QT learning 17 dialog box and its types

Qt Study 17 Dialog box and its type

Concept of dialog box

• Dialog box Is to communicate with users Brief interaction The top window of
• QDialog yes Qt The base class of all multi frame windows in
• QDialog Inherited from QWidget It's a kind of Container type The components of

• QDialog The meaning of
  • QDialog As a kind of Dedicated interactive window And exist
  • QDialog You can't Embedded in other containers as a subassembly
  • QDialog The window style is customized special QWidget

experiment 1 - QWidget and QDialog The difference between

#include "Dialog.h"
#include <QApplication>
#include <QWidget>
#include <QDialog>

int main(int argc, char *argv[])
{
    
    QApplication a(argc, argv);
    QWidget widget;
    QDialog dialog(&widget);	//  although dialog Set the parent component , however dialog It will still be the top window 
    dialog.show();
    dialog.setWindowTitle("I'am dialog");
    widget.show();
    widget.setWindowTitle("I'am widget");

    return a.exec();
}

#include <QApplication>
#include <QWidget>
#include <QDialog>

int main(int argc, char *argv[])
{
    
    QApplication a(argc, argv);
    QDialog dialog;
    QWidget widget(&dialog);	// widget Set the parent component ,widget Will be embedded dialog in 
    dialog.show();
    dialog.setWindowTitle("I'am dialog");
    widget.show();
    widget.setWindowTitle("I'am widget");

    return a.exec();
}

Type of dialog

• Modal dialog （ QDialog::exec() ）

  • After the show Cannot interact with parent window
  • It's a kind of Blocking type Dialog call method

• modeless dialog box （ QDialog::show() ）

  • After the show Independent existence Sure At the same time, interact with the parent window
  • It's a kind of Non-blocking type Dialog call method

• General situation

  • The modal dialog box is used for It must depend on the occasion chosen by the user （80%）
  • Message tip , File selection , Print settings , etc.

• Modeless dialog boxes are used for Occasions with special function settings （20%）

  • Search operation , Property settings , etc.

• Tips

  • stay Stack To create a Modal dialog Is the simplest and most commonly used way
  • In general modeless dialog box Need to be in Pile up To create a
  • adopt QDialog::setModel Function can create Mixing characteristics The dialog
  • modeless dialog box You need to specify the Qt::WA_DeleteOnClose attribute

experiment 2 - Dialog boxes with different features

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QPushButton>

class Dialog : public QDialog
{
    
    Q_OBJECT
protected:
    QPushButton ModalBtn;
    QPushButton NormalBtn;
    QPushButton MixedBtn;

protected slots:
    void ModalBtn_clicked();
    void NormalBtn_clicked();
    void MixedBtn_clicked();

public:
    Dialog(QWidget *parent = 0);
    ~Dialog();
};

#endif // DIALOG_H

#include "Dialog.h"
#include <QDebug>
//  Modal dialog 
void Dialog::ModalBtn_clicked()
{
    
    qDebug() << "ModalBtn_clicked() begin";
    QDialog dialog(this);
    dialog.exec();
    qDebug() << "ModalBtn_clicked() end";
}
//  modeless dialog box 
void Dialog::NormalBtn_clicked()
{
    
    qDebug() << "NormalBtn_clicked() begin";
    QDialog *dialog = new QDialog(this);	//  Modeless dialogs do not block programs , It must be put on the pile 
    dialog->setAttribute(Qt::WA_DeleteOnClose);	//  To prevent memory leaks , This line must be added 
    dialog->show();
    qDebug() << "NormalBtn_clicked() end";
}
//  Mixed properties dialog box 
void Dialog::MixedBtn_clicked()
{
    
    qDebug() << "MixedBtn_clicked() begin";
    QDialog *dialog = new QDialog(this);
    dialog->setAttribute(Qt::WA_DeleteOnClose);
    dialog->setModal(this);	//  The mixed attribute dialog is based on the modeless dialog 
    dialog->show();
    qDebug() << "MixedBtn_clicked() end";
}

Dialog::Dialog(QWidget *parent)
    : QDialog(parent), ModalBtn(this), NormalBtn(this), MixedBtn(this)
{
    
    ModalBtn.setText("Modal Dialog");
    ModalBtn.move(20, 20);
    ModalBtn.resize(100, 30);

    NormalBtn.setText("Normal Dialog");
    NormalBtn.move(20, 70);
    NormalBtn.resize(100, 30);

    MixedBtn.setText("Mixed Dialog");
    MixedBtn.move(20, 120);
    MixedBtn.resize(100, 30);

    connect(&ModalBtn, SIGNAL(clicked()), this, SLOT(ModalBtn_clicked()));
    connect(&NormalBtn, SIGNAL(clicked()), this, SLOT(NormalBtn_clicked()));
    connect(&MixedBtn, SIGNAL(clicked()), this, SLOT(MixedBtn_clicked()));

    resize(140, 170);
}

Dialog::~Dialog()
{
    
    qDebug() << "~Dialog()";
}

#include "Dialog.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    
    QApplication a(argc, argv);
    Dialog dlg;
    dlg.show();

    return a.exec();
}

The return value of the dialog

• Only Modal dialog Only then Return value The concept of
• Modal dialog Return value be used for Represent interaction results
• QDialog::exec() The return value of is the interaction result
  • void QDialog::done(int i) Close the dialog box and Take parameters as interaction results
  • QDialog::Accepted - User operation succeeded
  • QDialog::Rejected - User operation failed

experiment 3 - The return value of the dialog

#include "Dialog.h"
#include <QDebug>

void Dialog::ModalBtn_clicked()
{
    
    qDebug() << "ModalBtn_clicked() begin";
    done(Accepted);
    qDebug() << "ModalBtn_clicked() end";
}

void Dialog::NormalBtn_clicked()
{
    
    qDebug() << "NormalBtn_clicked() begin";
    done(Rejected);
    qDebug() << "NormalBtn_clicked() end";
}

void Dialog::MixedBtn_clicked()
{
    
    qDebug() << "MixedBtn_clicked() begin";
    done(100);
    qDebug() << "MixedBtn_clicked() end";
}

Dialog::Dialog(QWidget *parent)
    : QDialog(parent), ModalBtn(this), NormalBtn(this), MixedBtn(this)
{
    
    ModalBtn.setText("Modal Dialog");
    ModalBtn.move(20, 20);
    ModalBtn.resize(100, 30);

    NormalBtn.setText("Normal Dialog");
    NormalBtn.move(20, 70);
    NormalBtn.resize(100, 30);

    MixedBtn.setText("Mixed Dialog");
    MixedBtn.move(20, 120);
    MixedBtn.resize(100, 30);

    connect(&ModalBtn, SIGNAL(clicked()), this, SLOT(ModalBtn_clicked()));
    connect(&NormalBtn, SIGNAL(clicked()), this, SLOT(NormalBtn_clicked()));
    connect(&MixedBtn, SIGNAL(clicked()), this, SLOT(MixedBtn_clicked()));

    resize(140, 170);
}

Dialog::~Dialog()
{
    
    qDebug() << "~Dialog()";
}

#include "Dialog.h"
#include <QApplication>
#include <QDebug>

int main(int argc, char *argv[])
{
    
    QApplication a(argc, argv);
    Dialog dlg;
    int r = dlg.exec();

    if (r == QDialog::Accepted) {
    
        qDebug() << "QDialog::Accepted";
    }
    else if (r == QDialog::Rejected) {
    
        qDebug() << "QDialog::Rejected";
    }
    else {
    
        qDebug() << r;
    }

    return r;
}

Header file usage experiment 2 Header file in .

Summary

• The dialog box is divided into Modal dialog and modeless dialog box
• Modal dialogs are blocked
• Modal dialog boxes are used for user interaction results
• Modeless dialogs are non blocking
• Modeless dialog boxes are used for Occasion of function setting