如何在 QGraphicsview 内继续绘制透明线而不重叠？
How can I draw a transparent line continues inside the QGraphicsview without overlap?
我试图通过两种方式绘制一条由线组成的路径：
首先，路径由直线构成，直线有共同的末端。使用这种方法的问题是线条在四肢重叠，导致不良影响，如下图所示：
这是代码：
from PyQt5 import QtWidgets, QtCore, QtGui
import typing
import random
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points: list = [QtCore.QPointF(0, 0)]
self.__pen: QtGui.QPen = QtGui.QPen()
self.setPen()
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
def getPen(self) -> QtGui.QPen:
return self.__pen
def setPen(self, pen: QtGui.QPen = None, width: int = 10, color: QtGui.QColor = QtGui.QColor(0, 24, 128, 100),
cap: QtCore.Qt.PenCapStyle = QtCore.Qt.SquareCap, line_style: QtCore.Qt.PenStyle = QtCore.Qt.SolidLine,
join: QtCore.Qt.PenJoinStyle = QtCore.Qt.RoundJoin) -> None:
"""
Set the pen that will be used to paint the implement.
:param pen : set the pen or its arguments
:param width: the pen width.
:param color: the pen color.
:param cap: the cap style: rounded, flatted and squared.
:param line_style: dashed, solid ...
:param join: miter , rounded ...
:return: None
"""
if pen == None:
self.__pen.setWidth(width) # set the pen width
self.__pen.setColor(color) # define your color from QtCore, it is safer to use the statement:
self.__pen.setCapStyle(cap) # set the cap style of the line
self.__pen.setStyle(line_style) # set the line style for instance: solid, dash... whatever
self.__pen.setJoinStyle(join) # set how the lines will be connected.
else:
self.__pen = pen
def paint(self, painter: QtGui.QPainter, option: QtWidgets.QStyleOptionGraphicsItem,
widget: typing.Optional[QtWidgets.QWidget] = ...) -> None:
painter.setPen(self.getPen())
painter.setRenderHint(QtGui.QPainter.HighQualityAntialiasing)
try:
path = QtGui.QPainterPath()
path.moveTo(self.getPoints()[0])
for point in self.getPoints():
path.lineTo(point)
painter.drawPath(path)
except IndexError:
self.append(QtCore.QPointF(0, 0))
class Producer(QtCore.QObject):
def __init__(self, parent=None):
super(Producer, self).__init__(parent)
self.__last_point = QtCore.QPointF(10, 0)
self.__point = QtCore.QPointF(10, 0)
self.upper = 10
self.bottom = 0
def setPoint(self) -> None:
self.setLastpoint(self.getPoint())
x = random.randint(self.bottom, self.upper)
y = random.randint(self.bottom, self.upper)
self.upper += 50 # increases the range of probability at the upper limit
self.__point = QtCore.QPointF(x, y) # produce a new random point
def getPoint(self) -> QtCore.QPointF:
return self.__point
def setLastpoint(self, point: QtCore.QPointF):
self.__last_point = point
def getLastPoint(self) -> QtCore.QPointF:
return self.__last_point
class Window2(QtWidgets.QMainWindow):
def __init__(self):
super(Window2, self).__init__()
central_widget = QtWidgets.QWidget()
self.__pen = QtGui.QPen()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.setCentralWidget(central_widget)
self.setPen()
def getPen(self) -> QtGui.QPen:
return self.__pen
def getTrack(self):
print('run')
self.producer.setPoint()
line = QtCore.QLineF(self.producer.getPoint(), self.producer.getLastPoint())
self.scene.addLine(line, pen = self.getPen())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
print(dx, dy)
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
def setPen(self, pen: QtGui.QPen = None, width: int = 10, color: QtGui.QColor = QtGui.QColor(0, 24, 128, 100),
cap: QtCore.Qt.PenCapStyle = QtCore.Qt.SquareCap, line_style: QtCore.Qt.PenStyle = QtCore.Qt.SolidLine,
join: QtCore.Qt.PenJoinStyle = QtCore.Qt.RoundJoin) -> None:
"""
Set the pen that will be used to paint the implement.
:param pen : set the pen or its arguments
:param width: the pen width.
:param color: the pen color.
:param cap: the cap style: rounded, flatted and squared.
:param line_style: dashed, solid ...
:param join: miter , rounded ...
:return: None
"""
if pen == None:
self.__pen.setWidth(width) # set the pen width
self.__pen.setColor(color) # define your color from QtCore, it is safer to use the statement:
self.__pen.setCapStyle(cap) # set the cap style of the line
self.__pen.setStyle(line_style) # set the line style for instance: solid, dash... whatever
self.__pen.setJoinStyle(join) # set how the lines will be connected.
else:
self.__pen = pen
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
# w = Window()
w = Window2()
w.show()
sys.exit(app.exec_())
我使用的第二种方法是创建一条由点组成的连续路径。这个路径继承了class:QGraphicsPathItem。但是，当我 'update' 我的 'scene Rectangle' 这条路径的一端在我的边界之外时消失 = 'scene Rectangle'。有什么办法可以防止它消失吗？
我正在采用的这种方法的第二个问题是我需要保存构成我的路径的这些点......对于少量点这不是问题但是当我的路径充满点时它会有内存管理问题。图片：
代码在这里：
class Window(QtWidgets.QMainWindow):
def __init__(self):
super(Window, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.track = Track()
self.scene.addItem(self.track)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
print(dx, dy)
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
我正在模拟 GPS，我正在绘制的路径是
汽车的排量。但我不知道这两种方法中哪一种更好，是否还有另一种方法。
这里是一个最小的可重现示例：
from PyQt5 import QtWidgets, QtCore, QtGui
import typing
import random
pen = QtGui.QPen()
pen.setColor(QtGui.QColor(0, 24, 128, 100))
pen.setWidth(10)
pen.setStyle(QtCore.Qt.SolidLine)
pen.setCapStyle(QtCore.Qt.SquareCap)
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points: list = [QtCore.QPointF(0, 0)]
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
def paint(self, painter: QtGui.QPainter, option: QtWidgets.QStyleOptionGraphicsItem,
widget: typing.Optional[QtWidgets.QWidget] = ...) -> None:
painter.setPen(pen)
painter.setRenderHint(QtGui.QPainter.HighQualityAntialiasing)
path = QtGui.QPainterPath()
path.moveTo(self.getPoints()[0])
for point in self.getPoints():
path.lineTo(point)
painter.drawPath(path)
class Producer(QtCore.QObject):
def __init__(self, parent=None):
super(Producer, self).__init__(parent)
self.__last_point = QtCore.QPointF(10, 0)
self.__point = QtCore.QPointF(10, 0)
self.upper = 10
def setPoint(self) -> None:
self.setLastpoint(self.getPoint())
x = random.randint(0, self.upper)
y = random.randint(0, self.upper)
self.upper += 50 # increases the range of probability at the upper limit
self.__point = QtCore.QPointF(x, y) # produce a new random point
def getPoint(self) -> QtCore.QPointF:
return self.__point
def setLastpoint(self, point: QtCore.QPointF):
self.__last_point = point
def getLastPoint(self) -> QtCore.QPointF:
return self.__last_point
class Window(QtWidgets.QMainWindow):
def __init__(self):
super(Window, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.track = Track()
self.scene.addItem(self.track)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
class Window2(QtWidgets.QMainWindow):
def __init__(self):
super(Window2, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.scene.addLine(QtCore.QLineF(self.producer.getPoint(), self.producer.getLastPoint()), pen=pen)
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
# w = Window()
w = Window2()
w.show()
sys.exit(app.exec_())
使用多段显然不是正确的选择，因为线条被认为是独立的元素，没有折叠边缘是不可能绘制它们的。
关于 QPainterPath 方法最重要的问题是，当您使用 QGraphicsPathItem 时，您 根本没有 使用它，因为您正在覆盖它的 paint() 方法。
手动绘制路径使其完全无用，您应该使用它的 setPath() 代替。
你的实现也是错误的，因为它没有考虑路径的其余部分，并且使用增量翻译。正如在对您的另一个问题的评论中已经建议的那样，增量转换通常不是一个好主意，因为它们通常会产生误导并且通常会导致意外行为（就像在这种情况下一样）。
解决方法是正确使用QGraphicsPathItem:
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points = [QtCore.QPointF(0, 0)]
<b>self.setPen(pen)</b>
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
<b>path = self.path()
path.lineTo(point)
self.setPath(path)</b>
# no paint method override!
那么，为了保证item始终可见，可以使用已有的ensureVisible(item) or the centerOn(item)方法；请注意，我还删除了第一个 setSceneRect() 调用，这是因为将其保留为默认值可确保视图的 sceneRect 始终更新为场景的 sceneRect，默认为项目的除非明确指定，否则边界矩形：
class Window(QtWidgets.QMainWindow):
def __init__(self):
# ...
# remove the following!
<b># self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())</b>
# set the antialiasing for the whole view
<b>self.view.setRenderHints(QtGui.QPainter.HighQualityAntialiasing)</b>
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
<b>self.view.centerOn(self.track)</b>
# no setSceneRect() even here
最后，您真的不应该太在意内存使用情况。 QPoints 的内存占用非常小，如果您担心系统无法支持它，那么您就偏离了轨道：您需要大约 20 thousand 点才能获得只有一兆字节的内存。
注意与问题无关：我会避免不必要地过度使用类型提示。 Python 将始终保持动态类型的语言，虽然使用它们并不被认为是不好的做法，但过多地使用它们只会分散注意力，尤其是在处理 [=45= 内部使用的重写方法时];例如，paint() 中的类型提示是完全不需要的，因为您可以确定所有参数将始终以正确的类型调用
我试图通过两种方式绘制一条由线组成的路径： 首先，路径由直线构成，直线有共同的末端。使用这种方法的问题是线条在四肢重叠，导致不良影响，如下图所示：
这是代码：
from PyQt5 import QtWidgets, QtCore, QtGui
import typing
import random
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points: list = [QtCore.QPointF(0, 0)]
self.__pen: QtGui.QPen = QtGui.QPen()
self.setPen()
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
def getPen(self) -> QtGui.QPen:
return self.__pen
def setPen(self, pen: QtGui.QPen = None, width: int = 10, color: QtGui.QColor = QtGui.QColor(0, 24, 128, 100),
cap: QtCore.Qt.PenCapStyle = QtCore.Qt.SquareCap, line_style: QtCore.Qt.PenStyle = QtCore.Qt.SolidLine,
join: QtCore.Qt.PenJoinStyle = QtCore.Qt.RoundJoin) -> None:
"""
Set the pen that will be used to paint the implement.
:param pen : set the pen or its arguments
:param width: the pen width.
:param color: the pen color.
:param cap: the cap style: rounded, flatted and squared.
:param line_style: dashed, solid ...
:param join: miter , rounded ...
:return: None
"""
if pen == None:
self.__pen.setWidth(width) # set the pen width
self.__pen.setColor(color) # define your color from QtCore, it is safer to use the statement:
self.__pen.setCapStyle(cap) # set the cap style of the line
self.__pen.setStyle(line_style) # set the line style for instance: solid, dash... whatever
self.__pen.setJoinStyle(join) # set how the lines will be connected.
else:
self.__pen = pen
def paint(self, painter: QtGui.QPainter, option: QtWidgets.QStyleOptionGraphicsItem,
widget: typing.Optional[QtWidgets.QWidget] = ...) -> None:
painter.setPen(self.getPen())
painter.setRenderHint(QtGui.QPainter.HighQualityAntialiasing)
try:
path = QtGui.QPainterPath()
path.moveTo(self.getPoints()[0])
for point in self.getPoints():
path.lineTo(point)
painter.drawPath(path)
except IndexError:
self.append(QtCore.QPointF(0, 0))
class Producer(QtCore.QObject):
def __init__(self, parent=None):
super(Producer, self).__init__(parent)
self.__last_point = QtCore.QPointF(10, 0)
self.__point = QtCore.QPointF(10, 0)
self.upper = 10
self.bottom = 0
def setPoint(self) -> None:
self.setLastpoint(self.getPoint())
x = random.randint(self.bottom, self.upper)
y = random.randint(self.bottom, self.upper)
self.upper += 50 # increases the range of probability at the upper limit
self.__point = QtCore.QPointF(x, y) # produce a new random point
def getPoint(self) -> QtCore.QPointF:
return self.__point
def setLastpoint(self, point: QtCore.QPointF):
self.__last_point = point
def getLastPoint(self) -> QtCore.QPointF:
return self.__last_point
class Window2(QtWidgets.QMainWindow):
def __init__(self):
super(Window2, self).__init__()
central_widget = QtWidgets.QWidget()
self.__pen = QtGui.QPen()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.setCentralWidget(central_widget)
self.setPen()
def getPen(self) -> QtGui.QPen:
return self.__pen
def getTrack(self):
print('run')
self.producer.setPoint()
line = QtCore.QLineF(self.producer.getPoint(), self.producer.getLastPoint())
self.scene.addLine(line, pen = self.getPen())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
print(dx, dy)
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
def setPen(self, pen: QtGui.QPen = None, width: int = 10, color: QtGui.QColor = QtGui.QColor(0, 24, 128, 100),
cap: QtCore.Qt.PenCapStyle = QtCore.Qt.SquareCap, line_style: QtCore.Qt.PenStyle = QtCore.Qt.SolidLine,
join: QtCore.Qt.PenJoinStyle = QtCore.Qt.RoundJoin) -> None:
"""
Set the pen that will be used to paint the implement.
:param pen : set the pen or its arguments
:param width: the pen width.
:param color: the pen color.
:param cap: the cap style: rounded, flatted and squared.
:param line_style: dashed, solid ...
:param join: miter , rounded ...
:return: None
"""
if pen == None:
self.__pen.setWidth(width) # set the pen width
self.__pen.setColor(color) # define your color from QtCore, it is safer to use the statement:
self.__pen.setCapStyle(cap) # set the cap style of the line
self.__pen.setStyle(line_style) # set the line style for instance: solid, dash... whatever
self.__pen.setJoinStyle(join) # set how the lines will be connected.
else:
self.__pen = pen
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
# w = Window()
w = Window2()
w.show()
sys.exit(app.exec_())
我使用的第二种方法是创建一条由点组成的连续路径。这个路径继承了class:QGraphicsPathItem。但是，当我 'update' 我的 'scene Rectangle' 这条路径的一端在我的边界之外时消失 = 'scene Rectangle'。有什么办法可以防止它消失吗？ 我正在采用的这种方法的第二个问题是我需要保存构成我的路径的这些点......对于少量点这不是问题但是当我的路径充满点时它会有内存管理问题。图片：
代码在这里：
class Window(QtWidgets.QMainWindow):
def __init__(self):
super(Window, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.track = Track()
self.scene.addItem(self.track)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
print(dx, dy)
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
我正在模拟 GPS，我正在绘制的路径是 汽车的排量。但我不知道这两种方法中哪一种更好，是否还有另一种方法。
这里是一个最小的可重现示例：
from PyQt5 import QtWidgets, QtCore, QtGui
import typing
import random
pen = QtGui.QPen()
pen.setColor(QtGui.QColor(0, 24, 128, 100))
pen.setWidth(10)
pen.setStyle(QtCore.Qt.SolidLine)
pen.setCapStyle(QtCore.Qt.SquareCap)
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points: list = [QtCore.QPointF(0, 0)]
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
def paint(self, painter: QtGui.QPainter, option: QtWidgets.QStyleOptionGraphicsItem,
widget: typing.Optional[QtWidgets.QWidget] = ...) -> None:
painter.setPen(pen)
painter.setRenderHint(QtGui.QPainter.HighQualityAntialiasing)
path = QtGui.QPainterPath()
path.moveTo(self.getPoints()[0])
for point in self.getPoints():
path.lineTo(point)
painter.drawPath(path)
class Producer(QtCore.QObject):
def __init__(self, parent=None):
super(Producer, self).__init__(parent)
self.__last_point = QtCore.QPointF(10, 0)
self.__point = QtCore.QPointF(10, 0)
self.upper = 10
def setPoint(self) -> None:
self.setLastpoint(self.getPoint())
x = random.randint(0, self.upper)
y = random.randint(0, self.upper)
self.upper += 50 # increases the range of probability at the upper limit
self.__point = QtCore.QPointF(x, y) # produce a new random point
def getPoint(self) -> QtCore.QPointF:
return self.__point
def setLastpoint(self, point: QtCore.QPointF):
self.__last_point = point
def getLastPoint(self) -> QtCore.QPointF:
return self.__last_point
class Window(QtWidgets.QMainWindow):
def __init__(self):
super(Window, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.track = Track()
self.scene.addItem(self.track)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
class Window2(QtWidgets.QMainWindow):
def __init__(self):
super(Window2, self).__init__()
central_widget = QtWidgets.QWidget()
self.setMinimumHeight(500)
self.setMinimumWidth(500)
self.scene = QtWidgets.QGraphicsScene(self)
self.view = QtWidgets.QGraphicsView(self.scene)
self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())
self.btn = QtWidgets.QPushButton('Get Track')
self.btn.clicked.connect(self.getTrack)
self.producer = Producer()
hbox = QtWidgets.QHBoxLayout(central_widget)
hbox.addWidget(self.view)
hbox.addWidget(self.btn)
self.setCentralWidget(central_widget)
def getTrack(self):
self.producer.setPoint()
self.scene.addLine(QtCore.QLineF(self.producer.getPoint(), self.producer.getLastPoint()), pen=pen)
dx = self.producer.getPoint().x() - self.producer.getLastPoint().x()
dy = self.producer.getPoint().y() - self.producer.getLastPoint().y()
self.view.setSceneRect(self.view.sceneRect().translated(dx, dy))
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
# w = Window()
w = Window2()
w.show()
sys.exit(app.exec_())
使用多段显然不是正确的选择，因为线条被认为是独立的元素，没有折叠边缘是不可能绘制它们的。
关于 QPainterPath 方法最重要的问题是，当您使用 QGraphicsPathItem 时，您 根本没有 使用它，因为您正在覆盖它的 paint() 方法。
手动绘制路径使其完全无用，您应该使用它的 setPath() 代替。
你的实现也是错误的，因为它没有考虑路径的其余部分，并且使用增量翻译。正如在对您的另一个问题的评论中已经建议的那样，增量转换通常不是一个好主意，因为它们通常会产生误导并且通常会导致意外行为（就像在这种情况下一样）。
解决方法是正确使用QGraphicsPathItem:
class Track(QtWidgets.QGraphicsPathItem):
def __init__(self, parent=None, offset: float = 50):
super(Track, self).__init__(parent) # initiate the parent class
self.__points = [QtCore.QPointF(0, 0)]
<b>self.setPen(pen)</b>
def getPoints(self) -> list:
return self.__points
def append(self, point: QtCore.QPointF):
self.__points.append(point)
<b>path = self.path()
path.lineTo(point)
self.setPath(path)</b>
# no paint method override!
那么，为了保证item始终可见，可以使用已有的ensureVisible(item) or the centerOn(item)方法；请注意，我还删除了第一个 setSceneRect() 调用，这是因为将其保留为默认值可确保视图的 sceneRect 始终更新为场景的 sceneRect，默认为项目的除非明确指定，否则边界矩形：
class Window(QtWidgets.QMainWindow):
def __init__(self):
# ...
# remove the following!
<b># self.view.setSceneRect(self.view.mapToScene(self.view.viewport().rect()).boundingRect())</b>
# set the antialiasing for the whole view
<b>self.view.setRenderHints(QtGui.QPainter.HighQualityAntialiasing)</b>
def getTrack(self):
self.producer.setPoint()
self.track.append(self.producer.getPoint())
<b>self.view.centerOn(self.track)</b>
# no setSceneRect() even here
最后，您真的不应该太在意内存使用情况。 QPoints 的内存占用非常小，如果您担心系统无法支持它，那么您就偏离了轨道：您需要大约 20 thousand 点才能获得只有一兆字节的内存。
注意与问题无关：我会避免不必要地过度使用类型提示。 Python 将始终保持动态类型的语言，虽然使用它们并不被认为是不好的做法，但过多地使用它们只会分散注意力，尤其是在处理 [=45= 内部使用的重写方法时];例如，paint() 中的类型提示是完全不需要的，因为您可以确定所有参数将始终以正确的类型调用