PyGame rect.move movement not functioning properly

Question

I am developing my first pygame application in the form of a brick breaker clone. For the player paddle, I am checking for key holds in the main game loop and then redrawing the player object's sprite every frame, as show in the code snippet below:

class Player():

def __init__(self):
    self.sprite = pg.transform.scale(pg.image.load('49-Breakout-Tiles.png'), (61,16))
    self.rect = self.sprite.get_rect()
    self.rect.right += displayRect.center[0]-25
    self.rect.top += displayRect.center[1]+450
    self.draw(0)

def draw(self, x):
    pg.draw.rect(display, black, (self.rect.x, self.rect.y, 61, 16))
    self.rect.right += x

    if not displayRect.contains(self.rect):
        self.rect.right -= x

    display.blit(self.sprite, self.rect)


#from gameloop
moveNeg, movePos = False, False

while True:
    for event in pg.event.get():
        if event.type == pg.KEYDOWN:
            if event.key == pg.K_LEFT or event.key == pg.K_a:
                moveNeg = True
            if event.key == pg.K_RIGHT or event.key == pg.K_d:
                movePos = True
        if event.type == pg.KEYUP:
            if event.key == pg.K_LEFT or event.key == pg.K_a:
                moveNeg = False
            if event.key == pg.K_RIGHT or event.key == pg.K_d:
                movePos = False

    if moveNeg:
        player.draw(-1)
    if movePos:
        player.draw(1)

This code works fine, and also ensures that the player paddle stays within the display bounds.

However, for the ball object, I am trying to use rect.move(x,y) to move it. I have already tried with rect.right and rect.top but the ball object is still unresponsive. Here is the code I have so far:

class Ball():

def __init__(self):
    self.sprite = pg.transform.scale(pg.image.load('58-Breakout-Tiles.png'), (16, 16))
    self.rect = self.sprite.get_rect()
    self.rect.x += displayRect.center[0]
    self.rect.y += displayRect.center[1]
    self.dir = [random.uniform(-1.0,1.0), random.uniform(-1.0,1.0)]
    print(self.dir)

def draw(self, xy):
    pg.draw.rect(display, black, (self.rect.x, self.rect.y, 16, 16))
    self.rect = self.rect.move(xy[0], xy[1])
    display.blit(self.sprite, self.rect)

The ball is centered when the object is initialised (as shown on lines 3/4 of the __init__ function, but I don't see why this would affect the movement of the ball's rect . Also for clarity, self.dir is used to give the ball a random starting direction, and I am aware that it is able to move upward with this current configuration.

Since I am new to pygame it completely baffles me as to why my logic is flawed so any help is much appreciated. Thanks

Answer 1

pygame.Rect.move doesn't change the Rect object itself, but it returns an new Rect object (Probably the name of the method is misleading).

This means, that

self.rect.move(xy[0], xy[1])

doesn't change anything. You've to assign the rectangle which is returned by .move to "itself":

self.rect = self.rect.move(xy)

---

Alternatively you can use pygame.Rect.move_ip() , moves the rectangle "in place" and changes the Rect object:

self.rect.move_ip(xy[0], xy[1])