Qt 4.0: QDialog Class Reference

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# QDialog Class Reference
[QtGui module]

The QDialog class is the base class of dialog windows. More...

    #include <QDialog>

Inherits QWidget.

Inherited by Q3FileDialog, Q3ProgressDialog, Q3TabDialog, Q3Wizard, QAbstractPrintDialog, QColorDialog, QErrorMessage, QFileDialog, QFontDialog, QInputDialog, QMessageBox, QPageSetupDialog, and QProgressDialog.

- List of all members, including inherited members
- Qt 3 support members

### Public Types

- enum DialogCode { Accepted, Rejected }

### Properties

- modal : bool
- sizeGripEnabled : bool

- 52 properties inherited from QWidget
- 1 property inherited from QObject

### Public Functions

- QDialog ( QWidget * parent = 0, Qt::WFlags f = 0 )
- ~QDialog ()
- QWidget * extension () const
- bool isSizeGripEnabled () const
- Qt::Orientation orientation () const
- int result () const
- void setExtension ( QWidget * extension )
- void setModal ( bool modal )
- void setOrientation ( Qt::Orientation orientation )
- void setResult ( int i )
- void setSizeGripEnabled ( bool )

- 184 public functions inherited from QWidget
- 28 public functions inherited from QObject
- 10 public functions inherited from QPaintDevice

### Public Slots

- virtual void accept ()
- virtual void done ( int r )
- int exec ()
- virtual void reject ()
- void showExtension ( bool showIt )

- 17 public slots inherited from QWidget
- 1 public slot inherited from QObject

### Additional Inherited Members

- 1 signal inherited from QWidget
- 1 signal inherited from QObject
- 4 static public members inherited from QWidget
- 4 static public members inherited from QObject
- 39 protected functions inherited from QWidget
- 7 protected functions inherited from QObject

## Detailed Description

The QDialog class is the base class of dialog windows.

A dialog window is a top-level window mostly used for short-term tasks and brief communications with the user. QDialogs may be modal or modeless. QDialogs support extensibility and can provide a return value. They can have default buttons. QDialogs can also have a QSizeGrip in their lower-right corner, using setSizeGripEnabled().

Note that QDialog uses the parent widget slightly differently from other classes in Qt. A dialog is always a top-level widget, but if it has a parent, its default location is centered on top of the parent's top-level widget (if it is not top-level itself). It will also share the parent's taskbar entry.

### Modal Dialogs

A modal dialog is a dialog that blocks input to other visible windows in the same application. Users must finish interacting with the dialog and close it before they can access any other window in the application. Dialogs that are used to request a file name from the user or that are used to set application preferences are usually modal.

The most common way to display a modal dialog is to call its exec() function. When the user closes the dialog, exec() will provide a useful return value. Typically, to get the dialog to close and return the appropriate value, we connect a default button, e.g. "OK", to the accept() slot and a "Cancel" button to the reject() slot. Alternatively you can call the done() slot with `Accepted` or `Rejected`.

An alternative is to call setModal(true), then show(). Unlike exec(), show() returns control to the caller immediately. Calling setModal(true) is especially useful for progress dialogs, where the user must have the ability to interact with the dialog, e.g. to cancel a long running operation. If you use show() and setModal(true) together you must call QApplication::processEvents() periodically during processing to enable the user to interact with the dialog. (See QProgressDialog.)

### Modeless Dialogs

A modeless dialog is a dialog that operates independently of other windows in the same application. Find and replace dialogs in word-processors are often modeless to allow the user to interact with both the application's main window and with the dialog.

Modeless dialogs are displayed using show(), which returns control to the caller immediately.

### Default Button

A dialog's default button is the button that's pressed when the user presses Enter (Return). This button is used to signify that the user accepts the dialog's settings and wants to close the dialog. Use QPushButton::setDefault(), QPushButton::isDefault() and QPushButton::autoDefault() to set and control the dialog's default button.

### Escape Key

If the user presses the Esc key in a dialog, QDialog::reject() will be called. This will cause the window to close: The close event cannot be ignored.

### Extensibility

Extensibility is the ability to show the dialog in two ways: a partial dialog that shows the most commonly used options, and a full dialog that shows all the options. Typically an extensible dialog will initially appear as a partial dialog, but with a "More" toggle button. If the user presses the "More" button down, the full dialog will appear. The extension widget will be resized to its sizeHint(). If orientation is Qt::Horizontal the extension widget's height() will be expanded to the height() of the dialog. If the orientation is Qt::Vertical the extension widget's width() will be expanded to the width() of the dialog. Extensibility is controlled with setExtension(), setOrientation() and showExtension().

### Return Value (Modal Dialogs)

Modal dialogs are often used in situations where a return value is required, e.g. to indicate whether the user pressed "OK" or "Cancel". A dialog can be closed by calling the accept() or the reject() slots, and exec() will return `Accepted` or `Rejected` as appropriate. The exec() call returns the result of the dialog. The result is also available from result() if the dialog has not been destroyed.

### Code Examples

A modal dialog:

        void EditorWindow::countWords()
        {
            WordCountDialog dialog(this);
            dialog.setWordCount(document().wordCount());
            dialog.exec();
        }

A modeless dialog:

        void EditorWindow::find()
        {
            if (!findDialog) {
                findDialog = new FindDialog(this);
                connect(findDialog, SIGNAL(findNext()), this, SLOT(findNext()));
            }

            findDialog->show();
            findDialog->raise();
            findDialog->activateWindow();
        }

See also QTabDialog, QWidget, QProgressDialog, and GUI Design Handbook: Dialogs, Standard.

## Member Type Documentation

### enum QDialog::DialogCode

The value returned by a modal dialog.

Constant | Value
--- | ---
`QDialog::Accepted` | `1`
`QDialog::Rejected` | `0`

## Property Documentation

### modal : bool

This property holds whether show() should pop up the dialog as modal or modeless.

By default, this property is false and show() pops up the dialog as modeless.

exec() ignores the value of this property and always pops up the dialog as modal.

Access functions:

- bool isModal () const
- void setModal ( bool modal )

See also show() and exec().

### sizeGripEnabled : bool

This property holds whether the size grip is enabled.

A QSizeGrip is placed in the bottom-right corner of the dialog when this property is enabled. By default, the size grip is disabled.

Access functions:

- bool isSizeGripEnabled () const
- void setSizeGripEnabled ( bool )

## Member Function Documentation

### QDialog::QDialog ( QWidget * parent = 0, Qt::WFlags f = 0 )

Constructs a dialog with parent parent.

A dialog is always a top-level widget, but if it has a parent, its default location is centered on top of the parent. It will also share the parent's taskbar entry.

The widget flags f are passed on to the QWidget constructor. If, for example, you don't want a What's This button in the title bar of the dialog, pass Qt::WindowTitleHint | Qt::WindowSystemMenuHint in f.

See also QWidget::setWindowFlags().

### QDialog::~QDialog ()

Destroys the QDialog, deleting all its children.

### void QDialog::accept () `[virtual slot]`

Hides the modal dialog and sets the result code to `Accepted`.

See also reject() and done().

### void QDialog::done ( int r ) `[virtual slot]`

Closes the dialog and sets its result code to r. If this dialog is shown with exec(), done() causes the local event loop to finish, and exec() to return r.

As with QWidget::close(), done() deletes the dialog if the Qt::WA_DeleteOnClose flag is set. If the dialog is the application's main widget, the application terminates. If the dialog is the last window closed, the QApplication::lastWindowClosed() signal is emitted.

See also accept(), reject(), QApplication::activeWindow(), and QApplication::quit().

### int QDialog::exec () `[slot]`

Shows the dialog as a modal dialog, blocking until the user closes it. The function returns a DialogCode result.

Users cannot interact with any other window in the same application until they close the dialog.

See also show() and result().

### QWidget * QDialog::extension () const

Returns the dialog's extension or 0 if no extension has been defined.

See also setExtension().

### Qt::Orientation QDialog::orientation () const

Returns the dialog's extension orientation.

See also setOrientation().

### void QDialog::reject () `[virtual slot]`

Hides the modal dialog and sets the result code to `Rejected`.

See also accept() and done().

### int QDialog::result () const

Returns the modal dialog's result code, `Accepted` or `Rejected`.

Do not call this function if the dialog was constructed with the Qt::WA_DeleteOnClose attribute.

See also setResult().

### void QDialog::setExtension ( QWidget * extension )

Sets the widget, extension, to be the dialog's extension, deleting any previous extension. The dialog takes ownership of the extension. Note that if 0 is passed any existing extension will be deleted.

This function must only be called while the dialog is hidden.

See also showExtension(), setOrientation(), and extension().

### void QDialog::setOrientation ( Qt::Orientation orientation )

If orientation is Qt::Horizontal, the extension will be displayed to the right of the dialog's main area. If orientation is Qt::Vertical, the extension will be displayed below the dialog's main area.

See also orientation() and setExtension().

### void QDialog::setResult ( int i )

Sets the modal dialog's result code to i.

See also result().

### void QDialog::showExtension ( bool showIt ) `[slot]`

If showIt is true, the dialog's extension is shown; otherwise the extension is hidden.

This slot is usually connected to the QPushButton::toggled() signal of a QPushButton.

A dialog with a visible extension is not resizeable.

See also show(), setExtension(), and setOrientation().