Add layer height role to profiles model

This layer height computation is rather complex, but because the items are now computed in a separate function, we can safely overwrite that and the update is made only once in the UI.

Contributes to issue CURA-2737.

cura/Settings/ProfilesModel.py

@@ -1,18 +1,23 @@
 # Copyright (c) 2016 Ultimaker B.V.
-# Uranium is released under the terms of the AGPLv3 or higher.
+# Cura is released under the terms of the AGPLv3 or higher.
+
+from PyQt5.QtCore import Qt
 
 from UM.Application import Application
+from UM.Settings.ContainerRegistry import ContainerRegistry
 from UM.Settings.Models.InstanceContainersModel import InstanceContainersModel
 
 from cura.QualityManager import QualityManager
 from cura.Settings.ExtruderManager import ExtruderManager
-from cura.Settings.MachineManager import MachineManager
 
 ##  QML Model for listing the current list of valid quality profiles.
 #
 class ProfilesModel(InstanceContainersModel):
+    LayerHeightRole = Qt.UserRole + 1001
+
     def __init__(self, parent = None):
         super().__init__(parent)
+        self.addRoleName(self.LayerHeightRole, "layer_height")
 
         Application.getInstance().globalContainerStackChanged.connect(self._update)
 
@@ -40,3 +45,50 @@ class ProfilesModel(InstanceContainersModel):
         # The actual list of quality profiles come from the first extruder in the extruder list.
         return QualityManager.getInstance().findAllUsableQualitiesForMachineAndExtruders(global_container_stack,
                                                                                          extruder_stacks)
+
+    ##  Re-computes the items in this model, and adds the layer height role.
+    def _recomputeItems(self):
+        #Some globals that we can re-use.
+        global_container_stack = Application.getInstance().getGlobalContainerStack()
+        if global_container_stack is None:
+            return
+        container_registry = ContainerRegistry.getInstance()
+        machine_manager = Application.getInstance().getMachineManager()
+
+        for item in super()._recomputeItems():
+            profile = container_registry.findContainers(id = item["id"])
+            if not profile:
+                item["layer_height"] = "" #Can't update a profile that is unknown.
+                yield item
+                continue
+
+            #Easy case: This profile defines its own layer height.
+            profile = profile[0]
+            if profile.hasProperty("layer_height", "value"):
+                item["layer_height"] = str(profile.getProperty("layer_height", "value")) + "mm"
+                yield item
+                continue
+
+            #Quality-changes profile that has no value for layer height. Get the corresponding quality profile and ask that profile.
+            quality_type = profile.getMetaDataEntry("quality_type", None)
+            if quality_type:
+                quality_results = machine_manager.determineQualityAndQualityChangesForQualityType(quality_type)
+                for quality_result in quality_results:
+                    if quality_result["stack"] is global_container_stack:
+                        quality = quality_result["quality"]
+                        break
+                else: #No global container stack in the results:
+                    quality = quality_results[0]["quality"] #Take any of the extruders.
+                if quality and quality.hasProperty("layer_height", "value"):
+                    item["layer_height"] = str(quality.getProperty("layer_height", "value")) + "mm"
+                    yield item
+                    continue
+
+            #Quality has no value for layer height either. Get the layer height from somewhere lower in the stack.
+            skip_until_container = global_container_stack.findContainer({"type": "material"})
+            if not skip_until_container: #No material in stack.
+                skip_until_container = global_container_stack.findContainer({"type": "variant"})
+                if not skip_until_container: #No variant in stack.
+                    skip_until_container = global_container_stack.getBottom()
+            item["layer_height"] = str(global_container_stack.getRawProperty("layer_height", "value", skip_until_container = skip_until_container.getId())) + "mm" #Fall through to the currently loaded material.
+            yield item