How to make a program with 2 windows that open simultaneously upon runtime in Qt?

问题

Initially I made it in the main of the window I had made earlier

回答1:

There is nothing complicated to open a 2^nd window (or dialog) with the main window.

To demonstrate this, I made an MCVE.

C++ source testQMainWindowWithQDialog.cc:

// Qt header:
#include <QtWidgets>

class Dialog: public QDialog {
  private:
    QVBoxLayout _qVBox;
    QLabel _qLbl;

  public:
    Dialog(QWidget *pQParent = nullptr):
      QDialog(pQParent),
      _qLbl("the dialog")
    {
      setWindowTitle("the Dialog Window");
      _qVBox.addWidget(&_qLbl, 1, Qt::AlignCenter);
      setLayout(&_qVBox);
    }

    virtual ~Dialog() = default;

    Dialog(const Dialog&) = delete;
    Dialog& operator=(const Dialog&) = delete;
};

class MainWindow: public QMainWindow {
  private:
    Dialog _qDlg;
    QWidget _qWidgetCentral;
    QVBoxLayout _qVBox;
    QLabel _qLbl;

  public:
    MainWindow():
      QMainWindow(),
      _qDlg(this),
      _qLbl("the main window")
    {
      setWindowTitle("Test QMainWindow with QDialog");
      _qVBox.addWidget(&_qLbl, 1, Qt::AlignCenter);
      _qWidgetCentral.setLayout(&_qVBox);
      setCentralWidget(&_qWidgetCentral);
      _qDlg.show();
    }
};

// main application
int main(int argc, char **argv)
{
  qDebug() << "Qt Version:" << QT_VERSION_STR;
  QApplication app(argc, argv);
  // setup GUI
  MainWindow qWinMain;
  qWinMain.show();
  // runtime loop
  return app.exec();
}

Build script CMakeLists.txt (to prepare a VS solution for VS2017):

project(QMainWindowWithQDialog)

cmake_minimum_required(VERSION 3.10.0)

set_property(GLOBAL PROPERTY USE_FOLDERS ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

find_package(Qt5Widgets CONFIG REQUIRED)

include_directories("${CMAKE_SOURCE_DIR}")

add_executable(testQMainWindowWithQDialog testQMainWindowWithQDialog.cc)

target_link_libraries(testQMainWindowWithQDialog Qt5::Widgets)

Built and run on Windows 10, VS2017, Qt 5.13:

a Qt project file testQMainWindowWithQDialog.pro:

SOURCES = testQMainWindowWithQDialog.cc

QT += widgets

Built and tested on cygwin64 (with X11 server):

$ qmake-qt5 testQMainWindowWithQDialog.pro 

$ make && ./testQMainWindowWithQDialog 
g++ -c -fno-keep-inline-dllexport -D_GNU_SOURCE -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtCore -I. -I/usr/lib/qt5/mkspecs/cygwin-g++ -o testQMainWindowWithQDialog.o testQMainWindowWithQDialog.cc
g++  -o testQMainWindowWithQDialog.exe testQMainWindowWithQDialog.o   -lQt5Widgets -lQt5Gui -lQt5Core -lGL -lpthread 
Qt Version: 5.9.4

I still believe that there must be something else wrong in OP's code.

来源：https://stackoverflow.com/questions/61673728/how-to-make-a-program-with-2-windows-that-open-simultaneously-upon-runtime-in-qt

标签

c++

qt5