Add an example of filtering pre-installed fonts by language

examples/font_filter_by_language.py

@@ -0,0 +1,88 @@
+"""
+This example demonstrates how to find fonts for each language.
+"""
+
+from typing import Iterator
+
+from pygame.font import get_fonts
+from pygame import freetype
+import pygame
+
+
+def enum_font_from_lang(lang) -> Iterator[str]:
+    """
+    Enumerates fonts that are suitable for a specified language.
+    """
+    text = DISCRIMINANTS[lang]
+    for font_name in get_fonts():
+        if can_render_text(font_name, text):
+            yield font_name
+
+
+def can_render_text(font_name, text, *, font_size=14) -> bool:
+    """
+    Whether a specified font is capable of rendering a specified text.
+
+    The result of this function is not guaranteed to be correct due to its
+    implementation strategy.
+    """
+    try:
+        font = freetype.SysFont(font_name, font_size)
+    except AttributeError as e:
+        # AttributeError occurs on certain fonts, which may be a PyGame bug.
+        if e.args[0] == r"this style is unsupported for a bitmap font":
+            return False
+        else:
+            raise
+    rendered = []
+    for c in text:
+        pixels = font.render_raw(c)
+        if pixels in rendered:
+            return False
+        rendered.append(pixels)
+    return True
+
+
+DISCRIMINANTS = {
+    "ja": "経伝説あAB",
+    "ko": "안녕조AB",
+    "zh-Hans": "哪经传说AB",
+    "zh-Hant": "哪經傳說AB",
+    "zh": "哪經傳說经传说AB",
+}
+"""
+You may have noticed the 'AB' in the values of this dictionary.
+If you don't include ASCII characters, you might choose a font that cannot
+render them, such as a fallback font, which is probably not what you want.
+"""
+
+
+def main():
+    pygame.init()
+
+    screen = pygame.display.set_mode((800, 800))
+    screen.fill("white")
+    x, y = 40, 10
+    spacing = 10
+    for font_name in enum_font_from_lang("ja"):
+        font = freetype.SysFont(font_name, 30)
+        rect = font.render_to(screen, (x, y), "経伝説 한글 经传说 ABC 經傳說 あいう")
+        y = y + rect.height + spacing
+    pygame.display.flip()
+
+    clock = pygame.time.Clock()
+    running = True
+
+    while running:
+        for event in pygame.event.get():
+            if event.type == pygame.QUIT:
+                running = False
+            elif event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE:
+                running = False
+        clock.tick(4)
+
+    pygame.quit()
+
+
+if __name__ == "__main__":
+    main()