forked from OpenPDU/openpdu-libs
41 lines
1.4 KiB
Python
41 lines
1.4 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (c) 2016 Richard Hull and contributors
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# See LICENSE.rst for details.
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from PIL import Image, ImageDraw
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class canvas(object):
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"""
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A canvas returns a properly-sized :py:mod:`PIL.ImageDraw` object onto
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which the caller can draw upon. As soon as the with-block completes, the
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resultant image is flushed onto the device.
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By default, any color (other than black) will be treated as white and
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displayed on the device. However, this behaviour can be changed by adding
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``dither=True`` and the image will be converted from RGB space into a 1-bit
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monochrome image where dithering is employed to differentiate colors at the
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expense of resolution.
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"""
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def __init__(self, device, dither=False):
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self.draw = None
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self.image = Image.new("RGB" if dither else device.mode, device.size)
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self.device = device
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self.dither = dither
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def __enter__(self):
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self.draw = ImageDraw.Draw(self.image)
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return self.draw
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def __exit__(self, type, value, traceback):
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if type is None:
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if self.dither:
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self.image = self.image.convert(self.device.mode)
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# do the drawing onto the device
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self.device.display(self.image)
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del self.draw # Tidy up the resources
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return False # Never suppress exceptions
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