line: show image in tab 'image/pdf'

line.py

@@ -48,6 +48,18 @@ class Line(metaclass=PoolMeta):
     media_id = fields.Char(string='File ID', readonly=True)
     media_mime = fields.Char(string='MIME', readonly=True)
     media_size = fields.Integer(string='File size', readonly=True)
+    media_image = fields.Function(fields.Binary(string='Image', readonly=True,
+        states={
+            'invisible': ~Eval('media_mime', '').in_(['image/png', 'image/jpg', 'image/jpeg']),
+        }, depends=['media_mime']),
+        'on_change_with_media_image')
+
+    @fields.depends('media', 'media_mime')
+    def on_change_with_media_image(self, name=True):
+        """ return binary if its a image
+        """
+        if (self.media_mime or '-').startswith('image/'):
+            return self.media
 
     @classmethod
     def _identify_file(cls, data, mime=True):

locale/de.po

@@ -46,3 +46,6 @@ msgctxt "field:cashbook.line,media_size:"
 msgid "File size"
 msgstr "Dateigröße"
 
+msgctxt "field:cashbook.line,media_image:"
+msgid "Image"
+msgstr "Bild"

view/line_form.xml

@@ -13,10 +13,10 @@ full copyright notices and license terms. -->
 
             <label name="media_name"/>
             <field name="media_name"/>
-
             <label name="media_mime"/>
             <field name="media_mime"/>
 
+            <field name="media_image" readonly="1" colspan="4" widget="image" xexpand="1" yexpand="1"/>
         </page>
 
     </xpath>