Add per-object display modes to the Objects panel

README.md

@@ -21,6 +21,9 @@ Additional screenshots are available in [the wiki](https://github.com/CadQuery/C
 * CadQuery object stack inspector
   * Visual inspection of current workplane and selected items
   * Insight into evolution of the model
+* Per-object display modes
+  * Show each object as shaded, transparent or wireframe, or hide it
+  * A global override applies one mode to every object at once
 * Export to various formats
   * STL
   * STEP

cq_editor/display.py

@@ -0,0 +1,34 @@
+from enum import Enum
+
+
+class DisplayMode(Enum):
+    """How a single object is drawn. HIDDEN means it is erased from the view."""
+
+    HIDDEN = "Hidden"
+    WIREFRAME = "Wireframe"
+    TRANSPARENT = "Transparent"
+    SHADED = "Shaded"
+
+
+class GlobalMode(Enum):
+    """Panel-wide override. AS_SET means every object keeps its own DisplayMode."""
+
+    AS_SET = "As set below"
+    WIREFRAME = "Wireframe"
+    TRANSPARENT = "Transparent"
+    SHADED = "Shaded"
+
+
+def effective_mode(item: DisplayMode, glob: GlobalMode) -> DisplayMode:
+
+    # An override never unhides an object.
+    if item is DisplayMode.HIDDEN:
+        return DisplayMode.HIDDEN
+
+    if glob is GlobalMode.AS_SET:
+        return item
+
+    return DisplayMode[glob.name]
+
+
+HIDDEN_COL, WIREFRAME_COL, TRANSPARENT_COL, SHADED_COL, NAME_COL = range(5)

cq_editor/main_window.py

@@ -291,9 +291,11 @@ def prepare_panes(self):
         for d in self.docks.values():
             d.show()
 
-        PRINT_REDIRECTOR.sigStdoutWrite.connect(
-            lambda text: self.components["log"].append(text)
-        )
+        # Connect the bound method rather than a lambda: PRINT_REDIRECTOR is a
+        # module-level singleton, and PyQt drops a connection to a QObject's
+        # bound method when that QObject is destroyed. A lambda would outlive
+        # the LogViewer and call into a deleted C++ object.
+        PRINT_REDIRECTOR.sigStdoutWrite.connect(self.components["log"].append)
 
     def prepare_menubar(self):
 
@@ -459,6 +461,15 @@ def prepare_actions(self):
         self.components["object_tree"].sigHelpersResized.connect(
             self.components["viewer"].redisplay
         )
+        self.components["object_tree"].sigDisplayModesChanged.connect(
+            self.components["viewer"].apply_display_modes
+        )
+        self.components["object_tree"].sigGlobalModeChanged.connect(
+            self.components["viewer"].sync_global_actions
+        )
+        self.components["viewer"].sigGlobalModeChanged.connect(
+            self.components["object_tree"].setGlobalMode
+        )
 
         self.components["viewer"].sigObjectSelected.connect(
             self.components["object_tree"].handleGraphicalSelection