class RESIZE(object): 
    def __init__(self,nx=160,ny=80,error_message='niepoprawny plik'): 
        (self.nx,self.ny,self.error_message)=(nx,ny,error_message) 
    def __call__(self,value):
        if isinstance(value, str) and len(value)==0: 
            return (value,None) 
        from PIL import Image 
        import cStringIO 
        try: 
            img = Image.open(value.file) 
            img.thumbnail((self.nx,self.ny), Image.ANTIALIAS) 
            s = cStringIO.StringIO() 
            img.save(s, 'JPEG', quality=100) 
            s.seek(0) 
            value.file = s 
        except: 
            return (value, self.error_message) 
        else: 
            return (value, None)
            
def THUMB(image, nx=120, ny=120):
    from PIL import Image 
    import os  
    img = Image.open(request.folder + 'uploads/' + image)
    img.thumbnail((nx,ny), Image.ANTIALIAS) 
    root,ext = os.path.splitext(image)
    thumb='%s_thumb%s' %(root, ext)
    img.save(request.folder + 'uploads/' + thumb)
    return thumb


db.define_table('gallery',
    Field('image', 'upload', required=True, notnull=True, requires=[IS_IMAGE(), RESIZE(650, 650)]),
    Field('image_thumb', 'upload', compute=lambda r: THUMB(r['image'])))