fix(artwork): letterbox images and back alpha art with black

beefy_player/artwork.py

@@ -230,22 +230,38 @@ async def fetch(client: httpx.AsyncClient, url: str) -> bytes | None:
 
 
 def fit_image(data: bytes, width: int, height: int):
-    """Decode and center-crop an image to exactly ``width`` x ``height`` cells."""
+    """Decode and letterbox an image into exactly ``width`` x ``height`` cells.
+
+    Scale to fit, never crop.  Square album art fills the box either way, but a
+    wide station wordmark (Bassdrive's logo is 3:1) used to be centre-cropped
+    down to a zoomed slice of its middle.  The padding stays transparent, so
+    the mosaic behind the artwork shows through instead of a black bar.
+    """
     try:
         from PIL import Image, ImageOps
 
         with Image.open(BytesIO(data)) as source:
+            # A PNG with transparency is drawn *over* the mosaic, which reads
+            # as noise behind a logo; composite those onto black instead.
+            has_alpha = source.mode in ("RGBA", "LA", "PA", "RGBa", "La") or (
+                "transparency" in source.info
+            )
             image = source.convert("RGBA")
         cell_width, cell_height = cell_size()
         target = (
             max(1, width * cell_width),
             max(1, height * cell_height),
         )
-        return ImageOps.fit(
-            image,
-            target,
-            method=Image.Resampling.LANCZOS,
-            centering=(0.5, 0.5),
+        fitted = ImageOps.contain(image, target, method=Image.Resampling.LANCZOS)
+        background = (0, 0, 0, 255) if has_alpha else (0, 0, 0, 0)
+        canvas = Image.new("RGBA", target, background)
+        canvas.alpha_composite(
+            fitted,
+            (
+                (target[0] - fitted.width) // 2,
+                (target[1] - fitted.height) // 2,
+            ),
         )
+        return canvas
     except Exception:
         return None