# Copyright (c) 2023, Teriks
#
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import math
import typing
import PIL.Image
import dgenerate.types as _types
__doc__ = """
Image operations commonly used by dgenerate.
"""
[docs]
def resize_image_calc(old_size: _types.Size,
new_size: _types.OptionalSize,
aspect_correct: bool = True,
align: typing.Optional[int] = 8):
"""
Calculate the new dimensions for a requested resize of an image..
:param old_size: The old image size
:param new_size: The new image size
:param aspect_correct: preserve aspect ratio?
:param align: Ensure returned size is aligned to this value.
:return: calculated new size
"""
if align is not None and align < 1:
raise ValueError('align value may not be less than 1.')
if new_size is None:
if align is not None:
return align_by(old_size, align=align)
return old_size
if align is not None:
new_size = align_by(new_size, align=align)
if old_size == new_size:
return old_size
if aspect_correct:
width = new_size[0]
w_percent = (width / float(old_size[0]))
hsize = int((float(old_size[1]) * float(w_percent)))
if align is not None:
return width, hsize - hsize % align
return width, hsize
else:
return new_size
[docs]
def is_power_of_two(iterable: typing.Iterable[int]) -> bool:
"""
Check if all elements are a power of 2.
:param iterable: Elements to test
:param align: The alignment value, ``None`` indicates no alignment.
:return: bool
"""
for n in iterable:
if n <= 0:
return False
if not (n & (n - 1)) == 0:
return False
return True
[docs]
def nearest_power_of_two(iterable: typing.Iterable[int]) -> tuple:
"""
Round all elements to the nearest power of two and return a tuple.
:param iterable: Elements to round
:param align: The alignment value, ``None`` indicates no alignment.
:return: tuple(...)
"""
result = []
for number in iterable:
if number <= 0:
result.append(0)
continue
lower_power_of_two = 2 ** int(math.log2(number))
higher_power_of_two = 2 ** (int(math.log2(number)) + 1)
if abs(number - lower_power_of_two) < abs(number - higher_power_of_two):
result.append(lower_power_of_two)
else:
result.append(higher_power_of_two)
return tuple(result)
[docs]
def is_aligned(iterable: typing.Iterable[int], align: int) -> bool:
"""
Check if all elements are aligned by a specific value.
:param iterable: Elements to test
:param align: The alignment value, ``None`` indicates no alignment.
:return: bool
"""
if align is None:
return True
if align < 1:
raise ValueError('align value may not be less than 1.')
return all(i % align == 0 for i in iterable)
[docs]
def align_by(iterable: typing.Iterable[int], align: int) -> tuple:
"""
Align all elements by a value and return a tuple
:param iterable: Elements to align
:param align: The alignment value, ``None`` indicates no alignment.
:return: tuple(...)
"""
if align is None:
align = 1
if align < 1:
raise ValueError('align value may not be less than 1.')
return tuple(i - i % align for i in iterable)
[docs]
def copy_img(img: PIL.Image.Image):
"""
Copy a :py:class:`PIL.Image.Image` while preserving its filename attribute.
:param img: the image
:return: a copy of the image
"""
c = img.copy()
if hasattr(img, 'filename'):
c.filename = img.filename
return c
[docs]
def resize_image(img: PIL.Image.Image,
size: _types.OptionalSize,
aspect_correct: bool = True,
align: typing.Optional[int] = 8):
"""
Resize a :py:class:`PIL.Image.Image` and return a copy.
This function always returns a copy even if the images size did not change.
The new image dimension will always be forcefully aligned by ``align``,
specifying ``None`` or ``1`` indicates no alignment.
The filename attribute is preserved.
:param img: the image to resize
:param size: requested new size for the image, may be ``None``.
:param aspect_correct: preserve aspect ratio?
:param align: Force alignment by this amount of pixels.
:return: the resized image
"""
new_size = resize_image_calc(old_size=img.size,
new_size=size,
aspect_correct=aspect_correct,
align=align)
if img.size == new_size:
# probably less costly
return copy_img(img)
r = img.resize(new_size, PIL.Image.Resampling.LANCZOS)
if hasattr(img, 'filename'):
r.filename = img.filename
return r
[docs]
def to_rgb(img: PIL.Image.Image):
"""
Convert a :py:class:`PIL.Image.Image` to RGB format while preserving its filename attribute.
:param img: the image
:return: a converted copy of the image
"""
c = img.convert('RGB')
if hasattr(img, 'filename'):
c.filename = img.filename
return c
[docs]
def get_filename(img: PIL.Image.Image):
"""
Get the :py:attr:`PIL.Image.Image.filename` attribute or "NO_FILENAME" if it does not exist.
:param img: :py:class:`PIL.Image.Image`
:return: filename string or "NO_FILENAME"
"""
if hasattr(img, 'filename'):
return img.filename
return 'NO_FILENAME'