Refactor ID copying (and to some extent, ID freeing).

This will allow much finer controll over how we copy data-blocks, from
full copy in Main database, to "lighter" ones (out of Main, inside an
already allocated datablock, etc.).

This commit also transfers a llot of what was previously handled by
per-ID-type custom code to generic ID handling code in BKE_library.
Hopefully will avoid in future inconsistencies and missing bits we had
all over the codebase in the past.

It also adds missing copying handling for a few types, most notably
Scene (which where using a fully customized handling previously).

Note that the type of allocation used during copying (regular in Main,
allocated but outside of Main, or not allocated by ID handling code at
all) is stored in ID's, which allows to handle them correctly when
freeing. This needs to be taken care of with caution when doing 'weird'
unusual things with ID copying and/or allocation!

As a final note, while rather noisy, this commit will hopefully not
break too much existing branches, old 'API' has been kept for the main
part, as a wrapper around new code. Cleaning it up will happen later.

Design task : T51804
Phab Diff: D2714

1 files changed, 48 insertions, 33 deletions

diff --git a/source/blender/blenkernel/intern/gpencil.c b/source/blender/blenkernel/intern/gpencil.c
index 758438bb051..ee0d0b41898 100644
--- a/source/blender/blenkernel/intern/gpencil.c
+++ b/source/blender/blenkernel/intern/gpencil.c
@@ -627,7 +627,7 @@ bGPdata *BKE_gpencil_data_addnew(const char name[])
 	bGPdata *gpd;
 	
 	/* allocate memory for a new block */
-	gpd = BKE_libblock_alloc(G.main, ID_GD, name);
+	gpd = BKE_libblock_alloc(G.main, ID_GD, name, 0);
 	
 	/* initial settings */
 	gpd->flag = (GP_DATA_DISPINFO | GP_DATA_EXPAND);
@@ -753,47 +753,62 @@ bGPDlayer *BKE_gpencil_layer_duplicate(const bGPDlayer *gpl_src)
 	return gpl_dst;
 }
 
-/* make a copy of a given gpencil datablock */
-bGPdata *BKE_gpencil_data_duplicate(Main *bmain, const bGPdata *gpd_src, bool internal_copy)
+/**
+ * Only copy internal data of GreasePencil ID from source to already allocated/initialized destination.
+ * You probably nerver want to use that directly, use id_copy or BKE_id_copy_ex for typical needs.
+ *
+ * WARNING! This function will not handle ID user count!
+ *
+ * \param flag  Copying options (see BKE_library.h's LIB_ID_COPY_... flags for more).
+ */
+void BKE_gpencil_copy_data(Main *UNUSED(bmain), bGPdata *gpd_dst, const bGPdata *gpd_src, const int UNUSED(flag))
 {
-	const bGPDlayer *gpl_src;
-	bGPDlayer *gpl_dst;
-	bGPdata *gpd_dst;
+	/* copy layers */
+	BLI_listbase_clear(&gpd_dst->layers);
+	for (const bGPDlayer *gpl_src = gpd_src->layers.first; gpl_src; gpl_src = gpl_src->next) {
+		/* make a copy of source layer and its data */
+		bGPDlayer *gpl_dst = BKE_gpencil_layer_duplicate(gpl_src);  /* TODO here too could add unused flags... */
+		BLI_addtail(&gpd_dst->layers, gpl_dst);
+	}
 
-	/* error checking */
-	if (gpd_src == NULL) {
-		return NULL;
+	/* copy palettes */
+	BLI_listbase_clear(&gpd_dst->palettes);
+	for (const bGPDpalette *palette_src = gpd_src->palettes.first; palette_src; palette_src = palette_src->next) {
+		bGPDpalette *palette_dst = BKE_gpencil_palette_duplicate(palette_src);  /* TODO here too could add unused flags... */
+		BLI_addtail(&gpd_dst->palettes, palette_dst);
 	}
-	
-	/* make a copy of the base-data */
+}
+
+/* make a copy of a given gpencil datablock */
+bGPdata *BKE_gpencil_data_duplicate(Main *bmain, const bGPdata *gpd_src, bool internal_copy)
+{
+	/* Yuck and super-uber-hyper yuck!!!
+	 * Should be replaceable with a no-main copy (LIB_ID_COPY_NO_MAIN etc.), but not sure about it,
+	 * so for now keep old code for that one. */
 	if (internal_copy) {
+		const bGPDlayer *gpl_src;
+		bGPDlayer *gpl_dst;
+		bGPdata *gpd_dst;
+
 		/* make a straight copy for undo buffers used during stroke drawing */
 		gpd_dst = MEM_dupallocN(gpd_src);
+
+		/* copy layers */
+		BLI_listbase_clear(&gpd_dst->layers);
+		for (gpl_src = gpd_src->layers.first; gpl_src; gpl_src = gpl_src->next) {
+			/* make a copy of source layer and its data */
+			gpl_dst = BKE_gpencil_layer_duplicate(gpl_src);
+			BLI_addtail(&gpd_dst->layers, gpl_dst);
+		}
+
+		/* return new */
+		return gpd_dst;
 	}
 	else {
-		/* make a copy when others use this */
-		gpd_dst = BKE_libblock_copy(bmain, &gpd_src->id);
-	}
-	
-	/* copy layers */
-	BLI_listbase_clear(&gpd_dst->layers);
-	for (gpl_src = gpd_src->layers.first; gpl_src; gpl_src = gpl_src->next) {
-		/* make a copy of source layer and its data */
-		gpl_dst = BKE_gpencil_layer_duplicate(gpl_src);
-		BLI_addtail(&gpd_dst->layers, gpl_dst);
-	}
-	if (!internal_copy) {
-		/* copy palettes */
-		bGPDpalette *palette_src, *palette_dst;
-		BLI_listbase_clear(&gpd_dst->palettes);
-		for (palette_src = gpd_src->palettes.first; palette_src; palette_src = palette_src->next) {
-			palette_dst = BKE_gpencil_palette_duplicate(palette_src);
-			BLI_addtail(&gpd_dst->palettes, palette_dst);
-		}
+		bGPdata *gpd_copy;
+		BKE_id_copy_ex(bmain, &gpd_src->id, (ID **)&gpd_copy, 0, false);
+		return gpd_copy;
 	}
-	
-	/* return new */
-	return gpd_dst;
 }
 
 void BKE_gpencil_make_local(Main *bmain, bGPdata *gpd, const bool lib_local)