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59 lines
1.5 KiB
Python
59 lines
1.5 KiB
Python
"""Converters used in the image data fetching methods."""
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import io
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from typing import Any, Optional, Union
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class ImageConverter:
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"""Base class for image data conversion."""
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def expected_data_format(self) -> str:
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raise NotImplementedError()
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def do_conversion(self, data: bytes) -> Any:
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raise NotImplementedError()
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class IdentityImageConverter(ImageConverter):
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"""Data converter that applies an identity function."""
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data_format: str
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def __init__(self, data_format: str):
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self.data_format = data_format
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def expected_data_format(self) -> str:
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return self.data_format
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def do_conversion(self, data: bytes) -> bytes:
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return data
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class NumPyConverter(ImageConverter):
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"""Data converter that converts from a binary string to a NumPy array."""
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def expected_data_format(self) -> str:
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return 'NPY'
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def do_conversion(self, data: bytes) -> Any:
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try:
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import numpy # pylint: disable=g-import-not-at-top
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except ImportError as exc:
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raise ImportError('Using format NUMPY_NDARRAY requires numpy.') from exc
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return numpy.load(io.BytesIO(data))
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_PIXEL_DATA_CONVERTERS: dict[str, type[ImageConverter]] = {
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'NUMPY_NDARRAY': NumPyConverter
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}
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def from_file_format(
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file_format: Union[str, ImageConverter]
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) -> Optional[ImageConverter]:
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if isinstance(file_format, ImageConverter):
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return file_format
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if file_format in _PIXEL_DATA_CONVERTERS:
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return _PIXEL_DATA_CONVERTERS[file_format.upper()]()
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return None
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