Merge pull request #1718 from gasman/feature/image-library-system-check

Add system check for presence of libjpeg / zlib

wagtail/wagtailimages/apps.py

@@ -1,5 +1,7 @@
 from django.apps import AppConfig
 
+from . import checks  # NOQA
+
 
 class WagtailImagesAppConfig(AppConfig):
     name = 'wagtail.wagtailimages'

wagtail/wagtailimages/checks.py

@@ -0,0 +1,57 @@
+import os
+
+from django.core.checks import register, Warning
+from django.utils.lru_cache import lru_cache
+
+from willow.image import Image
+
+
+@lru_cache()
+def has_jpeg_support():
+    wagtail_jpg = os.path.join(os.path.dirname(__file__), 'check_files', 'wagtail.jpg')
+    succeeded = True
+
+    with open(wagtail_jpg, 'rb') as f:
+        try:
+            Image.open(f)
+        except (IOError, Image.LoaderError):
+            succeeded = False
+
+    return succeeded
+
+
+@lru_cache()
+def has_png_support():
+    wagtail_png = os.path.join(os.path.dirname(__file__), 'check_files', 'wagtail.png')
+    succeeded = True
+
+    with open(wagtail_png, 'rb') as f:
+        try:
+            Image.open(f)
+        except (IOError, Image.LoaderError):
+            succeeded = False
+
+    return succeeded
+
+
+@register()
+def image_library_check(app_configs, **kwargs):
+    errors = []
+
+    if not has_jpeg_support():
+        errors.append(
+            Warning(
+                'JPEG image support is not available',
+                hint="Check that the 'libjpeg' library is installed, then reinstall Pillow."
+            )
+        )
+
+    if not has_png_support():
+        errors.append(
+            Warning(
+                'PNG image support is not available',
+                hint="Check that the 'zlib' library is installed, then reinstall Pillow."
+            )
+        )
+
+    return errors