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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.gui.QWidget
com.trolltech.qt.gui.QDialog
com.trolltech.qt.gui.QProgressDialog
public class QProgressDialog
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.
Compared to a modeless QProgressDialog, a modal QProgressDialog is simpler to use for the programmer. Do the operation in a loop, call setValue at intervals, and check for cancellation with wasCanceled. For example:
QProgressDialog progress("Copying files...", "Abort Copy", 0, numFiles, this);
progress.setWindowModality(Qt::WindowModal);
for (int i = 0; i < numFiles; i++) {
progress.setValue(i);
if (progress.wasCanceled())
break;
//... copy one file
}
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 Operation::Operation(QObject *parent) : QObject(parent), steps(0) { pd = new QProgressDialog("Operation in progress.", "Cancel", 0, 100); connect(pd, SIGNAL(canceled()), this, SLOT(cancel())); t = new QTimer(this); connect(t, SIGNAL(timeout()), this, SLOT(perform())); t->start(0); } void Operation::perform() { pd->setValue(steps); //... perform one percent of the operation steps++; if (steps > pd->maximum()) 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 by using setLabel, setBar, and setCancelButton. The functions setLabelText and setCancelButtonText set the texts shown.
The Standard Dialogs example shows how to use QProgressDialog as well as other built-in Qt dialogs.
Files Example
,
Example
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.gui.QDialog |
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QDialog.DialogCode |
Nested classes/interfaces inherited from class com.trolltech.qt.gui.QWidget |
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QWidget.RenderFlag, QWidget.RenderFlags |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
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QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Field Summary | |
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QSignalEmitter.Signal0 |
canceled
This signal is emitted when the cancel button is clicked. |
Fields inherited from class com.trolltech.qt.gui.QDialog |
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accepted, finished, rejected |
Fields inherited from class com.trolltech.qt.gui.QWidget |
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customContextMenuRequested |
Constructor Summary | |
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QProgressDialog()
Equivalent to QProgressDialog(0, 0). |
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QProgressDialog(QWidget parent)
Equivalent to QProgressDialog(parent, 0). |
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QProgressDialog(QWidget parent,
Qt.WindowFlags f)
Constructs a progress dialog. |
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QProgressDialog(java.lang.String labelText,
java.lang.String cancelButtonText,
int minimum,
int maximum)
Equivalent to QProgressDialog(labelText, cancelButtonText, minimum, maximum, 0, 0). |
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QProgressDialog(java.lang.String labelText,
java.lang.String cancelButtonText,
int minimum,
int maximum,
QWidget parent)
Equivalent to QProgressDialog(labelText, cancelButtonText, minimum, maximum, parent, 0). |
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QProgressDialog(java.lang.String labelText,
java.lang.String cancelButtonText,
int minimum,
int maximum,
QWidget parent,
Qt.WindowFlags f)
Constructs a progress dialog. |
Method Summary | |
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boolean |
autoClose()
Returns whether the dialog gets hidden by reset. |
boolean |
autoReset()
Returns whether the progress dialog calls reset as soon as progress() equals totalSteps(). |
void |
cancel()
Resets the progress dialog. |
protected void |
changeEvent(QEvent arg__1)
This function is reimplemented for internal reasons. |
protected void |
closeEvent(QCloseEvent arg__1)
This function is reimplemented for internal reasons. |
protected void |
forceShow()
Shows the dialog if it is still hidden after the algorithm has been started and minimumDuration milliseconds have passed. |
static QProgressDialog |
fromNativePointer(QNativePointer nativePointer)
This function returns the QProgressDialog instance pointed to by nativePointer |
java.lang.String |
labelText()
Returns the label's text. |
int |
maximum()
Returns the highest value represented by the progress bar. |
int |
minimum()
Returns the lowest value represented by the progress bar. |
int |
minimumDuration()
Returns the time that must pass before the dialog appears. |
void |
reset()
Resets the progress dialog. |
protected void |
resizeEvent(QResizeEvent arg__1)
This function is reimplemented for internal reasons. |
void |
setAutoClose(boolean b)
Sets whether the dialog gets hidden by reset to b. |
void |
setAutoReset(boolean b)
Sets whether the progress dialog calls reset as soon as progress() equals totalSteps() to b. |
void |
setBar(QProgressBar bar)
Sets the progress bar widget to bar. |
void |
setCancelButton(QPushButton button)
Sets the cancel button to the push button, button. |
void |
setCancelButtonText(java.lang.String arg__1)
Sets the cancel button's text to arg__1. |
void |
setLabel(QLabel label)
Sets the label to label. |
void |
setLabelText(java.lang.String arg__1)
Sets the label's text to arg__1. |
void |
setMaximum(int maximum)
Sets the highest value represented by the progress bar to maximum. |
void |
setMinimum(int minimum)
Sets the lowest value represented by the progress bar to minimum. |
void |
setMinimumDuration(int ms)
Sets the time that must pass before the dialog appears to ms. |
void |
setRange(int minimum,
int maximum)
Sets the progress dialog's minimum and maximum values to minimum and maximum, respectively. |
void |
setValue(int progress)
Sets the current amount of progress made. to progress. |
protected void |
showEvent(QShowEvent e)
This function is reimplemented for internal reasons. |
QSize |
sizeHint()
Returns a size that fits the contents of the progress dialog. |
int |
value()
Returns the current amount of progress made.. |
boolean |
wasCanceled()
Returns whether the dialog was canceled. |
Methods inherited from class com.trolltech.qt.gui.QDialog |
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accept, adjustPosition, contextMenuEvent, done, eventFilter, exec, isSizeGripEnabled, keyPressEvent, minimumSizeHint, reject, result, setModal, setResult, setSizeGripEnabled, setVisible |
Methods inherited from class com.trolltech.qt.core.QObject |
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blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread, timerEvent |
Methods inherited from class com.trolltech.qt.QtJambiObject |
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dispose, disposed, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
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disconnect, disconnect, signalSender |
Methods inherited from class java.lang.Object |
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clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
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disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Field Detail |
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public final QSignalEmitter.Signal0 canceled
This signal is emitted when the cancel button is clicked. It is connected to the cancel slot by default.
Constructor Detail |
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public QProgressDialog(QWidget parent)
Equivalent to QProgressDialog(parent, 0).
public QProgressDialog()
Equivalent to QProgressDialog(0, 0).
public QProgressDialog(QWidget parent, Qt.WindowFlags f)
Constructs a progress dialog.
Default settings:
The parent argument is dialog's parent widget. The widget flags, f, are passed to the QDialog::QDialog() constructor.
public QProgressDialog(java.lang.String labelText, java.lang.String cancelButtonText, int minimum, int maximum, QWidget parent)
Equivalent to QProgressDialog(labelText, cancelButtonText, minimum, maximum, parent, 0).
public QProgressDialog(java.lang.String labelText, java.lang.String cancelButtonText, int minimum, int maximum)
Equivalent to QProgressDialog(labelText, cancelButtonText, minimum, maximum, 0, 0).
public QProgressDialog(java.lang.String labelText, java.lang.String cancelButtonText, int minimum, int maximum, QWidget parent, Qt.WindowFlags f)
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.
Method Detail |
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public final boolean autoClose()
Returns whether the dialog gets hidden by reset.
The default is true.
public final boolean autoReset()
Returns whether the progress dialog calls reset as soon as progress() equals totalSteps().
The default is true.
public final void cancel()
Resets the progress dialog. wasCanceled becomes true until the progress dialog is reset. The progress dialog becomes hidden.
protected final void forceShow()
Shows the dialog if it is still hidden after the algorithm has been started and minimumDuration milliseconds have passed.
public final java.lang.String labelText()
Returns the label's text.
The default text is an empty string.
public final int maximum()
Returns the highest value represented by the progress bar.
The default is 0.
public final int minimum()
Returns the lowest value represented by the progress bar.
The default is 0.
public final int minimumDuration()
Returns the time that must pass before the dialog appears.
If the expected duration of the task is less than the minimumDuration, the dialog will not appear at all. This prevents the dialog popping up for tasks that are quickly over. For tasks that are expected to exceed the minimumDuration, the dialog will pop up after the minimumDuration time or as soon as any progress is set.
If set to 0, the dialog is always shown as soon as any progress is set. The default is 4000 milliseconds.
public final void reset()
Resets the progress dialog. The progress dialog becomes hidden if autoClose is true.
public final void setAutoClose(boolean b)
Sets whether the dialog gets hidden by reset to b.
The default is true.
public final void setAutoReset(boolean b)
Sets whether the progress dialog calls reset as soon as progress() equals totalSteps() to b.
The default is true.
public final void 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.
public final void setCancelButton(QPushButton button)
Sets the cancel button to the push button, button. 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.
public final void setCancelButtonText(java.lang.String arg__1)
Sets the cancel button's text to arg__1.
public final void 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.
public final void setLabelText(java.lang.String arg__1)
Sets the label's text to arg__1.
The default text is an empty string.
public final void setMaximum(int maximum)
Sets the highest value represented by the progress bar to maximum.
The default is 0.
public final void setMinimum(int minimum)
Sets the lowest value represented by the progress bar to minimum.
The default is 0.
public final void setMinimumDuration(int ms)
Sets the time that must pass before the dialog appears to ms.
If the expected duration of the task is less than the minimumDuration, the dialog will not appear at all. This prevents the dialog popping up for tasks that are quickly over. For tasks that are expected to exceed the minimumDuration, the dialog will pop up after the minimumDuration time or as soon as any progress is set.
If set to 0, the dialog is always shown as soon as any progress is set. The default is 4000 milliseconds.
public final void 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.
public final void setValue(int progress)
Sets the current amount of progress made. to progress.
For the progress dialog to work as expected, you should initially set this property to 0 and finally set it to QProgressDialog::maximum(); you can call setValue 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 in your code. For example, don't use a QProgressDialog inside a paintEvent!
public final int value()
Returns the current amount of progress made..
For the progress dialog to work as expected, you should initially set this property to 0 and finally set it to QProgressDialog::maximum(); you can call setValue 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 in your code. For example, don't use a QProgressDialog inside a paintEvent!
public final boolean wasCanceled()
Returns whether the dialog was canceled.
protected void changeEvent(QEvent arg__1)
This function is reimplemented for internal reasons.
changeEvent
in class QWidget
protected void closeEvent(QCloseEvent arg__1)
This function is reimplemented for internal reasons.
closeEvent
in class QDialog
protected void resizeEvent(QResizeEvent arg__1)
This function is reimplemented for internal reasons.
resizeEvent
in class QDialog
Example
protected void showEvent(QShowEvent e)
This function is reimplemented for internal reasons.
showEvent
in class QDialog
visible
,
event,
QShowEventpublic QSize sizeHint()
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.
sizeHint
in class QDialog
public static QProgressDialog fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.
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