calculate image-size in device-messages

eg. android relies on that and fallsback to wrong aspect ratios otherwise.
also, this makes job.rs a little more readable
as some things are moved to message.rs :)

src/chat.rs

@@ -1984,6 +1984,7 @@ pub fn add_device_msg(
         chat_id = create_or_lookup_by_contact_id(context, DC_CONTACT_ID_DEVICE, Blocked::Not)?.0;
 
         let rfc724_mid = dc_create_outgoing_rfc724_mid(None, "@device");
+        msg.try_calc_and_set_dimensions(context).ok();
         prepare_msg_blob(context, msg)?;
         unarchive(context, chat_id)?;
 

src/job.rs

@@ -605,27 +605,7 @@ fn set_delivered(context: &Context, msg_id: MsgId) {
 #[allow(non_snake_case)]
 pub fn job_send_msg(context: &Context, msg_id: MsgId) -> Result<(), Error> {
     let mut mimefactory = MimeFactory::load_msg(context, msg_id)?;
-
+    mimefactory.msg.try_calc_and_set_dimensions(context).ok();
-    if chat::msgtype_has_file(mimefactory.msg.type_0) {
-        let file_param = mimefactory.msg.param.get_path(Param::File, context)?;
-        if let Some(pathNfilename) = file_param {
-            if (mimefactory.msg.type_0 == Viewtype::Image
-                || mimefactory.msg.type_0 == Viewtype::Gif)
-                && !mimefactory.msg.param.exists(Param::Width)
-            {
-                mimefactory.msg.param.set_int(Param::Width, 0);
-                mimefactory.msg.param.set_int(Param::Height, 0);
-
-                if let Ok(buf) = dc_read_file(context, pathNfilename) {
-                    if let Ok((width, height)) = dc_get_filemeta(&buf) {
-                        mimefactory.msg.param.set_int(Param::Width, width as i32);
-                        mimefactory.msg.param.set_int(Param::Height, height as i32);
-                    }
-                }
-                mimefactory.msg.save_param_to_disk(context);
-            }
-        }
-    }
 
     /* create message */
     if let Err(msg) = unsafe { mimefactory.render() } {

src/message.rs

@@ -309,6 +309,32 @@ impl Message {
         self.param.get_path(Param::File, context).unwrap_or(None)
     }
 
+    pub fn try_calc_and_set_dimensions(&mut self, context: &Context) -> Result<(), Error> {
+        if chat::msgtype_has_file(self.type_0) {
+            let file_param = self.param.get_path(Param::File, context)?;
+            if let Some(path_and_filename) = file_param {
+                if (self.type_0 == Viewtype::Image || self.type_0 == Viewtype::Gif)
+                    && !self.param.exists(Param::Width)
+                {
+                    self.param.set_int(Param::Width, 0);
+                    self.param.set_int(Param::Height, 0);
+
+                    if let Ok(buf) = dc_read_file(context, path_and_filename) {
+                        if let Ok((width, height)) = dc_get_filemeta(&buf) {
+                            self.param.set_int(Param::Width, width as i32);
+                            self.param.set_int(Param::Height, height as i32);
+                        }
+                    }
+
+                    if !self.id.is_unset() {
+                        self.save_param_to_disk(context);
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+
     /// Check if a message has a location bound to it.
     /// These messages are also returned by dc_get_locations()
     /// and the UI may decide to display a special icon beside such messages,