diff -r e7855eefb4c7 -r 55cb7fc9c8fb degal/exif.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/degal/exif.py	Sun Jun 14 23:43:40 2009 +0300
@@ -0,0 +1,137 @@
+"""
+    The various Exif backends that we have
+"""
+
+from __future__ import with_statement
+
+import utils
+
+class ExifHandler (object) :
+    """
+        Our generic interface for Exif data
+    """
+
+    def __init__ (self, file) :
+        """
+            Load Exif data from the given File.
+        """
+
+        self.file = file
+    
+    def image_tag (self, tag, default=None) :
+        """
+            Load and return the human-readable unicode-safe value for the given main image tag.
+        """
+
+        abstract
+
+    def image_tags (self, tags) :
+        """
+            Load and return the given tags for the main image as a sequence of (tag, value) tuples , following the same
+            rules as image_tag, except there should mainly be only one call to this function, encompassing all the
+            relevant tags.
+
+            The returned list should omit those values which were not found.
+        """
+    
+        for tag in tags :
+            # try and fetch value
+            value = self.image_tag(tag)
+
+            # filter out default not-found
+            if value is not None :
+                yield tag, value
+
+try :
+    import pyexiv2
+
+except ImportError :
+    PyExiv2_Handler = None
+
+else :
+    class PyExiv2_Handler (ExifHandler) :
+        NAME = 'pyexiv2'
+
+        def __init__ (self, file) :
+            """
+                Load as pyexiv2.Image
+            """
+            
+            # create
+            self.image = pyexiv2.Image(file.path)
+
+            # load
+            self.image.readMetadata()
+        
+        def image_tag (self, tag, default=None) :
+            try :
+                # XXX: this is wrong
+                return self.image.interpretedExifValue("Exif.Photo.%s" % tag)
+            
+            except (IndexError, KeyError) :
+                return default
+    
+try :
+    from lib import EXIF
+
+except ImportError :
+    EXIF_Handler = None
+
+else :
+    class EXIF_Handler (ExifHandler) :
+        NAME = 'EXIFpy'
+
+        def __init__ (self, file) :
+            """
+                Load using EXIF.process_file
+            """
+            
+            with file.open('rb') as fh :
+                self.tags = EXIF.process_file(fh)
+        
+        def image_tag (self, tag, default=None) :
+            # XXX: this is wrong
+            return self.tags.get('Image %s' % (tag, ), default)
+
+# ExifHandler implementations to use, in preference order
+EXIF_HANDLERS = [
+    # reasonably fast, but requires the native library and extension module
+    PyExiv2_Handler,
+
+    # pure-python, but very, very slow
+    EXIF_Handler,
+]
+
+# default ExifHandler to use
+EXIF_HANDLER = utils.first(EXIF_HANDLERS)
+
+# ExifHandler implementations by name
+EXIF_HANDLERS_BY_NAME = dict((h.NAME, h) for h in EXIF_HANDLERS)
+
+def load (config, file) :
+    """
+        Load Exif data using the configured Exif handler, and return the instance.
+
+        Returns None if there wasn't any Exif handler available for use.
+    """
+
+    if config.exif_handler :
+        # explicit
+        exif_handler = config.exif_handler
+
+    elif config.exif_handler_name :
+        # by name
+        exif_handler = EXIF_HANDLERS_BY_NAME[config.exif_handler_name]
+
+    else :
+        # default
+        exif_handler = EXIF_HANDLER
+    
+    if exif_handler :
+        # found one, use it
+        return exif_handler(file)
+
+    else :
+        # nothing :(
+        return None
+