82 lines
2.7 KiB
Python
82 lines
2.7 KiB
Python
import threading
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from tornado.gen import coroutine, Future, Return
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from tornado.ioloop import IOLoop
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from PIL import Image
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from sys import exc_info
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from io import BytesIO
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class ImageResizer(object):
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def __init__(self, log, pool, io_loop=None):
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if io_loop is None:
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io_loop = IOLoop.current()
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self._log = log
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self._io_loop = io_loop
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self._pool = pool
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@coroutine
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def resize(self, avatar, width, height):
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log = self._log.getChild('avatar[%d]' % avatar.avatar_id)
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log.audit('Resizing to bounding box %sx%s', width, height)
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future = Future()
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if (width is None) and (height is None):
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raise ValueError('width and height cannot both be None')
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# Handing the value back to the coroutine
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def _on_done(result):
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if isinstance(result, tuple):
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log.audit('Passing back exception')
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future.set_exc_info(result)
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else:
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log.audit('Passing back result')
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future.set_result(result)
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# What to do in the thread pool
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def _do_resize(image_data, image_format, width, height):
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try:
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log.audit('Opening image, format %s', image_format)
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image = Image.open(BytesIO(image_data))
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# Get the aspect ratio
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raw_width, raw_height = image.size
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ratio = float(raw_width) / float(raw_height)
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log.audit('Raw size: %dx%d, ratio %f',
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raw_width, raw_height, ratio)
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if (ratio >= 1.0) or (height is None):
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# Fit to width
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height = int(width / ratio)
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else:
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# Fit to height
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width = int(height * ratio)
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# Scale
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log.audit('Scaling to %dx%d', width, height)
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image = image.resize((width, height), Image.LANCZOS)
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# Write out result
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if image_format == 'image/jpeg':
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pil_format = 'JPEG'
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else:
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pil_format = 'PNG'
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out_buffer = BytesIO()
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log.audit('Saving output as %s', pil_format)
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image.save(out_buffer, pil_format)
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self._io_loop.add_callback(_on_done, out_buffer.getvalue())
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except:
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log.exception('Failed to resize')
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self._io_loop.add_callback(_on_done, exc_info())
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# Run the above in the thread pool:
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yield self._pool.apply(_do_resize, (avatar.avatar,
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avatar.avatar_type, width, height))
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# Wait for the result
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resized_data = yield future
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# Return the data
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raise Return(resized_data)
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