145 lines
4.2 KiB
Python
Executable File
145 lines
4.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# encoding: utf-8
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import asyncio
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import base64
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import contextlib
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import io
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import logging
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import sys
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import typing
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logger = logging.getLogger(__name__)
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try:
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import wand.image
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except (ImportError, OSError):
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logger.warn('Failed to import wand.image. Image manipulation functions will be unavailable.')
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else:
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import wand.exceptions
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from utils import errors
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def resize_until_small(image_data: io.BytesIO) -> None:
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"""If the image_data is bigger than 256KB, resize it until it's not."""
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# It's important that we only attempt to resize the image when we have to,
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# ie when it exceeds the Discord limit of 256KiB.
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# Apparently some <256KiB images become larger when we attempt to resize them,
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# so resizing sometimes does more harm than good.
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max_resolution = 128 # pixels
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image_size = size(image_data)
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while image_size > 256 * 2**10 and max_resolution >= 32: # don't resize past 32x32 or 256KiB
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logger.debug('image size too big (%s bytes)', image_size)
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logger.debug('attempting resize to at most%s*%s pixels', max_resolution, max_resolution)
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try:
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thumbnail(image_data, (max_resolution, max_resolution))
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except wand.exceptions.CoderError:
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raise errors.InvalidImageError
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image_size = size(image_data)
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max_resolution //= 2
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def thumbnail(image_data: io.BytesIO, max_size=(128, 128)) -> None:
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"""Resize an image in place to no more than max_size pixels, preserving aspect ratio."""
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with wand.image.Image(blob=image_data) as image:
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new_resolution = scale_resolution((image.width, image.height), max_size)
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image.resize(*new_resolution)
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image_data.truncate(0)
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image_data.seek(0)
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image.save(file=image_data)
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# allow resizing the original image more than once for memory profiling
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image_data.seek(0)
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def scale_resolution(old_res, new_res):
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"""Resize a resolution, preserving aspect ratio. Returned w,h will be <= new_res"""
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# https://stackoverflow.com/a/6565988
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old_width, old_height = old_res
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new_width, new_height = new_res
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old_ratio = old_width / old_height
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new_ratio = new_width / new_height
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if new_ratio > old_ratio:
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return (old_width * new_height//old_height, new_height)
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return new_width, old_height * new_width//old_width
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def mime_type_for_image(data):
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if data.startswith(b'\x89PNG\r\n\x1a\n'):
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return 'image/png'
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elif data.startswith(b'\xFF\xD8') and data.rstrip(b'\0').endswith(b'\xFF\xD9'):
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return 'image/jpeg'
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elif data.startswith((b'GIF87a', b'GIF89a')):
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return 'image/gif'
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elif data.startswith(b'RIFF') and data[8:12] == b'WEBP':
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return 'image/webp'
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else:
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raise errors.InvalidImageError
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def image_to_base64_url(data):
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fmt = 'data:{mime};base64,{data}'
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mime = mime_type_for_image(data)
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b64 = base64.b64encode(data).decode('ascii')
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return fmt.format(mime=mime, data=b64)
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def main() -> typing.NoReturn:
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"""resize an image from stdin and write the resized version to stdout."""
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import sys
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data = io.BytesIO(sys.stdin.buffer.read())
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try:
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resize_until_small(data)
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except errors.InvalidImageError:
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# 2 is used because 1 is already used by python's default error handler
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sys.exit(2)
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stdout_write = sys.stdout.buffer.write # getattr optimization
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while True:
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buf = data.read(16 * 1024)
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if not buf:
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break
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stdout_write(buf)
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sys.exit(0)
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async def resize_in_subprocess(image_data: bytes):
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proc = await asyncio.create_subprocess_exec(
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sys.executable, '-m', __name__,
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stdin=asyncio.subprocess.PIPE,
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.PIPE)
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try:
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image_data, err = await asyncio.wait_for(proc.communicate(image_data), timeout=30)
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except asyncio.TimeoutError:
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proc.kill()
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raise errors.ImageResizeTimeoutError
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else:
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if proc.returncode == 2:
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raise errors.InvalidImageError
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if proc.returncode != 0:
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raise RuntimeError(err.decode('utf-8') + f'Return code: {proc.returncode}')
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return image_data
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def size(fp):
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"""return the size, in bytes, of the data a file-like object represents"""
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with preserve_position(fp):
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fp.seek(0, io.SEEK_END)
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return fp.tell()
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class preserve_position(contextlib.AbstractContextManager):
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def __init__(self, fp):
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self.fp = fp
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self.old_pos = fp.tell()
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def __exit__(self, *excinfo):
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self.fp.seek(self.old_pos)
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if __name__ == '__main__':
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main()
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