option --auto-connect, connect automatically if one device detected (#645)

* option --auto-connect, connect automatically to the 1st detected device
* autoconnect only if there is exactly one device

Signed-off-by: Martin <Ho-Ro@users.noreply.github.com>

src/NanoVNASaver/NanoVNASaver.py

@@ -473,6 +473,10 @@ class NanoVNASaver(QWidget):
 
         logger.debug("Finished building interface")
 
+    def auto_connect( self ): # connect if there is exactly one detected serial device
+        if self.serial_control.inp_port.count() == 1:
+            self.serial_control.connect_device()
+
     def _sweep_control(self, start: bool = True) -> None:
         self.sweep_control.progress_bar.setValue(0 if start else 100)
         self.sweep_control.btn_start.setDisabled(start)

src/NanoVNASaver/__main__.py

@@ -46,6 +46,9 @@ def main():
     parser.add_argument(
         "-D", "--debug-file", help="File to write debug logging output to"
     )
+    parser.add_argument(
+        "-a", "--auto-connect", action="store_true", help="Auto connect if one device detected"
+    )
     parser.add_argument(
         "-f",
         "--file",
@@ -92,6 +95,8 @@ def main():
     window = NanoVNASaver()
     window.show()
 
+    if args.auto_connect:
+        window.auto_connect()
     if args.file:
         t = Touchstone(args.file)
         t.load()