Make to code more robust

openlp/core/ui/themeform.py

@@ -36,7 +36,7 @@ from openlp.core.lib import Receiver, translate
 from openlp.core.lib.theme import BackgroundType, BackgroundGradientType
 from openlp.core.lib.ui import UiStrings, critical_error_message_box
 from openlp.core.ui import ThemeLayoutForm
-from openlp.core.utils import get_images_filter
+from openlp.core.utils import get_images_filter, is_not_image_file
 from themewizard import Ui_ThemeWizard
 
 log = logging.getLogger(__name__)
@@ -233,8 +233,7 @@ class ThemeForm(QtGui.QWizard, Ui_ThemeWizard):
         background_image = BackgroundType.to_string(BackgroundType.Image)
         if self.page(self.currentId()) == self.backgroundPage and \
             self.theme.background_type == background_image and \
-            (self.imageFileEdit.text().isEmpty() or
+            is_not_image_file(self.imageFileEdit.text()):
-            os.path.exists(self.imageFileEdit.text())):
             QtGui.QMessageBox.critical(self,
                 translate('OpenLP.ThemeWizard', 'Background Image Empty'),
                 translate('OpenLP.ThemeWizard', 'You have not selected a '

openlp/core/utils/__init__.py

@@ -364,6 +364,22 @@ def get_images_filter():
             visible_formats, actual_formats)
     return IMAGES_FILTER
 
+def is_not_image_file(file_name):
+    """
+    Validate that the file is an image file.
+
+    ``file_name``
+        File name to be checked.
+    """
+    formats = [unicode(fmt)
+            for fmt in QtGui.QImageReader.supportedImageFormats()]
+    if file_name.isEmpty():
+        return True
+    else:
+        file_part, file_extension = os.path.splitext(unicode(file_name))
+        if file_extension[1:] in formats and os.path.exists(file_name):
+            return False
+        return True
 
 def join_url(base, *args):
     """