如何通过简单地在 PyQt5 中拖动图形来移动图形（使用paintEvent 创建）

Question

我在画布中的随机位置创建了一个圆圈，但我无法通过单击并拖动它来移动或编辑它的属性，例如它的标签。 我想创建一个可通过拖动移动的圆圈，其标签等属性可随时编辑，请提出编辑建议或新方法。 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_())

图像显示窗口中随机位置的圆圈，不可拖动

Answer 1

解决方法类似，代码只改变了如何判断按下的点是否在圆内：

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() < 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_())