summaryrefslogtreecommitdiff
path: root/lib/python2.7/site-packages/django/utils/image.py
diff options
context:
space:
mode:
Diffstat (limited to 'lib/python2.7/site-packages/django/utils/image.py')
-rw-r--r--lib/python2.7/site-packages/django/utils/image.py154
1 files changed, 154 insertions, 0 deletions
diff --git a/lib/python2.7/site-packages/django/utils/image.py b/lib/python2.7/site-packages/django/utils/image.py
new file mode 100644
index 0000000..4bece2e
--- /dev/null
+++ b/lib/python2.7/site-packages/django/utils/image.py
@@ -0,0 +1,154 @@
+# -*- coding: utf-8 -*-
+"""
+To provide a shim layer over Pillow/PIL situation until the PIL support is
+removed.
+
+
+Combinations To Account For
+===========================
+
+* Pillow:
+
+ * never has ``_imaging`` under any Python
+ * has the ``Image.alpha_composite``, which may aid in detection
+
+* PIL
+
+ * CPython 2.x may have _imaging (& work)
+ * CPython 2.x may *NOT* have _imaging (broken & needs a error message)
+ * CPython 3.x doesn't work
+ * PyPy will *NOT* have _imaging (but works?)
+ * On some platforms (Homebrew and RHEL6 reported) _imaging isn't available,
+ the needed import is from PIL import _imaging (refs #21355)
+
+Restated, that looks like:
+
+* If we're on Python 2.x, it could be either Pillow or PIL:
+
+ * If ``import _imaging`` results in ``ImportError``, either they have a
+ working Pillow installation or a broken PIL installation, so we need to
+ detect further:
+
+ * To detect, we first ``import Image``.
+ * If ``Image`` has a ``alpha_composite`` attribute present, only Pillow
+ has this, so we assume it's working.
+ * If ``Image`` DOES NOT have a ``alpha_composite``attribute, it must be
+ PIL & is a broken (likely C compiler-less) install, which we need to
+ warn the user about.
+
+ * If ``import _imaging`` works, it must be PIL & is a working install.
+
+* Python 3.x
+
+ * If ``import Image`` works, it must be Pillow, since PIL isn't Python 3.x
+ compatible.
+
+* PyPy
+
+ * If ``import _imaging`` results in ``ImportError``, it could be either
+ Pillow or PIL, both of which work without it on PyPy, so we're fine.
+
+
+Approach
+========
+
+* Attempt to import ``Image``
+
+ * ``ImportError`` - nothing is installed, toss an exception
+ * Either Pillow or the PIL is installed, so continue detecting
+
+* Attempt to ``hasattr(Image, 'alpha_composite')``
+
+ * If it works, it's Pillow & working
+ * If it fails, we've got a PIL install, continue detecting
+
+ * The only option here is that we're on Python 2.x or PyPy, of which
+ we only care about if we're on CPython.
+ * If we're on CPython, attempt to ``from PIL import _imaging`` and
+ ``import _imaging``
+
+ * ``ImportError`` - Bad install, toss an exception
+
+"""
+from __future__ import unicode_literals
+
+import warnings
+
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.translation import ugettext_lazy as _
+
+
+Image = None
+_imaging = None
+ImageFile = None
+
+
+def _detect_image_library():
+ global Image
+ global _imaging
+ global ImageFile
+
+ # Skip re-attempting to import if we've already run detection.
+ if Image is not None:
+ return Image, _imaging, ImageFile
+
+ # Assume it's not there.
+ PIL_imaging = False
+
+ try:
+ # Try from the Pillow (or one variant of PIL) install location first.
+ from PIL import Image as PILImage
+ except ImportError as err:
+ try:
+ # If that failed, try the alternate import syntax for PIL.
+ import Image as PILImage
+ except ImportError as err:
+ # Neither worked, so it's likely not installed.
+ raise ImproperlyConfigured(
+ _("Neither Pillow nor PIL could be imported: %s") % err
+ )
+
+ # ``Image.alpha_composite`` was added to Pillow in SHA: e414c6 & is not
+ # available in any version of the PIL.
+ if hasattr(PILImage, 'alpha_composite'):
+ PIL_imaging = False
+ else:
+ # We're dealing with the PIL. Determine if we're on CPython & if
+ # ``_imaging`` is available.
+ import platform
+
+ # This is the Alex Approved™ way.
+ # See http://mail.python.org/pipermail//pypy-dev/2011-November/008739.html
+ if platform.python_implementation().lower() == 'cpython':
+ # We're on CPython (likely 2.x). Since a C compiler is needed to
+ # produce a fully-working PIL & will create a ``_imaging`` module,
+ # we'll attempt to import it to verify their kit works.
+ try:
+ from PIL import _imaging as PIL_imaging
+ except ImportError:
+ try:
+ import _imaging as PIL_imaging
+ except ImportError as err:
+ raise ImproperlyConfigured(
+ _("The '_imaging' module for the PIL could not be "
+ "imported: %s") % err
+ )
+
+ # Try to import ImageFile as well.
+ try:
+ from PIL import ImageFile as PILImageFile
+ except ImportError:
+ import ImageFile as PILImageFile
+
+ # Finally, warn about deprecation...
+ if PIL_imaging is not False:
+ warnings.warn(
+ "Support for the PIL will be removed in Django 1.8. Please " +
+ "uninstall it & install Pillow instead.",
+ PendingDeprecationWarning
+ )
+
+ return PILImage, PIL_imaging, PILImageFile
+
+
+Image, _imaging, ImageFile = _detect_image_library()