(C++) Exercise: Qt hide and show #3

 

Difficulty: 1/10

Date added: 19th of October 2012

 

In this exercise I will elaborate on the answer of exercise 'Qt hide and show #2'.

 

The following program flow works:

• On startup, the first dialog shows:
  
• On the first dialog, pressing the button with the text 'Show second', results in hiding the first and showing the second dialog:
  
• On the second dialog, pressing the button with the text 'Back to first', results in going back to the first dialog\
• On the second dialog, pressing the button with the text 'Go to third', results in hiding the second and showing the third dialog:
  
• On the third dialog, pressing the button with the text 'Back to first', results in going back to the first dialog.
• On the third dialog, pressing the button with the text 'Back to second', results in going back to the second dialog.

 

The solution given at the answer of exercise 'Qt hide and show #2' works, but there is still the need to add the needed signals and slots to every child and parent window.

 

 

 

 

 

Question

 

Refactor the code, by adding a new class called QtHideAndShowDialog.

 

• Download the Qt Creator project 'CppExerciseQtHideAndShow3' (zip)
• View the answer

 

 

 

 

 

Code

 

Qt project file: CppExerciseQtHideAndShow3.pro

 

---

QT       += core gui TARGET = CppExerciseQtHideAndShow3 TEMPLATE = app SOURCES += \     main.cpp\     firstdialog.cpp \     seconddialog.cpp \     thirddialog.cpp HEADERS  +=  \     firstdialog.h \     seconddialog.h \     thirddialog.h FORMS    += \     firstdialog.ui \     seconddialog.ui \     thirddialog.ui

 

 

 

 

 

firstdialog.h

 

---

#ifndef FIRSTDIALOG_H #define FIRSTDIALOG_H #include <QDialog> namespace Ui { class FirstDialog; } class FirstDialog : public QDialog {     Q_OBJECT      public:     explicit FirstDialog(QWidget *parent = 0);     ~FirstDialog();      private slots:     void close_child();     void on_pushButton_clicked(); private:     Ui::FirstDialog *ui;     bool m_show_child; }; #endif // FIRSTDIALOG_H

 

 

 

 

 

firstdialog.cpp

 

---

#include "seconddialog.h" #include "firstdialog.h" #include "ui_firstdialog.h" FirstDialog::FirstDialog(QWidget *parent) :     QDialog(parent),     ui(new Ui::FirstDialog),     m_show_child(false) {   ui->setupUi(this); } FirstDialog::~FirstDialog() {   delete ui; } void FirstDialog::close_child() {   m_show_child = false; } void FirstDialog::on_pushButton_clicked() {   SecondDialog d;   this->hide();   QObject::connect(&d,SIGNAL(close_me()),this,SLOT(close_child()));   m_show_child = true;   while (m_show_child)   {     d.exec();   }   this->show(); }

 

 

 

 

 

main.cpp

 

---

#include <QtGui/QApplication> #include "firstdialog.h" int main(int argc, char *argv[]) {   QApplication a(argc, argv);   FirstDialog w;   w.show();   a.exec(); }

 

 

 

 

 

seconddialog.h

 

---

#ifndef SECONDDIALOG_H #define SECONDDIALOG_H #include <QDialog> namespace Ui { class SecondDialog; } class SecondDialog : public QDialog {     Q_OBJECT      public:     explicit SecondDialog(QWidget *parent = 0);     ~SecondDialog();      private slots:     void close_child();     void on_button_goto_third_clicked();     void on_button_back_to_first_clicked(); protected:     void closeEvent(QCloseEvent *); signals:     void close_me(); private:     Ui::SecondDialog *ui;     bool m_show_child; }; #endif // SECONDDIALOG_H

 

 

 

 

 

seconddialog.cpp

 

---

#include <cassert> #include "seconddialog.h" #include "ui_seconddialog.h" #include "thirddialog.h" SecondDialog::SecondDialog(QWidget *parent) :     QDialog(parent),     ui(new Ui::SecondDialog),     m_show_child(false) {   ui->setupUi(this); } SecondDialog::~SecondDialog() {   delete ui; } void SecondDialog::close_child() {   m_show_child = false; } void SecondDialog::closeEvent(QCloseEvent *) {   emit close_me(); } void SecondDialog::on_button_back_to_first_clicked() {   close(); } void SecondDialog::on_button_goto_third_clicked() {   ThirdDialog d;   this->hide();   QObject::connect(&d,SIGNAL(close_me()),this,SLOT(close_child()));   m_show_child = true;   while (m_show_child)   {     d.exec();   }   if (d.m_back_to_which_dialog == 1)   {     this->close();   }   else   {     this->show();   } }

 

 

 

 

 

thirddialog.h

 

---

#ifndef THIRDDIALOG_H #define THIRDDIALOG_H #include <QDialog> namespace Ui { class ThirdDialog; } class ThirdDialog : public QDialog {     Q_OBJECT      public:     explicit ThirdDialog(QWidget *parent = 0);     ~ThirdDialog();     int m_back_to_which_dialog; protected:     void closeEvent(QCloseEvent *); private slots:     void on_button_back_to_first_clicked();     void on_button_back_to_second_clicked(); signals:   void close_me(); private:     Ui::ThirdDialog *ui; }; #endif // THIRDDIALOG_H

 

 

 

 

 

thirddialog.cpp

 

---

#include "thirddialog.h" #include "ui_thirddialog.h" ThirdDialog::ThirdDialog(QWidget *parent) :     QDialog(parent),     m_back_to_which_dialog(2), //When user closes the dialog, go back to the previous/second dialog     ui(new Ui::ThirdDialog) {   ui->setupUi(this); } ThirdDialog::~ThirdDialog() {   delete ui; } void ThirdDialog::closeEvent(QCloseEvent *) {   emit close_me(); } void ThirdDialog::on_button_back_to_first_clicked() {   m_back_to_which_dialog = 1;   close(); } void ThirdDialog::on_button_back_to_second_clicked() {   m_back_to_which_dialog = 2;   close(); }