QDialog(3qt)QDialog(3qt)NAMEQDialog - The base class of dialog windows
SYNOPSIS
#include <qdialog.h>
Inherits QWidget.
Inherited by QColorDialog, QErrorMessage, QFileDialog, QFontDialog,
QInputDialog, QMessageBox, QMotifDialog, QProgressDialog, QTabDialog,
and QWizard.
Public Members
explicit QDialog ( QWidget * parent = 0, const char * name = 0, bool
modal = FALSE, WFlags f = 0 )
~QDialog ()
enum DialogCode { Rejected, Accepted }
int result () const
virtual void show ()
void setOrientation ( Orientation orientation )
Orientation orientation () const
void setExtension ( QWidget * extension )
QWidget * extension () const
void setSizeGripEnabled ( bool )
bool isSizeGripEnabled () const
void setModal ( bool modal )
bool isModal () const
Public Slots
int exec ()
Properties
bool modal - whether show() should pop up the dialog as modal or
modeless
bool sizeGripEnabled - whether the size grip is enabled
Protected Members
void setResult ( int i )
Protected Slots
virtual void done ( int r )
virtual void accept ()
virtual void reject ()
void showExtension ( bool showIt )
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 we connect a default button, e.g. "OK", to the
accept() slot and a" Cancel" button to the reject() slot, to get the
dialog to close and return the appropriate value. Alternatively you can
connect to the done() slot, passing it 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 closeEvent 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 Horizontal the extension widget's height() will be
expanded to the height() of the dialog. If the orientation is 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. If the WDestructiveClose
flag is set, the dialog is deleted after exec() returns.
Examples
A modal dialog.
QFileDialog *dlg = new QFileDialog( workingDirectory,
QString::null, 0, 0, TRUE );
dlg->setCaption( QFileDialog::tr( "Open" ) );
dlg->setMode( QFileDialog::ExistingFile );
QString result;
if ( dlg->exec() == QDialog::Accepted ) {
result = dlg->selectedFile();
workingDirectory = dlg->url();
}
delete dlg;
return result;
A modeless dialog. After the show() call, control returns to the main
event loop.
int main( int argc, char **argv )
{
QApplication a( argc, argv );
int scale = 10;
LifeDialog *life = new LifeDialog( scale );
a.setMainWidget( life );
life->setCaption("Qt Example - Life");
life->show();
return a.exec();
}
See also QTabDialog, QWidget, QProgressDialog, GUI Design Handbook:
Dialogs, Standard, Abstract Widget Classes, and Dialog Classes.
Member Type Documentation
QDialog::DialogCode
The value returned by a modal dialog.
QDialog::Accepted
QDialog::Rejected
MEMBER FUNCTION DOCUMENTATIONexplicit QDialog::QDialog ( QWidget * parent = 0, const char * name = 0, bool
modal = FALSE, WFlags f = 0 )
Constructs a dialog called name, 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 titlebar of the
dialog, pass WStyle_Customize | WStyle_NormalBorder | WStyle_Title |
WStyle_SysMenu in f.
Warning: In Qt 3.2, the modal flag is obsolete. There is now a
setModal() function that can be used for obtaining a modal behavior
when calling show(). This is rarely needed, because modal dialogs are
usually invoked using exec(), which ignores the modal flag.
See also QWidget::setWFlags() and Qt::WidgetFlags.
QDialog::~QDialog ()
Destroys the QDialog, deleting all its children.
void QDialog::accept () [virtual protected slot]
Hides the modal dialog and sets the result code to Accepted.
See also reject() and done().
Examples:
void QDialog::done ( int r ) [virtual protected 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
WDestructiveClose 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::mainWidget(), 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().
Examples:
QWidget * QDialog::extension () const
Returns the dialog's extension or 0 if no extension has been defined.
See also setExtension().
bool QDialog::isModal () const
Returns TRUE if show() should pop up the dialog as modal or modeless;
otherwise returns FALSE. See the "modal" property for details.
bool QDialog::isSizeGripEnabled () const
Returns TRUE if the size grip is enabled; otherwise returns FALSE. See
the "sizeGripEnabled" property for details.
Orientation QDialog::orientation () const
Returns the dialog's extension orientation.
See also setOrientation().
void QDialog::reject () [virtual protected 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
WDestructiveClose flag.
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::setModal ( bool modal )
Sets whether show() should pop up the dialog as modal or modeless to
modal. See the "modal" property for details.
void QDialog::setOrientation ( Orientation orientation )
If orientation is Horizontal, the extension will be displayed to the
right of the dialog's main area. If orientation is Vertical, the
extension will be displayed below the dialog's main area.
See also orientation() and setExtension().
void QDialog::setResult ( int i ) [protected]
Sets the modal dialog's result code to i.
void QDialog::setSizeGripEnabled ( bool )
Sets whether the size grip is enabled. See the "sizeGripEnabled"
property for details.
void QDialog::show () [virtual]
Shows the dialog as a modeless dialog. Control returns immediately to
the calling code.
The dialog will be modal or modeless according to the value of the
modal property.
See also exec() and modal.
Examples:
Reimplemented from QWidget.
void QDialog::showExtension ( bool showIt ) [protected slot]
If showIt is TRUE, the dialog's extension is shown; otherwise the
extension is hidden.
This slot is usually connected to the QButton::toggled() signal of a
QPushButton.
A dialog with a visible extension is not resizeable.
See also show(), setExtension(), and setOrientation().
Property Documentation
bool modal
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.
See also show() and exec().
Set this property's value with setModal() and get this property's value
with isModal().
bool sizeGripEnabled
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.
Set this property's value with setSizeGripEnabled() and get this
property's value with isSizeGripEnabled().
SEE ALSO
http://doc.trolltech.com/qdialog.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
license file included in the distribution for a complete license
statement.
AUTHOR
Generated automatically from the source code.
BUGS
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Trolltech AS 2 February 2007 QDialog(3qt)