Implement Animation Libraries

* Instead of containing single animations, AnimationPlayer now contains libraries.
* Libraries, in turn, contain the animations.

This paves the way for implementing the possibility of importing scenes as animation libraries, finally allowing to import animations separate from the 3D models.

Missing (will be done on separate PRs):

* Make it possible to import scenes (dae/fbx/gltf) as animation libraries.
* Make it possible for AnimationTree to import animation libraries on its own, so it does not rely on AnimationPlayer for everything.

4 files changed, 80 insertions, 15 deletions

diff --git a/scene/gui/option_button.cpp b/scene/gui/option_button.cpp
index 1e8a149e11..307696c44a 100644
--- a/scene/gui/option_button.cpp
+++ b/scene/gui/option_button.cpp
@@ -203,16 +203,18 @@ void OptionButton::pressed() {
 }
 
 void OptionButton::add_icon_item(const Ref<Texture2D> &p_icon, const String &p_label, int p_id) {
+	bool first_selectable = !has_selectable_items();
 	popup->add_icon_radio_check_item(p_icon, p_label, p_id);
-	if (popup->get_item_count() == 1) {
-		select(0);
+	if (first_selectable) {
+		select(get_item_count() - 1);
 	}
 }
 
 void OptionButton::add_item(const String &p_label, int p_id) {
+	bool first_selectable = !has_selectable_items();
 	popup->add_radio_check_item(p_label, p_id);
-	if (popup->get_item_count() == 1) {
-		select(0);
+	if (first_selectable) {
+		select(get_item_count() - 1);
 	}
 }
 
@@ -280,6 +282,9 @@ bool OptionButton::is_item_disabled(int p_idx) const {
 	return popup->is_item_disabled(p_idx);
 }
 
+bool OptionButton::is_item_separator(int p_idx) const {
+	return popup->is_item_separator(p_idx);
+}
 void OptionButton::set_item_count(int p_count) {
 	ERR_FAIL_COND(p_count < 0);
 
@@ -299,12 +304,37 @@ void OptionButton::set_item_count(int p_count) {
 	notify_property_list_changed();
 }
 
+bool OptionButton::has_selectable_items() const {
+	for (int i = 0; i < get_item_count(); i++) {
+		if (!is_item_disabled(i) && !is_item_separator(i)) {
+			return true;
+		}
+	}
+	return false;
+}
+int OptionButton::get_selectable_item(bool p_from_last) const {
+	if (!p_from_last) {
+		for (int i = 0; i < get_item_count(); i++) {
+			if (!is_item_disabled(i) && !is_item_separator(i)) {
+				return i;
+			}
+		}
+	} else {
+		for (int i = get_item_count() - 1; i >= 0; i++) {
+			if (!is_item_disabled(i) && !is_item_separator(i)) {
+				return i;
+			}
+		}
+	}
+	return -1;
+}
+
 int OptionButton::get_item_count() const {
 	return popup->get_item_count();
 }
 
-void OptionButton::add_separator() {
-	popup->add_separator();
+void OptionButton::add_separator(const String &p_text) {
+	popup->add_separator(p_text);
 }
 
 void OptionButton::clear() {
@@ -407,7 +437,8 @@ void OptionButton::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_item_metadata", "idx"), &OptionButton::get_item_metadata);
 	ClassDB::bind_method(D_METHOD("get_item_tooltip", "idx"), &OptionButton::get_item_tooltip);
 	ClassDB::bind_method(D_METHOD("is_item_disabled", "idx"), &OptionButton::is_item_disabled);
-	ClassDB::bind_method(D_METHOD("add_separator"), &OptionButton::add_separator);
+	ClassDB::bind_method(D_METHOD("is_item_separator", "idx"), &OptionButton::is_item_separator);
+	ClassDB::bind_method(D_METHOD("add_separator", "text"), &OptionButton::add_separator, DEFVAL(String()));
 	ClassDB::bind_method(D_METHOD("clear"), &OptionButton::clear);
 	ClassDB::bind_method(D_METHOD("select", "idx"), &OptionButton::select);
 	ClassDB::bind_method(D_METHOD("get_selected"), &OptionButton::get_selected);
@@ -420,6 +451,8 @@ void OptionButton::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("set_item_count", "count"), &OptionButton::set_item_count);
 	ClassDB::bind_method(D_METHOD("get_item_count"), &OptionButton::get_item_count);
+	ClassDB::bind_method(D_METHOD("has_selectable_items"), &OptionButton::has_selectable_items);
+	ClassDB::bind_method(D_METHOD("get_selectable_item", "from_last"), &OptionButton::get_selectable_item, DEFVAL(false));
 
 	// "selected" property must come after "item_count", otherwise GH-10213 occurs.
 	ADD_ARRAY_COUNT("Items", "item_count", "set_item_count", "get_item_count", "popup/item_");
diff --git a/scene/gui/option_button.h b/scene/gui/option_button.h
index 921b76c52a..7896132626 100644
--- a/scene/gui/option_button.h
+++ b/scene/gui/option_button.h
@@ -77,12 +77,16 @@ public:
 	int get_item_index(int p_id) const;
 	Variant get_item_metadata(int p_idx) const;
 	bool is_item_disabled(int p_idx) const;
+	bool is_item_separator(int p_idx) const;
 	String get_item_tooltip(int p_idx) const;
 
+	bool has_selectable_items() const;
+	int get_selectable_item(bool p_from_last = false) const;
+
 	void set_item_count(int p_count);
 	int get_item_count() const;
 
-	void add_separator();
+	void add_separator(const String &p_text = "");
 
 	void clear();
 
diff --git a/scene/gui/tree.cpp b/scene/gui/tree.cpp
index ccd24ed2cf..24cd485e1b 100644
--- a/scene/gui/tree.cpp
+++ b/scene/gui/tree.cpp
@@ -101,6 +101,7 @@ void TreeItem::_change_tree(Tree *p_tree) {
 
 		if (tree->popup_edited_item == this) {
 			tree->popup_edited_item = nullptr;
+			tree->popup_pressing_edited_item = nullptr;
 			tree->pressing_for_editor = false;
 		}
 
@@ -2670,8 +2671,8 @@ int Tree::propagate_mouse_event(const Point2i &p_pos, int x_ofs, int y_ofs, int
 		}
 
 		click_handled = true;
-		popup_edited_item = p_item;
-		popup_edited_item_col = col;
+		popup_pressing_edited_item = p_item;
+		popup_pressing_edited_item_column = col;
 
 		pressing_item_rect = Rect2(get_global_position() + Point2i(col_ofs, _get_title_button_height() + y_ofs) - cache.offset, Size2(col_width, item_h));
 		pressing_for_editor_text = editor_text;
@@ -3206,10 +3207,16 @@ void Tree::gui_input(const Ref<InputEvent> &p_event) {
 			update();
 		}
 
-		if (pressing_for_editor && popup_edited_item && (popup_edited_item->get_cell_mode(popup_edited_item_col) == TreeItem::CELL_MODE_RANGE)) {
-			//range drag
+		if (pressing_for_editor && popup_pressing_edited_item && (popup_pressing_edited_item->get_cell_mode(popup_pressing_edited_item_column) == TreeItem::CELL_MODE_RANGE)) {
+			/* This needs to happen now, because the popup can be closed when pressing another item, and must remain the popup edited item until it actually closes */
+			popup_edited_item = popup_pressing_edited_item;
+			popup_edited_item_col = popup_pressing_edited_item_column;
+
+			popup_pressing_edited_item = nullptr;
+			popup_pressing_edited_item_column = -1;
 
 			if (!range_drag_enabled) {
+				//range drag
 				Vector2 cpos = mm->get_position();
 				if (rtl) {
 					cpos.x = get_size().width - cpos.x;
@@ -3994,6 +4001,7 @@ void Tree::clear() {
 	selected_item = nullptr;
 	edited_item = nullptr;
 	popup_edited_item = nullptr;
+	popup_pressing_edited_item = nullptr;
 
 	update();
 };
@@ -4309,12 +4317,16 @@ int Tree::get_pressed_button() const {
 	return pressed_button;
 }
 
-Rect2 Tree::get_item_rect(TreeItem *p_item, int p_column) const {
+Rect2 Tree::get_item_rect(TreeItem *p_item, int p_column, int p_button) const {
 	ERR_FAIL_NULL_V(p_item, Rect2());
 	ERR_FAIL_COND_V(p_item->tree != this, Rect2());
 	if (p_column != -1) {
 		ERR_FAIL_INDEX_V(p_column, columns.size(), Rect2());
 	}
+	if (p_button != -1) {
+		ERR_FAIL_COND_V(p_column == -1, Rect2()); // pass a column if you want to pass a button
+		ERR_FAIL_INDEX_V(p_button, p_item->cells[p_column].buttons.size(), Rect2());
+	}
 
 	int ofs = get_item_offset(p_item);
 	int height = compute_item_height(p_item);
@@ -4332,6 +4344,19 @@ Rect2 Tree::get_item_rect(TreeItem *p_item, int p_column) const {
 		}
 		r.position.x = accum;
 		r.size.x = get_column_width(p_column);
+		if (p_button != -1) {
+			const TreeItem::Cell &c = p_item->cells[p_column];
+			Vector2 ofst = Vector2(r.position.x + r.size.x, r.position.y);
+			for (int j = c.buttons.size() - 1; j >= 0; j--) {
+				Ref<Texture2D> b = c.buttons[j].texture;
+				Size2 size = b->get_size() + cache.button_pressed->get_minimum_size();
+				ofst.x -= size.x;
+
+				if (j == p_button) {
+					return Rect2(ofst, size);
+				}
+			}
+		}
 	}
 
 	return r;
@@ -4870,7 +4895,7 @@ void Tree::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_edited_column"), &Tree::get_edited_column);
 	ClassDB::bind_method(D_METHOD("edit_selected"), &Tree::edit_selected);
 	ClassDB::bind_method(D_METHOD("get_custom_popup_rect"), &Tree::get_custom_popup_rect);
-	ClassDB::bind_method(D_METHOD("get_item_area_rect", "item", "column"), &Tree::get_item_rect, DEFVAL(-1));
+	ClassDB::bind_method(D_METHOD("get_item_area_rect", "item", "column", "button_index"), &Tree::get_item_rect, DEFVAL(-1), DEFVAL(-1));
 	ClassDB::bind_method(D_METHOD("get_item_at_position", "position"), &Tree::get_item_at_position);
 	ClassDB::bind_method(D_METHOD("get_column_at_position", "position"), &Tree::get_column_at_position);
 	ClassDB::bind_method(D_METHOD("get_drop_section_at_position", "position"), &Tree::get_drop_section_at_position);
diff --git a/scene/gui/tree.h b/scene/gui/tree.h
index 74ad4f94b8..b704495444 100644
--- a/scene/gui/tree.h
+++ b/scene/gui/tree.h
@@ -379,6 +379,9 @@ private:
 	TreeItem *selected_item = nullptr;
 	TreeItem *edited_item = nullptr;
 
+	TreeItem *popup_pressing_edited_item = nullptr; // Candidate.
+	int popup_pressing_edited_item_column = -1;
+
 	TreeItem *drop_mode_over = nullptr;
 	int drop_mode_section = 0;
 
@@ -673,7 +676,7 @@ public:
 	Rect2 get_custom_popup_rect() const;
 
 	int get_item_offset(TreeItem *p_item) const;
-	Rect2 get_item_rect(TreeItem *p_item, int p_column = -1) const;
+	Rect2 get_item_rect(TreeItem *p_item, int p_column = -1, int p_button = -1) const;
 	bool edit_selected();
 	bool is_editing();