Added image for midi/mid file format. Store only common file formats (e.g. same image for different formats) in the code, otherwise get the image file directly from the statics

boards/models/attachment/viewers.py

@@ -10,6 +10,7 b' from boards.utils import get_domain, cac'
 
 FILE_STUB_IMAGE = 'images/file.png'
 FILE_STUB_URL = 'url'
+FILE_FILEFORMAT = 'images/fileformats/{}.png'
 
 
 FILE_TYPES_VIDEO = (
@@ -33,14 +34,10 b' FILE_TYPES_IMAGE = ('
 )
 
 PLAIN_FILE_FORMATS = {
-    'pdf': 'pdf',
-    'djvu': 'djvu',
-    'txt': 'txt',
-    'tex': 'tex',
-    'xcf': 'xcf',
     'zip': 'archive',
     'tar': 'archive',
     'gz': 'archive',
+    'mid' : 'midi',
 }
 
 URL_PROTOCOLS = {
@@ -84,9 +81,11 b' class AbstractViewer:'
                                self.file_type, filesizeformat(self.file.size))
 
     def get_format_view(self):
-        if self.file_type in PLAIN_FILE_FORMATS:
-            image = 'images/fileformats/{}.png'.format(
-                    PLAIN_FILE_FORMATS[self.file_type])
+        image_name = PLAIN_FILE_FORMATS.get(self.file_type, self.file_type)
+        file_name = FILE_FILEFORMAT.format(image_name)
+
+        if file_exists(file_name):
+            image = file_name
         else:
             image = FILE_STUB_IMAGE