QT learning diary 9 - dialog box

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newest QT From introduction to actual combat full version | Intellectual education _ Bili, Bili _bilibilihttps://www.bilibili.com/video/BV1g4411H78N?spm_id_from=333.337.search-card.all.click&vd_source=0471cde1c644648fafd07b54e303c905

Catalog

One 、 Custom dialog

1.1 Modal dialog ：

1.2 modeless dialog box ：

1.3 Case study

Two 、 The system provides a good dialog

2.1 Standard dialog box

2.2 Warning dialog  

2.3 Color dialog

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One 、 Custom dialog

1.1 Modal dialog ：

You cannot operate on other windows

1.2 modeless dialog box ：

You can operate other windows

1.3 Case study

The following figure shows the modeless dialog

After opening the window in the interface , You can modify the original interface

Modal dialog

When running pop-up , The function is blocked in dlg.exec(); This line of code here , Click on X after , Output QDebug

establish modeless dialog box  

Function is not blocked in dlg2->show(); Here is the sentence , Because it prevents a flash , So create to heap

At the same time, we should pay attention to , After this function applies for memory , No memory Freed , Memory leaks may occur later

We need to be in X Free the memory when you drop the window , Add the middle line of code

Two 、 The system provides a good dialog

2.1 Standard dialog box

The so-called standard dialog box , yes Qt A set of built-in dialog boxes , Used to simplify development . in fact , There are a lot of dialog boxes that are generic , Like opening a file 、 Set the color 、 Print settings, etc . These dialog boxes are almost the same in all programs , Therefore, there is no need to implement such a dialog box in every program

Qt The built-in dialog boxes of are roughly divided into the following categories ：

QColorDialog： Choose a color

FileDialog： Choose a file or directory

FontDialog： Select the font

QInputDialog： Allow the user to enter a value , And return its value to

QMessageBox： Modal dialog , Used to display information 、 Asking questions, etc

QPageSetupDialog： Provide paper related options for the printer

QPrintDialog： Printer configuration

QPrintPreviewDialog： Print preview

ProgressDialog： Display operation process

2.2 Message dialog

2.3 Color dialog

  Click on OK in the future , Function to get the return value , And jump into the main window

Be careful ：

1、2.2 and 2.3 The function of can be written in connect Inside

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDialog>
#include <QDebug>
#include <QMessageBox>
#include <QColorDialog>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    connect(ui->actionnew, &QAction::trigger, [](){
        //  Warning dialog 
        // QMessageBox::warning(this, "warning", " Warning ");

        //  Other standard dialog boxes 
        //  Color dialog 
        QColor color = QColorDialog::getColor(QColor(255, 0, 0));
        qDebug() << "r = " << color.red() << " g = " << color.green() << " b = " << color.blue();
    });
}

MainWindow::~MainWindow()
{
    delete ui;
}

2、 Color dialog QColor(255, 0, 0, 255) There is a fourth parameter , The default is 255 That is, four parameters

2.4 File dialog

Pass in the parameter ：

this： father

...： title

...： Default open path

...： Format to open （ Filter other formats ）

Return value ：

Qstring、 Selected file path