Using a function closes pygame window

hippozhipos :

The following is the String class. Using the draw function from this class in my main loop immediately closes the game without any errors and as long i dont include it, the game runs fine. It does give me the following warning.

Warning (from warnings module):
  File "C:\Users\rahul\OneDrive\Documents\A level python codes\shootingGame.py", line 44
    D.blit(self.player, (self.pos[0], self.pos[1]))
DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.

---

import math, sys, os, pygame
from pygame.locals import *

pygame.init()

win = pygame.display
D = win.set_mode((1200, 600))

class String:
    def __init__(self, x, y):
        self.pos = [x, y]
        self.dx = 0
        self.dy = 0
        self.string = pygame.Surface((1, 1)).convert_alpha()
        self.string.fill((0, 255, 0))

    def draw(self):
        angle = pygame.transform.rotate(self.string, (player.orbital_angle))
        length = math.hypot(self.dx, self.dy)
        self.string = pygame.Surface((3, length))
        D.blit(angle, (self.pos[0], self.pos[1]))

string = String(600, 300)
While True:
    string.draw()

I initially had everything in draw function in differnet functions but it got a bit messy while debugging.Specifically, it is the last two lines in draw() that's causing the window to crash i.e

self.string = pygame.Surface((3, length))
D.blit(angle, (self.pos[0], self.pos[1]))

Rabbid76 :

The position (dest) argument to pygame.Surface.blit() is ought to be a tuple of 2 integral numbers.
In your case self.pos[0] and/or self.pos[1] seems to be a floating point number.

You can get rid of the warning by rounding the floating point coordinates to integral coordinates (round):

D.blit(self.player, (round(self.pos[0]), round(self.pos[1])))

---

Furthermore you have create a Surface with an integral length and you have to rotate the surface after it is (re)created:

class String:
    # [...]

    def draw(self):

        # compute INTEGRAL length        
        length = math.hypot(self.dx, self.dy)
        length = max(1, int(length))

        # create surface
        self.string = pygame.Surface((1, length)).convert_alpha()
        self.string.fill((0, 255, 0))

        # roatet surface
        angle = pygame.transform.rotate(self.string, player.orbital_angle)

        # blit rotated surface
        D.blit(angle, (round(self.pos[0]), round(self.pos[1])))