Retrieving the Selected Date in Qt Widgets: QCalendarWidget::selectedDate

Purpose

• It retrieves the currently selected date within the calendar widget.
• QCalendarWidget::selectedDate is a member function of the QCalendarWidget class in Qt Widgets.

Return Type

• The function returns a QDate object representing the user's chosen date.

Usage

1. #include <QtWidgets>
   

2. Create a QCalendarWidget object
   

   QCalendarWidget *calendar = new QCalendarWidget(this);
   

3. Get the selected date
   

   QDate selectedDate = calendar->selectedDate();
   

   • This will store the currently selected date in the selectedDate variable.

Additional Notes

• You can also set the selected date programmatically using the setSelectedDate function.
• Users can interact with the calendar widget (clicking on dates) to change the selection, which will be reflected by this function.
• The initial selected date is typically set to the current date when the calendar widget is created.

Example

#include <QApplication>
#include <QtWidgets>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QCalendarWidget *calendar = new QCalendarWidget;

    // Connect the signal emitted when the selected date changes
    QObject::connect(calendar, &QCalendarWidget::selectionChanged,
                     [&calendar] {
                         QDate selectedDate = calendar->selectedDate();
                         // Do something with the selected date, e.g., display it
                         qDebug() << "Selected Date:" << selectedDate;
                     });

    calendar->show();

    return app.exec();
}

In this example:

• The selectionChanged signal is connected to a slot that retrieves and prints the newly selected date whenever the user interacts with the calendar.

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Highlighting the selected date

#include <QApplication>
#include <QtWidgets>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QCalendarWidget *calendar = new QCalendarWidget;

    // Access the calendar's style sheet
    QString styleSheet = calendar->styleSheet();

    // Modify the style sheet to highlight the selected date
    QString newStyleSheet = styleSheet +
                             "QCalendarWidget QPushButton:pressed {"
                             "background-color: #ADD8E6;"  // Light blue highlight
                             "}";
    calendar->setStyleSheet(newStyleSheet);

    // ... (rest of your code)

    calendar->show();

    return app.exec();
}

This code modifies the calendar's style sheet to visually indicate the selected date with a light blue background.

Disabling specific dates

#include <QApplication>
#include <QtWidgets>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QCalendarWidget *calendar = new QCalendarWidget;

    // Set a date to be disabled (e.g., simulate a non-working day)
    QDate disabledDate(2024, 7, 15);  // Monday, July 15th, 2024

    calendar->setDateTextFormat(disabledDate, "Unavailable");  // Optional: display text for disabled date

    calendar->setEnabledDate(disabledDate, false);  // Disable the specific date

    // ... (rest of your code)

    calendar->show();

    return app.exec();
}

This code disables a specific date (July 15th, 2024 in this example) on the calendar. You can optionally set custom text to be displayed for the disabled date.

Displaying a custom message based on the selected date

#include <QApplication>
#include <QtWidgets>
#include <QMessageBox>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QCalendarWidget *calendar = new QCalendarWidget;

    QObject::connect(calendar, &QCalendarWidget::selectionChanged,
                     [&calendar] {
                         QDate selectedDate = calendar->selectedDate();
                         QString message;

                         if (selectedDate.dayOfWeek() == QCalendarWidget::Sunday) {
                             message = "Selected date is a Sunday!";
                         } else {
                             message = "You selected a non-Sunday date.";
                         }

                         QMessageBox::information(nullptr, "Selected Date Information", message);
                     });

    // ... (rest of your code)

    calendar->show();

    return app.exec();
}

This code demonstrates connecting the selectionChanged signal to a slot that checks the selected date's day of the week. Based on the day, it displays a different message in a pop-up window using QMessageBox::information.

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selectedDates()

• It returns a QList<QDate> containing all currently selected dates.
• If you need to handle scenarios where multiple dates can be selected simultaneously (depending on the selectionMode property), use selectedDates().

Example

QObject::connect(calendar, &QCalendarWidget::selectionChanged,
                 [&calendar] {
                     QList<QDate> selectedDates = calendar->selectedDates();
                     // Use the list of selected dates for further processing
                     for (const QDate& date : selectedDates) {
                         // Do something with each selected date
                     }
                 });

setCurrentDate(QDate)

• This function takes a QDate object as an argument and sets it as the new selected date.
• To programmatically set the selected date, use setCurrentDate(QDate).

Example

// Set the selected date to July 4th, 2024
calendar->setCurrentDate(QDate(2024, 7, 4));

minimumDate() and maximumDate()

• These functions set the minimum and maximum allowable dates (inclusive) that the user can select in the calendar.
• While not directly related to retrieving the selected date, minimumDate() and maximumDate() can influence user selection.

Example

// Allow selection only from July 1st to July 15th, 2024
calendar->setMinimumDate(QDate(2024, 7, 1));
calendar->setMaximumDate(QDate(2024, 7, 15));

• Use minimumDate() and maximumDate() to restrict the user's date selection range.
• Use setCurrentDate() for programmatic control over the selected date.
• Use selectedDates() when dealing with multiple selections or want to iterate through all selected dates.
• Use selectedDate() when you need the single currently selected date in single-selection mode.