#include "mainwindow.h"
#include "centralwidget.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow *mainWindow = new MainWindow;
CentralWidget *centralWidget = new CentralWidget;
mainWindow->setCentralWidget(centralWidget);
mainWindow->show();
return a.exec();
}
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QMenu>
#include <QMenuBar>
#include <QStatusBar>
#include <QAction>
#include <QFileDialog>
#include <QString>
class MainWindow : public QMainWindow
{
public:
MainWindow();
public slots:
void slotFileDialog();
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
MainWindow::MainWindow()
{
QMenu *fileMenu = new QMenu("File");
QAction *openAction = new QAction(tr("&Open..."), this);
connect(openAction, SIGNAL(triggered()),
this, SLOT(slotFileDialog()));
fileMenu->addAction(openAction);
QMenuBar *mainMenu = new QMenuBar;
mainMenu->addMenu(fileMenu);
mainMenu->show();
QStatusBar *mainStatusBar = new QStatusBar;
setMenuBar(mainMenu);
setStatusBar(mainStatusBar);
}
void MainWindow::slotFileDialog()
{
QString fileName = QFileDialog::getOpenFileName(
this, tr("Open File"),"/home",tr("Text (*.txt)"));
}
You haven't included the Q_OBJECT macro in the class definition, so the moc will not generate the associated files for it.
Related
I want my qwebengineview can't scroll to the left/right/up/down.
My situation is like this:
It was asked in Qt Fourm first, however I can't find a solution for this.
QT Fourm link: link
Please see the minimum code example code below. It's not the same website but can also show this problem.
I'm using Mac Os 10.15 and Qt 5.13.1.
Update
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QWebEngineView>
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;
QWebEngineView* m_pWebView;
};
#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);
this->setFixedSize(920,580);
m_pWebView = new QWebEngineView(this);
// Set WebView Size
m_pWebView->setGeometry(0,0,920,580);
// Disable Right Click
m_pWebView->setContextMenuPolicy(Qt::NoContextMenu);
m_pWebView->load(QUrl("https://clash.razord.top/#/proxies"));
}
MainWindow::~MainWindow()
{
delete ui;
}
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
In the program, I am trying to create a image player using QT. When I click a button in the UI, the program will create a image slideshow with a 2s pause. I tried to use the QTimer to such things, but failed to do so. Hence, I want to ask how to achieve my purpose by using QTimer.
Let me describe the flow of my program. When the user click a button in the main window, the sub-window showpic will be opened and then start showing each image for a pause of 2s in its qgraphsview. The images filepath are stored in the "QStringlist filenames".
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QFileSystemModel>
#include "showpic.h"
#include <QBasicTimer>
#include <QTimer>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
void display(const QString & , ShowPic* );
private slots:
void tick();
void on_pushButton_clicked();
private:
Ui::MainWindow *ui;
QFileSystemModel *model;
QString filesPath;
ShowPic *showpic;
QStringList filenames;
QStringList::const_iterator m_imageIt;
QTimer m_timer;
};
#endif // MAINWINDOW_H
showpic.h
#ifndef SHOWPIC_H
#define SHOWPIC_H
#include <QWidget>
namespace Ui {
class ShowPic;
}
class ShowPic : public QWidget
{
Q_OBJECT
public:
explicit ShowPic(QWidget *parent = 0);
~ShowPic();
private:
Ui::ShowPic *ui;
public:
void addPixmap(const QPixmap &pixmap);
};
#endif // SHOWPIC_H
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QFileDialog>
#include<QFileSystemModel>
#include<QStringList>
#include <QTreeView>
#include <QGraphicsScene>
#include <QTime>
#include <QThread>
#include <QDebug>
#include <iostream>
#include <QTimer>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
filenames.append("C:\\test\\image.jpg");
filenames.append("C:\\test\\apple.jpg");
filenames.append("C:\\test\\orange.jpg");
filenames.append("C:\\test\\lemon.jpg");
filenames.append("C:\\test\\grape.jpg");
m_imageIt = filenames.begin();
m_timer.setInterval(5000);
connect(&m_timer, SIGNAL(timeout()), this, SLOT(tick()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::display(const QString & filename, ShowPic* showpic) {
showpic->addPixmap(filename);
}
void MainWindow::tick(){
showpic = new ShowPic();
showpic->show();
display(*m_imageIt, showpic);
m_imageIt ++;
}
/*
void timerEvent(QTimerEvent * ev) {
if (ev->timerId() == m_timer.timerId()) tick();
}*/
void MainWindow::on_pushButton_clicked()
{
/*showpic = new ShowPic();
QPixmap pixmap("C:\\test\\image.jpg");
showpic->addPixmap(pixmap);
showpic->show();*/
m_timer.start();
}
showpic.cpp
#include "showpic.h"
#include "ui_showpic.h"
#include <QThread>
ShowPic::ShowPic(QWidget *parent) :
QWidget(parent),
ui(new Ui::ShowPic)
{
ui->setupUi(this);
ui->graphicsView->setScene(new QGraphicsScene);
}
ShowPic::~ShowPic()
{
delete ui;
}
void ShowPic::addPixmap(const QPixmap &pixmap){
ui->graphicsView->scene()->addPixmap(pixmap);
}
The compiling message error:
The error has nothing to do with the timer, it is because you forgot to declare display(), tick(), and timerEvent() as part of the MainWindow:: class, so they cannot access MainWindow members.
The timer should be even easier to use than your code. First I recommend you use a QTimer instead of QBasicTimer. Then you can simply connect to its timeout() signal.
mainwindow.h
#include <QTimer>
QTimer m_timer;
mainwindow.cpp
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
...
m_imageIt = filenames.begin();
m_timer.setInterval(5000);
connect(&m_timer, SIGNAL(timeout()), this, SLOT(tick()));
}
void MainWindow::on_pushButton_clicked()
{
m_timer.start();
}
You do not need timerEvent() function at all.
i am trying to take a feedback data which is published from arduino and subscribed to my GUI created in QT.
Now i have main.cpp and mainwindow.cpp.
main.cpp
#include <QtGui>
#include <ros/ros.h>
#include <QApplication>
#include "../include/abc/main_window.hpp"
#include "std_msgs/String.h"
#include <std_msgs/UInt16.h>
#include <QMainWindow>
#include <std_msgs/Float32.h>
void chatterCallback(const std_msgs::UInt16 &fb_msg){
ROS_INFO("Feedback: [%f]", fb_msg.data);
ui.label_6->setText(QString("%1").arg(fb_msg.data));
}
int main(int argc, char **argv) {
ros::init(argc, argv, "talker");
ros::NodeHandle n;
ros::Subscriber sub = n.subscribe("feedback",1000, chatterCallback);
ros::spinOnce();
QApplication app(argc, argv);
abc::MainWindow w(argc,argv);
w.show();
w.setWindowTitle("GUI for Controlling Servo Motor");
app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit()));
int result = app.exec();
return result;}
mainwindow.cpp
namespace abc {
using namespace Qt;
QSerialPort *serial;
MainWindow::MainWindow(int argc, char** argv, QWidget *parent)
: QMainWindow(parent)
, qnode(argc,argv)
{
ui.setupUi(this);
}
MainWindow::~MainWindow() {}
void MainWindow::on_horizontalSlider_valueChanged(int value)
{
ui.label_5->setText(QString("%1").arg(value));
msg.data = ui.label_5->text().toUInt();
ROS_INFO("%d", msg.data);
chatter_pub.publish(msg);
ros::spinOnce();
}
main_window.hpp
#ifndef abc_MAIN_WINDOW_H
#define abc_MAIN_WINDOW_H
#include <QtGui/QMainWindow>
#include "ui_main_window.h"
#include "qnode.hpp"
#include <QtSerialPort/QSerialPort>
#include <ros/ros.h>
#include "std_msgs/UInt16.h"
namespace abc {
class MainWindow : public QMainWindow {
Q_OBJECT
public:
MainWindow(int argc, char** argv, QWidget *parent = 0);
~MainWindow();
public Q_SLOTS:
private:
Ui::MainWindowDesign ui;
ros::NodeHandle n;
ros::Publisher chatter_pub = n.advertise <std_msgs::UInt16> ("chatter", 1000);
QSerialPort *arduino;
QNode qnode;
};
} // namespace abc
#endif // abc_MAIN_WINDOW_H
Now when i run this code, it shows me that UI is not declared in main.cpp.
I wanted to display the data from feedback to label_6 (TextBox). The data is only available in main.cpp, any suggestions are highly appreciable.
Thanks in advance.
You will have to pass the fb_msg.data as an argument to the MainWindow constructor. Then you can set the UI element in the MainWindow thread.
Alternatively once you create the MainWindow instance in your main, you can emit a signal which you catch and process in the MainWindow thread.
You cannot modify the UI elements from a different thread.
I need small help, I'm using class Qslider from qt, how can I get the number of the current position of the cursor (with which function I can do that) thanks in advance
edited
I want to implement one thing: when I reach the max of the interval I want to quit, how can I do this with slot and signal?
I am assuming you want the value of the slider?
int QSlider::value ()
I looked at the code in your other post and this is what I came up with after cleaning it up:
main.cpp
#include <QApplication>
#include "mywidget.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}
mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include <QObject>
include <QPushButton>
#include <QSlider>
class MyWidget : public QWidget
{
Q_OBJECT
public:
MyWidget(QWidget *parent = 0);
~MyWidget(){};
public slots:
void getSliderValueAndQuit();
private:
QPushButton *quit;
QSlider *slider;
};
#endif // MYWIDGET_H
myWidget.cpp
#include "mywidget.h"
#include <QWidget>
#include <QObject>
#include <QApplication>
#include <QFont>
#include <QLCDNumber>
#include <QPushButton>
#include <QSlider>
#include <QVBoxLayout>
MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 18, QFont::Bold));
QLCDNumber *lcd = new QLCDNumber(3);
lcd->setSegmentStyle(QLCDNumber::Flat);
slider = new QSlider(Qt::Horizontal);
slider->setRange(0, 999);
slider->setValue(0);
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
connect(slider, SIGNAL(valueChanged(int)),lcd, SLOT(display(int)));
connect(slider,SIGNAL(sliderReleased()), SLOT(getSliderValueAndQuit()));
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(quit);
layout->addWidget(lcd);
layout->addWidget(slider);
setLayout(layout);
}
void MyWidget::getSliderValueAndQuit(){
if(slider->value() == slider->maximum())
close();
}
I have this snippet of the code:
#include <QApplication>
#include <QFont>
#include <QLCDNumber>
#include <QPushButton>
#include <QSlider>
#include <QVBoxLayout>
#include <QWidget>
class MyWidget : public QWidget
{
public:
MyWidget(QWidget *parent = 0);
};
MyWidget::MyWidget(QWidget *parent)
: QWidget(parent)
{
QPushButton *quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 18, QFont::Bold));
QLCDNumber *lcd = new QLCDNumber(3);
lcd->setSegmentStyle(QLCDNumber::Flat);
QSlider *slider = new QSlider(Qt::Horizontal);
slider->setRange(0, 999);
slider->setValue(0);
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
connect(slider, SIGNAL(valueChanged(int)),
lcd, SLOT(display(int)))
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(quit);
layout->addWidget(lcd);
layout->addWidget(slider);
setLayout(layout);
}
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}
when I reach the max of the interval, I want to quit, how can I implement this with signals and slots, thanks in advance
Add one more slot-function to your MyWidget class, for example on_maximum_exit(int) like that:
class MyWidget : public QWidget
{
public:
MyWidget(QWidget *parent = 0);
public slots:
void on_maximum_exit(int );
};
Define new function:
void MyWidget::on_maximum_exit(int value)
{
if (value == slider->maximum())
close();
}
In MyWidget consctuctor, after connect(slider, SIGNAL(valueChanged(int)),... add:
/* ... */
connect(slider, SIGNAL(valueChanged(int)), this, SLOT(on_maximum_exit(int)));
/* ... */
And of course use Qt docs!
Like I said in the other post this should work for you:
main.cpp
#include <QApplication>
#include "mywidget.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MyWidget widget;
widget.show();
return app.exec();
}
mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include <QObject>
include <QPushButton>
#include <QSlider>
class MyWidget : public QWidget
{
Q_OBJECT
public:
MyWidget(QWidget *parent = 0);
~MyWidget(){};
public slots:
void getSliderValueAndQuit();
private:
QPushButton *quit;
QSlider *slider;
};
#endif // MYWIDGET_H
myWidget.cpp
#include "mywidget.h"
#include <QWidget>
#include <QObject>
#include <QApplication>
#include <QFont>
#include <QLCDNumber>
#include <QPushButton>
#include <QSlider>
#include <QVBoxLayout>
MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
quit = new QPushButton(tr("Quit"));
quit->setFont(QFont("Times", 18, QFont::Bold));
QLCDNumber *lcd = new QLCDNumber(3);
lcd->setSegmentStyle(QLCDNumber::Flat);
slider = new QSlider(Qt::Horizontal);
slider->setRange(0, 999);
slider->setValue(0);
connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
connect(slider, SIGNAL(valueChanged(int)),lcd, SLOT(display(int)));
connect(slider,SIGNAL(sliderReleased()), SLOT(getSliderValueAndQuit()));
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(quit);
layout->addWidget(lcd);
layout->addWidget(slider);
setLayout(layout);
}
void MyWidget::getSliderValueAndQuit(){
if(slider->value() == slider->maximum())
close();
}