如何通过在PyQt5中拖动图形来移动图形（使用paintEvent创建）

Question

我已经在画布上的任意位置创建了一个圆，但是仅通过单击并拖动它就无法移动或编辑其属性（如标签）。我想创建一个可通过拖动移动的圆，并且其标签之类的属性可随时编辑，请提出修改建议或新方法。我是初学者，请帮助...

import sys
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow,QPushButton,QWidget
from PyQt5 import QtGui
from PyQt5.QtCore import QRect,Qt
from PyQt5.QtGui import QPainter,QBrush, QPen
from PyQt5 import QtCore
from random import randint

class Window(QMainWindow):
    def __init__(self):
        super(Window,self).__init__()
        title="layout management"
        left=500
        top=200
        width=500
        height=400
        iconName="Ash.jpg"
        self.setWindowTitle(title)
        self.setWindowIcon(QtGui.QIcon(iconName))
        self.setGeometry(left, top, width, height)
        self.should_paint_circle = False
        self.windowcomponents()
        self.initUI()
        self.show()
    def initUI(self):
        if self.should_paint_circle:
            self.label=QtWidgets.QLabel(self)
            self.label.setText('<h2>circle<h2>')
    def windowcomponents(self):
        button=QPushButton("Add", self)
        button.setGeometry(QRect(0, 0, 50, 28))
        button.setIcon(QtGui.QIcon("addbutton.png"))
        button.setToolTip("<h3>This is for creating random circles<h3>")
        button.clicked.connect(self.paintcircle)
        button=QPushButton("Generate Report", self)
        button.setGeometry(QRect(49,0,150,28))
        button.setIcon(QtGui.QIcon("generatereport.png"))
        button.setToolTip("This is for generating pdf report of connection between two circles")
        button=QPushButton("Save", self)
        button.setGeometry(QRect(199,0,120,28))
        button.setIcon(QtGui.QIcon("saveicon.png"))
        button.setToolTip("This is for saving an image of canvas area")

    def paintEvent(self, event):
        super().paintEvent(event)
        if self.should_paint_circle:
            painter = QtGui.QPainter(self)
            painter.setRenderHint(QPainter.Antialiasing)
            painter.setPen(QPen(Qt.black, 5, Qt.SolidLine))
            painter.drawEllipse(randint(0,500), randint(0,500), 100, 100)
            self.initUI()
            self.label.move(60,100)
    def paintcircle(self, painter):
        self.should_paint_circle = True
        self.update()
app = QApplication(sys.argv)
circle=Window()
circle.show()
sys.exit(app.exec_())

图像在窗口中的随机位置处显示一个圆，不可拖动

Answer 1

解决方案是相似的，仅在如何确定按下的点是否在圆内方面更改了代码：

import random
import sys

from PyQt5 import QtCore, QtGui, QtWidgets


class Window(QtWidgets.QMainWindow):
    def __init__(self):
        super(Window, self).__init__()

        self.rect = QtCore.QRect()
        self.drag_position = QtCore.QPoint()

        button = QtWidgets.QPushButton("Add", self)
        button.clicked.connect(self.on_clicked)

        self.resize(640, 480)

    @QtCore.pyqtSlot()
    def on_clicked(self):
        if self.rect.isNull():
            self.rect = QtCore.QRect(
                QtCore.QPoint(*random.sample(range(200), 2)), QtCore.QSize(100, 100)
            )
            self.update()

    def paintEvent(self, event):
        super().paintEvent(event)
        if not self.rect.isNull():
            painter = QtGui.QPainter(self)
            painter.setRenderHint(QtGui.QPainter.Antialiasing)
            painter.setPen(QtGui.QPen(QtCore.Qt.black, 5, QtCore.Qt.SolidLine))
            painter.drawEllipse(self.rect)

    def mousePressEvent(self, event):
        if (
            2 * QtGui.QVector2D(event.pos() - self.rect.center()).length()
            &lt self.rect.width()
        ):
            self.drag_position = event.pos() - self.rect.topLeft()
        super().mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if not self.drag_position.isNull():
            self.rect.moveTopLeft(event.pos() - self.drag_position)
            self.update()
        super().mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        self.drag_position = QtCore.QPoint()
        super().mouseReleaseEvent(event)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    Rect = Window()
    Rect.show()
    sys.exit(app.exec_())