Add material indication to extruder boxes

Only if a material is known of course. But the case where it is unknown is not tested.

Contributes to issue CURA-3161.

cura/PrinterOutputDevice.py

@@ -323,6 +323,28 @@ class PrinterOutputDevice(QObject, OutputDevice):
                 result.append(i18n_catalog.i18nc("@item:material", "Unknown material"))
         return result
 
+    ##  List of the colours of the currently loaded materials.
+    #
+    #   The list is in order of extruders. If there is no material in an
+    #   extruder, the colour is shown as transparent.
+    #
+    #   The colours are returned in hex-format AARRGGBB or RRGGBB
+    #   (e.g. #800000ff for transparent blue or #00ff00 for pure green).
+    @pyqtProperty("QVariantList", notify = materialIdChanged)
+    def materialColors(self):
+        result = []
+        for material_id in self._material_ids:
+            if material_id is None:
+                result.append("#800000FF") #No material.
+                continue
+
+            containers = self._container_registry.findInstanceContainers(type = "material", GUID = material_id)
+            if containers:
+                result.append(containers[0].getMetaDataEntry("color_code"))
+            else:
+                result.append("#800000FF") #Unknown material.
+        return result
+
     ##  Protected setter for the current material id.
     #   /param index Index of the extruder
     #   /param material_id id of the material

resources/qml/PrintMonitor.qml

@@ -110,6 +110,30 @@ Column
                         anchors.top: parent.top
                         anchors.topMargin: UM.Theme.getSize("default_margin").height
                     }
+                    Rectangle //Material colour indication.
+                    {
+                        id: materialColor
+                        width: materialName.height * 0.75
+                        height: materialName.height * 0.75
+                        color: printerConnected ? connectedPrinter.materialColors[index] : [0, 0, 0, 0] //Need to check for printerConnected or materialColors[index] gives an error.
+                        border.width: UM.Theme.getSize("default_lining").width
+                        border.color: UM.Theme.getColor("lining")
+                        visible: printerConnected
+                        anchors.left: parent.left
+                        anchors.leftMargin: UM.Theme.getSize("default_margin").width
+                        anchors.verticalCenter: materialName.verticalCenter
+                    }
+                    Text //Material name.
+                    {
+                        id: materialName
+                        text: printerConnected ? connectedPrinter.materialNames[index] : ""
+                        font: UM.Theme.getFont("default")
+                        color: UM.Theme.getColor("text")
+                        anchors.left: materialColor.right
+                        anchors.leftMargin: UM.Theme.getSize("default_margin").width
+                        anchors.bottom: parent.bottom
+                        anchors.bottomMargin: UM.Theme.getSize("default_margin").height
+                    }
                 }
             }
         }

resources/themes/cura/theme.json

@@ -255,7 +255,7 @@
         "sidebar_setup": [0.0, 2.0],
         "sidebar_tabs": [0.0, 3.5],
         "sidebar_inputfields": [0.0, 2.0],
-        "sidebar_extruder_box": [0.0, 4.0],
+        "sidebar_extruder_box": [0.0, 6.0],
         "simple_mode_infill_caption": [0.0, 5.0],
         "simple_mode_infill_height": [0.0, 8.0],