QProgressDialog Class Reference

#include <qprogressdialog.h>

Inheritance diagram for QProgressDialog:

[legend]Collaboration diagram for QProgressDialog:

[legend]List of all members.

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Detailed Description

The QProgressDialog class 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, and to demonstrate that the application has not frozen. It can also give the user an opportunity to abort the operation.

A common problem with progress dialogs is that it is difficult to know when to use them; operations take different amounts of time on different 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 setMinimum() and setMaximum() or the constructor to set the number of "steps" in the operation and call setValue() as the operation progresses. The number of steps can be chosen arbitrarily. It can be the number of files copied, the number of bytes received, the number of iterations through the main loop of your algorithm, or some other suitable unit. Progress starts at the value set by setMinimum(), and the progress dialog shows that the operation has finished when you call setValue() with the value set by setMaximum() as its argument.

The dialog automatically resets and hides itself at the end of the operation. Use setAutoReset() and setAutoClose() to change this behavior.

There are two ways of using QProgressDialog: modal and modeless.

Using a modal QProgressDialog is simpler for the programmer, but you must call QApplication::processEvents() or QEventLoop::processEvents(ExcludeUserInput) to keep the event loop running to ensure that the application doesn't freeze. Do the operation in a loop, call setValue() at intervals, and check for cancellation with wasCanceled(). For example:

snippets/dialogs/dialogs.cpp QProgressDialog progress("Copying files...", "Abort Copy", 0, numFiles, this); progress.setValue(numFiles);

A modeless 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 modeless progress dialog.

You need to have an event loop to be running, connect the canceled() signal to a slot that stops the operation, and call setValue() at intervals. For example:

Operation constructor } } }

In both modes the progress dialog may be customized by replacing the child widgets with custom widgets by using setLabel(), setBar(), and setCancelButton(). The functions setLabelText() and setCancelButtonText() set the texts shown.

The {dialogs/standarddialogs}{Standard Dialogs} example shows how to use QProgressDialog as well as other built-in Qt dialogs.

A progress dialog shown in the Plastique widget style.

See also:

QDialog, QProgressBar, {fowler}{GUI Design Handbook: Progress Indicator}, {Find Files Example}, {Pixelator Example}

Definition at line 41 of file qprogressdialog.h.

Public Slots
void	cancel ()
void	reset ()
void	setMaximum (int maximum)
void	setMinimum (int minimum)
void	setValue (int progress)
void	setLabelText (const QString &)
void	setCancelButtonText (const QString &)
void	setMinimumDuration (int ms)
Signals
void	canceled ()
Public Member Functions
	QProgressDialog (QWidget *parent=0, Qt::WindowFlags f=0)
	QProgressDialog (const QString &labelText, const QString &cancelButtonText, int minimum, int maximum, QWidget *parent=0, Qt::WindowFlags f=0)
	~QProgressDialog ()
void	setLabel (QLabel *label)
void	setCancelButton (QPushButton *button)
void	setBar (QProgressBar *bar)
bool	wasCanceled () const
int	minimum () const
int	maximum () const
void	setRange (int minimum, int maximum)
int	value () const
QSize	sizeHint () const
QString	labelText () const
int	minimumDuration () const
void	setAutoReset (bool b)
bool	autoReset () const
void	setAutoClose (bool b)
bool	autoClose () const
Protected Slots
void	forceShow ()
Protected Member Functions
void	resizeEvent (QResizeEvent *)
void	closeEvent (QCloseEvent *)
void	changeEvent (QEvent *)
void	showEvent (QShowEvent *e)

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Constructor & Destructor Documentation

QProgressDialog::QProgressDialog	(	QWidget *	parent = 0,
		Qt::WindowFlags	f = 0
	)			[explicit]

Constructs a progress dialog.

Default settings: The label text is empty. The cancel button text is (translated) "Cancel". minimum is 0; maximum is 100

The parent argument is dialog's parent widget. The widget flags, f, are passed to the QDialog::QDialog() constructor.

See also:

setLabelText(), setCancelButtonText(), setCancelButton(), setMinimum(), setMaximum()

Definition at line 235 of file qprogressdialog.cpp.

References d, and QString::fromLatin1().

    : QDialog(*(new QProgressDialogPrivate), parent, f)
{
    Q_D(QProgressDialog);
    d->init(QString::fromLatin1(""), tr("Cancel"), 0, 100);
}

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QProgressDialog::QProgressDialog	(	const QString &	labelText,
		const QString &	cancelButtonText,
		int	minimum,
		int	maximum,
		QWidget *	parent = 0,
		Qt::WindowFlags	f = 0
	)

Constructs a progress dialog.

The labelText is the text used to remind the user what is progressing.

The cancelButtonText is the text to display on the cancel button, or 0 if no cancel button is to be shown.

The minimum and maximum is the number of steps in the operation for which this progress dialog shows progress. For example, if the operation is to examine 50 files, this value minimum value would be 0, and the maximum would be 50. Before examining the first file, call setValue(0). As each file is processed call setValue(1), setValue(2), etc., finally calling setValue(50) after examining the last file.

The parent argument is the dialog's parent widget. The and widget flags, f, are passed to the QDialog::QDialog() constructor.

See also:

setLabelText(), setLabel(), setCancelButtonText(), setCancelButton(), setMinimum(), setMaximum()

Definition at line 264 of file qprogressdialog.cpp.

References d, and labelText().

    : QDialog(*(new QProgressDialogPrivate), parent, f)
{
    Q_D(QProgressDialog);
    d->init(labelText, cancelButtonText, minimum, maximum);
}

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QProgressDialog::~QProgressDialog

(

)

Destroys the progress dialog.

Definition at line 279 of file qprogressdialog.cpp.

{
}

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Member Function Documentation

void QProgressDialog::setLabel

(

QLabel *

label

)

Sets the label to 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()

Definition at line 301 of file qprogressdialog.cpp.

References d, h, QWidget::height(), QWidget::hide(), QWidget::isVisible(), QWidget::parentWidget(), qMax(), QWidget::resize(), QWidget::setParent(), QWidget::show(), sizeHint(), w, and QWidget::width().

{
    Q_D(QProgressDialog);
    delete d->label;
    d->label = label;
    if (label) {
        if (label->parentWidget() == this) {
            label->hide(); // until we resize
        } else {
            label->setParent(this, 0);
        }
    }
    int w = qMax(isVisible() ? width() : 0, sizeHint().width());
    int h = qMax(isVisible() ? height() : 0, sizeHint().height());
    resize(w, h);
    if (label)
        label->show();
}

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void QProgressDialog::setCancelButton

(

QPushButton *

cancelButton

)

Sets the cancel button to the push button, cancelButton. The progress dialog takes ownership of this button which will be deleted when necessary, so do not pass the address of an object that is on the stack, i.e. use new() to create the button.

See also:

setCancelButtonText()

Definition at line 357 of file qprogressdialog.cpp.

References canceled(), QObject::connect(), d, h, QWidget::height(), QWidget::hide(), QWidget::isVisible(), Qt::Key_Escape, QWidget::parentWidget(), qMax(), QWidget::resize(), QWidget::setParent(), QWidget::show(), SIGNAL, sizeHint(), w, and QWidget::width().

Referenced by setCancelButtonText().

{
    Q_D(QProgressDialog);
    delete d->cancel;
    d->cancel = cancelButton;
    if (cancelButton) {
        if (cancelButton->parentWidget() == this) {
            cancelButton->hide(); // until we resize
        } else {
            cancelButton->setParent(this, 0);
        }
        connect(d->cancel, SIGNAL(clicked()), this, SIGNAL(canceled()));
#ifndef QT_NO_SHORTCUT
        new QShortcut(Qt::Key_Escape, this, SIGNAL(canceled()));
#endif
    }
    int w = qMax(isVisible() ? width() : 0, sizeHint().width());
    int h = qMax(isVisible() ? height() : 0, sizeHint().height());
    resize(w, h);
    if (cancelButton)
        cancelButton->show();
}

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void QProgressDialog::setBar

(

QProgressBar *

bar

)

Sets the progress bar widget to bar. The progress dialog resizes to fit. The progress dialog takes ownership of the progress bar which will be deleted when necessary, so do not use a progress bar allocated on the stack.

Definition at line 409 of file qprogressdialog.cpp.

References d, h, QWidget::height(), QWidget::isVisible(), qMax(), qWarning(), QWidget::resize(), sizeHint(), value(), w, and QWidget::width().

{
    Q_D(QProgressDialog);
#ifndef QT_NO_DEBUG
    if (value() > 0)
        qWarning("QProgressDialog::setBar: Cannot set a new progress bar "
                  "while the old one is active");
#endif
    delete d->bar;
    d->bar = bar;
    int w = qMax(isVisible() ? width() : 0, sizeHint().width());
    int h = qMax(isVisible() ? height() : 0, sizeHint().height());
    resize(w, h);
}

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bool QProgressDialog::wasCanceled

(

)

const

Definition at line 430 of file qprogressdialog.cpp.

References d.

Referenced by Window::findFiles(), MainWindow::printImage(), and BatchTranslationDialog::startTranslation().

{
    Q_D(const QProgressDialog);
    return d->cancellation_flag;
}

int QProgressDialog::minimum

(

)

const

Definition at line 467 of file qprogressdialog.cpp.

References d.

Referenced by setValue().

{
    Q_D(const QProgressDialog);
    return d->bar->minimum();
}

int QProgressDialog::maximum

(

)

const

Definition at line 446 of file qprogressdialog.cpp.

References d.

Referenced by setValue().

{
    Q_D(const QProgressDialog);
    return d->bar->maximum();
}

void QProgressDialog::setRange	(	int	minimum,
		int	maximum
	)

Sets the progress dialog's minimum and maximum values to minimum and maximum, respectively.

If maximum is smaller than minimum, minimum becomes the only legal value.

If the current value falls outside the new range, the progress dialog is reset with reset().

See also:

minimum, maximum

Definition at line 491 of file qprogressdialog.cpp.

References d.

Referenced by Window::findFiles().

{
    Q_D(QProgressDialog);
    d->bar->setRange(minimum, maximum);
}

int QProgressDialog::value

(

)

const

Definition at line 538 of file qprogressdialog.cpp.

References d.

Referenced by reset(), and setBar().

{
    Q_D(const QProgressDialog);
    return d->bar->value();
}

QSize QProgressDialog::sizeHint

(

)

const [virtual]

Returns a size that fits the contents of the progress dialog. The progress dialog resizes itself as required, so you should not need to call this yourself.

Reimplemented from QDialog.

Definition at line 620 of file qprogressdialog.cpp.

References d, h, QSize::height(), QStyle::pixelMetric(), QStyle::PM_DefaultLayoutSpacing, QStyle::PM_DefaultTopLevelMargin, qMax(), spacing, QWidget::style(), and QSize::width().

Referenced by setBar(), setCancelButton(), setCancelButtonText(), setLabel(), setLabelText(), setValue(), and showEvent().

{
    Q_D(const QProgressDialog);
    QSize sh = d->label->sizeHint();
    QSize bh = d->bar->sizeHint();
    int margin = style()->pixelMetric(QStyle::PM_DefaultTopLevelMargin);
    int spacing = style()->pixelMetric(QStyle::PM_DefaultLayoutSpacing);
    int h = margin * 2 + bh.height() + sh.height() + spacing;
    if (d->cancel)
        h += d->cancel->sizeHint().height() + spacing;
    return QSize(qMax(200, sh.width() + 2 * margin), h);
}

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QString QProgressDialog::labelText

(

)

const

Definition at line 328 of file qprogressdialog.cpp.

References d.

Referenced by QProgressDialog().

{
    Q_D(const QProgressDialog);
    if (d->label)
        return d->label->text();
    return QString();
}

int QProgressDialog::minimumDuration

(

)

const

Definition at line 676 of file qprogressdialog.cpp.

References d.

{
    Q_D(const QProgressDialog);
    return d->showTime;
}

void QProgressDialog::setAutoReset

(

bool

b

)

Definition at line 702 of file qprogressdialog.cpp.

References d.

{
    Q_D(QProgressDialog);
    d->autoReset = b;
}

bool QProgressDialog::autoReset

(

)

const

Definition at line 708 of file qprogressdialog.cpp.

References d.

{
    Q_D(const QProgressDialog);
    return d->autoReset;
}

void QProgressDialog::setAutoClose

(

bool

b

)

Definition at line 723 of file qprogressdialog.cpp.

References d.

{
    Q_D(QProgressDialog);
    d->autoClose = b;
}

bool QProgressDialog::autoClose

(

)

const

Definition at line 729 of file qprogressdialog.cpp.

References d.

{
    Q_D(const QProgressDialog);
    return d->autoClose;
}

void QProgressDialog::cancel

(

)

[slot]

Resets the progress dialog. wasCanceled() becomes true until the progress dialog is reset. The progress dialog becomes hidden.

Definition at line 528 of file qprogressdialog.cpp.

References d, and reset().

{
    Q_D(QProgressDialog);
    d->forceHide = true;
    reset();
    d->forceHide = false;
    d->cancellation_flag = true;
}

void QProgressDialog::reset

(

)

[slot]

Resets the progress dialog. The progress dialog becomes hidden if autoClose() is true.

See also:

setAutoClose(), setAutoReset()

Definition at line 505 of file qprogressdialog.cpp.

References d, QWidget::hide(), QWidget::parentWidget(), QWidget::setCursor(), and value().

Referenced by cancel(), and setValue().

{
    Q_D(QProgressDialog);
#ifndef QT_NO_CURSOR
    if (value() >= 0) {
        if (parentWidget())
            parentWidget()->setCursor(d->parentCursor);
    }
#endif
    if (d->autoClose || d->forceHide)
        hide();
    d->bar->reset();
    d->cancellation_flag = false;
    d->shown_once = false;
    d->forceTimer->stop();
}

void QProgressDialog::setMaximum

(

int

maximum

)

[slot]

Definition at line 452 of file qprogressdialog.cpp.

References d.

Referenced by HttpWindow::updateDataReadProgress(), and FtpWindow::updateDataTransferProgress().

{
    Q_D(QProgressDialog);
    d->bar->setMaximum(maximum);
}

void QProgressDialog::setMinimum

(

int

minimum

)

[slot]

Definition at line 473 of file qprogressdialog.cpp.

References d.

{
    Q_D(QProgressDialog);
    d->bar->setMinimum(minimum);
}

void QProgressDialog::setValue

(

int

progress

)

[slot]

Definition at line 561 of file qprogressdialog.cpp.

References d, QCoreApplication::flush(), h, QWidget::height(), QWidget::isModal(), QWidget::isVisible(), maximum(), minimum(), minWaitTime, qApp, qMax(), reset(), QWidget::resize(), QWidget::show(), sizeHint(), w, and QWidget::width().

Referenced by Window::findFiles(), MainWindow::printImage(), BatchTranslationDialog::startTranslation(), HttpWindow::updateDataReadProgress(), and FtpWindow::updateDataTransferProgress().

{
    Q_D(QProgressDialog);
    if (progress == d->bar->value() ||
         d->bar->value() == -1 && progress == d->bar->maximum())
        return;

    d->bar->setValue(progress);

    if (d->shown_once) {
        if (isModal())
            qApp->processEvents();
    } else {
        if (progress == 0) {
            d->starttime.start();
            d->forceTimer->start(d->showTime);
            return;
        } else {
            bool need_show;
            int elapsed = d->starttime.elapsed();
            if (elapsed >= d->showTime) {
                need_show = true;
            } else {
                if (elapsed > minWaitTime) {
                    int estimate;
                    int totalSteps = maximum() - minimum();
                    int myprogress = progress - minimum();
                    if ((totalSteps - myprogress) >= INT_MAX / elapsed)
                        estimate = (totalSteps - myprogress) / myprogress * elapsed;
                    else
                        estimate = elapsed * (totalSteps - myprogress) / myprogress;
                    need_show = estimate >= d->showTime;
                } else {
                    need_show = false;
                }
            }
            if (need_show) {
                int w = qMax(isVisible() ? width() : 0, sizeHint().width());
                int h = qMax(isVisible() ? height() : 0, sizeHint().height());
                resize(w, h);
                show();
                d->shown_once = true;
            }
        }
#ifdef Q_WS_MAC
        QApplication::flush();
#endif
    }

    if (progress == d->bar->maximum() && d->autoReset)
        reset();
}

void QProgressDialog::setLabelText

(

const QString &

)

[slot]

Definition at line 336 of file qprogressdialog.cpp.

References d, h, QWidget::height(), QWidget::isVisible(), qMax(), QWidget::resize(), sizeHint(), w, and QWidget::width().

Referenced by FtpWindow::downloadFile(), HttpWindow::downloadFile(), and Window::findFiles().

{
    Q_D(QProgressDialog);
    if (d->label) {
        d->label->setText(text);
        int w = qMax(isVisible() ? width() : 0, sizeHint().width());
        int h = qMax(isVisible() ? height() : 0, sizeHint().height());
        resize(w, h);
    }
}

void QProgressDialog::setCancelButtonText

(

const QString &

cancelButtonText

)

[slot]

Sets the cancel button's text to cancelButtonText.

See also:

setCancelButton()

Definition at line 385 of file qprogressdialog.cpp.

References d, h, QWidget::height(), QString::isNull(), QWidget::isVisible(), qMax(), QDialog::QPushButton, QWidget::resize(), setCancelButton(), sizeHint(), w, and QWidget::width().

Referenced by Window::findFiles().

{
    Q_D(QProgressDialog);
    if (!cancelButtonText.isNull()) {
        if (d->cancel)
            d->cancel->setText(cancelButtonText);
        else
            setCancelButton(new QPushButton(cancelButtonText, this));
    } else {
        setCancelButton(0);
    }
    int w = qMax(isVisible() ? width() : 0, sizeHint().width());
    int h = qMax(isVisible() ? height() : 0, sizeHint().height());
    resize(w, h);
}

void QProgressDialog::setMinimumDuration

(

int

ms

)

[slot]

Definition at line 666 of file qprogressdialog.cpp.

References d.

{
    Q_D(QProgressDialog);
    d->showTime = ms;
    if (d->bar->value() == 0) {
        d->forceTimer->stop();
        d->forceTimer->start(ms);
    }
}

void QProgressDialog::canceled

(

)

[signal]

This signal is emitted when the cancel button is clicked. It is connected to the cancel() slot by default.

See also:

wasCanceled()

Referenced by closeEvent(), and setCancelButton().

void QProgressDialog::resizeEvent

(

QResizeEvent *

)

[protected, virtual]

Reimplemented from QDialog.

Definition at line 635 of file qprogressdialog.cpp.

References d.

{
    Q_D(QProgressDialog);
    d->layout();
}

void QProgressDialog::closeEvent

(

QCloseEvent *

e

)

[protected, virtual]

Reimplemented from QDialog.

Definition at line 687 of file qprogressdialog.cpp.

References canceled(), QDialog::closeEvent(), and emit.

{
    emit canceled();
    QDialog::closeEvent(e);
}

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void QProgressDialog::changeEvent

(

QEvent *

ev

)

[protected, virtual]

Reimplemented from QWidget.

Definition at line 644 of file qprogressdialog.cpp.

References QWidget::changeEvent(), d, QEvent::StyleChange, and QEvent::type().

{
    Q_D(QProgressDialog);
    if(ev->type() == QEvent::StyleChange)
        d->layout();
    QDialog::changeEvent(ev);
}

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void QProgressDialog::showEvent

(

QShowEvent *

e

)

[protected, virtual]

Reimplemented from QDialog.

Definition at line 739 of file qprogressdialog.cpp.

References d, h, QWidget::height(), QWidget::isVisible(), qMax(), QWidget::resize(), QDialog::showEvent(), sizeHint(), w, and QWidget::width().

{
    Q_D(QProgressDialog);
    QDialog::showEvent(e);
    int w = qMax(isVisible() ? width() : 0, sizeHint().width());
    int h = qMax(isVisible() ? height() : 0, sizeHint().height());
    resize(w, h);
    d->forceTimer->stop();
}

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void QProgressDialog::forceShow

(

)

[protected, slot]

Shows the dialog if it is still hidden after the algorithm has been started and minimumDuration milliseconds have passed.

See also:

setMinimumDuration()

Definition at line 756 of file qprogressdialog.cpp.

References d, and QWidget::show().

{
    Q_D(QProgressDialog);
    if (d->shown_once || d->cancellation_flag)
        return;

    show();
    d->shown_once = true;
}

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The documentation for this class was generated from the following files:

• src/gui/dialogs/qprogressdialog.h
• src/gui/dialogs/qprogressdialog.cpp

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