Support drag & drop of collections across multiple hierarchy levels

Two issues are remaining, they'll be fixed separately:
* Graphical feedback when dragging within the master collection is wrong
* There's some bug where collections swap places instead, Dalai will investigate

1 files changed, 8 insertions, 29 deletions

diff --git a/source/blender/editors/space_outliner/outliner_draw.c b/source/blender/editors/space_outliner/outliner_draw.c
index 0ba60b21aa7..0b119b5d247 100644
--- a/source/blender/editors/space_outliner/outliner_draw.c
+++ b/source/blender/editors/space_outliner/outliner_draw.c
@@ -1520,34 +1520,14 @@ static void outliner_draw_tree_element(
 	}
 }
 
-/**
- * Count how many visible childs (and open grandchilds, great-grandchilds, ...) \a te has.
- */
-static int outliner_count_visible_childs(const SpaceOops *soops, const TreeElement *te)
-{
-	TreeStoreElem *tselem = TREESTORE(te);
-	int current_count = 0;
-
-	if (TSELEM_OPEN(tselem, soops)) {
-		for (TreeElement *te_child = te->subtree.first; te_child; te_child = te_child->next) {
-			current_count += outliner_count_visible_childs(soops, te_child);
-			current_count++;
-		}
-	}
-
-	return current_count;
-}
-
-static void outliner_draw_tree_element_floating(const SpaceOops *soops, const ARegion *ar,
-                                                const TreeElement *te_floating)
+static void outliner_draw_tree_element_floating(
+        const ARegion *ar, const TreeElement *te_floating)
 {
 	const TreeElement *te_insert = te_floating->drag_data->insert_handle;
-	const ListBase *lb_parent = te_floating->parent ? &te_floating->parent->subtree : &soops->tree;
-	const TreeElement *te_insert_fallback = te_insert ? te_insert : lb_parent->first;
 	const int line_width = 2;
 
 	unsigned int pos = add_attrib(immVertexFormat(), "pos", GL_FLOAT, 2, KEEP_FLOAT);
-	int coord_y = (te_insert ? te_insert->ys : (te_insert_fallback->ys + UI_UNIT_Y)) - (int)(line_width * 0.5f);
+	int coord_y = te_insert->ys;
 	unsigned char col[4];
 
 	if (te_insert == te_floating) {
@@ -1555,15 +1535,14 @@ static void outliner_draw_tree_element_floating(const SpaceOops *soops, const AR
 		return;
 	}
 
-	if (te_insert) {
-		coord_y -= UI_UNIT_Y * outliner_count_visible_childs(soops, te_insert);
-	}
-
 	UI_GetThemeColorShade4ubv(TH_BACK, -40, col);
 	immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 	glEnable(GL_BLEND);
 
-	if (!te_insert || (te_floating->drag_data->insert_type == TE_INSERT_AFTER)) {
+	if (ELEM(te_floating->drag_data->insert_type, TE_INSERT_BEFORE, TE_INSERT_AFTER)) {
+		if (te_floating->drag_data->insert_type == TE_INSERT_BEFORE) {
+			coord_y += UI_UNIT_Y;
+		}
 		immUniformColor4ubv(col);
 		glLineWidth(line_width);
 
@@ -1793,7 +1772,7 @@ static void outliner_draw_tree(
 		                           startx, &starty, te_edit, &te_floating);
 	}
 	if (te_floating) {
-		outliner_draw_tree_element_floating(soops, ar, te_floating);
+		outliner_draw_tree_element_floating(ar, te_floating);
 	}
 
 	if (has_restrict_icons) {