QWizard Class

Detailed Description

A wizard (also called an assistant on macOS) is a special type of input dialog that consists of a sequence of pages. A wizard's purpose is to guide the user through a process step by step. Wizards are useful for complex or infrequent tasks that users may find difficult to learn.

QWizard inherits QDialog and represents a wizard. Each page is a QWizardPage (a QWidget subclass). To create your own wizards, you can use these classes directly, or you can subclass them for more control.

A Trivial Example

The following example illustrates how to create wizard pages and add them to a wizard. For more advanced examples, see the License Wizard.

 QWizardPage *createIntroPage()
 {
     QWizardPage *page = new QWizardPage;
     page->setTitle("Introduction");

     QLabel *label = new QLabel("This wizard will help you register your copy "
                                "of Super Product Two.");
     label->setWordWrap(true);

     QVBoxLayout *layout = new QVBoxLayout;
     layout->addWidget(label);
     page->setLayout(layout);

     return page;
 }

 QWizardPage *createRegistrationPage()
 {
     ...
 }

 QWizardPage *createConclusionPage()
 {
     ...
 }

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

 #ifndef QT_NO_TRANSLATION
     QString translatorFileName = QLatin1String("qtbase_");
     translatorFileName += QLocale::system().name();
     QTranslator *translator = new QTranslator(&app);
     if (translator->load(translatorFileName, QLibraryInfo::path(QLibraryInfo::TranslationsPath)))
         app.installTranslator(translator);
 #endif

     QWizard wizard;
     wizard.addPage(createIntroPage());
     wizard.addPage(createRegistrationPage());
     wizard.addPage(createConclusionPage());

     wizard.setWindowTitle("Trivial Wizard");
     wizard.show();

     return app.exec();
 }

Wizard Look and Feel

QWizard supports four wizard looks:

• ClassicStyle
• ModernStyle
• MacStyle
• AeroStyle

You can explicitly set the look to use using setWizardStyle() (e.g., if you want the same look on all platforms).

ClassicStyle	ModernStyle	MacStyle	AeroStyle

Note: AeroStyle has effect only on a Windows Vista system with alpha compositing enabled. ModernStyle is used as a fallback when this condition is not met.

In addition to the wizard style, there are several options that control the look and feel of the wizard. These can be set using setOption() or setOptions(). For example, HaveHelpButton makes QWizard show a Help button along with the other wizard buttons.

You can even change the order of the wizard buttons to any arbitrary order using setButtonLayout(), and you can add up to three custom buttons (e.g., a Print button) to the button row. This is achieved by calling setButton() or setButtonText() with CustomButton1, CustomButton2, or CustomButton3 to set up the button, and by enabling the HaveCustomButton1, HaveCustomButton2, or HaveCustomButton3 options. Whenever the user clicks a custom button, customButtonClicked() is emitted. For example:

         wizard()->setButtonText(QWizard::CustomButton1, tr("&Print"));
         wizard()->setOption(QWizard::HaveCustomButton1, true);
         connect(wizard(), &QWizard::customButtonClicked,
                 this, &ConclusionPage::printButtonClicked);

Elements of a Wizard Page

Wizards consist of a sequence of QWizardPages. At any time, only one page is shown. A page has the following attributes:

• A title.
• A subTitle.
• A set of pixmaps, which may or may not be honored, depending on the wizard's style:
  • WatermarkPixmap (used by ClassicStyle and ModernStyle)
  • BannerPixmap (used by ModernStyle)
  • LogoPixmap (used by ClassicStyle and ModernStyle)
  • BackgroundPixmap (used by MacStyle)

The diagram belows shows how QWizard renders these attributes, assuming they are all present and ModernStyle is used:

When a subTitle is set, QWizard displays it in a header, in which case it also uses the BannerPixmap and the LogoPixmap to decorate the header. The WatermarkPixmap is displayed on the left side, below the header. At the bottom, there is a row of buttons allowing the user to navigate through the pages.

The page itself (the QWizardPage widget) occupies the area between the header, the watermark, and the button row. Typically, the page is a QWizardPage on which a QGridLayout is installed, with standard child widgets (QLabels, QLineEdits, etc.).

If the wizard's style is MacStyle, the page looks radically different:

The watermark, banner, and logo pixmaps are ignored by the MacStyle. If the BackgroundPixmap is set, it is used as the background for the wizard; otherwise, a default "assistant" image is used.

The title and subtitle are set by calling QWizardPage::setTitle() and QWizardPage::setSubTitle() on the individual pages. They may be plain text or HTML (see titleFormat and subTitleFormat). The pixmaps can be set globally for the entire wizard using setPixmap(), or on a per-page basis using QWizardPage::setPixmap().

Registering and Using Fields

In many wizards, the contents of a page may affect the default values of the fields of a later page. To make it easy to communicate between pages, QWizard supports a "field" mechanism that allows you to register a field (e.g., a QLineEdit) on a page and to access its value from any page. It is also possible to specify mandatory fields (i.e., fields that must be filled before the user can advance to the next page).

To register a field, call QWizardPage::registerField() field. For example:

     registerField("evaluate.name*", nameLineEdit);
     registerField("evaluate.email*", emailLineEdit);

The above code registers three fields, className, baseClass, and qobjectMacro, which are associated with three child widgets. The asterisk (*) next to className denotes a mandatory field.

The fields of any page are accessible from any other page. For example:

 void ConclusionPage::initializePage()
 {
     QString licenseText;

     if (wizard()->hasVisitedPage(LicenseWizard::Page_Evaluate)) {
         licenseText = tr("<u>Evaluation License Agreement:</u> "
                          "You can use this software for 30 days and make one "
                          "backup, but you are not allowed to distribute it.");
     } else if (wizard()->hasVisitedPage(LicenseWizard::Page_Details)) {
         const QString emailAddress = field("details.email").toString();
         licenseText = tr("<u>First-Time License Agreement:</u> "
                          "You can use this software subject to the license "
                          "you will receive by email sent to %1.").arg(emailAddress);
     } else {
         licenseText = tr("<u>Upgrade License Agreement:</u> "
                          "This software is licensed under the terms of your "
                          "current license.");
     }
     bottomLabel->setText(licenseText);
 }

Here, we call QWizardPage::field() to access the contents of the details.email field (which was defined in the DetailsPage) and use it to initialize the ConclusionPage. The field's contents is returned as a QVariant.

When we create a field using QWizardPage::registerField(), we pass a unique field name and a widget. We can also provide a Qt property name and a "changed" signal (a signal that is emitted when the property changes) as third and fourth arguments; however, this is not necessary for the most common Qt widgets, such as QLineEdit, QCheckBox, and QComboBox, because QWizard knows which properties to look for.

If an asterisk (*) is appended to the name when the property is registered, the field is a mandatory field. When a page has mandatory fields, the Next and/or Finish buttons are enabled only when all mandatory fields are filled.

To consider a field "filled", QWizard simply checks that the field's current value doesn't equal the original value (the value it had when initializePage() was called). For QLineEdit and QAbstractSpinBox subclasses, QWizard also checks that hasAcceptableInput() returns true, to honor any validator or mask.

QWizard's mandatory field mechanism is provided for convenience. A more powerful (but also more cumbersome) alternative is to reimplement QWizardPage::isComplete() and to emit the QWizardPage::completeChanged() signal whenever the page becomes complete or incomplete.

The enabled/disabled state of the Next and/or Finish buttons is one way to perform validation on the user input. Another way is to reimplement validateCurrentPage() (or QWizardPage::validatePage()) to perform some last-minute validation (and show an error message if the user has entered incomplete or invalid information). If the function returns true, the next page is shown (or the wizard finishes); otherwise, the current page stays up.

Creating Linear Wizards

Most wizards have a linear structure, with page 1 followed by page 2 and so on until the last page. The Trivial Wizard example is such a wizard. With QWizard, linear wizards are created by instantiating the QWizardPages and inserting them using addPage(). By default, the pages are shown in the order in which they were added. For example:

     QWizard wizard;
     wizard.addPage(createIntroPage());
     wizard.addPage(createRegistrationPage());
     wizard.addPage(createConclusionPage());

When a page is about to be shown, QWizard calls initializePage() (which in turn calls QWizardPage::initializePage()) to fill the page with default values. By default, this function does nothing, but it can be reimplemented to initialize the page's contents based on other pages' fields (see the example above).

If the user presses Back, cleanupPage() is called (which in turn calls QWizardPage::cleanupPage()). The default implementation resets the page's fields to their original values (the values they had before initializePage() was called). If you want the Back button to be non-destructive and keep the values entered by the user, simply enable the IndependentPages option.

Creating Non-Linear Wizards

Some wizards are more complex in that they allow different traversal paths based on the information provided by the user. The License Wizard example illustrates this. It provides several wizard pages; depending on which options are selected, the user can reach different pages.

In complex wizards, pages are identified by IDs. These IDs are typically defined using an enum. For example:

 class LicenseWizard : public QWizard
 {
     ...
     enum { Page_Intro, Page_Evaluate, Page_Register, Page_Details,
            Page_Conclusion };
     ...
 };

The pages are inserted using setPage(), which takes an ID and an instance of QWizardPage (or of a subclass):

 LicenseWizard::LicenseWizard(QWidget *parent)
     : QWizard(parent)
 {
     setPage(Page_Intro, new IntroPage);
     setPage(Page_Evaluate, new EvaluatePage);
     setPage(Page_Register, new RegisterPage);
     setPage(Page_Details, new DetailsPage);
     setPage(Page_Conclusion, new ConclusionPage);
     ...
 }

By default, the pages are shown in increasing ID order. To provide a dynamic order that depends on the options chosen by the user, we must reimplement QWizardPage::nextId(). For example:

 int IntroPage::nextId() const
 {
     if (evaluateRadioButton->isChecked()) {
         return LicenseWizard::Page_Evaluate;
     } else {
         return LicenseWizard::Page_Register;
     }
 }

 int EvaluatePage::nextId() const
 {
     return LicenseWizard::Page_Conclusion;
 }

 int RegisterPage::nextId() const
 {
     if (upgradeKeyLineEdit->text().isEmpty()) {
         return LicenseWizard::Page_Details;
     } else {
         return LicenseWizard::Page_Conclusion;
     }
 }

 int DetailsPage::nextId() const
 {
     return LicenseWizard::Page_Conclusion;
 }

 int ConclusionPage::nextId() const
 {
     return -1;
 }

It would also be possible to put all the logic in one place, in a QWizard::nextId() reimplementation. For example:

 int LicenseWizard::nextId() const
 {
     switch (currentId()) {
     case Page_Intro:
         if (field("intro.evaluate").toBool()) {
             return Page_Evaluate;
         } else {
             return Page_Register;
         }
     case Page_Evaluate:
         return Page_Conclusion;
     case Page_Register:
         if (field("register.upgradeKey").toString().isEmpty()) {
             return Page_Details;
         } else {
             return Page_Conclusion;
         }
     case Page_Details:
         return Page_Conclusion;
     case Page_Conclusion:
     default:
         return -1;
     }
 }

To start at another page than the page with the lowest ID, call setStartId().

To test whether a page has been visited or not, call hasVisitedPage(). For example:

 void ConclusionPage::initializePage()
 {
     QString licenseText;

     if (wizard()->hasVisitedPage(LicenseWizard::Page_Evaluate)) {
         licenseText = tr("<u>Evaluation License Agreement:</u> "
                          "You can use this software for 30 days and make one "
                          "backup, but you are not allowed to distribute it.");
     } else if (wizard()->hasVisitedPage(LicenseWizard::Page_Details)) {
         const QString emailAddress = field("details.email").toString();
         licenseText = tr("<u>First-Time License Agreement:</u> "
                          "You can use this software subject to the license "
                          "you will receive by email sent to %1.").arg(emailAddress);
     } else {
         licenseText = tr("<u>Upgrade License Agreement:</u> "
                          "This software is licensed under the terms of your "
                          "current license.");
     }
     bottomLabel->setText(licenseText);
 }