Preparing merge of id_override_static: add BKE_id_swap().

This function swaps the memory content of two data-blocks (of same type
obviously), while preserving most of the ID 'header' itself.

It is intended to be used to quickly and easily replace the data of an
existing ID by another one, presumably a temporary 'working' one,
without having to suffer from things like name changes,
registering/removing from Main database, etc.

2 files changed, 70 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_library.h b/source/blender/blenkernel/BKE_library.h
index f320597ef2d..468aab9bdf9 100644
--- a/source/blender/blenkernel/BKE_library.h
+++ b/source/blender/blenkernel/BKE_library.h
@@ -147,6 +147,7 @@ bool id_make_local(struct Main *bmain, struct ID *id, const bool test, const boo
 bool id_single_user(struct bContext *C, struct ID *id, struct PointerRNA *ptr, struct PropertyRNA *prop);
 bool id_copy(struct Main *bmain, const struct ID *id, struct ID **newid, bool test);
 bool BKE_id_copy_ex(struct Main *bmain, const struct ID *id, struct ID **r_newid, const int flag, const bool test);
+void BKE_id_swap(struct Main *bmain, struct ID *id_a, struct ID *id_b);
 void id_sort_by_name(struct ListBase *lb, struct ID *id);
 void BKE_id_expand_local(struct Main *bmain, struct ID *id);
 void BKE_id_copy_ensure_local(struct Main *bmain, const struct ID *old_id, struct ID *new_id);
diff --git a/source/blender/blenkernel/intern/library.c b/source/blender/blenkernel/intern/library.c
index 99dd6f86549..f57691fde3e 100644
--- a/source/blender/blenkernel/intern/library.c
+++ b/source/blender/blenkernel/intern/library.c
@@ -689,6 +689,75 @@ bool id_copy(Main *bmain, const ID *id, ID **newid, bool test)
 	return BKE_id_copy_ex(bmain, id, newid, 0, test);
 }
 
+/** Does a mere memory swap over the whole IDs data (including type-specific memory).
+ *  \note Most internal ID data itself is not swapped (only IDProperties are). */
+void BKE_id_swap(Main *bmain, ID *id_a, ID *id_b)
+{
+	BLI_assert(GS(id_a->name) == GS(id_b->name));
+
+	const ID id_a_back = *id_a;
+	const ID id_b_back = *id_b;
+
+#define CASE_SWAP(_gs, _type) \
+	case _gs: \
+		SWAP(_type, *(_type *)id_a, *(_type *)id_b); \
+		break
+
+	switch ((ID_Type)GS(id_a->name)) {
+		CASE_SWAP(ID_SCE, Scene);
+		CASE_SWAP(ID_LI, Library);
+		CASE_SWAP(ID_OB, Object);
+		CASE_SWAP(ID_ME, Mesh);
+		CASE_SWAP(ID_CU, Curve);
+		CASE_SWAP(ID_MB, MetaBall);
+		CASE_SWAP(ID_MA, Material);
+		CASE_SWAP(ID_TE, Tex);
+		CASE_SWAP(ID_IM, Image);
+		CASE_SWAP(ID_LT, Lattice);
+		CASE_SWAP(ID_LA, Lamp);
+		CASE_SWAP(ID_LP, LightProbe);
+		CASE_SWAP(ID_CA, Camera);
+		CASE_SWAP(ID_KE, Key);
+		CASE_SWAP(ID_WO, World);
+		CASE_SWAP(ID_SCR, bScreen);
+		CASE_SWAP(ID_VF, VFont);
+		CASE_SWAP(ID_TXT, Text);
+		CASE_SWAP(ID_SPK, Speaker);
+		CASE_SWAP(ID_SO, bSound);
+		CASE_SWAP(ID_GR, Group);
+		CASE_SWAP(ID_AR, bArmature);
+		CASE_SWAP(ID_AC, bAction);
+		CASE_SWAP(ID_NT, bNodeTree);
+		CASE_SWAP(ID_BR, Brush);
+		CASE_SWAP(ID_PA, ParticleSettings);
+		CASE_SWAP(ID_WM, wmWindowManager);
+		CASE_SWAP(ID_WS, WorkSpace);
+		CASE_SWAP(ID_GD, bGPdata);
+		CASE_SWAP(ID_MC, MovieClip);
+		CASE_SWAP(ID_MSK, Mask);
+		CASE_SWAP(ID_LS, FreestyleLineStyle);
+		CASE_SWAP(ID_PAL, Palette);
+		CASE_SWAP(ID_PC, PaintCurve);
+		CASE_SWAP(ID_CF, CacheFile);
+		case ID_IP:
+			break;  /* Deprecated. */
+	}
+
+#undef CASE_SWAP
+
+	/* Restore original ID's internal data. */
+	*id_a = id_a_back;
+	*id_b = id_b_back;
+
+	/* Exception: IDProperties. */
+	id_a->properties = id_b_back.properties;
+	id_b->properties = id_a_back.properties;
+
+	/* Swap will have broken internal references to itself, restore them. */
+	BKE_libblock_relink_ex(bmain, id_a, id_b, id_a, false);
+	BKE_libblock_relink_ex(bmain, id_b, id_a, id_b, false);
+}
+
 /** Does *not* set ID->newid pointer. */
 bool id_single_user(bContext *C, ID *id, PointerRNA *ptr, PropertyRNA *prop)
 {