QSignalMapper¶
The
QSignalMapper
class bundles signals from identifiable senders. More…
Synopsis¶
Functions¶
def
mapping
(id)def
mapping
(object)def
mapping
(text)def
mapping
(widget)def
removeMappings
(sender)def
setMapping
(sender, id)def
setMapping
(sender, object)def
setMapping
(sender, text)def
setMapping
(sender, widget)
Detailed Description¶
This class collects a set of parameterless signals, and re-emits them with integer, string or widget parameters corresponding to the object that sent the signal.
The class supports the mapping of particular strings or integers with particular objects using
setMapping()
. The objects’ signals can then be connected to themap()
slot which will emit themapped()
signal with the string or integer associated with the original signalling object. Mappings can be removed later usingremoveMappings()
.Example: Suppose we want to create a custom widget that contains a group of buttons (like a tool palette). One approach is to connect each button’s
clicked()
signal to its own custom slot; but in this example we want to connect all the buttons to a single slot and parameterize the slot by the button that was clicked.Here’s the definition of a simple custom widget that has a single signal,
clicked()
, which is emitted with the text of the button that was clicked:class ButtonWidget(QWidget): def __init__(self, texts, parent=None): QWidget.__init__(self, parent) ...The only function that we need to implement is the constructor:
def __init__(self, texts, parent): QWidget.__init__(self, parent) self.signalMapper = QSignalMapper(self) layout = QGridLayout() for text, index in enumerate(texts): button = QPushButton(text) self.connect(SIGNAL("clicked()"), self.signalMapper, SLOT("map()")) self.signalMapper.setMapping(button, text) layout.addWidget(button, index / 3, index % 3) self.signalMapper.connect(SIGNAL("mapped(const QString &)"), self, SLOT("clicked(const QString &)")) self.setLayout(layout)A list of texts is passed to the constructor. A signal mapper is constructed and for each text in the list a
QPushButton
is created. We connect each button’sclicked()
signal to the signal mapper’smap()
slot, and create a mapping in the signal mapper from each button to the button’s text. Finally we connect the signal mapper’smapped()
signal to the custom widget’sclicked()
signal. When the user clicks a button, the custom widget will emit a singleclicked()
signal whose argument is the text of the button the user clicked.This class was mostly useful before lambda functions could be used as slots. The example above can be rewritten simpler without
QSignalMapper
by connecting to a lambda function.ButtonWidget::ButtonWidget(const QStringList &texts, QWidget *parent) : QWidget(parent) { QGridLayout *gridLayout = new QGridLayout; for (int i = 0; i < texts.size(); ++i) { QString text = texts[i]; QPushButton *button = new QPushButton(text); connect(button, &QPushButton::clicked, [=] { clicked(text); }); gridLayout->addWidget(button, i / 3, i % 3); } setLayout(gridLayout); }See also
-
class
QSignalMapper
([parent=None])¶ - param parent
Constructs a
QSignalMapper
with parentparent
.
-
PySide2.QtCore.QSignalMapper.
map
(sender)¶ - Parameters
sender –
QObject
This slot emits signals based on the
sender
object.
-
PySide2.QtCore.QSignalMapper.
map
() This slot emits signals based on which object sends signals to it.
-
PySide2.QtCore.QSignalMapper.
mapped
(arg__1) - Parameters
arg__1 –
int
-
PySide2.QtCore.QSignalMapper.
mapped
(arg__1) - Parameters
arg__1 – unicode
-
PySide2.QtCore.QSignalMapper.
mapped
(arg__1) - Parameters
arg__1 –
QWidget
-
PySide2.QtCore.QSignalMapper.
mapping
(object)¶ -
This function overloads
mapping()
.Returns the sender
QObject
that is associated with theobject
.
-
PySide2.QtCore.QSignalMapper.
mapping
(widget) - Parameters
widget –
QWidget
- Return type
This function overloads
mapping()
.Returns the sender
QObject
that is associated with thewidget
.
-
PySide2.QtCore.QSignalMapper.
mapping
(text) - Parameters
text – unicode
- Return type
-
PySide2.QtCore.QSignalMapper.
mapping
(id) - Parameters
id –
int
- Return type
Returns the sender
QObject
that is associated with theid
.See also
-
PySide2.QtCore.QSignalMapper.
removeMappings
(sender)¶ - Parameters
sender –
QObject
Removes all mappings for
sender
.This is done automatically when mapped objects are destroyed.
Note
This does not disconnect any signals. If
sender
is not destroyed then this will need to be done explicitly if required.
-
PySide2.QtCore.QSignalMapper.
setMapping
(sender, object)¶ -
Adds a mapping so that when
map()
is signalled from thesender
, the signal mapped(object
) is emitted.There may be at most one object for each sender.
-
PySide2.QtCore.QSignalMapper.
setMapping
(sender, widget) - Parameters
sender –
QObject
widget –
QWidget
Adds a mapping so that when
map()
is signalled from thesender
, the signal mapped(widget
) is emitted.There may be at most one widget for each sender.
-
PySide2.QtCore.QSignalMapper.
setMapping
(sender, text) - Parameters
sender –
QObject
text – unicode
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