ShapeKeys: rework 'move skey' code, and add options to move to first/last position.

Main moving logic is moved to new `BKE_keyblock_move()`, which makes it available from anywhere.
In addition, move code was reworked so that it only loops once on whole keyblocks list,
and it accepts arbitrary org and dest indices, not only neighbor ones.

Partly based on work by revzin (Grigory Revzin) in his soc-2014-shapekey GSoC branch, thanks!

1 files changed, 88 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/key.c b/source/blender/blenkernel/intern/key.c
index 2dc615c19f9..5cca948cd49 100644
--- a/source/blender/blenkernel/intern/key.c
+++ b/source/blender/blenkernel/intern/key.c
@@ -2055,3 +2055,91 @@ void BKE_key_convert_from_offset(Object *ob, KeyBlock *kb, float (*ofs)[3])
 		}
 	}
 }
+
+/* ==========================================================*/
+
+/** Move shape key from org_index to new_index. Safe, clamps index to valid range, updates reference keys,
+ * the object's active shape index, the 'frame' value in case of absolute keys, etc.
+ * Note indices are expected in real values (not 'fake' shapenr +1 ones).
+ *
+ * \param org_index if < 0, current object's active shape will be used as skey to move.
+ * \return true if something was done, else false.
+ */
+bool BKE_keyblock_move(Object *ob, int org_index, int new_index)
+{
+	Key *key = BKE_key_from_object(ob);
+	KeyBlock *kb;
+	const int act_index = ob->shapenr - 1;
+	const int totkey = key->totkey;
+	int i;
+	bool rev, in_range = false;
+
+	if (org_index < 0) {
+		org_index = act_index;
+	}
+
+	CLAMP(new_index, 0, key->totkey - 1);
+	CLAMP(org_index, 0, key->totkey - 1);
+
+	if (new_index == org_index) {
+		return false;
+	}
+
+	rev = ((new_index - org_index) < 0) ? true : false;
+
+	/* We swap 'org' element with its previous/next neighbor (depending on direction of the move) repeatedly,
+	 * until we reach final position.
+	 * This allows us to only loop on the list once! */
+	for (kb = (rev ? key->block.last : key->block.first), i = (rev ? totkey - 1 : 0);
+	     kb;
+	     kb = (rev ? kb->prev : kb->next), rev ? i-- : i++)
+	{
+		if (i == org_index) {
+			in_range = true;  /* Start list items swapping... */
+		}
+		else if (i == new_index) {
+			in_range = false;  /* End list items swapping. */
+		}
+
+		if (in_range) {
+			KeyBlock *other_kb = rev ? kb->prev : kb->next;
+
+			/* Swap with previous/next list item. */
+			BLI_swaplinks(&key->block, kb, other_kb);
+
+			/* Swap absolute positions. */
+			SWAP(float, kb->pos, other_kb->pos);
+
+			kb = other_kb;
+		}
+
+		/* Adjust relative indices, this has to be done on the whole list! */
+		if (kb->relative == org_index) {
+			kb->relative = new_index;
+		}
+		else if (kb->relative < org_index && kb->relative >= new_index) {
+			/* remove after, insert before this index */
+			kb->relative++;
+		}
+		else if (kb->relative > org_index && kb->relative <= new_index) {
+			/* remove before, insert after this index */
+			kb->relative--;
+		}
+	}
+
+	/* Need to update active shape number if it's affected, same principle as for relative indices above. */
+	if (org_index == act_index) {
+		ob->shapenr = new_index + 1;
+	}
+	else if (act_index < org_index && act_index >= new_index) {
+		ob->shapenr++;
+	}
+	else if (act_index > org_index && act_index <= new_index) {
+		ob->shapenr--;
+	}
+
+	/* First key is always refkey, matches interface and BKE_key_sort */
+	key->refkey = key->block.first;
+
+	return true;
+}