images-demo/images_demo.py

   1 #!/usr/bin/python2.5
   2 #
   3 # Copyright 2008 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #      http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16
  17
  18 """Demo for the Google App Engine images API.
  19
  20 Provides a simple way to apply transforms to canned images.
  21
  22 This file contains all request handlers.
  23 """
  24
  25 import os
  26 import urllib
  27 import wsgiref.handlers
  28
  29 from google.appengine.api import images
  30 from google.appengine.ext import webapp
  31 from google.appengine.ext.webapp import template
  32
  33 import image_transformer
  34
  35
  36 class TemplatedPage(webapp.RequestHandler):
  37   """Base class for templatized handlers."""
  38
  39   def write_template(self, values):
  40     """Write out the template with the same name as the class name."""
  41     path = os.path.join(os.path.dirname(__file__), 'templates',
  42                         self.__class__.__name__ + '.html')
  43     self.response.out.write(template.render(path, values))
  44
  45
  46 class MainPage(TemplatedPage):
  47   """Request handler for main index page."""
  48
  49   def get(self):
  50     """Handle GET request."""
  51     imagelist = os.listdir(os.path.join(os.path.dirname(__file__), 'samples'))
  52
  53     values = {
  54         'imagelist': imagelist,
  55         'title': 'App Engine Image Demo'
  56     }
  57
  58     self.write_template(values)
  59
  60
  61 class ImagePage(TemplatedPage):
  62   """Request handler for image information display page."""
  63
  64   def get(self):
  65     """Handle GET request."""
  66     image = self.request.get('image')
  67     if not image:
  68       # TODO: More friendly error.
  69       self.error(400)
  70       return
  71
  72     # Transformer is used here only to validate parameters.
  73     transformer = image_transformer.ImageTransformer(self.request.params,
  74                                                      images.JPEG)
  75     transformer.unknown_params.remove('image')
  76     # format is not really a transform.
  77     while 'format' in transformer.unknown_params:
  78       transformer.unknown_params.remove('format')
  79
  80     transform_args = urllib.urlencode(transformer.transforms).replace('%2C',',')
  81     if (self.request.get('format') == 'png'
  82         or self.request.get('format') == 'jpeg'):
  83       transform_args += '&format=%s' % (self.request.get('format'))
  84
  85     documentation = {}
  86     for (method, _) in image_transformer.VALID_TRANSFORMS.iteritems():
  87       documentation[method] = getattr(images.Image, method).__doc__
  88
  89     values = {
  90         'documentation': documentation,
  91         'image': image,
  92         'title': 'App Engine Image Demo',
  93         'transformer': transformer,
  94         'transform_args': transform_args,
  95     }
  96
  97     self.write_template(values)
  98
  99
 100 class SamplePage(TemplatedPage):
 101   """Request handler for image transform sample page."""
 102
 103   def get(self):
 104     """Handle GET request."""
 105     image = self.request.get('image')
 106     if not image:
 107       # TODO: More friendly error.
 108       self.error(400)
 109       return
 110
 111     transform_list = [
 112         'resize=200,200',
 113         'im_feeling_lucky&resize=200,200',
 114         'rotate=90&resize=200,200',
 115         'rotate=180&resize=200,200',
 116         'rotate=360&resize=200,200',
 117         'resize=50,50',
 118         'resize=50,50&resize=200,200',
 119         'resize=200,200&crop=0.0,0.0,0.5,0.5',
 120         'crop=0.5,0.0,1.0,0.5&resize=200,200',
 121         'horizontal_flip&resize=200,200',
 122         'vertical_flip&resize=200,200',
 123     ]
 124
 125     values = {
 126         'image': image,
 127         'title': 'App Engine Image Demo',
 128         'transform_list': transform_list,
 129     }
 130     self.write_template(values)
 131
 132
 133 class ViewSource(TemplatedPage):
 134   """Page handler for view source page."""
 135
 136   def get(self):
 137     """Handle GET request.
 138
 139     An extremely simple implementation of view source using a template.
 140     """
 141     files = ['images_demo.py', 'image_transformer.py']
 142     file_contents = []
 143     for filename in files:
 144       f = open(filename, 'r')
 145       file_contents += [{'name': filename,
 146                          'contents': f.read()}]
 147       f.close()
 148
 149     values = {
 150         'filecontents': file_contents,
 151         'title': 'App Engine Image Demo Source Code',
 152     }
 153     self.write_template(values)
 154
 155
 156 class ImageData(webapp.RequestHandler):
 157   """Request handler for image binary data output."""
 158
 159   def load_local_sample_image(self, filename):
 160     """Load a sample image from a (local to this script) filename."""
 161     path = os.path.join(os.path.dirname(__file__), 'samples', filename)
 162     f = open(path, 'rb')
 163     data = f.read()
 164     f.close()
 165     return data
 166
 167   def get(self):
 168     """Handle image data GET."""
 169     image = self.request.get('image')
 170     if not image:
 171       # TODO: More friendly error.
 172       self.error(400)
 173       return
 174
 175     format = images.JPEG
 176     if self.request.get('format') == 'png':
 177       format = images.PNG
 178
 179     data = self.load_local_sample_image(image)
 180
 181     transformer = image_transformer.ImageTransformer(self.request.params,
 182                                                      format)
 183     data = transformer.transform_image(data)
 184
 185     if format == images.PNG:
 186       self.response.headers['Content-Type'] = 'image/png'
 187     else:
 188       self.response.headers['Content-Type'] = 'image/jpeg'
 189
 190     self.response.out.write(data)
 191
 192
 193 def main():
 194   application = webapp.WSGIApplication([('/', MainPage),
 195                                         ('/tryit', ImagePage),
 196                                         ('/imagedata', ImageData),
 197                                         ('/sample', SamplePage),
 198                                         ('/viewsource', ViewSource),
 199                                        ],
 200                                        debug=True)
 201   wsgiref.handlers.CGIHandler().run(application)
 202
 203 if __name__ == '__main__':
 204   main()