class QSignalMapper#

The QSignalMapper class bundles signals from identifiable senders. More

Inheritance diagram of PySide6.QtCore.QSignalMapper

Synopsis#

Methods#

Slots#

Signals#

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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. Note that in most cases you can use lambdas for passing custom parameters to slots. This is less costly and will simplify the code.

The class supports the mapping of particular strings, integers, objects and widgets with particular objects using setMapping() . The objects’ signals can then be connected to the map() slot which will emit a signal (it could be mappedInt() , mappedString() and mappedObject() ) with a value associated with the original signalling object. Mappings can be removed later using removeMappings() .

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):

    Q_OBJECT
# public
    ButtonWidget(QStringList texts, QWidget parent = None)
# signals
    def clicked(text):
# private
    signalMapper = QSignalMapper()

The only function that we need to implement is the constructor:

def __init__(self, texts, parent):
    super().__init__(parent)

    signalMapper = QSignalMapper(self)
    gridLayout = QGridLayout(self)
    for i in range(0, texts.size()):
        button = QPushButton(texts[i])
        button.clicked.connect(signalMapper, qOverload<>(&QSignalMapper::map))
    signalMapper.setMapping(button, texts[i])
    gridLayout.addWidget(button, i / 3, i % 3)

signalMapper.mappedString.connect(
self.clicked)

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’s clicked() signal to the signal mapper’s map() slot, and create a mapping in the signal mapper from each button to the button’s text. Finally we connect the signal mapper’s mappedString() signal to the custom widget’s clicked() signal. When the user clicks a button, the custom widget will emit a single clicked() 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.

def __init__(self, texts, parent):
    super().__init__(parent)

    gridLayout = QGridLayout(self)
    for i in range(0, texts.size()):
        text = texts[i]
        button = QPushButton(text)
        button.clicked.connect([this, text] { clicked(text); })
        gridLayout.addWidget(button, i / 3, i % 3)

See also

QObject QButtonGroupQActionGroup

__init__([parent=None])#
Parameters:

parentQObject

Constructs a QSignalMapper with parent parent.

map()#

This slot emits signals based on which object sends signals to it.

map(sender)
Parameters:

senderQObject

This slot emits signals based on the sender object.

mappedInt(arg__1)#
Parameters:

arg__1 – int

This signal is emitted when map() is signalled from an object that has an integer mapping set. The object’s mapped integer is passed in i.

See also

setMapping()

mappedObject(arg__1)#
Parameters:

arg__1QObject

This signal is emitted when map() is signalled from an object that has an object mapping set. The object provided by the map is passed in object.

See also

setMapping()

mappedString(arg__1)#
Parameters:

arg__1 – str

This signal is emitted when map() is signalled from an object that has a string mapping set. The object’s mapped string is passed in text.

See also

setMapping()

mapping(object)#
Parameters:

objectQObject

Return type:

QObject

This function overloads mapping() .

Returns the sender QObject that is associated with the object.

mapping(text)
Parameters:

text – str

Return type:

QObject

This function overloads mapping() .

mapping(id)
Parameters:

id – int

Return type:

QObject

Returns the sender QObject that is associated with the id.

See also

setMapping()

removeMappings(sender)#
Parameters:

senderQObject

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.

setMapping(sender, object)#
Parameters:

Adds a mapping so that when map() is signalled from the sender, the signal mappedObject (object ) is emitted.

There may be at most one object for each sender.

setMapping(sender, text)
Parameters:

Adds a mapping so that when map() is signalled from the sender, the signal mappedString (text ) is emitted.

There may be at most one text for each sender.

setMapping(sender, id)
Parameters:

Adds a mapping so that when map() is signalled from the given sender, the signal mappedInt (id) is emitted.

There may be at most one integer ID for each sender.

See also

mapping()