在Widget移动上运行方法

Question

我正在尝试设计一个从PyQt5基QLabel类继承的标签类，该类能够跟踪另一个小部件。下面是我的类的当前代码:

class AttachedLabel(QLabel):
def __init__(self, attachedTo, *args, side="left", ** kwargs):
super().__init__(*args, **kwargs) # Run parent initialization
# Define instance variables
self.attached = attachedTo
self.side = side
# Update label position
self.updatePos()
def updatePos(self):
# Get "attached widget" position and dimensions
x = self.attached.geometry().x()
y = self.attached.geometry().y()
aWidth = self.attached.geometry().width()
aHeight = self.attached.geometry().height()
# Get own dimensions
width = self.geometry().width()
height = self.geometry().height()
if self.side == "top":  # Above of attached widget
self.setGeometry(x, y-height, width, height)
elif self.side == "bottom":  # Below attached widget
self.setGeometry(x, y+height+aHeight, width, height)
elif self.side == "right":  # Right of attached widget
self.setGeometry(x + width + aWidth, y, width, height)
else:  # Left of attached widget
self.setGeometry(x - width, y, width, height)

我希望能够像这样实例化标签:

AttachedLabel(self.pushButton, self.centralwidget)

其中self.pushButton是它应该跟随的小部件。问题是，我不知道如何检测当小部件移动，以运行我的updatePos()功能。理想情况下，我只会在其他小部件移动时更新标签位置，但我希望避免向正在跟踪的小部件的类添加额外的代码。我试过重写paintEvent，但只有当对象本身需要重新绘制时才会触发，所以它甚至不能作为次优解决方案。

是否有一些内置的方法，我可以使用/覆盖来检测小部件何时移动或何时屏幕本身更新?

Answer 1

您必须使用与QEvent::Move事件相交的eventFilter，并且您还应该通过QEvent::Resize事件跟踪调整大小。

from dataclasses import dataclass, field
import random
from PyQt5 import QtCore, QtWidgets

class GeometryTracker(QtCore.QObject):
geometryChanged = QtCore.pyqtSignal()
def __init__(self, widget):
super().__init__(widget)
self._widget = widget
self.widget.installEventFilter(self)
@property
def widget(self):
return self._widget
def eventFilter(self, source, event):
if self.widget is source and event.type() in (
QtCore.QEvent.Move,
QtCore.QEvent.Resize,
):
self.geometryChanged.emit()
return super().eventFilter(source, event)

@dataclass
class TrackerManager:
widget1: field(default_factory=QtWidgets.QWidget)
widget2: field(default_factory=QtWidgets.QWidget)
alignment: QtCore.Qt.Alignment = QtCore.Qt.AlignLeft
enabled: bool = True
valid_alignments = (
QtCore.Qt.AlignLeft,
QtCore.Qt.AlignRight,
QtCore.Qt.AlignHCenter,
QtCore.Qt.AlignTop,
QtCore.Qt.AlignBottom,
QtCore.Qt.AlignVCenter,
)
def __post_init__(self):
self._traker = GeometryTracker(self.widget1)
self._traker.geometryChanged.connect(self.update)
if not any(self.alignment & flag for flag in self.valid_alignments):
raise ValueError("alignment is not valid")
def update(self):
if not self.enabled:
return
r = self.widget1.rect()
p1 = r.center()
c1 = r.center()
if self.alignment & QtCore.Qt.AlignLeft:
p1.setX(r.left())
if self.alignment & QtCore.Qt.AlignRight:
p1.setX(r.right())
if self.alignment & QtCore.Qt.AlignTop:
p1.setY(r.top())
if self.alignment & QtCore.Qt.AlignBottom:
p1.setY(r.bottom())
p2 = self.convert_position(p1)
c2 = self.convert_position(c1)
g = self.widget2.geometry()
g.moveCenter(c2)
if self.alignment & QtCore.Qt.AlignLeft:
g.moveRight(p2.x())
if self.alignment & QtCore.Qt.AlignRight:
g.moveLeft(p2.x())
if self.alignment & QtCore.Qt.AlignTop:
g.moveBottom(p2.y())
if self.alignment & QtCore.Qt.AlignBottom:
g.moveTop(p2.y())
self.widget2.setGeometry(g)
def convert_position(self, point):
gp = self.widget1.mapToGlobal(point)
if self.widget2.isWindow():
return gp
return self.widget2.parent().mapFromGlobal(gp)

class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.button = QtWidgets.QPushButton("Press me", self)
self.label = QtWidgets.QLabel(
"TrackernLabel", self, alignment=QtCore.Qt.AlignCenter
)
self.label.setAttribute(QtCore.Qt.WA_TransparentForMouseEvents, True)
self.label.setFixedSize(200, 200)
self.label.setStyleSheet(
"background-color: salmon; border: 1px solid black; font-size: 40pt;"
)
self.resize(640, 480)
self.manager = TrackerManager(
widget1=self.button,
widget2=self.label,
alignment=QtCore.Qt.AlignRight | QtCore.Qt.AlignVCenter,
)
self.move_button()
def move_button(self):
pos = QtCore.QPoint(*random.sample(range(400), 2))
animation = QtCore.QPropertyAnimation(
targetObject=self.button,
parent=self,
propertyName=b"pos",
duration=1000,
startValue=self.button.pos(),
endValue=pos,
)
animation.finished.connect(self.move_button)
animation.start(QtCore.QAbstractAnimation.DeleteWhenStopped)

def main():
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())

if __name__ == "__main__":
main()