52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
"""
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Very inspired by zivezab's django-autograph
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https://github.com/zivezab/django-autograph/blob/master/autograph/utils.py
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"""
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import json
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import cStringIO
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from itertools import chain
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from tempfile import NamedTemporaryFile
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from PIL import Image, ImageDraw, ImageOps
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AA = 5 # super sampling gor antialiasing
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def draw_signature(data, as_file=False):
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""" Draw signature based on lines stored in json_string.
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`data` can be a json object (list in fact) or a json string
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if `as_file` is True, a temp file is returned instead of Image instance
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"""
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if type(data) is str:
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drawing = json.loads(data)
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elif type(data) is list:
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drawing = data
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else:
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raise ValueError
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# Compute box
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width = max(chain(*[d['x'] for d in drawing])) + 10
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height = max(chain(*[d['y'] for d in drawing])) + 10
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# Draw image
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im = Image.new("RGBA", (width*AA, height*AA))
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draw = ImageDraw.Draw(im)
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for line in drawing:
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len_line = len(line['x'])
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points = [(line['x'][i]*AA, line['y'][i]*AA) for i in range(0, len_line)]
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draw.line(points, fill="#000", width=2*AA)
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im = ImageOps.expand(im)
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# Smart crop
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bbox = im.getbbox()
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if bbox:
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im.crop(bbox)
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im.thumbnail((width, height), Image.ANTIALIAS)
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if as_file:
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ret = im._dump(format='PNG')
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else:
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ret = im
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return ret
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