如何将网格坐标转换回（x，y）？

我在PyQt5中创建一个游戏，用户可以在网格内单击以形成正方形 . 如果用户选择形成正方形的四个网格空间，则角落用线连接 . 我的代码目前看起来像这样：

import sys
from PyQt5.QtGui import QPainter, QColo, QPen, QBrush
from PyQt5.QtCore import Qt, QRect, QPoint
from PyQt5.QtWidgets import QWidget, QApplication

CELL_COUNT = 8
CELL_SIZE = 50
GRID_ORIGINX = 150
GRID_ORIGINY = 150
W_WIDTH = 700
W_HEIGHT = 700

class TribeSquares(QWidget):

def __init__(self):
    super().__init__()
    self.setGeometry(300, 300, W_WIDTH, W_HEIGHT)
    a = ''
    self.__board = [[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a],[a,a,a,a,a,a,a,a]]
    self.__row = None
    self.__col = None
    self.__clicked0 = []
    self.show()

首先，我将（x，y）坐标转换为网格坐标 .

def mousePressEvent(self, event):
    self.__x = event.x()
    self.__y = event.y()
    self.__row = (event.y() - GRID_ORIGINY) // CELL_SIZE
    self.__col = (event.x() - GRID_ORIGINX) // CELL_SIZE
    row = self.__row
    col = self.__col
    self.update()

对于另一种方法，我想将（row，col）转换回（x，y） . 我尝试颠倒过程并像这样做：

def cell2coord(self, row, col):
    return ((row * CELL_SIZE) + GRID_ORIGINX, (col * CELL_SIZE) + GRID_ORIGINY)

接下来，在paintEvent中，我尝试调用我创建的方法 .

def paintEvent(self, event):
    qp = QPainter()
    qp.begin(self)
    for r in range(CELL_COUNT):
        for c in range(CELL_COUNT):
            qp.setPen(QPen(Qt.black, 1))
            qp.drawRect(CELL_SIZE * c + GRID_ORIGINX, CELL_SIZE * r + GRID_ORIGINY, CELL_SIZE, CELL_SIZE)
            if (r, c) in self.__clicked0:
                qp.setPen(QPen(QColor(40, 85, 66), 1))
                qp.setBrush(QColor(40, 85, 66))
                qp.drawRect(CELL_SIZE * c + GRID_ORIGINX + 7.5, CELL_SIZE * r + GRID_ORIGINY + 7.5, 35, 35)
                qp.setBrush(QColor(237, 237, 237))
            elif (r, c) in self.__clicked1:
                qp.setPen(QPen(QColor(231, 181, 71), 1))
                qp.setBrush(QColor(231, 181, 71))
                qp.drawRect(CELL_SIZE * c + GRID_ORIGINX + 7.5, CELL_SIZE * r + GRID_ORIGINY + 7.5, 35, 35)
                qp.setBrush(QColor(237, 237, 237))
    for (r, c) in self.__clicked0:
        x,y = self.cell2coord(r,c)
        x2,y2 = self.cell2coord(self.__row, self.__col)
        if r == self.__row or c == self.__col:
            qp.setPen(QPen(QColor(40, 85, 66), 5))
            qp.drawLine(x, y, x2, y2)
    for (r, c) in self.__clicked1:
        if r == self.__row or c == self.__col:
            qp.setPen(QPen(QColor(231, 181, 71), 5))
            qp.drawLine(x, y, x2, y2)
    qp.end()

if __name__ == '__main__':
  app = QApplication(sys.argv)
  ex = TribeSquares()
  sys.exit(app.exec_())

但它没有用 . 线条没有显示在正确的位置，并连接用户点击网格中创建的方块 . 我能做什么？