QMessageBox(3qt)QMessageBox(3qt)NAME
QMessageBox - Displays a brief message, an icon, and some
buttons
#include <qmessagebox.h>
Inherits QDialog.
Public Members
enum Icon { NoIcon = 0, Information = 1, Warning = 2,
Critical = 3 }
QMessageBox ( QWidget * parent=0, const char * name=0 )
QMessageBox ( const QString & caption, const QString &
text, Icon icon, int button0, int button1, int
button2, QWidget * parent=0, const char * name=0, bool
modal=TRUE, WFlags f=WStyle_DialogBorder )
~QMessageBox ()
enum { NoButton = 0, Ok = 1, Cancel = 2, Yes = 3, No = 4,
Abort = 5, Retry = 6, Ignore = 7, ButtonMask = 0x07,
Default = 0x100, Escape = 0x200, FlagMask = 0x300 }
QString text () const
void setText ( const QString & )
Icon icon () const
void setIcon ( Icon )
const QPixmap* iconPixmap () const
void setIconPixmap ( const QPixmap & )
QString buttonText ( int button ) const
void setButtonText ( int button, const QString & )
virtual void adjustSize ()
TextFormat textFormat () const
void setTextFormat ( TextFormat )
Static Public Members
int information ( QWidget * parent, const QString &
caption, const QString & text, int button0, int
button1=0, int button2=0 )
int information ( QWidget * parent, const QString &
caption, const QString & text, const QString &
button0Text = QString::null, const QString &
button1Text = QString::null, const QString &
button2Text = QString::null, int defaultButtonNumber =
0, int escapeButtonNumber = -1 )
int warning ( QWidget * parent, const QString & caption,
const QString & text, int button0, int button1, int
button2=0 )
int warning ( QWidget * parent, const QString & caption,
const QString & text, const QString & button0Text =
QString::null, const QString & button1Text =
QString::null, const QString & button2Text =
QString::null, int defaultButtonNumber = 0, int
escapeButtonNumber = -1 )
int critical ( QWidget * parent, const QString & caption,
const QString & text, int button0, int button1, int
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button2=0 )
int critical ( QWidget * parent, const QString & caption,
const QString & text, const QString & button0Text =
QString::null, const QString & button1Text =
QString::null, const QString & button2Text =
QString::null, int defaultButtonNumber = 0, int
escapeButtonNumber = -1 )
void about ( QWidget * parent, const QString & caption,
const QString & text )
void aboutQt ( QWidget * parent, const QString &
caption=QString::null )
QPixmap standardIcon ( Icon icon, GUIStyle style )
Properties
Type Name READ WRITE Options
---------------------------------------------------------------
QString text text setText
Icon icon icon setIcon
QPixmap iconPixmap iconPixmap setIconPixmap
TextFormat textFormat textFormat setTextFormat
DESCRIPTION
Displays a brief message, an icon, and some buttons.
A message box is a modal dialog that displays an icon, a
text and up to three push buttons. It's used for simple
messages and questions.
QMessageBox provides a range of different messages,
arranged roughly along two axes: Severity and complexity.
Severity is
Information - for message boxes that are part of normal
operation
Warning - for message boxes that tell the user about
unusual errors
Critical - as Warning, but for critical errors
The message box has a different icon for each of the
severity levels.
Complexity is one button (Ok) for a simple messages, or
two or even three buttons for questions.
There are static functions that let you do most of the
common jobs, for example:
If a program is unable to find a supporting file, but can
do perfectly well without:
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QMessageBox::information( this, "Application name",
"Unable to find the user preferences file.\n"
"The factory default will be used instead." );
warning() can be used to tell the user about unusual
errors, or errors which can't be easily fixed:
switch( QMessageBox::warning( this, "Application name",
"Could not connect to the <mumble> server.\n"
"This program can't function correctly "
"without the server.\n\n",
"Try again", "Quit", 0,
0, 1 );
case 0: // Try again or Enter
// try again
break;
case 1: // Quit or Escape
// exit
break;
}
Finally,
The text part of all message box messages can be either
rich text or plain text. If you specify a rich text
formatted string, it will be rendered using the default
stylesheet. See QStyleSheet::defaultSheet() for details.
With certain strings that contain XML meta characters, the
auto-rich text detection may fail, interpreting plain text
falsely as rich text. In these rare cases, use
QStyleSheet::convertFromPlainText() to convert your plain
text string to a visually equivalent rich text string or
set the text format explicitly with setTextFormat().
Here are some examples of how to use the static member
functions. After these examples you will find an overview
of the non-static member functions.
If a program is unable to find a supporting file, it may
perhaps do:
QMessageBox::information( this, "Application name here",
"Unable to find the file \"index.html\".\n"
"The factory default will be used instead." );
The Microsoft Windows User Interface Guidelines strongly
recommends using the application name as window caption.
The message box has just one button, OK, and its text
tells the user both what happened and what the program
will do about it. Since the application is able to make
do, the message box is just information, not a warning or
a critical error.
Exiting a program is part of its normal operation, and if
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there are unsaved data the user probably should be asked
what to do, for example like this:
switch( QMessageBox::information( this, "Application name here",
"The document contains unsaved work\n"
"Do you want to save it before exiting?",
"&Save", "&Don't Save", "&Cancel",
0, // Enter == button 0
2 ) ) { // Escape == button 2
case 0: // Save clicked, Alt-S or Enter pressed.
// save
break;
case 1: // Don't Save clicked or Alt-D pressed
// don't save but exit
break;
case 2: // Cancel clicked, Alt-C or Escape pressed
// don't exit
break;
}
Again, the application name is used as window caption, as
Microsoft recommends. The Escape button cancels the entire
Exit operation, and Enter/Return saves the document and
exits.
Disk full errors are unusual (in a perfect world, they
are) and they certainly can be hard to correct. This
example uses predefined buttons instead of hardcoded
button texts:
switch( QMessageBox::warning( this, "Application name here",
"Could not save the the user preferences,\n"
"because the disk is full. You can delete\n"
"some files and press Retry, or you can\n"
"abort the Save Preferences operation.",
QMessageBox::Retry | QMessageBox::Default,
QMessageBox::Abort | QMessageBox::Escape )) {
case QMessageBox::Retry: // Retry or Enter
// try again
break;
case QMessageBox::Abort: // Abort or Cancel
// abort
break;
}
The critical() function should be reserved for critical
errors. In this example, errorDetails is a QString or
const char*, and QString is used to concatenate several
strings:
QMessageBox::critical( 0, "Application name here",
QString("An internal error occurred. Please ") +
"call technical support at 123456789 and report\n"+
"these numbers:\n\n" + errorDetails +
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"\n\n<Application> will now exit." );
QMessageBox provides a very simple About box, which
displays an appropriate icon and the string you give it:
QMessageBox::about( this, "About <Application>",
"<Application> is a <one-paragraph blurb>\n\n"
"Copyright 1951-1997 Such-and-such. "
"<License words here.>\n\n"
"For technical support, call 123456789 or see\n"
"http://www.such-and-such.com/Application/\n" );
See about() for more information.
Finally, you can make a QMessageBox from scratch and set
custom button texts:
QMessageBox mb( "Application name here",
"Saving the file will overwrite the old file on disk.\n"
"Do you really want to save?",
QMessageBox::Information,
QMessageBox::Yes | QMessageBox::Default,
QMessageBox::No,
QMessageBox::Cancel | QMessageBox::Escape );
mb.setButtonText( QMessageBox::Yes, "Save" );
mb.setButtonText( QMessageBox::No, "Don't Save" );
switch( mb.exec() ) {
case QMessageBox::Yes:
// save and exit
break;
case QMessageBox::No:
// exit without saving
break;
case QMessageBox::Cancel:
// don't save and don't exit
break;
}
QMessageBox defines two enum types, Icon and an unnamed
button type. Icon defines the Information, Warning and
Critical icons for each GUI style. It is used by the
constructor, by the static member functions information(),
warning() and critical(), and there is a function called
standardIcon() which gives you access to the various
icons.
The button types are:
Ok - the default for single-button message boxes
Cancel - note that this is not automatically Escape
Yes
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No
Abort
Retry
Ignore
Button types can be combined with two modifiers by using
OR:
Default - makes pressing Enter or Return be equivalent
with clicking this button. Normally used with Ok, Yes or
similar.
Escape - makes pressing Escape be equivalent with this
button. Normally used with Abort, Cancel or similar.
The text(), icon() and iconPixmap() functions provide
access to the current text and pixmap of a message box,
and setText(), setIcon() and setIconPixmap() lets you
change it. The difference between setIcon() and
setIconPixmap() is that the former accepts a
QMessageBox::Icon and can it be used to set standard icons
while the latter accepts a QPixmap and can be used to set
custom icons.
setButtonText() and buttonText() provide access to the
buttons.
QMessageBox has no signals or slots.
[Image Omitted]
[Image Omitted]
See also QDialog, Isys on error messages, and GUI Design
Handbook: Message Box.
Member Type Documentation
QMessageBox::Icon
This type includes the following values:
QMessageBox::NoIcon
QMessageBox::Information
QMessageBox::Warning
QMessageBox::Critical
MEMBER FUNCTION DOCUMENTATIONTrolltech AS 13 June 2001 6
QMessageBox(3qt)QMessageBox(3qt)QMessageBox::QMessageBox ( QWidget * parent=0, const char *
name=0 )
Constructs a message box with no text and a button with
the text "OK".
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
The parent and name arguments are passed to the QDialog
constructor.
QMessageBox::QMessageBox ( const QString & caption, const QString
& text, Icon icon, int button0, int button1, int button2,
QWidget * parent=0, const char * name=0, bool modal=TRUE,
WFlags f=WStyle_DialogBorder )
Constructs a message box with a caption, a text, an icon
and up to three buttons.
The icon must be one of:
QMessageBox::NoIcon
QMessageBox::Information
QMessageBox::Warning
QMessageBox::Critical
Each button can have one of the following values:
QMessageBox::NoButton
QMessageBox::Ok
QMessageBox::Cancel
QMessageBox::Yes
QMessageBox::No
QMessageBox::Abort
QMessageBox::Retry
QMessageBox::Ignore
Use QMessageBox::NoButton for the later parameters to have
less than three buttons in your message box.
One of the buttons can be combined with the
QMessageBox::Default flag to make a default button.
One of the buttons can be combined with the
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QMessageBox::Escape flag to make an escape option. Hitting
the Esc key on the keyboard has the same effect as
clicking this button with the mouse.
Example:
QMessageBox mb( "Hardware failure",
"Disk error detected\nDo you want to stop?",
QMessageBox::NoIcon,
QMessageBox::Yes | QMessageBox::Default,
QMessageBox::No | QMessageBox::Escape );
if ( mb.exec() == QMessageBox::No )
// try again
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
If modal is TRUE the message becomes modal, otherwise it
becomes modeless.
The parent, name, modal and f arguments are passed to the
QDialog constructor.
See also setCaption(), setText() and setIcon().
QMessageBox::~QMessageBox ()
Destructs the message box.
void QMessageBox::about ( QWidget * parent, const QString &
caption, const QString & text ) [static]
Displays a simple about box with window caption caption
and body text text.
about() looks for a suitable icon for the box in four
locations:
1 It prefers parent->icon() if that exists.
2 If not, it tries the top level widget containing
parent
3 If that too fails, it tries the main widget.
4 As a last resort it uses the Information icon.
The about box has a single button labelled OK.
See also QWidget::icon() and QApplication::mainWidget().
Examples: menu/menu.cpp
void QMessageBox::aboutQt ( QWidget * parent, const QString &
caption=QString::null ) [static]
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Displays a simple message box about Qt, with window
caption caption and optionally centered over parent. The
message includes the version number of Qt being used by
the application.
This is neat for inclusion into the Help menu. See the
menu.cpp example.
Examples: menu/menu.cpp trivial/trivial.cpp
void QMessageBox::adjustSize () [virtual]
Adjusts the size of the message box to fit the contents
just before QDialog::exec() or QDialog::show() is called.
This function will not be called if the message box has
been explicitly resized before showing it.
Reimplemented from QWidget.
QString QMessageBox::buttonText ( int button ) const
Returns the text of the message box button button, or null
if the message box does not contain the button.
See also setButtonText().
int QMessageBox::critical ( QWidget * parent, const QString &
caption, const QString & text, const QString & button0Text
= QString::null, const QString & button1Text =
QString::null, const QString & button2Text =
QString::null, int defaultButtonNumber = 0, int
escapeButtonNumber = -1 ) [static]
Displays a critical error message box with a caption, a
text and 1-3 buttons. Returns the number of the button
that was clicked (0, 1 or 2).
button0Text is the text of the first button and is
optional. If button0Text is not supplied, "OK"
(translated) will be used. button1Text is the text of the
second button and is optional, and button2Text is the text
of the third button and is optional. defaultbuttonNumber
(0-2) is the index of the default button; pressing Return
or Enter is the same as clicking the default button. It
defaults to 0 (the first button). escapeButtonNumber is
the index of the Escape button; pressing Escape is the
same as clicking this button. It defaults to -1 (pressing
Escape does nothing); supply 0, 1 or 2 to make pressing
Escape be equivalent with clicking the relevant button.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
See also information() and warning().
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QMessageBox(3qt)QMessageBox(3qt)int QMessageBox::critical ( QWidget * parent, const QString &
caption, const QString & text, int button0, int button1,
int button2=0 ) [static]
Opens a critical message box with a caption, a text and up
to three buttons. Returns the identifier of the button
that was clicked.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
See also information() and warning().
QMessageBox::Icon QMessageBox::icon() const
Returns the icon of the message box.
See also setIcon() and iconPixmap().
const QPixmap * QMessageBox::iconPixmap () const
Returns the icon pixmap of the message box.
Example:
QMessageBox mb(...);
mb.setIcon( QMessageBox::Warning );
mb.iconPixmap(); // returns the warning icon pixmap
See also setIconPixmap() and icon().
int QMessageBox::information ( QWidget * parent, const QString &
caption, const QString & text, const QString & button0Text
= QString::null, const QString & button1Text =
QString::null, const QString & button2Text =
QString::null, int defaultButtonNumber = 0, int
escapeButtonNumber = -1 ) [static]
Displays an information message box with a caption, a text
and 1-3 buttons. Returns the number of the button that was
clicked (0, 1 or 2).
button0Text is the text of the first button and is
optional. If button0Text is not supplied, "OK"
(translated) will be used. button1Text is the text of the
second button and is optional. button2Text is the text of
the third button and is optional. defaultbuttonNumber
(0-2) is the index of the default button; pressing Return
or Enter is the same as clicking the default button. It
defaults to 0 (the first button). escapeButtonNumber is
the index of the Escape button; pressing Escape is the
same as clicking this button. It defaults to -1 (pressing
Escape does nothing); supply 0, 1 or 2 to make pressing
Escape be equivalent with clicking the relevant button.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
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widget, the message box becomes modal relative to parent.
See also warning() and critical().
Examples: picture/picture.cpp
int QMessageBox::information ( QWidget * parent, const QString &
caption, const QString & text, int button0, int button1=0,
int button2=0 ) [static]
Opens an information message box with a caption, a text
and up to three buttons. Returns the identifier of the
button that was clicked.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
See also warning() and critical().
void QMessageBox::keyPressEvent ( QKeyEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QMessageBox::resizeEvent ( QResizeEvent * ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QMessageBox::setButtonText ( int button, const QString &
text )
Sets the text of the message box button button to text.
Setting the text of a button that is not in the message
box is quietly ignored.
See also buttonText().
void QMessageBox::setIcon ( Icon icon )
Sets the icon of the message box to icon, which is a
predefined icon:
QMessageBox::NoIcon
QMessageBox::Information
QMessageBox::Warning
QMessageBox::Critical
The actual pixmap used for displaying the icon depends on
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the current GUI style. You can also set a custom pixmap
icon using the setIconPixmap() function.
See also icon(), setIconPixmap() and iconPixmap().
void QMessageBox::setIcon ( const QPixmap & pix ) [virtual]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QMessageBox::setIconPixmap ( const QPixmap & pixmap )
Sets the icon of the message box to a custom pixmap. Note
that it's often hard to draw one pixmap which looks
appropriate in both Motif and Windoes GUI styles. You may
want to draw two.
See also iconPixmap() and setIcon().
void QMessageBox::setText ( const QString & text )
Sets the message box text to be displayed.
text will be interpreted either as a plain text or as a
rich text, depending on the text format setting; see
setTextFormat(). The default setting is AutoText, i.e. the
message box will try to auto-detect the format of text.
See also text() and setTextFormat().
void QMessageBox::setTextFormat ( Qt::TextFormat format )
Sets the text format to format. See the Qt::TextFormat
enum for an explanation of the possible options.
The default format is AutoText.
See also textFormat() and setText().
QPixmap QMessageBox::standardIcon ( Icon icon, GUIStyle style )
[static]
Returns the pixmap used for a standard icon. This allows
the pixmaps to be used in more complex message boxes.
void QMessageBox::styleChanged ( QStyle & ) [protected]
Reimplemented for internal reasons; the API is not
affected.
QString QMessageBox::text () const
Returns the message box text currently set, or a null
string if no text has been set.
See also setText() and textFormat().
Qt::TextFormat QMessageBox::textFormat() const
Returns the current text format.
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See also setTextFormat().
int QMessageBox::warning ( QWidget * parent, const QString &
caption, const QString & text, const QString & button0Text
= QString::null, const QString & button1Text =
QString::null, const QString & button2Text =
QString::null, int defaultButtonNumber = 0, int
escapeButtonNumber = -1 ) [static]
Displays a warning message box with a caption, a text and
1-3 buttons. Returns the number of the button that was
clicked (0, 1 or 2).
button0Text is the text of the first button and is
optional. If button0Text is not supplied, "OK"
(translated) will be used. button1Text is the text of the
second button and is optional, and button2Text is the text
of the third button and is optional. defaultbuttonNumber
(0-2) is the index of the default button; pressing Return
or Enter is the same as clicking the default button. It
defaults to 0 (the first button). escapeButtonNumber is
the index of the Escape button; pressing Escape is the
same as clicking this button. It defaults to -1 (pressing
Escape does nothing); supply 0, 1 or 2 to make pressing
Escape be equivalent with clicking the relevant button.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
See also information() and critical().
Examples: i18n/main.cpp
int QMessageBox::warning ( QWidget * parent, const QString &
caption, const QString & text, int button0, int button1,
int button2=0 ) [static]
Opens a warning message box with a caption, a text and up
to three buttons. Returns the identifier of the button
that was clicked.
If parent is 0, then the message box becomes an
application-global modal dialog box. If parent is a
widget, the message box becomes modal relative to parent.
See also information() and critical().
SEE ALSO
http://doc.trolltech.com/qmessagebox.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
in the distribution for a complete license statement.
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QMessageBox(3qt)QMessageBox(3qt)AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
Please include the name of the manual page
(qmessagebox.3qt) and the Qt version (2.3.1).
Trolltech AS 13 June 2001 14
