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52 lines
2.1 KiB
Python
52 lines
2.1 KiB
Python
"""Various utilities for working with Pillow images"""
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from PIL import Image
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from typing import List, Tuple, Optional
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import math
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def mip_sizes(dimensions: Tuple[int, int], mip_count: Optional[int] = None) -> List[Tuple[int, int]]:
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"""
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Create a chain of mipmap sizes for a given source source size, where each source is half the size of the one before.
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Note that the division by 2 rounds down. So a 63x63 texture has as its next lowest mipmap level 31x31. And so on.
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See the `OpenGL wiki page on mipmaps <https://www.khronos.org/opengl/wiki/Texture#Mip_maps>`_ for more info.
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:param dimensions: Size of the source source in pixels
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:param mip_count: Number of mipmap sizes to generate. By default, generate until the last mip level is 1x1.
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Resulting mip chain will be smaller if a 1x1 mip level is reached before this value.
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:return: A list of 2-tuples representing the dimensions of each mip level, including ``dimensions`` at element 0.
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"""
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assert all([dim > 0 for dim in dimensions]), "Invalid source dimensions"
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if not mip_count:
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mip_count = math.ceil(math.log2(max(dimensions)) + 1) # maximum possible number of mips for a given source
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assert mip_count > 0, "mip_count must be greater than 0"
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chain = []
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for mip in range(mip_count):
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chain.append(dimensions)
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if all([dim == 1 for dim in dimensions]):
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break # we've reached a 1x1 mip and can get no smaller
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dimensions = tuple([max(dim // 2, 1) for dim in dimensions])
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return chain
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def resize_no_premultiply(image: Image.Image, size: Tuple[int, int]) -> Image.Image:
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"""
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Resize an image without premulitplying the alpha. Required due to a quick in Pillow
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:param image: Image to resize
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:param size: Size to resize to
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:return: The resized image
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"""
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if image.mode == 'RGBA':
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rgb = image.convert('RGB').resize(size, Image.BILINEAR)
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a = image.getchannel('A').resize(size, Image.BILINEAR)
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rgb.putalpha(a)
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return rgb
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else:
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return image.resize(size, Image.BILINEAR)
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