Pygame - rect disappears before I reach it

Question

I am trying to make a rectangle pop up when middle click is pressed, and stay popped up until I press left click in pygame.

Here is my code:

button1, button2, button3 = pygame.mouse.get_pressed()
if button2 == True:
    pygame.draw.rect(screen, ((255, 0, 0)), (0, int(h/2), int(w/6), int(h/2)-40), 0)
pygame.display.update()

The thing is, when I press middle click, the rectangle appears, then disappears instantly. I have tried putting it as while button2 == 2:, but the program hangs.

Thank you!!

Answer 1

Since you want to react to different mousebutton clicks, it's better to listen for the MOUSEBUTTONUP (or MOUSEBUTTONDOWN) events instead of using pygame.mouse.get_pressed().

You want to change the state of your application when a mousebutton is pressed, so you have to keep track of that state. In this case, a single variable will do.

Here's a minimal complete example:

import pygame, sys
pygame.init()
screen = pygame.display.set_mode((300, 300))
draw_rect = False
rect = pygame.rect.Rect((100, 100, 50, 50))
while True:
    for e in pygame.event.get():
        if e.type == pygame.QUIT:
            sys.exit()
        if e.type == pygame.MOUSEBUTTONUP:
            if e.button == 2:
                draw_rect = True
            elif e.button == 1:
                draw_rect = False

    screen.fill((255, 255, 255))
    if draw_rect:
        pygame.draw.rect(screen, (0, 0, 0), rect, 2)

    pygame.display.flip()

Answer 2

Change

button1, button2, button3 = pygame.mouse.get_pressed()
if button2 == True:
    pygame.draw.rect(screen, ((255, 0, 0)), (0, int(h/2), int(w/6), int(h/2)-40), 0)
pygame.display.update()

to

button1, button2, button3 = pygame.mouse.get_pressed()
if button2 == True:
      rect_blit=True
pygame.display.update()

then have

if rect_blit==True:
    pygame.draw.rect(screen, ((255, 0, 0)), (0, int(h/2), int(w/6), int(h/2)-40), 0)

somewhere in your main loop (before pygame.display.update).

Another thing is that you do not need to say if some_variable == True:. Instead you can just say if some_variable:. They do the exact same thing.