Copy of example program with some comments and modifications

watersteal.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+
+import sys, pygame
+
+pygame.init()
+
+# Define screen size
+size = width, height = 640, 480
+
+speed = [1, 1]
+
+# Define colors
+black = 0, 0, 0
+white = 255, 255, 255
+
+# Set up screen
+screen = pygame.display.set_mode(size)
+
+# Define ball
+ball = pygame.image.load("ball.bmp")
+ballrect = ball.get_rect()
+
+while True:
+    # Handle events
+    for event in pygame.event.get():
+        # Handle keypresses
+        if event.type == pygame.KEYDOWN:
+            pressedKeys = pygame.key.get_pressed()
+
+            if pressedKeys[pygame.K_q]:
+                sys.exit()
+
+        if event.type == pygame.QUIT:
+            sys.exit()
+
+    # Move ball
+    ballrect = ballrect.move(speed)
+
+    # Direct ball movement
+    if ballrect.left < 0 or ballrect.right > width:
+        speed[0] = -speed[0]
+    if ballrect.top < 0 or ballrect.bottom > height:
+        speed[1] = -speed[1]
+
+    # Fill screen buffer with black color
+    screen.fill(black)
+
+    # Draw ball on buffer
+    screen.blit(ball, ballrect)
+
+    # Upload buffer to real screen
+    pygame.display.flip()