Action now has a list of found UM3 keys

CURA-336

DiscoverUM3Action.py

@@ -1,9 +1,32 @@
 from cura.MachineAction import MachineAction
 
+from UM.Application import Application
+
+from PyQt5.QtCore import pyqtSignal, pyqtProperty, pyqtSlot
+
 class DiscoverUM3Action(MachineAction):
     def __init__(self):
         super().__init__("DiscoverUM3Action", "Discover printers")
         self._qml_url = "DiscoverUM3Action.qml"
 
-    def _execute(self):
-        pass
+        self._network_plugin = None
+
+    printerDetected = pyqtSignal()
+
+    @pyqtSlot()
+    def startDiscovery(self):
+        if not self._network_plugin:
+            self._network_plugin = Application.getInstance().getOutputDeviceManager().getOutputDevicePlugin("JediWifiPrintingPlugin")
+            self._network_plugin.addPrinterSignal.connect(self._onPrinterAdded)
+            self.printerDetected.emit()
+
+    def _onPrinterAdded(self, *args):
+        self.printerDetected.emit()
+
+    @pyqtProperty("QVariantList", notify = printerDetected)
+    def foundDevices(self):
+        if self._network_plugin:
+            print(list(self._network_plugin.getPrinters().keys()))
+            return list(self._network_plugin.getPrinters().keys())
+        else:
+            return []