Pygame Subset for Android Sprite Optimization with RenderUpdates

In order to get 2D map games written in python working faster on low-end Android phones, I experimented with optimizations. I purposely selected a complex background image in order to stress the application.

The first set of huge gains came from using the Surface.convert_alpha() method to optimize the images. This was easy and resulted in significant performance gains.

The trickier part was to update only the sections of the screen that had changed since the last cycle.

I decided to use sprites for this since many of the optimization examples I've seen use sprites.  Instead of using pygame.sprite.Group, I used pygame.sprite.RenderUpdates.  This is basically the same as the sprite group, but it as the enhanced ability to track the changed areas of the screen.

The images in the group are drawn to the screen with the standard sprite.Group.draw(SCREEN) method.  The cool little addition is the RenderUpdates.clear(SCREEN, background) method which clears the sprite by blitting a piece of the background over it.  Nice.

The final section is to update the display with a list of the rectangles, pygame.display.update(rectlist).

That's the main things to change.  I experimented with not ticking the pygame.time.Clock under android.   I'm not sure if it makes a difference, but the application appeared to me to run slower on android when I used the clock tick.

This is the first time that I've used this bit of code to pause the android device when the user hits things like the home button on the phone.

if android: if android.check_pause(): android.wait_for_resume()
I was pretty happy that my alpha transparency worked with the sprite group.
def __init__(self): pygame.sprite.Sprite.__init__(self) self.image = pygame.Surface((60, 60)) self.image.fill(GREEN) self.image.set_alpha(70)

I also experimented with different ways to optimize the events. However, I couldn't find anything useful.

Here's the full code.
__author__ = 'craig' import pygame, sys import random class Player(pygame.sprite.Sprite): def __init__(self): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("ninja.png").convert_alpha() self.rect = pygame.Rect(226, 100, 32, 32) self.direction = "stop" self.mouse_press = False def update(self): if self.mouse_press: if self.direction == "right" and self.rect.centerx < 480: self.rect.centerx += 8 elif self.direction == "left" and self.rect.centerx > 0: self.rect.centerx -= 8 elif self.direction == "up" and self.rect.centery > 0: self.rect.centery -= 8 elif self.direction == "down" and self.rect.centery < 320: self.rect.centery += 8 class Control(pygame.sprite.Sprite): def __init__(self): pygame.sprite.Sprite.__init__(self) self.image = pygame.Surface((60, 60)) self.image.fill(GREEN) self.image.set_alpha(70) class Girl(pygame.sprite.Sprite): def __init__(self, x): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("girl.png").convert_alpha() self.rect = pygame.Rect(x, 5, 32, 32) self.direction = "down" self.speed = random.randrange(1, 3) def update(self): if self.direction == "down": if self.rect.centery < 320: self.rect.centery += self.speed else: self.direction = "up" self.speed = random.randrange(1,3) elif self.direction == "up": if self.rect.centery > 0: self.rect.centery -= self.speed else: self.direction = "down" self.speed = random.randrange(1,3) try: import android except ImportError: android = None pygame.init() if android: android.init() android.map_key(android.KEYCODE_BACK, pygame.K_ESCAPE) SCREEN = pygame.display.set_mode((480, 320)) BLACK = (0, 0, 0) RED = (255, 0, 0) GREEN = (0, 255, 0) DARKGREEN = (0x0b, 0x61, 0x0b) clock = pygame.time.Clock() mouse_pos = (0,0) mouse_press = False control_left_rect = pygame.Rect(300, 170, 60, 60) control_right_rect = pygame.Rect(400, 170, 60, 60) control_up_rect = pygame.Rect(350, 100, 60, 60) control_down_rect = pygame.Rect(350, 240, 60, 60) control_list = [control_left_rect, control_right_rect, control_up_rect, control_down_rect] control_group = pygame.sprite.RenderUpdates() for control_rect in control_list: control = Control() control.rect = control_rect control_group.add(control) player = Player() player_group = pygame.sprite.RenderUpdates() player_group.add(player) girl_group = pygame.sprite.RenderUpdates() for x in range (80, 480, 80): girl = Girl(x) girl_group.add(girl) direction = "stop" background = pygame.image.load("background.png").convert_alpha() SCREEN.blit(background, (0,0)) pygame.display.update() pygame.event.set_allowed([pygame.KEYDOWN, pygame.MOUSEBUTTONDOWN, pygame.MOUSEBUTTONUP, pygame.QUIT, pygame.ACTIVEEVENT]) while True: if android: if android.check_pause(): android.wait_for_resume() for event in pygame.event.get(): #event = pygame.event.poll() if (event.type == pygame.QUIT) or (event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE): pygame.quit() sys.exit() elif event.type == pygame.MOUSEBUTTONDOWN: mouse_press = True elif event.type == pygame.MOUSEBUTTONUP: mouse_press = False mouse_pos = pygame.mouse.get_pos() control_group.clear(SCREEN, background) control_rect_list = control_group.draw(SCREEN) # SCREEN.blit(background, (0,0)) if mouse_press and control_left_rect.collidepoint(mouse_pos): pygame.draw.rect(SCREEN, DARKGREEN, control_left_rect) direction = "left" if mouse_press and control_right_rect.collidepoint(mouse_pos): pygame.draw.rect(SCREEN, DARKGREEN, control_right_rect) direction = "right" if mouse_press and control_up_rect.collidepoint(mouse_pos): pygame.draw.rect(SCREEN, DARKGREEN, control_up_rect) direction = "up" if mouse_press and control_down_rect.collidepoint(mouse_pos): pygame.draw.rect(SCREEN, DARKGREEN, control_down_rect) direction = "down" player.mouse_press = mouse_press player.direction = direction player_group.update() player_group.clear(SCREEN, background) rectlist = player_group.draw(SCREEN) girl_group.update() girl_group.clear(SCREEN, background) girl_rectlist = girl_group.draw(SCREEN) rectlist.extend(control_rect_list) rectlist.extend(girl_rectlist) pygame.event.pump() if not android: clock.tick(40) pygame.display.update(rectlist)