Extending QML - Binding Example¶
This example builds on the Extending QML - Adding Types Example, the Extending QML (advanced) - Attached Properties, the Extending QML (advanced) - Default Properties, the Extending QML (advanced) - Inheritance and Coercion the Extending QML - Object and List Property Types Example and the Extending QML (advanced) - Property Value Source.
Running the Example¶
The main.py file in the example includes a simple shell application that
loads and runs the QML snippet shown below.
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
"""PySide6 port of the qml/examples/qml/referenceexamples/binding example from Qt v6.x"""
from pathlib import Path
import sys
from PySide6.QtCore import QCoreApplication
from PySide6.QtQml import QQmlComponent, QQmlEngine, qmlAttachedPropertiesObject
from person import Boy, Girl # noqa: F401
from birthdayparty import BirthdayParty # noqa: F401
from happybirthdaysong import HappyBirthdaySong # noqa: F401
if __name__ == "__main__":
app = QCoreApplication(sys.argv)
engine = QQmlEngine()
engine.addImportPath(Path(__file__).parent)
component = QQmlComponent(engine)
component.loadFromModule("People", "Main")
party = component.create()
if not party:
print(component.errors())
del engine
sys.exit(-1)
host = party.host
print(f"{host.name} is having a birthday!")
if isinstance(host, Boy):
print("He is inviting:")
else:
print("She is inviting:")
for g in range(party.guestCount()):
guest = party.guest(g)
name = guest.name
rsvp_date = None
attached = qmlAttachedPropertiesObject(BirthdayParty, guest, False)
if attached:
rsvp_date = attached.rsvp.toString()
if rsvp_date:
print(f" {name} RSVP date: {rsvp_date}")
else:
print(f" {name} RSVP date: Hasn't RSVP'd")
party.startParty()
r = app.exec()
del engine
sys.exit(r)
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
from PySide6.QtCore import QDate, QObject, ClassInfo, Property, QTime, Signal
from PySide6.QtQml import QmlAnonymous, QmlAttached, QmlElement, ListProperty
from person import Person
# To be used on the @QmlElement decorator
# (QML_IMPORT_MINOR_VERSION is optional)
QML_IMPORT_NAME = "People"
QML_IMPORT_MAJOR_VERSION = 1
@QmlAnonymous
class BirthdayPartyAttached(QObject):
rsvp_changed = Signal()
def __init__(self, parent=None):
super().__init__(parent)
self._rsvp = QDate()
@Property(QDate, notify=rsvp_changed)
def rsvp(self):
return self._rsvp
@rsvp.setter
def rsvp(self, d):
if self._rsvp != d:
self._rsvp = d
self.rsvp_changed.emit()
@QmlElement
@ClassInfo(DefaultProperty="guests")
@QmlAttached(BirthdayPartyAttached)
class BirthdayParty(QObject):
partyStarted = Signal(QTime)
host_changed = Signal()
def __init__(self, parent=None):
super().__init__(parent)
self._host = None
self._guests = []
def startParty(self):
self.partyStarted.emit(QTime.currentTime())
@Property(Person, notify=host_changed)
def host(self):
return self._host
@host.setter
def host(self, h):
if self._host != h:
self._host = h
self.host_changed.emit()
@Property(str)
def announcement(self):
return ""
@announcement.setter
def announcement(self, a):
print(a)
def guest(self, n):
return self._guests[n]
def guestCount(self):
return len(self._guests)
def appendGuest(self, guest):
self._guests.append(guest)
@staticmethod
def qmlAttachedProperties(self, o):
return BirthdayPartyAttached(o)
guests = ListProperty(Person, appendGuest)
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
from PySide6.QtCore import QTimer, Property, Slot
from PySide6.QtQml import QmlElement, QPyQmlPropertyValueSource
# To be used on the @QmlElement decorator
# (QML_IMPORT_MINOR_VERSION is optional)
QML_IMPORT_NAME = "People"
QML_IMPORT_MAJOR_VERSION = 1
@QmlElement
class HappyBirthdaySong(QPyQmlPropertyValueSource):
def __init__(self, parent=None):
super().__init__(parent)
self.m_target = None
self.m_name = ""
self.m_line = -1
self.m_lyrics = []
self.m_timer = QTimer(self)
self.m_timer.timeout.connect(self.advance)
self.m_timer.start(1000)
def setTarget(self, property):
self.m_target = property
@Property(str)
def name(self):
return self.m_name
@name.setter
def name(self, n):
self.m_name = n
self.m_lyrics = ["Happy birthday to you,",
"Happy birthday to you,",
f"Happy birthday dear {self.m_name},",
"Happy birthday to you!",
""]
@Slot()
def advance(self):
self.m_line = (self.m_line + 1) % len(self.m_lyrics)
self.m_target.write(self.m_lyrics[self.m_line])
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
from PySide6.QtCore import QObject, Property, Signal
from PySide6.QtQml import QmlAnonymous, QmlElement
# To be used on the @QmlElement decorator
# (QML_IMPORT_MINOR_VERSION is optional)
QML_IMPORT_NAME = "People"
QML_IMPORT_MAJOR_VERSION = 1
@QmlAnonymous
class Person(QObject):
name_changed = Signal()
shoe_size_changed = Signal()
def __init__(self, parent=None):
super().__init__(parent)
self._name = ''
self._shoe_size = 0
@Property(str, notify=name_changed)
def name(self):
return self._name
@name.setter
def name(self, n):
if self._name != n:
self._name = n
self.name_changed.emit()
@Property(int, notify=shoe_size_changed)
def shoe_size(self):
return self._shoe_size
@shoe_size.setter
def shoe_size(self, s):
if self._shoe_size != s:
self._shoe_size = s
self.shoe_size_changed.emit()
@QmlElement
class Boy(Person):
def __init__(self, parent=None):
super().__init__(parent)
@QmlElement
class Girl(Person):
def __init__(self, parent=None):
super().__init__(parent)
// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
import People
BirthdayParty {
id: theParty
HappyBirthdaySong on announcement { name: theParty.host.name }
onPartyStarted: (time) => { console.log("This party started rockin' at " + time); }
host: Boy {
name: "Bob Jones"
shoe_size: 12
}
Boy {
name: "Leo Hodges"
BirthdayParty.rsvp: "2009-07-06"
}
Boy {
name: "Jack Smith"
}
Girl {
name: "Anne Brown"
BirthdayParty.rsvp: "2009-07-01"
}
}
module People
typeinfo coercion.qmltypes
Main 1.0 Main.qml