QProgressDialog(3qt)QProgressDialog(3qt)NAME
QProgressDialog - Provides feedback on the progress of a
slow operation
#include <qprogressdialog.h>
Inherits QSemiModal.
Public Members
QProgressDialog ( QWidget * parent=0, const char * name=0,
bool modal=FALSE, WFlags f=0 )
QProgressDialog ( const QString & labelText, const QString
& cancelButtonText, int totalSteps, QWidget *
parent=0, const char * name=0, bool modal=FALSE,
WFlags f=0 )
~QProgressDialog ()
void setLabel ( QLabel * )
void setCancelButton ( QPushButton * )
void setBar ( QProgressBar * )
bool wasCancelled () const
int totalSteps () const
int progress () const
virtual QSize sizeHint () const
QString labelText () const
void setAutoReset ( bool b )
bool autoReset () const
void setAutoClose ( bool b )
bool autoClose () const
int minimumDuration () const
Public Slots
void cancel ()
void reset ()
void setTotalSteps ( int totalSteps )
void setProgress ( int progress )
void setLabelText ( const QString & )
void setCancelButtonText ( const QString & )
void setMinimumDuration ( int ms )
Signals
void cancelled ()
Protected Slots
void forceShow ()
Properties
Type Name READ WRITE Options
----------------------------------------------------------------
bool wasCancelled wasCancelled
int totalSteps totalSteps setTotalSteps
int progress progress setProgress
bool autoReset autoReset setAutoReset
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QProgressDialog(3qt)QProgressDialog(3qt)
bool autoClose autoClose setAutoClose
QString labelText labelText setLabelText
DESCRIPTION
Provides feedback on the progress of a slow operation.
A progress dialog is used to give the user an indication
of how long an operation is going to take to perform, and
to reassure them that the application has not frozen. It
also gives the user an opportunity to abort the operation.
A potential problem with progress dialogs is that it is
difficult to know when to use them, as operations take
different amounts of time on different computer hardware.
QProgressDialog offers a solution to this problem: it
estimates the time the operation will take (based on time
for steps), and only shows itself if that estimate is
beyond minimumDuration() (4 seconds by default).
Use setTotalSteps() (or the constructor) to set the number
of" steps" in the operation and call setProgress() as the
operation progresses. The step value can be chosen
arbitrarily. It can be eg. the number of files copied, the
number of bytes received, or the number of iterations
through the main loop of your algorithm. You must call
setProgress() with parameter 0 initially, and with
parameter totalSteps() at the end.
The dialog will automatically be reset and hidden at the
end of the operation, Use setAutoReset() and
setAutoClose() to change this behavior.
There are two ways of using QProgressDialog, modal and
non-modal.
Using a modal QProgressDialog is simpler for the
programmer, but you have to call qApp->processEvents() to
keep the event loop running and prevent the application
from freezing. Do the operation in a loop, calling
setProgress() at intervals, and checking for cancellation
with wasCancelled().
Example:
QProgressDialog progress( "Copying files...", "Abort Copy", numFiles,
this, "progress", TRUE );
for (int i=0; i<numFiles; i++) {
progress.setProgress( i );
qApp->processEvents();
if ( progress.wasCancelled() )
break;
... // copy one file
}
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QProgressDialog(3qt)QProgressDialog(3qt)
progress.setProgress( numFiles );
A non-modal progress dialog is suitable for operations
that take place in the background, where the user is able
to interact with the application. Such operations are
typically based on QTimer (or QObject::timerEvent()),
QSocketNotifier, or QUrlOperator; or performed in a
separate thread. A QProgressBar in the status bar of your
main window is often an alternative to a non-modal
progress dialog.
You need an event loop to be running. Connect the
cancelled() signal to a slot that stops the operation, and
call setProgress() at intervals.
Example:
Operation::Operation( QObject *parent = 0 )
: QObject( parent ), steps(0)
{
pd = new QProgressDialog( "Operation in progress.", "Cancel", 100 );
connect( pd, SIGNAL(cancelled()), this, SLOT(cancel()) );
t = new QTimer( this );
connect( t, SIGNAL(timeout()), this, SLOT(perform()) );
t->start(0);
}
void Operation::perform()
{
pd->setProgress( steps );
... //perform one percent of the operation
steps++;
if ( steps > pd->totalSteps() )
t->stop();
}
void Operation::cancel()
{
t->stop();
... //cleanup
}
In both modes, the progress dialog may be customized by
replacing the child widgets with custom widgets, using
setLabel(), setBar() and setCancelButton(). The functions
setLabelText() and setCancelButtonText() sets the texts
shown.
[Image Omitted]
[Image Omitted]
See also QDialog, QProgressBar and GUI Design Handbook:
Progress Indicator
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QProgressDialog(3qt)QProgressDialog(3qt)
Examples: progress/progress.cpp
MEMBER FUNCTION DOCUMENTATIONQProgressDialog::QProgressDialog ( QWidget * creator=0, const
char * name=0, bool modal=FALSE, WFlags f=0 )
Constructs a progress dialog.
Default settings:
The label text is empty.
The cancel button text is "Cancel".
The total number of steps is 100.
parent, name, modal, and f are sent to the
QSemiModal::QSemiModal() constructor. Note that if modal
is FALSE (the default), you will need to have an event
loop proceeding for any redrawing of the dialog to occur.
If it is TRUE, the dialog ensures events are processed
when needed.
See also setLabelText(), setLabel(),
setCancelButtonText(), setCancelButton() and
setTotalSteps().
QProgressDialog::QProgressDialog ( const QString & labelText,
const QString & cancelButtonText, int totalSteps, QWidget
* creator=0, const char * name=0, bool modal=FALSE, WFlags
f=0 )
Constructs a progress dialog.
labelText is text telling the user what is progressing.
cancelButtonText is the text on the cancel button, or 0 if
no cancel button is to be shown.
totalSteps is the total number of steps in the operation
of which this progress dialog shows the progress. For
example, if the operation is to examine 50 files, this
value would be 50, then before examining the first file,
call setProgress(0), and after examining the last file
call setProgress(50).
name, modal, and f are sent to the
QSemiModal::QSemiModal() constructor. Note that if modal
is FALSE (the default), you will need to have an event
loop proceeding for any redrawing of the dialog to occur.
If it is TRUE, the dialog ensures events are processed
when needed.
See also setLabelText(), setLabel(),
setCancelButtonText(), setCancelButton() and
setTotalSteps().
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QProgressDialog(3qt)QProgressDialog(3qt)QProgressDialog::~QProgressDialog ()
Destructs the progress dialog.
bool QProgressDialog::autoClose () const
Returns if the dialog gets hidden by reset().
See also setAutoClose().
bool QProgressDialog::autoReset () const
Returns if the dialog resets itself when progress() equals
totalSteps().
See also setAutoReset().
void QProgressDialog::cancel () [slot]
Reset the progress dialog. wasCancelled() becomes TRUE
until the progress dialog is reset. The progress dialog
becomes hidden.
void QProgressDialog::cancelled () [signal]
This signal is emitted when the cancel button is clicked.
It is connected to the cancel() slot by default.
See also wasCancelled().
void QProgressDialog::closeEvent ( QCloseEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QProgressDialog::forceShow () [protected slot]
Shows the dialog if it is still hidden after the algorithm
has been started and the minimumDuration is over.
See also setMinimumDuration().
QString QProgressDialog::labelText () const
Returns the labels text.
See also setLabelText.
int QProgressDialog::minimumDuration () const
Returns the currently set minimum duration for the
QProgressDialog
See also setMinimumDuration().
int QProgressDialog::progress () const
Returns the current amount of progress, or -1 if the
progress counting has not started.
See also setProgress().
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QProgressDialog(3qt)QProgressDialog(3qt)void QProgressDialog::reset () [slot]
Reset the progress dialog. The progress dialog becomes
hidden if autoClose() is TRUE.
See also setAutoClose() and setAutoReset().
void QProgressDialog::resizeEvent ( QResizeEvent * ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
void QProgressDialog::setAutoClose ( bool b )
If you set b to TRUE, the dialog gets closed (hidden) if
reset() is called, else this does not happen.
See also autoClose() and setAutoReset().
void QProgressDialog::setAutoReset ( bool b )
If you set b to TRUE, the progress dialog calls reset() if
progress() equals totalSteps(), if you set it to FALSE,
this does not happen.
See also autoReset() and setAutoClose().
void QProgressDialog::setBar ( QProgressBar * bar )
Sets the progress bar widget. The progress dialog resizes
to fit. The progress bar becomes owned by the progress
dialog and will be deleted when necessary.
void QProgressDialog::setCancelButton ( QPushButton *
cancelButton )
Sets the cancellation button. The button becomes owned by
the progress dialog and will be deleted when necessary, so
do not pass the address of an object on the stack.
See also setCancelButtonText().
void QProgressDialog::setCancelButtonText ( const QString &
cancelButtonText ) [slot]
Sets the cancellation button text.
See also setCancelButton().
void QProgressDialog::setLabel ( QLabel * label )
Sets the label. The progress dialog resizes to fit. The
label becomes owned by the progress dialog and will be
deleted when necessary, so do not pass the address of an
object on the stack.
See also setLabelText().
Examples: progress/progress.cpp
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QProgressDialog(3qt)QProgressDialog(3qt)void QProgressDialog::setLabelText ( const QString & text )
[slot]
Sets the label text. The progress dialog resizes to fit.
See also setLabel().
void QProgressDialog::setMinimumDuration ( int ms ) [slot]
Sets the minimum duration to ms milliseconds. The dialog
will not appear if the anticipated duration of the
progressing task is less than the minimum duration.
If ms is 0 the dialog is always shown as soon as any
progress is set.
See also minimumDuration().
Examples: progress/progress.cpp
void QProgressDialog::setProgress ( int progress ) [slot]
Sets the current amount of progress made to prog units of
the total number of steps. For the progress dialog to work
correctly, you must at least call this with the parameter
0 initially, then later with
QProgressDialog::totalSteps(), and you may call it any
number of times in between.
Warning: If the progress dialog is modal (see
QProgressDialog::QProgressDialog()), this function calls
QApplication::processEvents(), so take care that this does
not cause undesirable re-entrancy to your code. For
example, don't use a QProgressDialog inside a
paintEvent()!
See also progress().
Examples: progress/progress.cpp
void QProgressDialog::setTotalSteps ( int totalSteps ) [slot]
Sets the total number of steps.
See also totalSteps() and QProgressBar::setTotalSteps().
void QProgressDialog::showEvent ( QShowEvent * e ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
QSize QProgressDialog::sizeHint () const [virtual]
Returns a size which fits the contents of the progress
dialog. The progress dialog resizes itself as required, so
this should not be needed in user code.
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QProgressDialog(3qt)QProgressDialog(3qt)
Reimplemented from QWidget.
void QProgressDialog::styleChange ( QStyle & s ) [virtual
protected]
Reimplemented for internal reasons; the API is not
affected.
Reimplemented from QWidget.
int QProgressDialog::totalSteps () const
Returns the total number of steps.
See also setTotalSteps() and QProgressBar::totalSteps().
Examples: progress/progress.cpp
bool QProgressDialog::wasCancelled () const
Returns the TRUE if the dialog was cancelled, otherwise
FALSE.
See also setProgress(), cancel() and cancelled().
Examples: progress/progress.cpp
SEE ALSO
http://doc.trolltech.com/qprogressdialog.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.
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
(qprogressdialog.3qt) and the Qt version (2.3.1).
Trolltech AS 13 June 2001 8
