How to draw a chessboard with Pygame and move the pieces on the board?

Question

I've been trying different ways how to get my chess pieces to drag and drop I've found ways, but the problem is that I'm using a dictionary to load my images via pygame.image.load. I've created a dictionary for my images like this:

IMAGES = {}

def loadImages():
    pieces = ['wp', 'wR', 'wN', 'wB', 'wK', 'wQ', 'bp', 'bR', 'bN', 'bB', 'bK', 'bQ']
    for piece in pieces:
        IMAGES[piece] = pygame.transform.scale(
                            pygame.image.load("images/" + piece + ".png"), 
                                              (SQ_SIZE, SQ_SIZE))
    # Note we can access an image by saying "IMAGES['wp']'

I've been through these questions for sprite drop and drag:
How to move Sprite in Pygame

Drag multiple sprites with different "update ()" methods from the same Sprite class in Pygame

python pygame - how to create a drag and drop with multiple images?

I've attempted many of these, but I can't seem to figure out how to implement any of them in my code for image dictionaries. I'm just lost. I need help. If you need anymore information or code let me know.

Answer 1

You need to createpygame.sprite.Sprite objects with the images. Create a dictionary with the sprites from the dictionary with the images. You have to create a pygame.sprite.Sprite object for each piece. Hence you have to create 8 Sprites with the image of the white pawn. Create 1 dictionary for the white pieces and one for the black pieces. Add all the pices to one pygame.sprite.Group:

class ChessSprite(pygame.sprite.Sprite):
    def __init__(self, i, j, image):
        super().__init__() 
        # [...]

white = {}
for i, f in enumerate(['wR', 'wN', 'wB', 'wQ', 'wK', 'wB', 'wN', 'wR']):
    white[f] = ChessSprite(i, 0, IMAGES[f])
for i in range(8):
    pawn_name = 'wp' + str(i+1)
    white[pawn_name] = ChessSprite(i, 1, IMAGES['wp'])

black = {}
for i, f in enumerate(['bR', 'bN', 'bB', 'bQ', 'bK', 'bB', 'bN', 'bR']):
    black[f] = ChessSprite(i, 7, IMAGES[f])
for i in range(8):
    pawn_name = 'bp' + str(i+1)
    black[pawn_name] = ChessSprite(i, 6, IMAGES['bp'])

group = pygame.sprite.Group()
group.add(white.values())
group.add(black.values())

With this setup you can drag each piece individually. See Draw Sprite and Drag multiple sprites with different “update ()” methods from the same Sprite class in Pygame.

---

Minimal example:

import pygame

class DragOperator:
    def __init__(self, sprite):
        self.sprite = sprite
        self.dragging = False
        self.rel_pos = (0, 0)
    def update(self, event_list):
        for event in event_list:
            if event.type == pygame.MOUSEBUTTONDOWN:
                self.dragging = self.sprite.rect.collidepoint(event.pos)
                self.rel_pos = event.pos[0] - self.sprite.rect.x, event.pos[1] - self.sprite.rect.y
            if event.type == pygame.MOUSEBUTTONUP:
                self.dragging = False
            if event.type == pygame.MOUSEMOTION and self.dragging:
                self.sprite.rect.topleft = event.pos[0] - self.rel_pos[0], event.pos[1] - self.rel_pos[1]

class ChessSprite(pygame.sprite.Sprite):
    def __init__(self, board_rect, i, j, image):
        super().__init__() 
        self.board = board_rect
        self.image = image 
        self.set_pos(i, j)
        self.drag = DragOperator(self)
    def set_pos(self, i, j):
        x = self.board.left + self.board.width // 8 * i + self.board.width // 16
        y = self.board.left + self.board.height // 8 * (7 - j) + self.board.height // 16
        self.rect = self.image.get_rect(center = (x, y))
    def update(self, event_list):
        self.drag.update(event_list)
        if not self.drag.dragging:
            i = max(0, min(7, (self.rect.centerx - self.board.left) // (self.board.width // 8)))
            j = 7 - max(0, min(7, (self.rect.centery - self.board.top) // (self.board.height // 8)))
            self.set_pos(i, j)
        
pygame.init()
window = pygame.display.set_mode((500, 500))
clock = pygame.time.Clock()

board = pygame.Surface(window.get_size())
board.fill((255, 255, 255))
size = (min(window.get_size()) - 20) // 8
start = (window.get_width() - size * 8) // 2, (window.get_height() - size * 8) // 2
board_rect = pygame.Rect(*start, size*8, size*8)
ts, w, h, c1, c2 = 50, *window.get_size(), (128, 128, 128), (64, 64, 64)
for y in range(8):
    for x in range(8):
        color = (192, 192, 164) if (x+y) % 2 == 0 else (96, 64, 32)
        pygame.draw.rect(board, color, (start[0]+ x*size, start[1] + y*size, size, size))

# https://en.wikipedia.org/wiki/Chess_symbols_in_Unicode
white_figures = { 'king': '♔', 'queen': '♕', 'rook': '♖', 'bishop': '♗', 'knight': '♘', 'pawn': '♙'}
black_figures = { 'king': '♚', 'queen': '♛', 'rook': '♜', 'bishop': '♝', 'knight': '♞', 'pawn': '♟'}

seguisy = pygame.font.SysFont("segoeuisymbol", size-4)
white_images = { k : seguisy.render(c, True, (255, 255, 255)) for k, c in white_figures.items() }
black_images = { k : seguisy.render(c, True, (0, 0, 0)) for k, c in black_figures.items() } 

group = pygame.sprite.Group()
figures = ['rook', 'knight', 'bishop', 'queen', 'king', 'bishop', 'knight', 'rook']
for i, figure in enumerate(figures):
    group.add(ChessSprite(board_rect, i, 0, white_images[figure]))
    group.add(ChessSprite(board_rect, i, 1, white_images['pawn']))
    group.add(ChessSprite(board_rect, i, 7, black_images[figure]))
    group.add(ChessSprite(board_rect, i, 6, black_images['pawn']))
   
run = True
while run:
    clock.tick(60)
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            run = False

    group.update(event_list)

    window.blit(board, (0, 0))
    group.draw(window)
    pygame.display.flip()

pygame.quit()
exit()