from .color import Color import pygame # TODO: fix this with a dynamic load from .draw_engine import DrawEngine # TODO: make configurable DEFAULT_FONT_SIZE = 24 class PygameDrawEngine(DrawEngine): # Having each bit of text on the screen load a separate copy # of its font would be wasteful, since the most common case would # be for most text to use the same font. # # The solution here is to use a class attribute, shared by *all* instances # of the class. # # This is an implementation of the Flyweight design pattern, which # allows multiple objects to share some state. # # This can quickly become a mess if the shared state is mutable, # note that here, once a font is loaded it does not change. # This avoids nearly all pitfalls associated with this approach. _fonts: dict[str, pygame.font.Font] = {} # this method is attached to the class `Text`, not individual instances # like normal methods (which take self as their implicit parameter) @classmethod def make_font(cls, name, size, font=None, bold=False, italic=False): """ The way fonts work in most graphics libraries requires choosing a font size, as well as any variation (bold, italic) at the time of creation. It would be nice if we could allow individual Text objects vary these, but doing so would be much more complex or require significantly more memory. """ if font is None: font = pygame.font.Font(None, size) else: path = pygame.font.match_font(font, bold=bold, italic=italic) font = pygame.font.Font(path, size) cls._fonts[name] = font @classmethod def get_font(cls, name=None): if not name: # None -> default font # load on demand if None not in cls._fonts: cls._fonts[None] = pygame.font.Font(None, DEFAULT_FONT_SIZE) return cls._fonts[None] else: return cls._fonts[name] def init(self): self.screen = pygame.display.set_mode((world.WIDTH, world.HEIGHT)) self.buffer = pygame.Surface((world.WIDTH, world.HEIGHT), pygame.SRCALPHA) # TODO: depending on system these fonts often do not have all the # necessary characters, find 3 widely available fonts that do world.draw_engine.make_font("small", 16, "mono") world.draw_engine.make_font("medium", 24, "copperplate") world.draw_engine.make_font("large", 48, "papyrus") def render(self, background_color: Color, drawables: list["Doodle"]): self.buffer.fill((*background_color, 255)) for d in sorted(drawables, key=lambda d: d._z_index): d.draw() self.screen.blit(self.buffer, (0, 0)) pygame.display.flip() def circle_draw(self, c: "Circle"): pygame.draw.circle(self.buffer, c.rgba, c.world_vec, c.radius_val) def rect_draw(self, r: "Rectangle"): # TODO: make accessors rect = pygame.Rect( r.world_x - r._width / 2, r.world_y - r._height / 2, r._width, r._height, ) pygame.draw.rect(self.buffer, r.rgba, rect) def line_draw(self, ll: "Line"): pygame.draw.aaline(self.buffer, ll.rgba, ll.world_vec, ll.end_vec) def text_render(self, text: str, font: str, color: Color) -> "TODO": """ returns an intermediated RenderedText """ # TODO: add accessor text_val return font.render(text, True, color) def text_draw(self, txt: "Text"): # this is a tight coupling, intentionally left text_rect = txt._rendered.get_rect(center=txt.world_vec) self.buffer.blit(txt._rendered, text_rect) class World: """ This class is a singleton, only one instance should ever exist. A common reason for this is a class that manages a resource of some kind, in this case, our screen. This class needs to track where entities are in relation to the screen, and will hold a reference to a pygame variable that lets it draw to the screen. Multiple instances of this class would There are two schools of thought about this pattern: You can use this pattern as we do here, with no extra code. We instead define an instance variable "world" below, and documentation would show users to use that global variable. It would technically be possible for someone to instantiate a "world2 = World()" instance, but doing so would be admonished in documentation and not supported. You could optionally denote this by naming the class _World. Others prefer to have code-level enforcement of this policy. There's a nearly infinite number of ways to do this, including simply keeping a global "_instance_created" variable that gets set to a non-None value after first creation, and then raises an exception on invalid use, or with a bit of cleverness returns the single-instance no matter how hard the user tries to create a new one. """ WIDTH = 800 HEIGHT = 600 FPS = 60 MS_PER_FRAME = 1000 / FPS _instance = None def __init__(self): # This logic forms the basis of a check for prior instances. # Code could be added here to explicitly disallow them. if self._instance is None: self._instance = self self._drawables = [] self.background_color = Color.WHITE self.screen = None self.draw_engine = PygameDrawEngine() def init(self): """ Delayed initialization, can't be run at start but must be run once. """ if self.screen: raise ValueError("Can't initialize world twice!") pygame.init() self.clock = pygame.time.Clock() self._elapsed = 0 self.draw_engine.init() def clear(self): self._drawables = [] def add(self, drawable): self._drawables.append(drawable) def tick(self): for d in self._drawables: d.update() def update(self): """ Update & draw world to screen. """ # update self._elapsed += self.clock.tick(self.FPS) while self._elapsed > self.MS_PER_FRAME: self._elapsed -= self.MS_PER_FRAME self.tick() # rendering self.draw_engine.render(self.background_color, self._drawables) # our singleton instance world = World()