Add more sample captchas

hiboo/captcha/captcha.py

@@ -41,19 +41,69 @@ class DummyCaptchaField(fields.CaptchaField):
         )
 
 
-class GeneratedTextImageCaptchaField(fields.CaptchaField):
+class ImageCaptchaField(fields.CaptchaField):
+    """ Image-based captcha base class, displays an image and requests that the
+    user inputs some text deduced from the image.
+    """
+
+    widget = widgets.TextInput()
+
+    def __init__(self, *args, **kwargs):
+        self.font = ImageFont.truetype("captcha.ttf", 14)
+        self.bgcolor = "#ffffff"
+        self.fgcolor = "#ff6677"
+        super(ImageCaptchaField, self).__init__(*args, **kwargs)
+
+    def __call__(self, **kwargs):
+        png = io.BytesIO()
+        self.make_image(self.context["challenge"]).save(png, "PNG")
+        output = base64.b64encode(png.getvalue()).decode("ascii")
+        return widgets.HTMLString(
+            '<p>{}</p>'.format(self.context["challenge"]) +
+            '<p><img src="data:image/png;base64,{}"></p>'.format(output)
+            + super(ImageCaptchaField, self).__call__(**kwargs)
+        )
+
+    def make_char(self, char, rotation_range=15):
+        """ Renders a character
+        """
+        drawn = " {} ".format(char)
+        rotation = random.randrange(-rotation_range, rotation_range)
+        image = Image.new("L", self.font.getsize(drawn), self.bgcolor)
+        draw = ImageDraw.Draw(image)
+        draw.text((0, 0), drawn, font=self.font, fill=self.fgcolor)
+        return image.rotate(rotation, expand=0, resample=Image.BICUBIC) \
+                    .crop(image.getbbox())
+
+    def make_text(self, text, **kwargs):
+        """ Renders a text
+        """
+        size = self.font.getsize(text)
+        size = (size[0] * 2, int(size[1] * 1.4))
+        image = Image.new("RGB", size, self.bgcolor)
+        xpos = 2
+        for char in text:
+            charimage = self.make_char(char)
+            image.paste(charimage, (xpos, 4, xpos + charimage.size[0], 4 + charimage.size[1]))
+            xpos = xpos + 2 + charimage.size[0]
+        return image.crop((0, 0, xpos + 1, size[1]))
+
+    def make_image(self, challenge):
+        pass
+
+    def _value(self):
+        return ""
+
+
+class GeneratedTextImageCaptchaField(ImageCaptchaField):
     """ Generate a random text and build a fuzzy image based on that text.
 
     This is the most common historical captcha type, although pretty easily
     defeated by OCR nowadays.
     """
 
-    widget = widgets.TextInput()
     charset = string.ascii_uppercase + string.digits
 
-    def _value(self):
-        return ""
-
     def challenge(self):
         self.label = "Please copy the following text: "
         length = random.randint(5,8)
@@ -62,34 +112,5 @@ class GeneratedTextImageCaptchaField(fields.CaptchaField):
     def check(self, challenge, form, field):
         return challenge.lower() == field.data.lower()
 
-    def make_image(self, text):
-        font = ImageFont.truetype("captcha.ttf", 14)
-        size = font.getsize(text)
-        size = (size[0] * 2, int(size[1] * 1.4))
-        image = Image.new("RGB", size, "#ffffff")
-        xpos = 2
-        for char in text:
-            drawn = " {} ".format(char)
-            fgimage = Image.new("RGB", size, "#000000")
-            charimage = Image.new("L", font.getsize(drawn), "#000000")
-            chardraw = ImageDraw.Draw(charimage)
-            chardraw.text((0, 0), drawn, font=font, fill="#ffffff")
-            charimage = charimage.rotate(random.randrange(-15,15), expand=0, resample=Image.BICUBIC)
-            charimage = charimage.crop(charimage.getbbox())
-            maskimage = Image.new("L", size)
-            maskimage.paste(charimage, (xpos, 4, xpos + charimage.size[0], 4 + charimage.size[1]))
-            size = maskimage.size
-            image = Image.composite(fgimage, image, maskimage)
-            xpos = xpos + 2 + charimage.size[0]
-        image = image.crop((0, 0, xpos + 1, size[1]))
-        return image
-
-    def __call__(self, **kwargs):
-        image = self.make_image(self.context["challenge"])
-        image_png = io.BytesIO()
-        image.save(image_png, "PNG")
-        image_string = base64.b64encode(image_png.getvalue()).decode("ascii")
-        return widgets.HTMLString(
-            '<img src="data:image/png;base64,{}">'.format(image_string) +
-            super(GeneratedTextImageCaptchaField, self).__call__(**kwargs)
-        )
+    def make_image(self, challenge):
+        return self.make_text(challenge)