mirror of
https://github.com/MCV-Software/TWBlue.git
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78 lines
3.0 KiB
Python
78 lines
3.0 KiB
Python
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# -*- coding: utf-8 -*-
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""" Helpers to turn arbitrary image data into wx.Image objects.
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wx only knows about the image formats its own handlers support. Fediverse
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instances (and Bluesky) happily serve avatars and headers in formats such as
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WebP, which makes wx.Image fail and pop up a modal "Unknown image format"
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error dialog, blocking the user. Pillow understands many more formats, so we
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decode everything with it and hand the raw pixel data over to wx.
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"""
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from io import BytesIO
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from logging import getLogger
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from typing import Optional, Tuple, Union
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import wx
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from PIL import Image as PILImage
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log = getLogger("mysc.image_utils")
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ImageSource = Union[bytes, bytearray, str]
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#: Pillow modes that carry per pixel transparency.
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_TRANSPARENT_MODES = ("RGBA", "LA", "PA")
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def decode_image(source: ImageSource) -> Tuple[int, int, bytes, Optional[bytes]]:
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""" Decodes an image into raw pixel data suitable for wx.
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:param source: Raw image bytes or a path to an image file.
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:returns: A (width, height, rgb_data, alpha_data) tuple. alpha_data is None
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when the image has no transparency.
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:raises Exception: Whatever Pillow raises when the data cannot be decoded.
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"""
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if isinstance(source, (bytes, bytearray)):
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source = BytesIO(bytes(source))
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with PILImage.open(source) as image:
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image.load()
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has_alpha = image.mode in _TRANSPARENT_MODES or (image.mode == "P" and "transparency" in image.info)
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if has_alpha:
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image = image.convert("RGBA")
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return image.width, image.height, image.convert("RGB").tobytes(), image.getchannel("A").tobytes()
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image = image.convert("RGB")
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return image.width, image.height, image.tobytes(), None
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def load_image(source: ImageSource) -> Optional[wx.Image]:
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""" Builds a wx.Image from raw image bytes or a path to an image file.
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:param source: Raw image bytes or a path to an image file.
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:returns: The decoded wx.Image, or None if the data could not be decoded.
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Callers are expected to skip drawing when None is returned, instead of
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letting wx show its own error dialog.
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"""
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try:
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width, height, rgb_data, alpha_data = decode_image(source)
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except Exception:
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log.exception("Unable to decode image data.")
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return None
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image = wx.Image(width, height)
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image.SetData(rgb_data)
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if alpha_data is not None:
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image.SetAlpha(alpha_data)
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return image
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def load_scaled_image(source: ImageSource, width: int, height: int) -> Optional[wx.Image]:
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""" Same as load_image, but rescales the result to the given size.
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:param source: Raw image bytes or a path to an image file.
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:param width: Width, in pixels, of the resulting image.
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:param height: Height, in pixels, of the resulting image.
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:returns: The rescaled wx.Image, or None if the data could not be decoded.
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"""
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image = load_image(source)
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if image is None:
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return None
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image.Rescale(width, height, wx.IMAGE_QUALITY_HIGH)
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return image
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