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87
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1 """ Captcha.Visual.Backgrounds
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2
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3 Background layers for visual CAPTCHAs
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4 """
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5 #
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6 # PyCAPTCHA Package
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7 # Copyright (C) 2004 Micah Dowty <micah@navi.cx>
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8 #
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9
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10 from Captcha.Visual import Layer, Pictures
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11 import random, os
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12 import ImageDraw, Image
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13
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14
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15 class SolidColor(Layer):
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16 """A solid color background. Very weak on its own, but good
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17 to combine with other backgrounds.
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18 """
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19 def __init__(self, color="white"):
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20 self.color = color
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21
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22 def render(self, image):
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23 image.paste(self.color)
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24
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25
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26 class Grid(Layer):
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27 """A grid of lines, with a given foreground color.
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28 The size is given in pixels. The background is transparent,
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29 so another layer (like SolidColor) should be put behind it.
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30 """
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31 def __init__(self, size=16, foreground="black"):
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32 self.size = size
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33 self.foreground = foreground
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34 self.offset = (random.uniform(0, self.size),
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35 random.uniform(0, self.size))
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36
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37 def render(self, image):
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38 draw = ImageDraw.Draw(image)
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39
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40 for i in xrange(image.size[0] / self.size + 1):
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41 draw.line( (i*self.size+self.offset[0], 0,
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42 i*self.size+self.offset[0], image.size[1]), fill=self.foreground)
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43
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44 for i in xrange(image.size[0] / self.size + 1):
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45 draw.line( (0, i*self.size+self.offset[1],
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46 image.size[0], i*self.size+self.offset[1]), fill=self.foreground)
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47
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48
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49 class TiledImage(Layer):
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50 """Pick a random image and a random offset, and tile the rendered image with it"""
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51 def __init__(self, imageFactory=Pictures.abstract):
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52 self.tileName = imageFactory.pick()
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53 self.offset = (random.uniform(0, 1),
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54 random.uniform(0, 1))
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55
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56 def render(self, image):
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57 tile = Image.open(self.tileName)
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58 for j in xrange(-1, int(image.size[1] / tile.size[1]) + 1):
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59 for i in xrange(-1, int(image.size[0] / tile.size[0]) + 1):
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60 dest = (int((self.offset[0] + i) * tile.size[0]),
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61 int((self.offset[1] + j) * tile.size[1]))
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62 image.paste(tile, dest)
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63
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64
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65 class CroppedImage(Layer):
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66 """Pick a random image, cropped randomly. Source images should be larger than the CAPTCHA."""
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67 def __init__(self, imageFactory=Pictures.nature):
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68 self.imageName = imageFactory.pick()
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69 self.align = (random.uniform(0,1),
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70 random.uniform(0,1))
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71
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72 def render(self, image):
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73 i = Image.open(self.imageName)
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74 image.paste(i, (int(self.align[0] * (image.size[0] - i.size[0])),
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75 int(self.align[1] * (image.size[1] - i.size[1]))))
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76
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77
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78 class RandomDots(Layer):
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79 """Draw random colored dots"""
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80 def __init__(self, colors=("white", "black"), dotSize=4, numDots=400):
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81 self.colors = colors
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82 self.dotSize = dotSize
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83 self.numDots = numDots
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84 self.seed = random.random()
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85
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86 def render(self, image):
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87 r = random.Random(self.seed)
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88 for i in xrange(self.numDots):
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89 bx = int(r.uniform(0, image.size[0]-self.dotSize))
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90 by = int(r.uniform(0, image.size[1]-self.dotSize))
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91 image.paste(r.choice(self.colors), (bx, by,
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92 bx+self.dotSize-1,
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93 by+self.dotSize-1))
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94
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95 ### The End ###
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