Time lag during a chess game in pyqt5 python

Question

I've been designing a GUI-based chess game in PyQt5 (Python) . Since it is incomplete , there are some issues . But the biggest issue is , that after every move , the time lag in the GUI increases . After a particular time (say , move 8) , the GUI would almost stop working . Please help . The code is given below :

import PyQt5
from PyQt5 import QtWidgets
from PyQt5 import QtCore
from PyQt5 import QtGui
from PyQt5 import uic

import chess

import sys
import tabulate


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

        uic.loadUi("CHESS.ui", self)

        self.move_name = ""
        self.move = ""

        self.board_rows = [8,7,6,5,4,3,2,1]
        self.board_columns = 'a b c d e f g h'.split(" ")
        # variable_needed = f"{self.board_columns[7-(n//8)]}{self.board_rows[n%8]}"

        font = QtGui.QFont()
        font.setPointSize(1)

        self.win = None
        self.draw = None
        self.valid_move = True

        self.Chess_Board = {n:QtWidgets.QPushButton(self) for n in range(64)}

        for i in range(64):
            self.Chess_Board[i].setStyleSheet("QPushButton {background-color : lightgreen ; color : lightgreen}")
            self.Chess_Board[i].setFont(font)
            self.Chess_Board[i].setObjectName(f"{self.board_columns[i%8]}{self.board_rows[i//8]}")

        self.lineEdit_2.setDisabled(True)

        for i in range(64):
            if (i // 8) % 2 == 0:
                if i % 2 == 0:
                    self.Chess_Board[i].setStyleSheet("QPushButton {background-color : white}")

            if (i // 8) % 2 == 1:
                if i % 2 == 1:
                    self.Chess_Board[i].setStyleSheet("QPushButton {background-color : white}")
                
            self.Chess_Board[i].setGeometry(60+((i%8)*50),140+((i//8)*50),50,50)
            self.Chess_Board[i].clicked.connect(self.initiate_move)

        self.lineEdit.isReadOnly()
        self.pushButton_A.clicked.connect(self.play_move)
        self.pushButton_B.clicked.connect(self.resignation)
        self.pushButton_C.clicked.connect(self.draw_game)
        self.pushButton_D.clicked.connect(self.save_game)
        self.pushButton_E.clicked.connect(self.reset_game)

        self.board = chess.Board()

        self.chessboard()
        self.show_board()

        self.show()


    def chessboard(self):
        self.pgn = self.board.epd()

        self.final_list = []
        self.printable_list = []

        pieces = self.pgn.split(" ", 1)[0]
        rows = pieces.split("/")

        for row in rows:
            self.initial_list = []

            for chessmen in row:
                if chessmen.isdigit():
                    for i in range(0, int(chessmen)):
                        self.initial_list.append(".")

                else:
                    self.initial_list.append(chessmen)
               
            self.final_list.append(self.initial_list)


    def initiate_move(self):
        for i in range(64):
            self.Chess_Board[i].setStyleSheet("QPushButton {background-color : lightgreen ; color : lightgreen}")

            if (i // 8) % 2 == 0:
                if i % 2 == 0:
                    self.Chess_Board[i].setStyleSheet("QPushButton {background-color : white}")

            if (i // 8) % 2 == 1:
                if i % 2 == 1:
                    self.Chess_Board[i].setStyleSheet("QPushButton {background-color : white}")

        self.value = self.sender()
        self.move = self.value.text().upper()

        if self.move == "":
            pass

        elif len(self.move) == 1:
            if self.move == "P":
                pass
            else:
                self.move_name += self.move

            self.value.setStyleSheet("QPushButton {background-color : cyan}")

        for i in range(64):
            self.Chess_Board[i].clicked.connect(self.play_move)        


    def play_move(self):
        self.textBrowser.setText("")
        self.valid_move = True

        self.button = self.sender()

        if len(self.button.text()) == 1:
            self.move_name += f"x{self.button.objectName()}"

        if self.button.text() == "":
            self.move_name += self.button.objectName()

        # if self.lineEdit.isEnabled():
        #     self.move = self.lineEdit.text()

        # elif self.lineEdit_2.isEnabled():
        #     self.move = self.lineEdit_2.text()

        try:
            self.board.push_san(self.move_name)

        except Exception as ex:
            self.textBrowser.setText(f"{ex}")
            self.valid_move = False

        if self.valid_move == True:
            if self.lineEdit.isEnabled():  
                self.lineEdit.setDisabled(True)
                self.lineEdit_2.setDisabled(False)

            else:
                self.lineEdit.setDisabled(False)
                self.lineEdit_2.setDisabled(True)

        elif self.valid_move == False:    
            self.move_name = ""
       
        if self.board.is_checkmate():
            self.textBrowser.setText("Checkmate !")
            self.win = True
            self.end_the_game()

        if self.board.is_variant_draw():
            self.textBrowser.setText("Draw !")
            self.draw = True
            self.end_the_game()

        if self.board.is_stalemate():
            self.textBrowser.setText("Stalemate !")
            self.draw = True
            self.end_the_game()

        if self.board.is_fifty_moves():
            self.textBrowser.setText("Draw by fifty-move rule !")
            self.draw = True
            self.end_the_game()

        if self.board.is_repetition():
            self.textBrowser.setText("Draw by three-fold repitition !")
            self.draw = True
            self.end_the_game()

        self.chessboard()
        self.show_board()

        for i in range(64):
            self.Chess_Board[i].clicked.connect(self.initiate_move)

        self.move = ""
        self.move_name = ""


    def show_board(self):
        for x in range(8):
            for y in range(8):
                if self.final_list[x][y].isupper():
                    self.Chess_Board[x*8+y].setText(f"{self.final_list[x][y]}".upper())
                    self.Chess_Board[x*8+y].setIcon(QtGui.QIcon(f"{self.final_list[x][y]}@.png"))
                    self.Chess_Board[x*8+y].setIconSize(QtCore.QSize(40,40))

                elif self.final_list[x][y].islower():
                    self.Chess_Board[x*8+y].setText(f"{self.final_list[x][y]}".lower())
                    self.Chess_Board[x*8+y].setIcon(QtGui.QIcon(f"{self.final_list[x][y]}&.png"))
                    self.Chess_Board[x*8+y].setIconSize(QtCore.QSize(40,40))

                elif self.final_list[x][y] == ".":
                    self.Chess_Board[x*8+y].setIcon(QtGui.QIcon())
                    self.Chess_Board[x*8+y].setText("")


    def reset_game(self):
        self.board.reset()

        self.lineEdit.setText("")
        self.lineEdit_2.setText("")
        
        self.lineEdit.setDisabled(False)
        self.lineEdit_2.setDisabled(True)

        self.textBrowser.setText("")

        self.chessboard()
        self.show_board()
        self.end_the_game()


    def draw_game(self):
        self.draw = True
        self.end_the_game()
        self.textBrowser.setText("It's a draw .")


    def resignation(self):
        if self.lineEdit.text() == self.lineEdit_2.text() == "":
            self.textBrowser.setText("Match Aborted")

        else:
            if self.move == self.lineEdit.text():
                self.win = True
                self.end_the_game()
                who_resigned = "Black"

            elif self.move == self.lineEdit_2.text():
                self.win = False
                self.end_the_game()
                who_resigned = "White"

            self.textBrowser.setText(f"{who_resigned} resigned")


    def save_game(self):
        self.chesstable = tabulate.tabulate(self.final_list, tablefmt="grid", stralign="left")

        with open("chess_save_list.txt","a") as writer:
            writer.write(self.chesstable)


    def end_the_game(self):
        if self.win != self.draw:
            self.pushButton_A.setDisabled(True)
            self.pushButton_B.setDisabled(True)
            self.pushButton_C.setDisabled(True)

            self.win, self.draw = None, None

        elif self.win == self.draw:
            self.pushButton_A.setDisabled(False)
            self.pushButton_B.setDisabled(False)
            self.pushButton_C.setDisabled(False)


app = QtWidgets.QApplication(sys.argv)
window = Chess_App()
app.exec_()

The link to get the .ui link for the code : https://github.com/Vishal01-VKP/Python-Projects/blob/master/GUIs/Games/Chess%20-%20By%20VK/CHESS.ui

Thank you .

Answer 1

It is lagging over time because after each and every move you are connecting the clicked signal again for all 64 buttons in play_move and initiate_move.. connected signal's slot function will be executed in event loop, causing the lag in game

if you are connecting the signal again doesn't mean it will disconnect previous signal but rather add other signals, so after one or two moves each move will cause the 64 signals to connect again, after 5 to 6 moves it will have more than 5000 slots connected to each signal..

If the signal is connected to slot, it will remain connected until it is destroyed or explicitly disconnected..

So Modify your code accordingly so signals doesn't have to be connected again or Disconnect the signals before connecting them again(It could work but not recommended)