Added caching headers and handling of If-Modified-Since headers to ImageFile objects.

lib/python/ImageFile.py

@@ -84,29 +84,49 @@
 ##############################################################################
 """Image object that is stored in a file"""
 
-__version__='$Revision: 1.8 $'[11:-2]
+__version__='$Revision: 1.9 $'[11:-2]
+
 
-from string import rfind
 from Globals import package_home
+from Common import rfc1123_date
 from DateTime import DateTime
+from string import rfind
+from time import time
+from os import stat
 import Acquisition
 
+
 class ImageFile(Acquisition.Explicit):
-    """Image object stored in an external file"""
+    """Image objects stored in external files."""
 
     def __init__(self,path,_prefix=None):
         if _prefix is None: _prefix=SOFTWARE_HOME
-        elif type(_prefix) is not type(''): _prefix=package_home(_prefix)
+        elif type(_prefix) is not type(''):
+            _prefix=package_home(_prefix)
         path='%s/%s' % (_prefix, path)
-
         self.path=path
         self.content_type='image/%s' % path[rfind(path,'.')+1:]
         self.__name__=path[rfind(path,'/')+1:]
-
-
-    def index_html(self, RESPONSE):
+        # Determine a reasonable last-modification time 
+        # to support aggressive image caching.
+        self.lmt=float(stat(path)[8]) or time()
+        self.lmh=rfc1123_date(self.lmt)
+
+    def _init_headers(self, request, response):
+        # attempt aggressive caching!
+        ms=request.get_header('If-Modified-Since', None)
+        if ms is not None:
+            mst=DateTime(ms).timeTime()
+            if mst >= self.lmt:
+                response.setStatus(304)
+                return response
+        response.setHeader('Content-Type', self.content_type)
+        response.setHeader('Last-Modified', self.lmh)
+        response.setHeader('Expires', rfc1123_date(time()+86400.0))
+        
+    def index_html(self, REQUEST, RESPONSE):
         """Default document"""
-        RESPONSE['content-type']=self.content_type
+        self._init_headers(REQUEST, RESPONSE)
         f=open(self.path,'rb')
         data=f.read()
         f.close()
@@ -115,7 +135,7 @@ class ImageFile(Acquisition.Explicit):
     HEAD__roles__=None
     def HEAD(self, REQUEST, RESPONSE):
         """ """
-        RESPONSE['content-type'] =self.content_type
+        self._init_headers(self, REQUEST, RESPONSE)
         return ''
 
     def __len__(self):
@@ -125,9 +145,3 @@ class ImageFile(Acquisition.Explicit):
     def __str__(self):
         return '<IMG SRC="%s" ALT="%s">' % (self.__name__, self.title_or_id()) 
 
-
-
-
-
-
-