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87
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1 """ Captcha.Visual.BAse
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2
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3 Base classes for visual CAPTCHAs. We use the Python Imaging Library
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4 to manipulate these images.
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5 """
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6 #
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7 # PyCAPTCHA Package
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8 # Copyright (C) 2004 Micah Dowty <micah@navi.cx>
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9 #
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10
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11 import Captcha
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12 import Image
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13
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14 __all__ = ['ImageCaptcha', 'Layer']
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15
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16
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17 class ImageCaptcha(Captcha.BaseCaptcha):
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18 """Base class for image-based CAPTCHA tests.
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19 The render() function generates the CAPTCHA image at the given size by
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20 combining Layer instances from self.layers, which should be created by
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21 the subclass-defined getLayers().
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22 """
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23 defaultSize = (256,96)
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24
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25 def __init__(self, *args, **kwargs):
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26 Captcha.BaseCaptcha.__init__(self)
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27 self._layers = self.getLayers(*args, **kwargs)
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28
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29 def getImage(self):
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30 """Get a PIL image representing this CAPTCHA test, creating it if necessary"""
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31 if not self._image:
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32 self._image = self.render()
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33 return self._image
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34
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35 def getLayers(self):
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36 """Subclasses must override this to return a list of Layer instances to render.
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37 Lists within the list of layers are recursively rendered.
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38 """
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39 return []
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40
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41 def render(self, size=None):
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42 """Render this CAPTCHA, returning a PIL image"""
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43 if size is None:
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44 size = self.defaultSize
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45 img = Image.new("RGB", size)
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46 return self._renderList(self._layers, Image.new("RGB", size))
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47
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48 def _renderList(self, l, img):
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49 for i in l:
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50 if type(i) == tuple or type(i) == list:
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51 img = self._renderList(i, img)
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52 else:
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53 img = i.render(img) or img
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54 return img
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55
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56
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57 class Layer(object):
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58 """A renderable object representing part of a CAPTCHA.
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59 The render() function should return approximately the same result, regardless
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60 of the image size. This means any randomization must occur in the constructor.
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61
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62 If the render() function returns something non-None, it is taken as an image to
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63 replace the current image with. This can be used to implement transformations
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64 that result in a separate image without having to copy the results back to the first.
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65 """
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66 def render(self, img):
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67 pass
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68
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69 ### The End ###
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