Outliner: Element mouse hover feedback

Some little UI polish to get familiar with outliner code (but also because it's a useful feature). Committing to blender2.8 branch but can also port to master (2.7) if wanted.

This basically causes the mouse hovered element to be highlighted. Contrast of the highlight should be fine, even with a non-default theme. Also did some minor cleanup.

1 files changed, 85 insertions, 6 deletions

diff --git a/source/blender/editors/space_outliner/outliner_edit.c b/source/blender/editors/space_outliner/outliner_edit.c
index 8eb53d0d7b9..bfb87b6cd7b 100644
--- a/source/blender/editors/space_outliner/outliner_edit.c
+++ b/source/blender/editors/space_outliner/outliner_edit.c
@@ -151,7 +151,69 @@ TreeElement *outliner_dropzone_find(const SpaceOops *soops, const float fmval[2]
 }
 
 /* ************************************************************** */
-/* Click Activated */
+
+/* Highlight --------------------------------------------------- */
+
+/**
+ * Try to find an item under y-coordinate \a view_co_y (view-space).
+ * \note Recursive
+ */
+static TreeElement *outliner_find_item_at_y(
+        const SpaceOops *soops, const ListBase *tree, float view_co_y)
+{
+	for (TreeElement *te_iter = tree->first; te_iter; te_iter = te_iter->next) {
+		if (view_co_y < (te_iter->ys + UI_UNIT_Y)) {
+			if (view_co_y > te_iter->ys) {
+				/* co_y is inside this element */
+				return te_iter;
+			}
+			else if (TSELEM_OPEN(te_iter->store_elem, soops)) {
+				/* co_y is lower than current element, possibly inside children */
+				TreeElement *te_sub = outliner_find_item_at_y(soops, &te_iter->subtree, view_co_y);
+				if (te_sub) {
+					return te_sub;
+				}
+			}
+		}
+	}
+
+	return NULL;
+}
+
+static int outliner_highlight_update(bContext *C, wmOperator *UNUSED(op), const wmEvent *event)
+{
+	ARegion *ar = CTX_wm_region(C);
+	SpaceOops *soops = CTX_wm_space_outliner(C);
+	const float my = UI_view2d_region_to_view_y(&ar->v2d, event->mval[1]);
+
+	TreeElement *hovered_te = outliner_find_item_at_y(soops, &soops->tree, my);
+	bool changed;
+
+	if (!hovered_te || !(hovered_te->store_elem->flag & TSE_HIGHLIGHTED)) {
+		changed = outliner_set_flag(soops, &soops->tree, TSE_HIGHLIGHTED, false);
+		if (hovered_te) {
+			hovered_te->store_elem->flag |= TSE_HIGHLIGHTED;
+			changed = true;
+		}
+	}
+
+	if (changed) {
+		ED_region_tag_redraw(ar);
+	}
+
+	return (OPERATOR_FINISHED | OPERATOR_PASS_THROUGH);
+}
+
+void OUTLINER_OT_highlight_update(wmOperatorType *ot)
+{
+	ot->name = "Update Highlight";
+	ot->idname = "OUTLINER_OT_highlight_update";
+	ot->description = "Update the item highlight based on the current mouse position";
+
+	ot->invoke = outliner_highlight_update;
+
+	ot->poll = ED_operator_outliner_active;
+}
 
 /* Toggle Open/Closed ------------------------------------------- */
 
@@ -742,17 +804,34 @@ int outliner_has_one_flag(SpaceOops *soops, ListBase *lb, short flag, const int
 	return 0;
 }
 
-void outliner_set_flag(SpaceOops *soops, ListBase *lb, short flag, short set)
+/**
+ * Set or unset \a flag for all outliner elements in \a lb and sub-trees.
+ * \return if any flag was modified.
+ */
+bool outliner_set_flag(SpaceOops *soops, ListBase *lb, short flag, short set)
 {
 	TreeElement *te;
 	TreeStoreElem *tselem;
-	
+	bool changed = false;
+	bool has_flag;
+
 	for (te = lb->first; te; te = te->next) {
 		tselem = TREESTORE(te);
-		if (set == 0) tselem->flag &= ~flag;
-		else tselem->flag |= flag;
-		outliner_set_flag(soops, &te->subtree, flag, set);
+		has_flag = (tselem->flag & flag);
+		if (set == 0) {
+			if (has_flag) {
+				tselem->flag &= ~flag;
+				changed = true;
+			}
+		}
+		else if (!has_flag){
+			tselem->flag |= flag;
+			changed = true;
+		}
+		changed |= outliner_set_flag(soops, &te->subtree, flag, set);
 	}
+
+	return changed;
 }
 
 /* Restriction Columns ------------------------------- */