Python: Serve Images + thumbnails list as JSON. Generate missing thumbnails on the fly.

images.py

#!/usr/bin/python

from urlparse import urlparse, parse_qs
from PIL import Image
import os
import json

print "Content-Type: application/json"
print ""

response_object = {}
image_dimensions = {}
thumb_dimensions = {}

IMAGES_PATH = '/images/'
THUMBS_PATH = '/image_thumbs/'
MAX_THUMB_SIZE = (500, 500)
base_path = os.environ['DOCUMENT_ROOT']
media_path = '/media/'
queryParams = parse_qs(urlparse(os.environ['REQUEST_URI']).query)

def thumbnail_image(in_path, out_path):
    global MAX_THUMB_SIZE
    image = Image.open(in_path)
    width, height = image.size
    cropped = image.crop((int(width * .15), int(height * .15), int(width * .80), int(height * .80)))
    cropped.thumbnail(MAX_THUMB_SIZE)
    cropped.save(out_path)

def get_image_dimensions(in_path):
    image = Image.open(in_path)
    width, height = image.size
    return { 'width': width, 'height': height }

def web_path(type, format, filename =''):
    global media_path
    return media_path + type + format + filename

def disk_path(type, format, filename =''):
    global base_path
    global media_path
    return base_path + media_path + type + format + filename

try:

    images = [ { \
    'thumbs': os.listdir(disk_path(image_type, THUMBS_PATH)), \
    'images': os.listdir(disk_path(image_type, IMAGES_PATH)), \
    'type': image_type} for image_type in queryParams['type']]

    for image_type in images:
        image_folder_for_type = disk_path(image_type['type'], IMAGES_PATH)
        thumb_folder_for_type = disk_path(image_type['type'], THUMBS_PATH)
        
        for imageFile in image_type['images']:
            image_path = image_folder_for_type + imageFile
            thumbnail_path = thumb_folder_for_type + imageFile
            
            if not os.path.exists(thumbnail_path):
                thumbnail_image(image_path, thumbnail_path)
                
        if 'include-dimensions' in queryParams:
            image_dimensions = [ get_image_dimensions(disk_path(image_type['type'], IMAGES_PATH, file)) for file in os.listdir(image_folder_for_type) ]
            thumb_dimensions = [ get_image_dimensions(disk_path(image_type['type'], THUMBS_PATH, file)) for file in os.listdir(image_folder_for_type) ] #avoid different sort order
            final_images_paths = [ web_path(image_type['type'], IMAGES_PATH, file) for file in os.listdir(image_folder_for_type) ]
            final_thumbs_paths = [ web_path(image_type['type'], THUMBS_PATH, file) for file in os.listdir(image_folder_for_type) ] #avoid different sort order
            final_tuple = zip(final_images_paths, final_thumbs_paths, image_dimensions, thumb_dimensions)
            response_object[image_type['type']] = [ {'image': final_image, \
            'thumbnail': final_thumb, \
            'imageDimensions': image_dim , \
            'thumbDimensions': thumb_dim } for (final_image, final_thumb, image_dim, thumb_dim) in final_tuple ]
        
        else:
            final_images_paths = [ web_path(image_type['type'], IMAGES_PATH, file) for file in os.listdir(image_folder_for_type) ]
            final_thumbs_paths = [ web_path(image_type['type'], THUMBS_PATH, file) for file in os.listdir(image_folder_for_type) ] #avoid different sort order
            final_tuple = zip(final_images_paths, final_thumbs_paths)
            response_object[image_type['type']] = [ {'image': final_image, 'thumbnail': final_thumb } for (final_image, final_thumb) in final_tuple ]
        
    print json.dumps(response_object)

except Exception as e:
    print json.dumps(e)

now optionally includes image width and height in the JSON images.py?type=some-type&include-dimensions=true.

for performance reasons, i don't know if i'd ask for dimensions in public facing pages if you've got a HUGE directory of images.

need to refactor to only read the os.listdir once... but later.