Visualization - Avoid redundant shape copies in AIS_ColoredShape::dispatchColors (#1068)

Defer EmptyCopied() and BRep_Builder::Add() in dispatchColors() to avoid
redundant shape construction when the copy is not actually needed.
Non-overridden sub-shapes are collected into pre-allocated
NCollection_DynamicArray and the compound is only built when
required (partial override case).
Added GTests covering dispatchColors() dispatch logic.

src/Visualization/TKV3d/AIS/AIS_ColoredShape.cxx

@@ -17,6 +17,7 @@
 
 #include <AIS_InteractiveContext.hxx>
 #include <BRep_Builder.hxx>
+#include <NCollection_DynamicArray.hxx>
 #include <BRepTools.hxx>
 #include <BRepMesh_IncrementalMesh.hxx>
 #include <Graphic3d_AspectFillArea3d.hxx>
@@ -745,10 +746,7 @@ bool AIS_ColoredShape::dispatchColors(
   }
 
   // iterate on sub-shapes
-  BRep_Builder aBBuilder;
-  TopoDS_Shape aShapeCopy = theShapeToParse.EmptyCopied();
-  aShapeCopy.Closed(theShapeToParse.Closed());
-  int nbDef = 0;
+  NCollection_DynamicArray<TopoDS_Shape> aSubShapes(theShapeToParse.NbChildren());
   for (TopoDS_Iterator aSubShapeIter(theShapeToParse); aSubShapeIter.More(); aSubShapeIter.Next())
   {
     const TopoDS_Shape& aSubShape = aSubShapeIter.Value();
@@ -762,20 +760,31 @@ bool AIS_ColoredShape::dispatchColors(
     {
       isSubOverride = true;
     }
-    else
+    else if (aShapeType != TopAbs_FACE)
     {
-      aBBuilder.Add(aShapeCopy, aSubShape);
-      ++nbDef;
+      aSubShapes.Append(aSubShape);
     }
   }
+
+  TopoDS_Shape aShapeCopy;
+  BRep_Builder aBBuilder;
   if (aShapeType == TopAbs_FACE || !isSubOverride)
   {
     aShapeCopy = theShapeToParse;
   }
-  else if (nbDef == 0)
+  else if (aSubShapes.IsEmpty())
   {
     return isOverriden || isSubOverride; // empty compound
   }
+  else
+  {
+    aShapeCopy = theShapeToParse.EmptyCopied();
+    aShapeCopy.Closed(theShapeToParse.Closed());
+    for (const TopoDS_Shape& aSubShape : aSubShapes)
+    {
+      aBBuilder.Add(aShapeCopy, aSubShape);
+    }
+  }
 
   // if any of styles is overridden regarding to default one, add rest to map
   if (isOverriden

src/Visualization/TKV3d/GTests/AIS_ColoredShape_Test.cxx

@@ -0,0 +1,326 @@
+// Copyright (c) 2025 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#include <gtest/gtest.h>
+
+#include <AIS_ColoredShape.hxx>
+
+#include <BRep_Builder.hxx>
+#include <BRepPrimAPI_MakeBox.hxx>
+#include <TopExp_Explorer.hxx>
+#include <TopoDS.hxx>
+#include <TopoDS_Compound.hxx>
+#include <TopoDS_Iterator.hxx>
+
+//! Test accessor exposing protected members of AIS_ColoredShape.
+class AIS_ColoredShapeTestAccessor : public AIS_ColoredShape
+{
+public:
+  using DrawerCompdMap = AIS_ColoredShape::DataMapOfDrawerCompd;
+
+  AIS_ColoredShapeTestAccessor(const TopoDS_Shape& theShape)
+      : AIS_ColoredShape(theShape)
+  {
+  }
+
+  static bool testDispatchColors(
+    const occ::handle<AIS_ColoredDrawer>&               theParentDrawer,
+    const TopoDS_Shape&                                 theShapeToParse,
+    const NCollection_DataMap<TopoDS_Shape,
+                              occ::handle<AIS_ColoredDrawer>,
+                              TopTools_ShapeMapHasher>& theShapeDrawerMap,
+    const TopAbs_ShapeEnum                              theParentType,
+    const bool                                          theIsParentClosed,
+    DataMapOfDrawerCompd*                               theDrawerOpenedShapePerType,
+    DataMapOfDrawerCompd&                               theDrawerClosedFaces)
+  {
+    return dispatchColors(theParentDrawer,
+                          theShapeToParse,
+                          theShapeDrawerMap,
+                          theParentType,
+                          theIsParentClosed,
+                          theDrawerOpenedShapePerType,
+                          theDrawerClosedFaces);
+  }
+};
+
+namespace
+{
+
+//! Count the total number of sub-shapes across all compounds in the dispatch map.
+static int countDispatchedShapes(const AIS_ColoredShapeTestAccessor::DrawerCompdMap& theMap)
+{
+  int aCount = 0;
+  for (AIS_ColoredShapeTestAccessor::DrawerCompdMap::Iterator anIter(theMap); anIter.More();
+       anIter.Next())
+  {
+    for (TopoDS_Iterator aChildIter(anIter.Value()); aChildIter.More(); aChildIter.Next())
+    {
+      ++aCount;
+    }
+  }
+  return aCount;
+}
+
+//! Count the number of faces in a shape.
+static int countFaces(const TopoDS_Shape& theShape)
+{
+  int aCount = 0;
+  for (TopExp_Explorer anExp(theShape, TopAbs_FACE); anExp.More(); anExp.Next())
+  {
+    ++aCount;
+  }
+  return aCount;
+}
+
+} // namespace
+
+class AIS_ColoredShapeDispatchTest : public testing::Test
+{
+protected:
+  void SetUp() override
+  {
+    // Create a box with 6 faces
+    myBox = BRepPrimAPI_MakeBox(10.0, 20.0, 30.0).Shape();
+    ASSERT_FALSE(myBox.IsNull());
+    ASSERT_EQ(countFaces(myBox), 6);
+
+    // Collect faces for individual manipulation
+    for (TopExp_Explorer anExp(myBox, TopAbs_FACE); anExp.More(); anExp.Next())
+    {
+      myFaces.Append(anExp.Current());
+    }
+
+    myDefaultDrawer = new Prs3d_Drawer();
+  }
+
+  TopoDS_Shape                       myBox;
+  NCollection_Sequence<TopoDS_Shape> myFaces;
+  occ::handle<Prs3d_Drawer>          myDefaultDrawer;
+};
+
+// Test: no overrides on a shell -> all faces dispatched, no override reported.
+TEST_F(AIS_ColoredShapeDispatchTest, Shell_NoOverrides)
+{
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+                                               aShapeDrawerMap;
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  // Dispatch on the box shell (first shell child of solid)
+  for (TopoDS_Iterator anIter(myBox); anIter.More(); anIter.Next())
+  {
+    if (anIter.Value().ShapeType() == TopAbs_SHELL)
+    {
+      const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                               anIter.Value(),
+                                                                               aShapeDrawerMap,
+                                                                               TopAbs_SOLID,
+                                                                               false,
+                                                                               aOpenedPerType,
+                                                                               aClosedFaces);
+      EXPECT_FALSE(isOverride);
+      break;
+    }
+  }
+
+  // All 6 faces should be dispatched as opened (not closed, since theIsParentClosed = false)
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 6);
+  EXPECT_EQ(countDispatchedShapes(aClosedFaces), 0);
+}
+
+// Test: one face overridden with custom color.
+TEST_F(AIS_ColoredShapeDispatchTest, Shell_OneFaceOverridden)
+{
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+    aShapeDrawerMap;
+
+  // Override a single face
+  occ::handle<AIS_ColoredDrawer> aCustomDrawer = new AIS_ColoredDrawer(myDefaultDrawer);
+  aCustomDrawer->SetOwnColor(Quantity_NOC_RED);
+  aShapeDrawerMap.Bind(myFaces.First(), aCustomDrawer);
+
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  for (TopoDS_Iterator anIter(myBox); anIter.More(); anIter.Next())
+  {
+    if (anIter.Value().ShapeType() == TopAbs_SHELL)
+    {
+      const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                               anIter.Value(),
+                                                                               aShapeDrawerMap,
+                                                                               TopAbs_SOLID,
+                                                                               false,
+                                                                               aOpenedPerType,
+                                                                               aClosedFaces);
+      EXPECT_TRUE(isOverride);
+      break;
+    }
+  }
+
+  // All 6 faces dispatched: 1 with custom drawer + 5 with default
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 6);
+}
+
+// Test: one face hidden -> override reported, only 5 faces dispatched.
+TEST_F(AIS_ColoredShapeDispatchTest, Shell_OneFaceHidden)
+{
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+    aShapeDrawerMap;
+
+  // Hide one face
+  occ::handle<AIS_ColoredDrawer> aHiddenDrawer = new AIS_ColoredDrawer(myDefaultDrawer);
+  aHiddenDrawer->SetHidden(true);
+  aShapeDrawerMap.Bind(myFaces.First(), aHiddenDrawer);
+
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  for (TopoDS_Iterator anIter(myBox); anIter.More(); anIter.Next())
+  {
+    if (anIter.Value().ShapeType() == TopAbs_SHELL)
+    {
+      const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                               anIter.Value(),
+                                                                               aShapeDrawerMap,
+                                                                               TopAbs_SOLID,
+                                                                               false,
+                                                                               aOpenedPerType,
+                                                                               aClosedFaces);
+      EXPECT_TRUE(isOverride);
+      break;
+    }
+  }
+
+  // Only 5 visible faces dispatched
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 5);
+}
+
+// Test: all faces overridden -> all dispatched individually.
+TEST_F(AIS_ColoredShapeDispatchTest, Shell_AllFacesOverridden)
+{
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+    aShapeDrawerMap;
+
+  // Override all faces
+  for (NCollection_Sequence<TopoDS_Shape>::Iterator aFaceIter(myFaces); aFaceIter.More();
+       aFaceIter.Next())
+  {
+    occ::handle<AIS_ColoredDrawer> aDrawer = new AIS_ColoredDrawer(myDefaultDrawer);
+    aDrawer->SetOwnColor(Quantity_NOC_GREEN);
+    aShapeDrawerMap.Bind(aFaceIter.Value(), aDrawer);
+  }
+
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  for (TopoDS_Iterator anIter(myBox); anIter.More(); anIter.Next())
+  {
+    if (anIter.Value().ShapeType() == TopAbs_SHELL)
+    {
+      const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                               anIter.Value(),
+                                                                               aShapeDrawerMap,
+                                                                               TopAbs_SOLID,
+                                                                               false,
+                                                                               aOpenedPerType,
+                                                                               aClosedFaces);
+      EXPECT_TRUE(isOverride);
+      break;
+    }
+  }
+
+  // All 6 faces dispatched with their custom drawers
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 6);
+}
+
+// Test: compound of two boxes, one box's shell overridden.
+TEST_F(AIS_ColoredShapeDispatchTest, Compound_PartialOverride)
+{
+  TopoDS_Shape aBox2 = BRepPrimAPI_MakeBox(5.0, 5.0, 5.0).Shape();
+
+  BRep_Builder    aBBuilder;
+  TopoDS_Compound aCompound;
+  aBBuilder.MakeCompound(aCompound);
+  aBBuilder.Add(aCompound, myBox);
+  aBBuilder.Add(aCompound, aBox2);
+
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+    aShapeDrawerMap;
+
+  // Override one face from the first box
+  occ::handle<AIS_ColoredDrawer> aCustomDrawer = new AIS_ColoredDrawer(myDefaultDrawer);
+  aCustomDrawer->SetOwnColor(Quantity_NOC_BLUE);
+  aShapeDrawerMap.Bind(myFaces.First(), aCustomDrawer);
+
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                           aCompound,
+                                                                           aShapeDrawerMap,
+                                                                           TopAbs_COMPOUND,
+                                                                           false,
+                                                                           aOpenedPerType,
+                                                                           aClosedFaces);
+  EXPECT_TRUE(isOverride);
+
+  // 12 faces total (6+6), all should be dispatched
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 12);
+}
+
+// Test: all faces hidden in a shell -> early return, empty dispatch.
+TEST_F(AIS_ColoredShapeDispatchTest, Shell_AllFacesHidden)
+{
+  NCollection_DataMap<TopoDS_Shape, occ::handle<AIS_ColoredDrawer>, TopTools_ShapeMapHasher>
+    aShapeDrawerMap;
+
+  // Hide all faces
+  for (NCollection_Sequence<TopoDS_Shape>::Iterator aFaceIter(myFaces); aFaceIter.More();
+       aFaceIter.Next())
+  {
+    occ::handle<AIS_ColoredDrawer> aDrawer = new AIS_ColoredDrawer(myDefaultDrawer);
+    aDrawer->SetHidden(true);
+    aShapeDrawerMap.Bind(aFaceIter.Value(), aDrawer);
+  }
+
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aOpenedPerType[(size_t)TopAbs_SHAPE];
+  AIS_ColoredShapeTestAccessor::DrawerCompdMap aClosedFaces;
+
+  occ::handle<AIS_ColoredDrawer> aParentDrawer;
+  for (TopoDS_Iterator anIter(myBox); anIter.More(); anIter.Next())
+  {
+    if (anIter.Value().ShapeType() == TopAbs_SHELL)
+    {
+      const bool isOverride = AIS_ColoredShapeTestAccessor::testDispatchColors(aParentDrawer,
+                                                                               anIter.Value(),
+                                                                               aShapeDrawerMap,
+                                                                               TopAbs_SOLID,
+                                                                               false,
+                                                                               aOpenedPerType,
+                                                                               aClosedFaces);
+      EXPECT_TRUE(isOverride);
+      break;
+    }
+  }
+
+  // No faces dispatched - all hidden
+  EXPECT_EQ(countDispatchedShapes(aOpenedPerType[(size_t)TopAbs_FACE]), 0);
+  EXPECT_EQ(countDispatchedShapes(aClosedFaces), 0);
+}

src/Visualization/TKV3d/GTests/FILES.cmake

@@ -2,4 +2,5 @@
 set(OCCT_TKV3d_GTests_FILES_LOCATION "${CMAKE_CURRENT_LIST_DIR}")
 
 set(OCCT_TKV3d_GTests_FILES
+  AIS_ColoredShape_Test.cxx
 )