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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
public class QDialog
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 can provide a return value, and they can have default buttons. QDialogs can also have a QSizeGrip in their lower-right corner, using setSizeGripEnabled.
Note that QDialog (an any other widget that has type Qt::Dialog) 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.
Use the overload of the QWidget::setParent() function to change the ownership of a QDialog widget. This function allows you to explicitly set the window flags of the reparented widget; using the overloaded function will clear the window flags specifying the window-system properties for the widget (in particular it will reset the Qt::Dialog flag).
A modal dialog is a dialog that blocks input to other visible windows in the same application. Dialogs that are used to request a file name from the user or that are used to set application preferences are usually modal. Dialogs can be application modal (the default) or window modal.
When an application modal dialog is opened, the user must finish interacting with the dialog and close it before they can access any other window in the application. Window modal dialogs only block access to the window associated with the dialog, allowing the user to continue to use other windows in an application.
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, to get the dialog to close and return the appropriate value, we connect a default button, e.g. OK, to the accept slot and a Cancel button to the reject slot. Alternatively you can call the done slot with Accepted or Rejected.
An alternative is to call setModal(true) or setWindowModality, 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 to perform a long operation, you must call QApplication::processEvents() periodically during processing to enable the user to interact with the dialog. (See QProgressDialog.)
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.
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.
If the user presses the Esc key in a dialog, QDialog::reject() will be called. This will cause the window to close: The close event cannot be ignored.
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 dialog is expanded. The Extension Example shows how to achieve extensible dialogs using Qt.
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.
A modal dialog:
void EditorWindow::countWords() { WordCountDialog dialog(this); dialog.setWordCount(document().wordCount()); dialog.exec(); }
A modeless dialog:
void EditorWindow::find() { if (!findDialog) { findDialog = new FindDialog(this); connect(findDialog, SIGNAL(findNext()), this, SLOT(findNext())); } findDialog->show(); findDialog->raise(); findDialog->activateWindow(); }
Example
,
Dialogs Example
Nested Class Summary | |
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static class |
QDialog.DialogCode
The value returned by a modal dialog. |
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.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 |
accepted
This signal is emitted when the dialog has been accepted either by the user or by calling accept or done with the QDialog::Accepted argument. |
QSignalEmitter.Signal1<java.lang.Integer> |
finished
This signal is emitted when the dialog's result code has been set, either by the user or by calling done, accept, or reject. |
QSignalEmitter.Signal0 |
rejected
This signal is emitted when the dialog has been rejected either by the user or by calling reject or done with the QDialog::Rejected argument. |
Fields inherited from class com.trolltech.qt.gui.QWidget |
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customContextMenuRequested |
Constructor Summary | |
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QDialog()
Equivalent to QDialog(0, 0). |
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QDialog(QWidget parent)
Equivalent to QDialog(parent, 0). |
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QDialog(QWidget parent,
Qt.WindowFlags f)
Constructs a dialog with parent parent. |
Method Summary | |
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void |
accept()
Hides the modal dialog and sets the result code to Accepted. |
protected void |
adjustPosition(QWidget arg__1)
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protected void |
closeEvent(QCloseEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive widget close events. |
protected void |
contextMenuEvent(QContextMenuEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive widget context menu events. |
void |
done(int arg__1)
Closes the dialog and sets its result code to arg__1. |
boolean |
eventFilter(QObject arg__1,
QEvent arg__2)
Filters events if this object has been installed as an event filter for the arg__1 object. |
int |
exec()
Shows the dialog as a modal dialog, blocking until the user closes it. |
static QDialog |
fromNativePointer(QNativePointer nativePointer)
This function returns the QDialog instance pointed to by nativePointer |
boolean |
isSizeGripEnabled()
Returns whether the size grip is enabled. |
protected void |
keyPressEvent(QKeyEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive key press events for the widget. |
QSize |
minimumSizeHint()
Returns the recommended minimum size for the widget. |
void |
reject()
Hides the modal dialog and sets the result code to Rejected. |
protected void |
resizeEvent(QResizeEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget resize events which are passed in the arg__1 parameter. |
int |
result()
Returns the modal dialog's result code, Accepted or Rejected. |
void |
setModal(boolean modal)
Sets whether show should pop up the dialog as modal or modeless to modal. |
void |
setResult(int r)
Sets the modal dialog's result code to r. |
void |
setSizeGripEnabled(boolean arg__1)
Sets whether the size grip is enabled to arg__1. |
void |
setVisible(boolean visible)
Sets whether the widget is visible to visible. |
protected void |
showEvent(QShowEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget show events which are passed in the arg__1 parameter. |
QSize |
sizeHint()
Returns the recommended size for the widget. |
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 accepted
This signal is emitted when the dialog has been accepted either by the user or by calling accept or done with the QDialog::Accepted argument.
Note that this signal is not emitted when hiding the dialog with hide or setVisible(false). This includes deleting the dialog while it is visible.
public final QSignalEmitter.Signal1<java.lang.Integer> finished
This signal is emitted when the dialog's result code has been set, either by the user or by calling done, accept, or reject.
Note that this signal is not emitted when hiding the dialog with hide or setVisible(false). This includes deleting the dialog while it is visible.
public final QSignalEmitter.Signal0 rejected
This signal is emitted when the dialog has been rejected either by the user or by calling reject or done with the QDialog::Rejected argument.
Note that this signal is not emitted when hiding the dialog with hide or setVisible(false). This includes deleting the dialog while it is visible.
Constructor Detail |
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public QDialog(QWidget parent)
Equivalent to QDialog(parent, 0).
public QDialog()
Equivalent to QDialog(0, 0).
public QDialog(QWidget parent, Qt.WindowFlags f)
Constructs a dialog 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 title bar of the dialog, pass Qt::WindowTitleHint | Qt::WindowSystemMenuHint in f.
Method Detail |
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protected final void adjustPosition(QWidget arg__1)
public int exec()
Shows the dialog as a modal dialog, blocking until the user closes it. The function returns a DialogCode result.
If the dialog is application modal, users cannot interact with any other window in the same application until they close the dialog. If the dialog is window modal, only interaction with the parent window is blocked while the dialog is open.
By default, the dialog is application modal.
public final boolean isSizeGripEnabled()
Returns 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.
public final int result()
Returns the modal dialog's result code, Accepted or Rejected.
Do not call this function if the dialog was constructed with the Qt::WA_DeleteOnClose attribute.
public final void setModal(boolean modal)
Sets whether show should pop up the dialog as modal or modeless to modal.
By default, this property is false and show pops up the dialog as modeless. Setting his property to true is equivalent to setting QWidget::windowModality to Qt::ApplicationModal.
exec ignores the value of this property and always pops up the dialog as modal.
public final void setResult(int r)
Sets the modal dialog's result code to r.
public final void setSizeGripEnabled(boolean arg__1)
Sets whether the size grip is enabled to arg__1.
A QSizeGrip is placed in the bottom-right corner of the dialog when this property is enabled. By default, the size grip is disabled.
public void accept()
Hides the modal dialog and sets the result code to Accepted.
protected void closeEvent(QCloseEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive widget close events.
closeEvent
in class QWidget
protected void contextMenuEvent(QContextMenuEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive widget context menu events.
The handler is called when the widget's contextMenuPolicy is Qt::DefaultContextMenu.
The default implementation ignores the context event. See the QContextMenuEvent documentation for more details.
contextMenuEvent
in class QWidget
public void done(int arg__1)
Closes the dialog and sets its result code to arg__1. If this dialog is shown with exec, done causes the local event loop to finish, and exec to return arg__1.
As with QWidget::close(), done deletes the dialog if the Qt::WA_DeleteOnClose 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.
public boolean eventFilter(QObject arg__1, QEvent arg__2)
Filters events if this object has been installed as an event filter for the arg__1 object.
In your reimplementation of this function, if you want to filter the arg__2 out, i.e. stop it being handled further, return true; otherwise return false.
Example:
class MainWindow : public QMainWindow
{
public:
MainWindow();
protected:
bool eventFilter(QObject *obj, QEvent *ev);
private:
QTextEdit *textEdit;
};
MainWindow::MainWindow()
{
textEdit = new QTextEdit;
setCentralWidget(textEdit);
textEdit->installEventFilter(this);
}
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if (obj == textEdit) {
if (event->type() == QEvent::KeyPress) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
qDebug() << "Ate key press" << keyEvent->key();
return true;
} else {
return false;
}
} else {
// pass the event on to the parent class
return QMainWindow::eventFilter(obj, event);
}
}
Notice in the example above that unhandled events are passed to the base class's eventFilter function, since the base class might have reimplemented eventFilter for its own internal purposes.
Warning: If you delete the receiver object in this function, be sure to return true. Otherwise, Qt will forward the event to the deleted object and the program might crash.
eventFilter
in class QObject
protected void keyPressEvent(QKeyEvent arg__1)
This event handler, for event arg__1, can be reimplemented in a subclass to receive key press events for the widget.
A widget must call setFocusPolicy to accept focus initially and have focus in order to receive a key press event.
If you reimplement this handler, it is very important that you ignore() the event if you do not understand it, so that the widget's parent can interpret it.
The default implementation closes popup widgets if the user presses Esc. Otherwise the event is ignored.
keyPressEvent
in class QWidget
public QSize minimumSizeHint()
Returns the recommended minimum size for the widget.
If the value of this property is an invalid size, no minimum size is recommended.
The default implementation of minimumSizeHint returns an invalid size if there is no layout for this widget, and returns the layout's minimum size otherwise. Most built-in widgets reimplement minimumSizeHint.
QLayout will never resize a widget to a size smaller than the minimum size hint unless minimumSize is set or the size policy is set to QSizePolicy::Ignore. If minimumSize is set, the minimum size hint will be ignored.
minimumSizeHint
in class QWidget
public void reject()
Hides the modal dialog and sets the result code to Rejected.
protected void resizeEvent(QResizeEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget resize events which are passed in the arg__1 parameter. When resizeEvent is called, the widget already has its new geometry. The old size is accessible through QResizeEvent::oldSize().
The widget will be erased and receive a paint event immediately after processing the resize event. No drawing need be (or should be) done inside this handler.
resizeEvent
in class QWidget
Example
public void setVisible(boolean visible)
Sets whether the widget is visible to visible.
Calling setVisible(true) or show sets the widget to visible status if all its parent widgets up to the window are visible. If an ancestor is not visible, the widget won't become visible until all its ancestors are shown. If its size or position has changed, Qt guarantees that a widget gets move and resize events just before it is shown. If the widget has not been resized yet, Qt will adjust the widget's size to a useful default using adjustSize.
Calling setVisible(false) or hide hides a widget explicitly. An explicitly hidden widget will never become visible, even if all its ancestors become visible, unless you show it.
A widget receives show and hide events when its visibility status changes. Between a hide and a show event, there is no need to waste CPU cycles preparing or displaying information to the user. A video application, for example, might simply stop generating new frames.
A widget that happens to be obscured by other windows on the screen is considered to be visible. The same applies to iconified windows and windows that exist on another virtual desktop (on platforms that support this concept). A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again.
You almost never have to reimplement the setVisible function. If you need to change some settings before a widget is shown, use showEvent instead. If you need to do some delayed initialization use the Polish event delivered to the event function.
setVisible
in class QWidget
protected void showEvent(QShowEvent arg__1)
This event handler can be reimplemented in a subclass to receive widget show events which are passed in the arg__1 parameter.
Non-spontaneous show events are sent to widgets immediately before they are shown. The spontaneous show events of windows are delivered afterwards.
Note: A widget receives spontaneous show and hide events when its mapping status is changed by the window system, e.g. a spontaneous hide event when the user minimizes the window, and a spontaneous show event when the window is restored again. After receiving a spontaneous hide event, a widget is still considered visible in the sense of isVisible.
showEvent
in class QWidget
visible
,
event,
QShowEventpublic QSize sizeHint()
Returns the recommended size for the widget.
If the value of this property is an invalid size, no size is recommended.
The default implementation of sizeHint returns an invalid size if there is no layout for this widget, and returns the layout's preferred size otherwise.
sizeHint
in class QWidget
public static QDialog fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.
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