Added ImageOps cover method

Tests/test_imageops.py

@@ -39,6 +39,9 @@ def test_sanity():
     ImageOps.contain(hopper("L"), (128, 128))
     ImageOps.contain(hopper("RGB"), (128, 128))
 
+    ImageOps.cover(hopper("L"), (128, 128))
+    ImageOps.cover(hopper("RGB"), (128, 128))
+
     ImageOps.crop(hopper("L"), 1)
     ImageOps.crop(hopper("RGB"), 1)
 
@@ -119,6 +122,20 @@ def test_contain_round():
     assert new_im.height == 5
 
 
+@pytest.mark.parametrize(
+    "image_name, expected_size",
+    (
+        ("colr_bungee.png", (1024, 256)),  # landscape
+        ("imagedraw_stroke_multiline.png", (256, 640)),  # portrait
+        ("hopper.png", (256, 256)),  # square
+    ),
+)
+def test_cover(image_name, expected_size):
+    with Image.open("Tests/images/" + image_name) as im:
+        new_im = ImageOps.cover(im, (256, 256))
+        assert new_im.size == expected_size
+
+
 def test_pad():
     # Same ratio
     im = hopper()

docs/handbook/tutorial.rst

@@ -268,6 +268,37 @@ true, to provide for the same changes to the image's size.
 A more general form of image transformations can be carried out via the
 :py:meth:`~PIL.Image.Image.transform` method.
 
+Relative resizing
+^^^^^^^^^^^^^^^^^
+
+Instead of calculating the size of the new image when resizing, you can also
+choose to resize relative to a given size.
+
+::
+
+    from PIL import Image, ImageOps
+    size = (100, 150)
+    with Image.open("Tests/images/hopper.png") as im:
+        ImageOps.contain(im, size).save("imageops_contain.png")
+        ImageOps.cover(im, size).save("imageops_cover.png")
+        ImageOps.fit(im, size).save("imageops_fit.png")
+        ImageOps.pad(im, size, color="#f00").save("imageops_pad.png")
+
+        # thumbnail() can also be used,
+        # but will modify the image object in place
+        im.thumbnail(size)
+        im.save("imageops_thumbnail.png")
+
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|                | :py:meth:`~PIL.Image.Image.thumbnail`     | :py:meth:`~PIL.ImageOps.contain`           | :py:meth:`~PIL.ImageOps.cover`           | :py:meth:`~PIL.ImageOps.fit`           | :py:meth:`~PIL.ImageOps.pad`           |
++================+===========================================+============================================+==========================================+========================================+========================================+
+|Given size      | ``(150, 100)``                            | ``(150, 100)``                             | ``(150, 150)``                           | ``(150, 100)``                         | ``(150, 100)``                         |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|Resulting image | .. image:: ../example/image_thumbnail.png | .. image:: ../example/imageops_contain.png | .. image:: ../example/imageops_cover.png | .. image:: ../example/imageops_fit.png | .. image:: ../example/imageops_pad.png |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|Resulting size  | ``100×100``                               | ``100×100``                                | ``150×150``                              | ``150×100``                            | ``150×100``                            |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+
 .. _color-transforms:
 
 Color transforms

docs/reference/ImageOps.rst

@@ -12,18 +12,50 @@ only work on L and RGB images.
 
 .. autofunction:: autocontrast
 .. autofunction:: colorize
-.. autofunction:: contain
-.. autofunction:: pad
 .. autofunction:: crop
 .. autofunction:: scale
 .. autofunction:: deform
 .. autofunction:: equalize
 .. autofunction:: expand
-.. autofunction:: fit
 .. autofunction:: flip
 .. autofunction:: grayscale
 .. autofunction:: invert
 .. autofunction:: mirror
 .. autofunction:: posterize
 .. autofunction:: solarize
 .. autofunction:: exif_transpose
+
+.. _relative-resize:
+
+Resize relative to a given size
+-------------------------------
+
+::
+
+    from PIL import Image, ImageOps
+    size = (100, 150)
+    with Image.open("Tests/images/hopper.png") as im:
+        ImageOps.contain(im, size).save("imageops_contain.png")
+        ImageOps.cover(im, size).save("imageops_cover.png")
+        ImageOps.fit(im, size).save("imageops_fit.png")
+        ImageOps.pad(im, size, color="#f00").save("imageops_pad.png")
+
+        # thumbnail() can also be used,
+        # but will modify the image object in place
+        im.thumbnail(size)
+        im.save("imageops_thumbnail.png")
+
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|                | :py:meth:`~PIL.Image.Image.thumbnail`     | :py:meth:`~PIL.ImageOps.contain`           | :py:meth:`~PIL.ImageOps.cover`           | :py:meth:`~PIL.ImageOps.fit`           | :py:meth:`~PIL.ImageOps.pad`           |
++================+===========================================+============================================+==========================================+========================================+========================================+
+|Given size      | ``(150, 100)``                            | ``(150, 100)``                             | ``(150, 150)``                           | ``(150, 100)``                         | ``(150, 100)``                         |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|Resulting image | .. image:: ../example/image_thumbnail.png | .. image:: ../example/imageops_contain.png | .. image:: ../example/imageops_cover.png | .. image:: ../example/imageops_fit.png | .. image:: ../example/imageops_pad.png |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+|Resulting size  | ``100×100``                               | ``100×100``                                | ``150×150``                              | ``150×100``                            | ``150×100``                            |
++----------------+-------------------------------------------+--------------------------------------------+------------------------------------------+----------------------------------------+----------------------------------------+
+
+.. autofunction:: contain
+.. autofunction:: cover
+.. autofunction:: fit
+.. autofunction:: pad

docs/releasenotes/10.1.0.rst

@@ -41,6 +41,15 @@ to be specified, rather than a single number for both dimensions. ::
 API Additions
 =============
 
+ImageOps.cover
+^^^^^^^^^^^^^^
+
+Returns a resized version of the image, so that the requested size is covered,
+while maintaining the original aspect ratio.
+
+See :ref:`relative-resize` for a comparison between this and similar ``ImageOps``
+methods.
+
 EpsImagePlugin.gs_binary
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

src/PIL/ImageOps.py

@@ -242,7 +242,7 @@ def contain(image, size, method=Image.Resampling.BICUBIC):
     Returns a resized version of the image, set to the maximum width and height
     within the requested size, while maintaining the original aspect ratio.
 
-    :param image: The image to resize and crop.
+    :param image: The image to resize.
     :param size: The requested output size in pixels, given as a
                  (width, height) tuple.
     :param method: Resampling method to use. Default is
@@ -266,6 +266,35 @@ def contain(image, size, method=Image.Resampling.BICUBIC):
     return image.resize(size, resample=method)
 
 
+def cover(image, size, method=Image.Resampling.BICUBIC):
+    """
+    Returns a resized version of the image, so that the requested size is
+    covered, while maintaining the original aspect ratio.
+
+    :param image: The image to resize.
+    :param size: The requested output size in pixels, given as a
+                 (width, height) tuple.
+    :param method: Resampling method to use. Default is
+                   :py:attr:`~PIL.Image.Resampling.BICUBIC`.
+                   See :ref:`concept-filters`.
+    :return: An image.
+    """
+
+    im_ratio = image.width / image.height
+    dest_ratio = size[0] / size[1]
+
+    if im_ratio != dest_ratio:
+        if im_ratio < dest_ratio:
+            new_height = round(image.height / image.width * size[0])
+            if new_height != size[1]:
+                size = (size[0], new_height)
+        else:
+            new_width = round(image.width / image.height * size[1])
+            if new_width != size[0]:
+                size = (new_width, size[1])
+    return image.resize(size, resample=method)
+
+
 def pad(image, size, method=Image.Resampling.BICUBIC, color=None, centering=(0.5, 0.5)):
     """
     Returns a resized and padded version of the image, expanded to fill the