Animated color change on button hover

menu.py

@@ -36,6 +36,7 @@ class Action(TypedDict):
 
 class Button:
     PRESS_OFFSET = 2
+    HOVER_ANIMATION_STEPS = 5
 
     def __init__(self, position: pygame.Rect, text: str, cbk: Callable[[], None]):
         self.position: pygame.Rect
@@ -47,6 +48,27 @@ class Button:
         self.text_pos = pygame.Rect((self.position.left + (self.position.width - text_rect.width)/2),
                                     (self.position.top + (self.position.height - text_rect.height)/2),
                                     text_rect.width, text_rect.height)
+        self.bg_color = pygame.Color("black")
+        self.hover_bg_color = pygame.Color("violetred4")
+        self.hover_animation_step = 0
+
+    def get_bg_color(self):
+        if self.pos_is_inside(pygame.mouse.get_pos()):
+            self.hover_animation_step = min(self.hover_animation_step + 1, self.HOVER_ANIMATION_STEPS)
+        else:
+            self.hover_animation_step = max(self.hover_animation_step - 1, 0)
+
+        if self.hover_animation_step == self.HOVER_ANIMATION_STEPS:
+            return self.hover_bg_color
+        if self.hover_animation_step == 0:
+            return self.bg_color
+
+        new_color = tuple(map(lambda v: v[0] + (((v[1]-v[0])/self.HOVER_ANIMATION_STEPS)*self.hover_animation_step),
+                              zip(self.bg_color, self.hover_bg_color)))
+        return new_color
+
+    def needs_redrawing(self) -> bool:
+        return self.hover_animation_step == self.HOVER_ANIMATION_STEPS or self.hover_animation_step == 0
 
     def set_position(self, position: pygame.Rect):
         self.position = position
@@ -64,7 +86,7 @@ class Button:
         return self.text_pos
 
     def draw(self, screen: pygame.Surface):
-        pygame.draw.rect(screen, "black", self.get_position(), 0)
+        pygame.draw.rect(screen, self.get_bg_color(), self.get_position(), 0)
         self.font.render_to(screen, self.get_text_pos(), self.text, fgcolor="pink")
 
     def pos_is_inside(self, pos: Tuple) -> bool:
@@ -130,7 +152,7 @@ class MenuBoard(IBoard):
             b.handle_event(event)
 
     def draw(self, screen: pygame.Surface, force_redraw: bool):
-        if force_redraw:
+        if force_redraw or any(map(Button.needs_redrawing, self.buttons)):
             screen.fill(self.bg_color)
             for b in self.buttons:
                 b.draw(screen)