Add the ability to reorder arrays from the inspector

editor/editor_properties_array_dict.cpp

@@ -31,15 +31,17 @@
 #include "editor_properties_array_dict.h"
 
 #include "core/io/marshalls.h"
+#include "core/os/input.h"
+#include "editor/editor_node.h"
 #include "editor/editor_scale.h"
 #include "editor_properties.h"
 
 bool EditorPropertyArrayObject::_set(const StringName &p_name, const Variant &p_value) {
-	String pn = p_name;
+	String name = p_name;
 
-	if (pn.begins_with("indices")) {
-		int idx = pn.get_slicec('/', 1).to_int();
-		array.set(idx, p_value);
+	if (name.begins_with("indices")) {
+		int index = name.get_slicec('/', 1).to_int();
+		array.set(index, p_value);
 		return true;
 	}
 
@@ -47,12 +49,12 @@ bool EditorPropertyArrayObject::_set(const StringName &p_name, const Variant &p_
 }
 
 bool EditorPropertyArrayObject::_get(const StringName &p_name, Variant &r_ret) const {
-	String pn = p_name;
+	String name = p_name;
 
-	if (pn.begins_with("indices")) {
-		int idx = pn.get_slicec('/', 1).to_int();
+	if (name.begins_with("indices")) {
+		int index = name.get_slicec('/', 1).to_int();
 		bool valid;
-		r_ret = array.get(idx, &valid);
+		r_ret = array.get(index, &valid);
 		if (r_ret.get_type() == Variant::OBJECT && Object::cast_to<EncodedObjectAsID>(r_ret)) {
 			r_ret = Object::cast_to<EncodedObjectAsID>(r_ret)->get_object_id();
 		}
@@ -77,21 +79,21 @@ EditorPropertyArrayObject::EditorPropertyArrayObject() {
 ///////////////////
 
 bool EditorPropertyDictionaryObject::_set(const StringName &p_name, const Variant &p_value) {
-	String pn = p_name;
+	String name = p_name;
 
-	if (pn == "new_item_key") {
+	if (name == "new_item_key") {
 		new_item_key = p_value;
 		return true;
 	}
 
-	if (pn == "new_item_value") {
+	if (name == "new_item_value") {
 		new_item_value = p_value;
 		return true;
 	}
 
-	if (pn.begins_with("indices")) {
-		int idx = pn.get_slicec('/', 1).to_int();
-		Variant key = dict.get_key_at_index(idx);
+	if (name.begins_with("indices")) {
+		int index = name.get_slicec('/', 1).to_int();
+		Variant key = dict.get_key_at_index(index);
 		dict[key] = p_value;
 		return true;
 	}
@@ -100,21 +102,21 @@ bool EditorPropertyDictionaryObject::_set(const StringName &p_name, const Varian
 }
 
 bool EditorPropertyDictionaryObject::_get(const StringName &p_name, Variant &r_ret) const {
-	String pn = p_name;
+	String name = p_name;
 
-	if (pn == "new_item_key") {
+	if (name == "new_item_key") {
 		r_ret = new_item_key;
 		return true;
 	}
 
-	if (pn == "new_item_value") {
+	if (name == "new_item_value") {
 		r_ret = new_item_value;
 		return true;
 	}
 
-	if (pn.begins_with("indices")) {
-		int idx = pn.get_slicec('/', 1).to_int();
-		Variant key = dict.get_key_at_index(idx);
+	if (name.begins_with("indices")) {
+		int index = name.get_slicec('/', 1).to_int();
+		Variant key = dict.get_key_at_index(index);
 		r_ret = dict[key];
 		if (r_ret.get_type() == Variant::OBJECT && Object::cast_to<EncodedObjectAsID>(r_ret)) {
 			r_ret = Object::cast_to<EncodedObjectAsID>(r_ret)->get_object_id();
@@ -155,15 +157,15 @@ EditorPropertyDictionaryObject::EditorPropertyDictionaryObject() {
 
 ///////////////////// ARRAY ///////////////////////////
 
-void EditorPropertyArray::_property_changed(const String &p_prop, Variant p_value, const String &p_name, bool changing) {
-	if (p_prop.begins_with("indices")) {
-		int idx = p_prop.get_slice("/", 1).to_int();
+void EditorPropertyArray::_property_changed(const String &p_property, Variant p_value, const String &p_name, bool p_changing) {
+	if (p_property.begins_with("indices")) {
+		int index = p_property.get_slice("/", 1).to_int();
 		Variant array = object->get_array();
-		array.set(idx, p_value);
+		array.set(index, p_value);
 		emit_changed(get_edited_property(), array, "", true);
 
 		if (array.get_type() == Variant::ARRAY) {
-			array = array.call("duplicate"); //dupe, so undo/redo works better
+			array = array.call("duplicate"); // Duplicate, so undo/redo works better.
 		}
 		object->set_array(array);
 	}
@@ -171,7 +173,7 @@ void EditorPropertyArray::_property_changed(const String &p_prop, Variant p_valu
 
 void EditorPropertyArray::_change_type(Object *p_button, int p_index) {
 	Button *button = Object::cast_to<Button>(p_button);
-	changing_type_idx = p_index;
+	changing_type_index = p_index;
 	Rect2 rect = button->get_global_rect();
 	change_type->set_as_minsize();
 	change_type->set_global_position(rect.position + rect.size - Vector2(change_type->get_combined_minimum_size().x, 0));
@@ -180,7 +182,7 @@ void EditorPropertyArray::_change_type(Object *p_button, int p_index) {
 
 void EditorPropertyArray::_change_type_menu(int p_index) {
 	if (p_index == Variant::VARIANT_MAX) {
-		_remove_pressed(changing_type_idx);
+		_remove_pressed(changing_type_index);
 		return;
 	}
 
@@ -188,12 +190,12 @@ void EditorPropertyArray::_change_type_menu(int p_index) {
 	Variant::CallError ce;
 	value = Variant::construct(Variant::Type(p_index), nullptr, 0, ce);
 	Variant array = object->get_array();
-	array.set(changing_type_idx, value);
+	array.set(changing_type_index, value);
 
 	emit_changed(get_edited_property(), array, "", true);
 
 	if (array.get_type() == Variant::ARRAY) {
-		array = array.call("duplicate"); //dupe, so undo/redo works better
+		array = array.call("duplicate"); // Duplicate, so undo/redo works better.
 	}
 
 	object->set_array(array);
@@ -214,7 +216,7 @@ void EditorPropertyArray::update_property() {
 
 		} break;
 
-		// arrays
+		// Arrays.
 		case Variant::POOL_BYTE_ARRAY: {
 			arrtype = "PoolByteArray";
 
@@ -254,7 +256,12 @@ void EditorPropertyArray::update_property() {
 		return;
 	}
 
-	edit->set_text(arrtype + " (size " + itos(array.call("size")) + ")");
+	int size = array.call("size");
+	int pages = MAX(0, size - 1) / page_length + 1;
+	page_index = MIN(page_index, pages - 1);
+	int offset = page_index * page_length;
+
+	edit->set_text(arrtype + " (size " + itos(size) + ")");
 
 	bool unfolded = get_edited_object()->editor_is_section_unfolded(get_edited_property());
 	if (edit->is_pressed() != unfolded) {
@@ -268,50 +275,50 @@ void EditorPropertyArray::update_property() {
 			vbox = memnew(VBoxContainer);
 			add_child(vbox);
 			set_bottom_editor(vbox);
-			HBoxContainer *hbc = memnew(HBoxContainer);
-			vbox->add_child(hbc);
+
+			HBoxContainer *hbox = memnew(HBoxContainer);
+			vbox->add_child(hbox);
+
 			Label *label = memnew(Label(TTR("Size: ")));
 			label->set_h_size_flags(SIZE_EXPAND_FILL);
-			hbc->add_child(label);
-			length = memnew(EditorSpinSlider);
-			length->set_step(1);
-			length->set_max(1000000);
-			length->set_h_size_flags(SIZE_EXPAND_FILL);
-			hbc->add_child(length);
-			length->connect("value_changed", this, "_length_changed");
-
-			page_hb = memnew(HBoxContainer);
-			vbox->add_child(page_hb);
-			label = memnew(Label(TTR("Page: ")));
-			label->set_h_size_flags(SIZE_EXPAND_FILL);
-			page_hb->add_child(label);
-			page = memnew(EditorSpinSlider);
-			page->set_step(1);
-			page_hb->add_child(page);
-			page->set_h_size_flags(SIZE_EXPAND_FILL);
-			page->connect("value_changed", this, "_page_changed");
-		} else {
-			//bye bye children of the box
-			while (vbox->get_child_count() > 2) {
-				vbox->get_child(2)->queue_delete(); // button still needed after pressed is called
-				vbox->remove_child(vbox->get_child(2));
-			}
-		}
+			hbox->add_child(label);
 
-		int len = array.call("size");
+			size_slider = memnew(EditorSpinSlider);
+			size_slider->set_step(1);
+			size_slider->set_max(1000000);
+			size_slider->set_h_size_flags(SIZE_EXPAND_FILL);
+			size_slider->connect("value_changed", this, "_length_changed");
+			hbox->add_child(size_slider);
 
-		length->set_value(len);
+			page_hbox = memnew(HBoxContainer);
+			vbox->add_child(page_hbox);
 
-		int pages = MAX(0, len - 1) / page_len + 1;
+			label = memnew(Label(TTR("Page: ")));
+			label->set_h_size_flags(SIZE_EXPAND_FILL);
+			page_hbox->add_child(label);
 
-		page->set_max(pages);
-		page_idx = MIN(page_idx, pages - 1);
-		page->set_value(page_idx);
-		page_hb->set_visible(pages > 1);
+			page_slider = memnew(EditorSpinSlider);
+			page_slider->set_step(1);
+			page_slider->set_h_size_flags(SIZE_EXPAND_FILL);
+			page_slider->connect("value_changed", this, "_page_changed");
+			page_hbox->add_child(page_slider);
+		} else {
+			// Bye bye children of the box.
+			for (int i = vbox->get_child_count() - 1; i >= 2; i--) {
+				Node *child = vbox->get_child(i);
+				if (child == reorder_selected_element_hbox) {
+					continue; // Don't remove the property that the user is moving.
+				}
 
-		int offset = page_idx * page_len;
+				child->queue_delete(); // Button still needed after pressed is called.
+				vbox->remove_child(child);
+			}
+		}
 
-		int amount = MIN(len - offset, page_len);
+		size_slider->set_value(size);
+		page_slider->set_max(pages);
+		page_slider->set_value(page_index);
+		page_hbox->set_visible(pages > 1);
 
 		if (array.get_type() == Variant::ARRAY) {
 			array = array.call("duplicate");
@@ -319,7 +326,31 @@ void EditorPropertyArray::update_property() {
 
 		object->set_array(array);
 
+		int amount = MIN(size - offset, page_length);
 		for (int i = 0; i < amount; i++) {
+			bool reorder_is_from_current_page = reorder_from_index / page_length == page_index;
+			if (reorder_is_from_current_page && i == reorder_from_index % page_length) {
+				// Don't duplicate the property that the user is moving.
+				continue;
+			}
+			if (!reorder_is_from_current_page && i == reorder_to_index % page_length) {
+				// Don't create the property the moving property will take the place of,
+				// e.g. (if page_length == 20) don't create element 20 if dragging an item from
+				// the first page to the second page because element 20 would become element 19.
+				continue;
+			}
+
+			HBoxContainer *hbox = memnew(HBoxContainer);
+			vbox->add_child(hbox);
+
+			Button *reorder_button = memnew(Button);
+			reorder_button->set_icon(get_icon("TripleBar", "EditorIcons"));
+			reorder_button->set_default_cursor_shape(Control::CURSOR_MOVE);
+			reorder_button->connect("gui_input", this, "_reorder_button_gui_input");
+			reorder_button->connect("button_down", this, "_reorder_button_down", varray(i + offset));
+			reorder_button->connect("button_up", this, "_reorder_button_up");
+			hbox->add_child(reorder_button);
+
 			String prop_name = "indices/" + itos(i + offset);
 
 			EditorProperty *prop = nullptr;
@@ -344,29 +375,29 @@ void EditorPropertyArray::update_property() {
 			prop->connect("property_changed", this, "_property_changed");
 			prop->connect("object_id_selected", this, "_object_id_selected");
 			prop->set_h_size_flags(SIZE_EXPAND_FILL);
-
-			HBoxContainer *hb = memnew(HBoxContainer);
-
-			vbox->add_child(hb);
-			hb->add_child(prop);
+			hbox->add_child(prop);
 
 			bool is_untyped_array = array.get_type() == Variant::ARRAY && subtype == Variant::NIL;
 
 			if (is_untyped_array) {
 				Button *edit = memnew(Button);
 				edit->set_icon(get_icon("Edit", "EditorIcons"));
-				hb->add_child(edit);
+				hbox->add_child(edit);
 				edit->connect("pressed", this, "_change_type", varray(edit, i + offset));
 			} else {
 				Button *remove = memnew(Button);
 				remove->set_icon(get_icon("Remove", "EditorIcons"));
 				remove->connect("pressed", this, "_remove_pressed", varray(i + offset));
-				hb->add_child(remove);
+				hbox->add_child(remove);
 			}
 
 			prop->update_property();
 		}
 
+		if (reorder_to_index % page_length > 0) {
+			vbox->move_child(vbox->get_child(2), reorder_to_index % page_length + 2);
+		}
+
 		updating = false;
 
 	} else {
@@ -382,17 +413,13 @@ void EditorPropertyArray::_remove_pressed(int p_index) {
 	Variant array = object->get_array();
 	array.call("remove", p_index);
 
-	if (array.get_type() == Variant::ARRAY) {
-		array = array.call("duplicate");
-	}
-
 	emit_changed(get_edited_property(), array, "", false);
-	object->set_array(array);
 	update_property();
 }
 
 void EditorPropertyArray::_notification(int p_what) {
 }
+
 void EditorPropertyArray::_edit_pressed() {
 	Variant array = get_edited_object()->get(get_edited_property());
 	if (!array.is_array()) {
@@ -410,7 +437,7 @@ void EditorPropertyArray::_page_changed(double p_page) {
 	if (updating) {
 		return;
 	}
-	page_idx = p_page;
+	page_index = p_page;
 	update_property();
 }
 
@@ -434,10 +461,10 @@ void EditorPropertyArray::_length_changed(double p_page) {
 				}
 			}
 		}
-		array = array.call("duplicate"); //dupe, so undo/redo works better
+		array = array.call("duplicate"); // Duplicate, so undo/redo works better.
 	} else {
 		int size = array.call("size");
-		// Pool*Array don't initialize their elements, have to do it manually
+		// Pool*Array don't initialize their elements, have to do it manually.
 		for (int i = previous_size; i < size; i++) {
 			Variant::CallError ce;
 			array.set(i, Variant::construct(array.get(i).get_type(), nullptr, 0, ce));
@@ -452,6 +479,8 @@ void EditorPropertyArray::_length_changed(double p_page) {
 void EditorPropertyArray::setup(Variant::Type p_array_type, const String &p_hint_string) {
 	array_type = p_array_type;
 
+	// The format of p_hint_string is:
+	// subType/subTypeHint:nextSubtype ... etc.
 	if (array_type == Variant::ARRAY && !p_hint_string.empty()) {
 		int hint_subtype_separator = p_hint_string.find(":");
 		if (hint_subtype_separator >= 0) {
@@ -468,6 +497,73 @@ void EditorPropertyArray::setup(Variant::Type p_array_type, const String &p_hint
 	}
 }
 
+void EditorPropertyArray::_reorder_button_gui_input(const Ref<InputEvent> &p_event) {
+	if (reorder_from_index < 0) {
+		return;
+	}
+
+	Ref<InputEventMouseMotion> mm = p_event;
+	if (mm.is_valid()) {
+		Variant array = object->get_array();
+		int size = array.call("size");
+
+		if ((reorder_to_index == 0 && mm->get_relative().y < 0.0f) || (reorder_to_index == size - 1 && mm->get_relative().y > 0.0f)) {
+			return;
+		}
+
+		reorder_mouse_y_delta += mm->get_relative().y;
+		float required_y_distance = 20.0f * EDSCALE;
+		if (ABS(reorder_mouse_y_delta) > required_y_distance) {
+			int direction = reorder_mouse_y_delta > 0.0f ? 1 : -1;
+			reorder_mouse_y_delta -= required_y_distance * direction;
+
+			reorder_to_index += direction;
+			if ((direction < 0 && reorder_to_index % page_length == page_length - 1) || (direction > 0 && reorder_to_index % page_length == 0)) {
+				// Automatically move to the next/previous page.
+				page_slider->set_value(page_index + direction);
+			}
+			vbox->move_child(reorder_selected_element_hbox, reorder_to_index % page_length + 2);
+			// Ensure the moving element is visible.
+			EditorNode::get_singleton()->get_inspector()->ensure_control_visible(reorder_selected_element_hbox);
+		}
+	}
+}
+
+void EditorPropertyArray::_reorder_button_down(int p_index) {
+	reorder_from_index = p_index;
+	reorder_to_index = p_index;
+	reorder_selected_element_hbox = Object::cast_to<HBoxContainer>(vbox->get_child(p_index % page_length + 2));
+	reorder_selected_button = Object::cast_to<Button>(reorder_selected_element_hbox->get_child(0));
+	// Ideally it'd to be able to show the mouse but I had issues with
+	// Control's `mouse_exit()`/`mouse_entered()` signals not getting called.
+	Input::get_singleton()->set_mouse_mode(Input::MOUSE_MODE_CAPTURED);
+}
+
+void EditorPropertyArray::_reorder_button_up() {
+	if (reorder_from_index != reorder_to_index) {
+		// Move the element.
+		Variant array = object->get_array();
+
+		Variant value_to_move = array.get(reorder_from_index);
+		array.call("remove", reorder_from_index);
+		array.call("insert", reorder_to_index, value_to_move);
+
+		emit_changed(get_edited_property(), array, "", false);
+		object->set_array(array);
+		update_property();
+	}
+
+	reorder_from_index = -1;
+	reorder_to_index = -1;
+	reorder_mouse_y_delta = 0.0f;
+
+	Input::get_singleton()->set_mouse_mode(Input::MOUSE_MODE_VISIBLE);
+	reorder_selected_button->warp_mouse(reorder_selected_button->get_size() / 2.0f);
+
+	reorder_selected_element_hbox = nullptr;
+	reorder_selected_button = nullptr;
+}
+
 void EditorPropertyArray::_bind_methods() {
 	ClassDB::bind_method("_edit_pressed", &EditorPropertyArray::_edit_pressed);
 	ClassDB::bind_method("_page_changed", &EditorPropertyArray::_page_changed);
@@ -481,7 +577,7 @@ void EditorPropertyArray::_bind_methods() {
 
 EditorPropertyArray::EditorPropertyArray() {
 	object.instance();
-	page_len = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
+	page_length = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
 	edit = memnew(Button);
 	edit->set_flat(true);
 	edit->set_h_size_flags(SIZE_EXPAND_FILL);
@@ -491,8 +587,8 @@ EditorPropertyArray::EditorPropertyArray() {
 	add_child(edit);
 	add_focusable(edit);
 	vbox = nullptr;
-	page = nullptr;
-	length = nullptr;
+	page_slider = nullptr;
+	size_slider = nullptr;
 	updating = false;
 	change_type = memnew(PopupMenu);
 	add_child(change_type);
@@ -504,7 +600,7 @@ EditorPropertyArray::EditorPropertyArray() {
 	}
 	change_type->add_separator();
 	change_type->add_item(TTR("Remove Item"), Variant::VARIANT_MAX);
-	changing_type_idx = -1;
+	changing_type_index = -1;
 
 	subtype = Variant::NIL;
 	subtype_hint = PROPERTY_HINT_NONE;
@@ -513,20 +609,20 @@ EditorPropertyArray::EditorPropertyArray() {
 
 ///////////////////// DICTIONARY ///////////////////////////
 
-void EditorPropertyDictionary::_property_changed(const String &p_prop, Variant p_value, const String &p_name, bool changing) {
-	if (p_prop == "new_item_key") {
+void EditorPropertyDictionary::_property_changed(const String &p_property, Variant p_value, const String &p_name, bool changing) {
+	if (p_property == "new_item_key") {
 		object->set_new_item_key(p_value);
-	} else if (p_prop == "new_item_value") {
+	} else if (p_property == "new_item_value") {
 		object->set_new_item_value(p_value);
-	} else if (p_prop.begins_with("indices")) {
-		int idx = p_prop.get_slice("/", 1).to_int();
+	} else if (p_property.begins_with("indices")) {
+		int index = p_property.get_slice("/", 1).to_int();
 		Dictionary dict = object->get_dict();
-		Variant key = dict.get_key_at_index(idx);
+		Variant key = dict.get_key_at_index(index);
 		dict[key] = p_value;
 
 		emit_changed(get_edited_property(), dict, "", true);
 
-		dict = dict.duplicate(); //dupe, so undo/redo works better
+		dict = dict.duplicate(); // Duplicate, so undo/redo works better\.
 		object->set_dict(dict);
 	}
 }
@@ -538,7 +634,7 @@ void EditorPropertyDictionary::_change_type(Object *p_button, int p_index) {
 	change_type->set_as_minsize();
 	change_type->set_global_position(rect.position + rect.size - Vector2(change_type->get_combined_minimum_size().x, 0));
 	change_type->popup();
-	changing_type_idx = p_index;
+	changing_type_index = p_index;
 }
 
 void EditorPropertyDictionary::_add_key_value() {
@@ -555,17 +651,17 @@ void EditorPropertyDictionary::_add_key_value() {
 
 	emit_changed(get_edited_property(), dict, "", false);
 
-	dict = dict.duplicate(); //dupe, so undo/redo works better
+	dict = dict.duplicate(); // Duplicate, so undo/redo works better.
 	object->set_dict(dict);
 	update_property();
 }
 
 void EditorPropertyDictionary::_change_type_menu(int p_index) {
-	if (changing_type_idx < 0) {
+	if (changing_type_index < 0) {
 		Variant value;
 		Variant::CallError ce;
 		value = Variant::construct(Variant::Type(p_index), nullptr, 0, ce);
-		if (changing_type_idx == -1) {
+		if (changing_type_index == -1) {
 			object->set_new_item_key(value);
 		} else {
 			object->set_new_item_value(value);
@@ -580,16 +676,16 @@ void EditorPropertyDictionary::_change_type_menu(int p_index) {
 		Variant value;
 		Variant::CallError ce;
 		value = Variant::construct(Variant::Type(p_index), nullptr, 0, ce);
-		Variant key = dict.get_key_at_index(changing_type_idx);
+		Variant key = dict.get_key_at_index(changing_type_index);
 		dict[key] = value;
 	} else {
-		Variant key = dict.get_key_at_index(changing_type_idx);
+		Variant key = dict.get_key_at_index(changing_type_index);
 		dict.erase(key);
 	}
 
 	emit_changed(get_edited_property(), dict, "", false);
 
-	dict = dict.duplicate(); //dupe, so undo/redo works better
+	dict = dict.duplicate(); // Duplicate, so undo/redo works better.
 	object->set_dict(dict);
 	update_property();
 }
@@ -598,7 +694,7 @@ void EditorPropertyDictionary::update_property() {
 	Variant updated_val = get_edited_object()->get(get_edited_property());
 
 	if (updated_val.get_type() == Variant::NIL) {
-		edit->set_text("Dictionary (Nil)"); //This provides symmetry with the array property.
+		edit->set_text("Dictionary (Nil)"); // This provides symmetry with the array property.
 		edit->set_pressed(false);
 		if (vbox) {
 			set_bottom_editor(nullptr);
@@ -625,16 +721,16 @@ void EditorPropertyDictionary::update_property() {
 			add_child(vbox);
 			set_bottom_editor(vbox);
 
-			page_hb = memnew(HBoxContainer);
-			vbox->add_child(page_hb);
+			page_hbox = memnew(HBoxContainer);
+			vbox->add_child(page_hbox);
 			Label *label = memnew(Label(TTR("Page: ")));
 			label->set_h_size_flags(SIZE_EXPAND_FILL);
-			page_hb->add_child(label);
-			page = memnew(EditorSpinSlider);
-			page->set_step(1);
-			page_hb->add_child(page);
-			page->set_h_size_flags(SIZE_EXPAND_FILL);
-			page->connect("value_changed", this, "_page_changed");
+			page_hbox->add_child(label);
+			page_slider = memnew(EditorSpinSlider);
+			page_slider->set_step(1);
+			page_hbox->add_child(page_slider);
+			page_slider->set_h_size_flags(SIZE_EXPAND_FILL);
+			page_slider->connect("value_changed", this, "_page_changed");
 		} else {
 			// Queue children for deletion, deleting immediately might cause errors.
 			for (int i = 1; i < vbox->get_child_count(); i++) {
@@ -642,18 +738,18 @@ void EditorPropertyDictionary::update_property() {
 			}
 		}
 
-		int len = dict.size();
+		int size = dict.size();
 
-		int pages = MAX(0, len - 1) / page_len + 1;
+		int pages = MAX(0, size - 1) / page_length + 1;
 
-		page->set_max(pages);
-		page_idx = MIN(page_idx, pages - 1);
-		page->set_value(page_idx);
-		page_hb->set_visible(pages > 1);
+		page_slider->set_max(pages);
+		page_index = MIN(page_index, pages - 1);
+		page_slider->set_value(page_index);
+		page_hbox->set_visible(pages > 1);
 
-		int offset = page_idx * page_len;
+		int offset = page_index * page_length;
 
-		int amount = MIN(len - offset, page_len);
+		int amount = MIN(size - offset, page_length);
 
 		dict = dict.duplicate();
 
@@ -685,7 +781,7 @@ void EditorPropertyDictionary::update_property() {
 
 				} break;
 
-				// atomic types
+				// Atomic types.
 				case Variant::BOOL: {
 					prop = memnew(EditorPropertyCheck);
 
@@ -706,7 +802,7 @@ void EditorPropertyDictionary::update_property() {
 
 				} break;
 
-				// math types
+				// Math types.
 				case Variant::VECTOR2: {
 					EditorPropertyVector2 *editor = memnew(EditorPropertyVector2);
 					editor->setup(-100000, 100000, 0.001, true);
@@ -762,7 +858,7 @@ void EditorPropertyDictionary::update_property() {
 
 				} break;
 
-				// misc types
+				// Miscellaneous types.
 				case Variant::COLOR: {
 					prop = memnew(EditorPropertyColor);
 
@@ -798,7 +894,7 @@ void EditorPropertyDictionary::update_property() {
 					prop = editor;
 				} break;
 
-				// arrays
+				// Arrays.
 				case Variant::POOL_BYTE_ARRAY: {
 					EditorPropertyArray *editor = memnew(EditorPropertyArray);
 					editor->setup(Variant::POOL_BYTE_ARRAY);
@@ -872,17 +968,17 @@ void EditorPropertyDictionary::update_property() {
 			prop->connect("property_changed", this, "_property_changed");
 			prop->connect("object_id_selected", this, "_object_id_selected");
 
-			HBoxContainer *hb = memnew(HBoxContainer);
+			HBoxContainer *hbox = memnew(HBoxContainer);
 			if (add_vbox) {
-				add_vbox->add_child(hb);
+				add_vbox->add_child(hbox);
 			} else {
-				vbox->add_child(hb);
+				vbox->add_child(hbox);
 			}
-			hb->add_child(prop);
+			hbox->add_child(prop);
 			prop->set_h_size_flags(SIZE_EXPAND_FILL);
 			Button *edit = memnew(Button);
 			edit->set_icon(get_icon("Edit", "EditorIcons"));
-			hb->add_child(edit);
+			hbox->add_child(edit);
 			edit->connect("pressed", this, "_change_type", varray(edit, change_index));
 
 			prop->update_property();
@@ -929,7 +1025,7 @@ void EditorPropertyDictionary::_page_changed(double p_page) {
 	if (updating) {
 		return;
 	}
-	page_idx = p_page;
+	page_index = p_page;
 	update_property();
 }
 
@@ -945,7 +1041,7 @@ void EditorPropertyDictionary::_bind_methods() {
 
 EditorPropertyDictionary::EditorPropertyDictionary() {
 	object.instance();
-	page_len = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
+	page_length = int(EDITOR_GET("interface/inspector/max_array_dictionary_items_per_page"));
 	edit = memnew(Button);
 	edit->set_flat(true);
 	edit->set_h_size_flags(SIZE_EXPAND_FILL);
@@ -955,7 +1051,7 @@ EditorPropertyDictionary::EditorPropertyDictionary() {
 	add_child(edit);
 	add_focusable(edit);
 	vbox = nullptr;
-	page = nullptr;
+	page_slider = nullptr;
 	updating = false;
 	change_type = memnew(PopupMenu);
 	add_child(change_type);
@@ -967,5 +1063,5 @@ EditorPropertyDictionary::EditorPropertyDictionary() {
 	}
 	change_type->add_separator();
 	change_type->add_item(TTR("Remove Item"), Variant::VARIANT_MAX);
-	changing_type_idx = -1;
+	changing_type_index = -1;
 }

editor/editor_properties_array_dict.h

@@ -82,19 +82,25 @@ class EditorPropertyArray : public EditorProperty {
 	bool updating;
 
 	Ref<EditorPropertyArrayObject> object;
-	int page_len = 20;
-	int page_idx = 0;
-	int changing_type_idx;
+	int page_length = 20;
+	int page_index = 0;
+	int changing_type_index;
 	Button *edit;
 	VBoxContainer *vbox;
-	EditorSpinSlider *length;
-	EditorSpinSlider *page;
-	HBoxContainer *page_hb;
+	EditorSpinSlider *size_slider;
+	EditorSpinSlider *page_slider;
+	HBoxContainer *page_hbox;
 	Variant::Type array_type;
 	Variant::Type subtype;
 	PropertyHint subtype_hint;
 	String subtype_hint_string;
 
+	int reorder_from_index = -1;
+	int reorder_to_index = -1;
+	float reorder_mouse_y_delta = 0.0f;
+	HBoxContainer *reorder_selected_element_hbox = nullptr;
+	Button *reorder_selected_button = nullptr;
+
 	void _page_changed(double p_page);
 	void _length_changed(double p_page);
 	void _edit_pressed();
@@ -105,6 +111,10 @@ class EditorPropertyArray : public EditorProperty {
 	void _object_id_selected(const String &p_property, ObjectID p_id);
 	void _remove_pressed(int p_index);
 
+	void _reorder_button_gui_input(const Ref<InputEvent> &p_event);
+	void _reorder_button_down(int p_index);
+	void _reorder_button_up();
+
 protected:
 	static void _bind_methods();
 	void _notification(int p_what);
@@ -122,14 +132,14 @@ class EditorPropertyDictionary : public EditorProperty {
 	bool updating;
 
 	Ref<EditorPropertyDictionaryObject> object;
-	int page_len = 20;
-	int page_idx = 0;
-	int changing_type_idx;
+	int page_length = 20;
+	int page_index = 0;
+	int changing_type_index;
 	Button *edit;
 	VBoxContainer *vbox;
-	EditorSpinSlider *length;
-	EditorSpinSlider *page;
-	HBoxContainer *page_hb;
+	EditorSpinSlider *size_slider;
+	EditorSpinSlider *page_slider;
+	HBoxContainer *page_hbox;
 
 	void _page_changed(double p_page);
 	void _edit_pressed();

editor/icons/icon_triple_bar.svg

@@ -0,0 +1 @@
+<svg width="16" height="16" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg"><path d="m1.9375 4h12.062zm0 4h12.062zm0 4h12.062z" fill="none" stroke="#e0e0e0" stroke-opacity=".99608" stroke-width=".92823"/></svg>