транскодирование изображений

library_service/services/__init__.py

@@ -13,6 +13,7 @@ from .captcha import (
     prng,
 )
 from .describe_er import SchemaGenerator
+from .image_processing import transcode_image
 
 __all__ = [
     "limiter",
@@ -28,4 +29,5 @@ __all__ = [
     "REDEEM_TTL",
     "prng",
     "SchemaGenerator",
+    "transcode_image",
 ]

library_service/services/image_processing.py

@@ -0,0 +1,81 @@
+from pathlib import Path
+from PIL import Image
+
+
+TARGET_RATIO = 5 / 7
+
+
+def crop_image(img: Image.Image, target_ratio: float = TARGET_RATIO) -> Image.Image:
+    w, h = img.size
+    current_ratio = w / h
+
+    if current_ratio > target_ratio:
+        new_w = int(h * target_ratio)
+        left = (w - new_w) // 2
+        right = left + new_w
+        top = 0
+        bottom = h
+    else:
+        new_h = int(w / target_ratio)
+        top = (h - new_h) // 2
+        bottom = top + new_h
+        left = 0
+        right = w
+
+    return img.crop((left, top, right, bottom))
+
+
+def transcode_image(
+    src_path: str | Path,
+    *,
+    jpeg_quality: int = 85,
+    webp_quality: int = 80,
+    webp_lossless: bool = False,
+    resize_to: tuple[int, int] | None = None,
+):
+    src_path = Path(src_path)
+
+    if not src_path.exists():
+        raise FileNotFoundError(src_path)
+
+    stem = src_path.stem
+    folder = src_path.parent
+
+    img = Image.open(src_path).convert("RGBA")
+    img = crop_image(img)
+
+    if resize_to:
+        img = img.resize(resize_to, Image.LANCZOS)
+
+    png_path = folder / f"{stem}.png"
+    img.save(
+        png_path,
+        format="PNG",
+        optimize=True,
+        interlace=1,
+    )
+
+    jpg_path = folder / f"{stem}.jpg"
+    img.convert("RGB").save(
+        jpg_path,
+        format="JPEG",
+        quality=jpeg_quality,
+        progressive=True,
+        optimize=True,
+        subsampling="4:2:0",
+    )
+
+    webp_path = folder / f"{stem}.webp"
+    img.save(
+        webp_path,
+        format="WEBP",
+        quality=webp_quality,
+        lossless=webp_lossless,
+        method=6,
+    )
+
+    return {
+        "png": png_path,
+        "jpeg": jpg_path,
+        "webp": webp_path,
+    }