1 files changed, 34 insertions, 0 deletions
diff --git a/bsie/reader/preview/utils.py b/bsie/reader/preview/utils.py
new file mode 100644
index 0000000..82ecc31
--- /dev/null
+++ b/bsie/reader/preview/utils.py
@@ -0,0 +1,34 @@
+
+# standard imports
+import typing
+
+# external imports
+import PIL.Image
+
+# exports
+__all__: typing.Sequence[str] = (
+    'resize',
+    )
+
+
+## code ##
+
+def resize(
+        img: PIL.Image.Image,
+        max_size: int,
+        ) -> PIL.Image.Image:
+    """Resize an image to a given maximum side length."""
+    # determine target dimensions
+    ratio = img.width / img.height
+    if img.width > img.height:
+        width, height = max_size, round(max_size / ratio)
+    else:
+        width, height = round(ratio * max_size), max_size
+    # rescale and return
+    return img.resize(
+        (width, height),
+        resample=PIL.Image.Resampling.LANCZOS, # create high-quality image
+        reducing_gap=3.0, # optimize computation via fast size reduction
+        )
+
+## EOF ##