Pre-read now checks for conflicts and asks the user what strategy for resolvement to use

CURA-1263

plugins/3MFReader/WorkspaceDialog.py

@@ -0,0 +1,79 @@
+from PyQt5.QtCore import Qt, QUrl, pyqtSignal, pyqtSlot, QObject
+from PyQt5.QtQml import QQmlComponent, QQmlContext
+from UM.PluginRegistry import PluginRegistry
+from UM.Application import Application
+
+import os
+import threading
+
+class WorkspaceDialog(QObject):
+    showDialogSignal = pyqtSignal()
+
+    def __init__(self, parent = None):
+        super().__init__(parent)
+        self._component = None
+        self._context = None
+        self._view = None
+        self._qml_url = "WorkspaceDialog.qml"
+        self._lock = threading.Lock()
+        self._result = None  # What option did the user pick?
+        self._visible = False
+        self.showDialogSignal.connect(self.__show)
+
+    def getResult(self):
+        return self._result
+
+    def _createViewFromQML(self):
+        path = QUrl.fromLocalFile(os.path.join(PluginRegistry.getInstance().getPluginPath("3MFReader"), self._qml_url))
+        self._component = QQmlComponent(Application.getInstance()._engine, path)
+        self._context = QQmlContext(Application.getInstance()._engine.rootContext())
+        self._context.setContextProperty("manager", self)
+        self._view = self._component.create(self._context)
+
+    def show(self):
+        # Emit signal so the right thread actually shows the view.
+        self._lock.acquire()
+        self._result = None
+        self._visible = True
+        self.showDialogSignal.emit()
+
+    @pyqtSlot()
+    ##  Used to notify the dialog so the lock can be released.
+    def notifyClosed(self):
+        if self._result is None:
+            self._result = "cancel"
+        self._lock.release()
+
+    def hide(self):
+        self._visible = False
+        self._lock.release()
+        self._view.hide()
+
+    @pyqtSlot()
+    def onOverrideButtonClicked(self):
+        self._view.hide()
+        self.hide()
+        self._result = "override"
+
+    @pyqtSlot()
+    def onNewButtonClicked(self):
+        self._view.hide()
+        self.hide()
+        self._result = "new"
+
+    @pyqtSlot()
+    def onCancelButtonClicked(self):
+        self._view.hide()
+        self.hide()
+        self._result = "cancel"
+
+    ##  Block thread until the dialog is closed.
+    def waitForClose(self):
+        if self._visible:
+            self._lock.acquire()
+            self._lock.release()
+
+    def __show(self):
+        if self._view is None:
+            self._createViewFromQML()
+        self._view.show()