MAYA-113642 disallow switching variants in a weaker layer.

lib/mayaUsd/ufe/UsdContextOps.cpp

@@ -16,6 +16,7 @@
 #include "UsdContextOps.h"
 
 #include "private/UfeNotifGuard.h"
+#include "private/Utils.h"
 
 #ifdef UFE_V3_FEATURES_AVAILABLE
 #include <mayaUsd/commands/PullPushCommands.h>
@@ -395,6 +396,11 @@ class SetVariantSelectionUndoableCommand : public Ufe::UndoableCommand
         , _oldSelection(_varSet.GetVariantSelection())
         , _newSelection(itemPath[2])
     {
+        const bool allowStronger = true;
+        MayaUsd::ufe::applyCommandRestriction(
+            prim,
+            "set variant set " + _varSet.GetName() + " to variant " + _newSelection + " on",
+            allowStronger);
     }
 
     void undo() override

lib/mayaUsd/ufe/private/Utils.cpp

@@ -148,6 +148,23 @@ SdfLayerHandle getStrongerLayer(
     return SdfLayerHandle();
 }
 
+bool allowedInStrongerLayer(
+    const UsdPrim&                 prim,
+    const SdfPrimSpecHandleVector& primStack,
+    bool                           allowStronger)
+{
+    // If the flag to allow edits in a stronger layer if off, then it is not allowed.
+    if (!allowStronger)
+        return false;
+
+    // If allowed, verify if the target layer is stronger than any existing layer with an opinion.
+    auto stage = prim.GetStage();
+    auto rootLayer = stage->GetRootLayer();
+    auto targetLayer = stage->GetEditTarget().GetLayer();
+    auto topLayer = primStack.front()->GetLayer();
+    return getStrongerLayer(rootLayer, targetLayer, topLayer) == targetLayer;
+}
+
 } // namespace
 void applyCommandRestriction(
     const UsdPrim&     prim,
@@ -207,6 +224,8 @@ void applyCommandRestriction(
     UsdPrimCompositionQuery query(prim);
     for (const auto& compQueryArc : query.GetCompositionArcs()) {
         if (!primSpec && PcpArcTypeVariant == compQueryArc.GetArcType()) {
+            if (allowedInStrongerLayer(prim, primStack, allowStronger))
+                return;
             std::string err = TfStringPrintf(
                 "Cannot %s [%s] because it is defined inside the variant composition arc %s.",
                 commandName.c_str(),
@@ -217,15 +236,8 @@ void applyCommandRestriction(
     }
 
     if (!layerDisplayName.empty()) {
-        if (allowStronger) {
-            auto stage = prim.GetStage();
-            auto rootLayer = stage->GetRootLayer();
-            auto targetLayer = stage->GetEditTarget().GetLayer();
-            auto topLayer = primStack.front()->GetLayer();
-            if (getStrongerLayer(rootLayer, targetLayer, topLayer) == targetLayer) {
-                return;
-            }
-        }
+        if (allowedInStrongerLayer(prim, primStack, allowStronger))
+            return;
         std::string err = TfStringPrintf(
             "Cannot %s [%s]. %s. Please set %s as the target layer to proceed.",
             commandName.c_str(),

test/lib/ufe/testContextOps.py

@@ -146,6 +146,62 @@ def testGetItems(self):
             if c.checked:
                 self.assertEqual(c.item, 'Ball_8')
 
+    def testSwitchVariantInWeakerLayer(self):
+        """
+        Test that switching variant in a weaker layer is restricted.
+        """
+        contextItems = self.contextOps.getItems([])
+
+        contextItemStrings = [c.item for c in contextItems]
+        self.assertIn('Variant Sets', contextItemStrings)
+
+        # Initial shadingVariant is "Ball_8"
+        contextItems = self.contextOps.getItems(
+            ['Variant Sets', 'shadingVariant'])
+
+        # Change variant in variant set.
+        def shadingVariant():
+            contextItems = self.contextOps.getItems(
+                ['Variant Sets', 'shadingVariant'])
+
+            for c in contextItems:
+                if c.checked:
+                    return c.item
+
+        def shadingVariantOnPrim():
+            variantSet = self.ball35Prim.GetVariantSet('shadingVariant')
+            self.assertIsNotNone(variantSet)
+            return variantSet.GetVariantSelection()
+
+        self.assertEqual(shadingVariant(), 'Ball_8')
+
+        cmd = self.contextOps.doOpCmd(
+            ['Variant Sets', 'shadingVariant', 'Cue'])
+        self.assertIsNotNone(cmd)
+
+        ufeCmd.execute(cmd)
+
+        self.assertEqual(shadingVariant(), 'Cue')
+        self.assertEqual(shadingVariantOnPrim(), 'Cue')
+
+        # Add a lower, weaker layer.
+        stage = self.ball35Prim.GetStage()
+        rootLayer = stage.GetRootLayer()
+        newLayerName = 'Layer_1'
+        usdFormat = Sdf.FileFormat.FindByExtension('usd')
+        subLayer = Sdf.Layer.New(usdFormat, newLayerName)
+        rootLayer.subLayerPaths.append(subLayer.identifier)
+        stage.SetEditTarget(subLayer)
+
+        # Verify we cannot switch variant in a weaker layer.
+        self.assertRaises(RuntimeError, lambda: self.contextOps.doOpCmd(
+            ['Variant Sets', 'shadingVariant', 'Ball_8']))
+
+        # Verify the variant has not switched.
+        self.assertEqual(shadingVariant(), 'Cue')
+        self.assertEqual(shadingVariantOnPrim(), 'Cue')
+
+
     def testDoOp(self):
         # Change visibility, undo / redo.
         cmd = self.contextOps.doOpCmd(['Toggle Visibility'])