EMSUSD-3210 Fix for Stitch/merge option

lib/mayaUsd/commands/abstractLayerEditorWindow.h

@@ -90,6 +90,8 @@ class MAYAUSD_CORE_PUBLIC AbstractLayerEditorWindow
     virtual bool        layerIsSystemLocked() = 0;
     virtual bool        layerIsReadOnly() = 0;
     virtual bool        layerHasSubLayers() = 0;
+    virtual bool        strongestLayerIsLocked() = 0;
+    virtual bool        selectionHasSessionAndNonSessionLayers() = 0;
     virtual std::string proxyShapeName(const bool fullPath = false) const = 0;
 
     virtual void removeSubLayer() = 0;

lib/mayaUsd/commands/layerEditorWindowCommand.cpp

@@ -52,6 +52,8 @@ DEF_FLAG(lo, layerIsLocked)
 DEF_FLAG(as, layerAppearsSystemLocked)
 DEF_FLAG(ls, layerIsSystemLocked)
 DEF_FLAG(ll, layerHasSubLayers)
+DEF_FLAG(sk, strongestLayerIsLocked)
+DEF_FLAG(ss, selectionHasSessionAndNonSessionLayers)
 
 // edit flags
 DEF_FLAG(rs, removeSubLayer)
@@ -145,6 +147,8 @@ MSyntax LayerEditorWindowCommand::createSyntax()
     ADD_FLAG(layerAppearsSystemLocked);
     ADD_FLAG(layerIsSystemLocked);
     ADD_FLAG(layerHasSubLayers);
+    ADD_FLAG(strongestLayerIsLocked);
+    ADD_FLAG(selectionHasSessionAndNonSessionLayers);
 
     ADD_FLAG(removeSubLayer);
     ADD_FLAG(saveEdits);
@@ -338,6 +342,8 @@ MStatus LayerEditorWindowCommand::handleQueries(
     HANDLE_Q_FLAG(layerAppearsSystemLocked)
     HANDLE_Q_FLAG(layerIsSystemLocked)
     HANDLE_Q_FLAG(layerHasSubLayers)
+    HANDLE_Q_FLAG(strongestLayerIsLocked)
+    HANDLE_Q_FLAG(selectionHasSessionAndNonSessionLayers)
 
     // proxyShape flag is both create/query.
     if (argParser.isFlagSet(FLAG(proxyShape)) && argParser.isQuery()) {

lib/usd/ui/layerEditor/mayaLayerEditorWindow.cpp

@@ -27,6 +27,8 @@
 
 #include <mayaUsd/utils/query.h>
 
+#include <usdUfe/utils/layers.h>
+
 #include <maya/MGlobal.h>
 #include <maya/MQtUtil.h>
 
@@ -177,6 +179,62 @@ std::string MayaLayerEditorWindow::proxyShapeName(const bool fullPath) const
     return fullPath ? stageEntry._proxyShapePath : stageEntry._displayName;
 }
 
+bool MayaLayerEditorWindow::strongestLayerIsLocked()
+{
+    const LayerItemVector selectedItems = treeView()->getSelectedLayerItems();
+    if (selectedItems.size() < 2) {
+        return false;
+    }
+
+    const UsdStageRefPtr stage = _sessionState.stage();
+    if (!stage)
+        return false;
+
+    // Finds strongest layer from selectedItems by folding over the selection.
+    SdfLayerHandle       strongestLayer;
+    const LayerTreeItem* strongestItem = nullptr;
+    for (const auto* item : selectedItems) {
+        SdfLayerHandle layer = item->layer();
+        if (!strongestLayer || UsdUfe::getStrongerLayer(stage, layer, strongestLayer) == layer) {
+            strongestLayer = layer;
+            strongestItem = item;
+        }
+    }
+
+    return strongestItem && strongestItem->isLocked();
+}
+
+bool MayaLayerEditorWindow::selectionHasSessionAndNonSessionLayers()
+{
+    const LayerItemVector selectedItems = treeView()->getSelectedLayerItems();
+    if (selectedItems.size() < 2)
+        return false;
+
+    const UsdStageRefPtr stage = _sessionState.stage();
+    if (!stage)
+        return false;
+
+    const auto sessionLayers = UsdUfe::getAllSublayerRefs(stage->GetSessionLayer(), true);
+
+    bool hasSessionLayerItem = false;
+    bool hasNonSessionLayerItem = false;
+
+    for (const auto* item : selectedItems) {
+        if (!item)
+            continue;
+
+        if (UsdUfe::isSessionLayer(item->layer(), sessionLayers))
+            hasSessionLayerItem = true;
+        else
+            hasNonSessionLayerItem = true;
+
+        if (hasSessionLayerItem && hasNonSessionLayerItem)
+            return true;
+    }
+
+    return false;
+}
+
 void MayaLayerEditorWindow::removeSubLayer()
 {
     QString name = "Remove";

lib/usd/ui/layerEditor/mayaLayerEditorWindow.h

@@ -65,6 +65,8 @@ class MayaLayerEditorWindow
     bool        layerAppearsSystemLocked() override;
     bool        layerIsSystemLocked() override;
     bool        layerHasSubLayers() override;
+    bool        strongestLayerIsLocked() override;
+    bool        selectionHasSessionAndNonSessionLayers() override;
 
     void removeSubLayer() override;
     void saveEdits() override;

plugin/adsk/scripts/mayaUsdMenu.mel

@@ -1038,10 +1038,11 @@ global proc mayaUsdMenu_layerEditorContextMenu(string $panelName) {
         return; // that's all we can support on invalid layers
     }
 
+    // Single selection flags
+    int $singleSelect = `mayaUsdLayerEditorWindow -q -selectionLength $panelName` == 1;
     int $isSessionLayer = `mayaUsdLayerEditorWindow -q -isSessionLayer $panelName`;
     int $isAnonymousLayer = `mayaUsdLayerEditorWindow -q -isAnonymousLayer $panelName`;
     int $needsSaving = `mayaUsdLayerEditorWindow -q -layerNeedsSaving $panelName`;
-    int $singleSelect = `mayaUsdLayerEditorWindow -q -selectionLength $panelName` == 1;
     int $appearsMuted = `mayaUsdLayerEditorWindow -q -layerAppearsMuted $panelName`;
     int $isSubLayer = `mayaUsdLayerEditorWindow -q -isSubLayer $panelName`;
     int $isMuted = `mayaUsdLayerEditorWindow -q -layerIsMuted $panelName`;
@@ -1053,6 +1054,11 @@ global proc mayaUsdMenu_layerEditorContextMenu(string $panelName) {
     int $isIncoming = `mayaUsdLayerEditorWindow -q -isIncomingLayer $panelName`;
     int $hasSublayers = `mayaUsdLayerEditorWindow -q -layerHasSubLayers $panelName`;
     string $proxyShape = `mayaUsdLayerEditorWindow -q -proxyShape $panelName`;
+
+    // Multi selection flags
+    int $multiSelect = `mayaUsdLayerEditorWindow -q -selectionLength $panelName` > 1;
+    int $strongestLayerIsLocked = `mayaUsdLayerEditorWindow -q -strongestLayerIsLocked $panelName`;
+    int $hasSessionAndNonSessionLayers = `mayaUsdLayerEditorWindow -q -selectionHasSessionAndNonSessionLayers $panelName`;
 
     string $label;
     int $enabled;
@@ -1096,12 +1102,11 @@ global proc mayaUsdMenu_layerEditorContextMenu(string $panelName) {
     $enabled = $singleSelect && !$appearsMuted && !$isReadOnly && !$isLocked && !$isSystemLocked;
     menuItem -label $label -enable $enabled -c $cmd;
 
-    int $multiSelect = `mayaUsdLayerEditorWindow -q -selectionLength $panelName` > 1;
     if ($multiSelect && !$singleSelect) {
-        $label = getMayaUsdString("kMenuStitchLayers");
-        $cmd = makeCommand($panelName, "stitchLayers");
-        $enabled = !$isReadOnly && !$appearsLocked && !$appearsSystemLocked && !$appearsMuted;
-        menuItem -label $label -enable $enabled -c $cmd;
+            $label = getMayaUsdString("kMenuStitchLayers");
+            $cmd = makeCommand($panelName, "stitchLayers");
+            $enabled = !$isReadOnly && !$appearsLocked && !$appearsSystemLocked && !$appearsMuted && !$strongestLayerIsLocked && !$hasSessionAndNonSessionLayers;
+            menuItem -label $label -enable $enabled -c $cmd;
     }
 
     if ($hasSublayers) {