Implemention of PLIP 1673: Automatic image rotation based on Exif data

PLIP 1673: plone/Products.CMFPlone#1673
This PLIP implementation introduced a straight foreward image rotation based on Exif information for JPEG and TIFF Images stored in plone.namedfile Image fields.
The concept of Exif orientation is described in detail in the following blog: http://www.daveperrett.com/articles/2012/07/28/exif-orientation-handling-is-a-ghetto/

It requires an additional external library as dependency: piexif (package: https://pypi.python.org/pypi/piexif; docs: http://piexif.readthedocs.org/en/latest/; github: https://github.com/hMatoba/Piexif)
piexif, allows reading and writing of Exif information, which offers more powerful image handling than a read only library. piexif also works very smart together with Pillow.

This PLIP superseeds prior attemts to add Exif based image rotation to plone.namedfile: #12, #13, #14

For testing of orientation change, images where needed to include for test files.
This is not part of this implementation.
The following github repositories have several examples of Images for orientation testing:
* https://github.com/recurser/exif-orientation-examples (JPEG Images with orientation 1-8 in Landscape and Portrait orientation)
* https://github.com/ianare/exif-samples (lots of different JPEG and TIFF Images, even corrupted images)

Additional to the PLIP implementation this commit includes a restructuring of the package.
* Image meta data detection has been moved to a subfolder utils and splited into several files for each image type
* Moved functions to utils as those are helper methods, so that base functionallity is easier to read
* Added basic TIFF Image handling. Prior TIFF were handled as Files not Images.

Last but not least:
Moved package version from 4.1.x to 4.2.0 as it introduced new features, following semantic versioning.

CHANGES.rst

@@ -1,7 +1,7 @@
 Changelog
 =========
 
-4.1.1 (unreleased)
+4.2.0 (unreleased)
 ------------------
 
 Breaking changes:
@@ -11,10 +11,22 @@ Breaking changes:
 New features:
 
 - *add item here*
+- Add automatic image rotation based on EXIF data for all images.
+  Based on piexif library and ideas of maartenkling and ezvirtual.
+  Choosen piexif as it allow read and write of exif data for future enhancements.
+  http://piexif.readthedocs.org/en/latest/
+  For Orientation examples and description see http://www.daveperrett.com/articles/2012/07/28/exif-orientation-handling-is-a-ghetto/ test data https://github.com/recurser/exif-orientation-examples
+  Additional Test Images with different MIME-Types (JPEG and TIFF) and possible problems: https://github.com/ianare/exif-samples.git
+  [loechel]
 
 Bug fixes:
 
 - *add item here*
+- Added handler for Tiff Images in getImageInfo.
+  [loechel]
+- Restructured packages.
+  Moved image meta data detection in an own subfolder
+  [loechel]
 
 
 4.1 (2016-09-14)

plone/namedfile/file.py

@@ -2,23 +2,29 @@
 # The implementations in this file are largely borrowed
 # from zope.app.file and z3c.blobfile
 # and are licensed under the ZPL.
-from cStringIO import StringIO
+from logging import getLogger
 from persistent import Persistent
 from plone.namedfile.interfaces import INamedBlobFile
 from plone.namedfile.interfaces import INamedBlobImage
 from plone.namedfile.interfaces import INamedFile
 from plone.namedfile.interfaces import INamedImage
 from plone.namedfile.interfaces import IStorage
 from plone.namedfile.utils import get_contenttype
+from plone.namedfile.utils import get_exif
+from plone.namedfile.utils import getImageInfo
+from plone.namedfile.utils import rotate_image
 from ZODB.blob import Blob
 from zope.component import getUtility
 from zope.interface import implementer
 from zope.schema.fieldproperty import FieldProperty
 
-import struct
+import piexif
 import transaction
 
 
+log = getLogger(__name__)
+
+
 MAXCHUNKSIZE = 1 << 16
 IMAGE_INFO_BYTES = 1024
 MAX_INFO_BYTES = 1 << 16
@@ -267,13 +273,24 @@ class NamedImage(NamedFile):
 
     def __init__(self, data='', contentType='', filename=None):
         self.contentType, self._width, self._height = getImageInfo(data)
-        self.data = data
         self.filename = filename
+        self._setData(data)
 
         # Allow override of the image sniffer
         if contentType:
             self.contentType = contentType
 
+        exif_data = get_exif(data)
+        if exif_data is not None:
+            log.debug('Image contains Exif Informations. '
+                      'Test for Image Orientation and Rotate if necessary.'
+                      'Exif Data: %s', exif_data)
+            orientation = exif_data['0th'].get(piexif.ImageIFD.Orientation, 1)
+            if 1 < orientation <= 8:
+                self.data, self._width, self._height, self.exif = rotate_image(
+                    self.data)
+            self.exif_data = exif_data
+
     def _setData(self, data):
         super(NamedImage, self)._setData(data)
 
@@ -288,81 +305,6 @@ def getImageSize(self):
     data = property(NamedFile._getData, _setData)
 
 
-def getImageInfo(data):
-    data = str(data)
-    size = len(data)
-    height = -1
-    width = -1
-    content_type = ''
-
-    # handle GIFs
-    if (size >= 10) and data[:6] in ('GIF87a', 'GIF89a'):
-        # Check to see if content_type is correct
-        content_type = 'image/gif'
-        w, h = struct.unpack('<HH', data[6:10])
-        width = int(w)
-        height = int(h)
-
-    # See PNG 2. Edition spec (http://www.w3.org/TR/PNG/)
-    # Bytes 0-7 are below, 4-byte chunk length, then 'IHDR'
-    # and finally the 4-byte width, height
-    elif (
-        (size >= 24) and data.startswith('\211PNG\r\n\032\n') and
-        (data[12:16] == 'IHDR')
-    ):
-        content_type = 'image/png'
-        w, h = struct.unpack('>LL', data[16:24])
-        width = int(w)
-        height = int(h)
-
-    # Maybe this is for an older PNG version.
-    elif (size >= 16) and data.startswith('\211PNG\r\n\032\n'):
-        # Check to see if we have the right content type
-        content_type = 'image/png'
-        w, h = struct.unpack('>LL', data[8:16])
-        width = int(w)
-        height = int(h)
-
-    # handle JPEGs
-    elif (size >= 2) and data.startswith('\377\330'):
-        content_type = 'image/jpeg'
-        jpeg = StringIO(data)
-        jpeg.read(2)
-        b = jpeg.read(1)
-        try:
-            w = -1
-            h = -1
-            while (b and ord(b) != 0xDA):
-                while (ord(b) != 0xFF):
-                    b = jpeg.read(1)
-                while (ord(b) == 0xFF):
-                    b = jpeg.read(1)
-                if (ord(b) >= 0xC0 and ord(b) <= 0xC3):
-                    jpeg.read(3)
-                    h, w = struct.unpack('>HH', jpeg.read(4))
-                    break
-                else:
-                    jpeg.read(int(struct.unpack('>H', jpeg.read(2))[0]) - 2)
-                b = jpeg.read(1)
-            width = int(w)
-            height = int(h)
-        except struct.error:
-            pass
-        except ValueError:
-            pass
-        except TypeError:
-            pass
-
-    # handle BMPs
-    elif (size >= 30) and data.startswith('BM'):
-        kind = struct.unpack('<H', data[14:16])[0]
-        if kind == 40:  # Windows 3.x bitmap
-            content_type = 'image/x-ms-bmp'
-            width, height = struct.unpack('<LL', data[18:26])
-
-    return content_type, width, height
-
-
 @implementer(INamedBlobFile)
 class NamedBlobFile(Persistent):
     """A file stored in a ZODB BLOB, with a filename"""
@@ -397,6 +339,7 @@ def _setData(self, data):
         # Search for a storable that is able to store the data
         dottedName = '.'.join((data.__class__.__module__,
                                data.__class__.__name__))
+        log.debug('Storage selected for data: %s', dottedName)
         storable = getUtility(IStorage, name=dottedName)
         storable.store(data, self._blob)
 
@@ -430,17 +373,30 @@ class NamedBlobImage(NamedBlobFile):
     """
 
     def __init__(self, data='', contentType='', filename=None):
-        super(NamedBlobImage, self).__init__(data, filename=filename)
+        super(NamedBlobImage, self).__init__(data,
+                                             contentType=contentType,
+                                             filename=filename)
 
         # Allow override of the image sniffer
         if contentType:
             self.contentType = contentType
+        exif_data = get_exif(self.data)
+        if exif_data is not None:
+            log.debug('Image contains Exif Informations. '
+                      'Test for Image Orientation and Rotate if necessary.'
+                      'Exif Data: %s', exif_data)
+            orientation = exif_data['0th'].get(piexif.ImageIFD.Orientation, 1)
+            if 1 < orientation <= 8:
+                self.data, self._width, self._height, self.exif = rotate_image(
+                    self.data)
+            else:
+                self.exif = exif_data
 
     def _setData(self, data):
         super(NamedBlobImage, self)._setData(data)
         firstbytes = self.getFirstBytes()
         res = getImageInfo(firstbytes)
-        if res == ('image/jpeg', -1, -1):
+        if res == ('image/jpeg', -1, -1) or res == ('image/tiff', -1, -1):
             # header was longer than firstbytes
             start = len(firstbytes)
             length = max(0, MAX_INFO_BYTES - start)
@@ -468,6 +424,5 @@ def getImageSize(self):
         if (self._width, self._height) != (-1, -1):
             return (self._width, self._height)
 
-        res = getImageInfo(self.data)
-        contentType, self._width, self._height = res
+        contentType, self._width, self._height = getImageInfo(self.data)
         return (self._width, self._height)