Add EditorResourcePicker control based on the Inspector editor for Resources

Fix formatting for the docs

4 files changed, 960 insertions, 0 deletions

diff --git a/doc/classes/EditorResourcePicker.xml b/doc/classes/EditorResourcePicker.xml
new file mode 100644
index 0000000000..e31a681b8b
--- /dev/null
+++ b/doc/classes/EditorResourcePicker.xml
@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="EditorResourcePicker" inherits="HBoxContainer" version="4.0">
+	<brief_description>
+		Godot editor's control for selecting [Resource] type properties.
+	</brief_description>
+	<description>
+		This is a [Control] node similar to the one used in the Inspector dock when editing [Resource]s. It provides options for creating, loading, saving and converting resources.
+		[b]Note:[/b] It does not include an editor for the resource.
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="can_drop_data_fw" qualifiers="const">
+			<return type="bool">
+			</return>
+			<argument index="0" name="position" type="Vector2">
+			</argument>
+			<argument index="1" name="data" type="Variant">
+			</argument>
+			<argument index="2" name="from" type="Control">
+			</argument>
+			<description>
+			</description>
+		</method>
+		<method name="drop_data_fw">
+			<return type="void">
+			</return>
+			<argument index="0" name="position" type="Vector2">
+			</argument>
+			<argument index="1" name="data" type="Variant">
+			</argument>
+			<argument index="2" name="from" type="Control">
+			</argument>
+			<description>
+			</description>
+		</method>
+		<method name="get_allowed_types" qualifiers="const">
+			<return type="PackedStringArray">
+			</return>
+			<description>
+				Returns a list of all allowed types and subtypes corresponding to the [member base_type]. If the [member base_type] is empty, an empty list is returned.
+			</description>
+		</method>
+		<method name="get_drag_data_fw">
+			<return type="Variant">
+			</return>
+			<argument index="0" name="position" type="Vector2">
+			</argument>
+			<argument index="1" name="from" type="Control">
+			</argument>
+			<description>
+			</description>
+		</method>
+	</methods>
+	<members>
+		<member name="base_type" type="String" setter="set_base_type" getter="get_base_type" default="&quot;&quot;">
+			The base type of allowed resource types. Can be a comma-separated list of several options.
+		</member>
+		<member name="editable" type="bool" setter="set_editable" getter="is_editable" default="true">
+			If [code]true[/code], the value can be selected and edited.
+		</member>
+		<member name="edited_resource" type="Resource" setter="set_edited_resource" getter="get_edited_resource">
+			The edited resource value.
+		</member>
+	</members>
+	<signals>
+		<signal name="resource_changed">
+			<argument index="0" name="resource" type="Resource">
+			</argument>
+			<description>
+				Emitted when the value of the edited resource was changed.
+			</description>
+		</signal>
+		<signal name="resource_selected">
+			<argument index="0" name="resource" type="Resource">
+			</argument>
+			<description>
+				Emitted when the resource value was set and user clicked to edit it.
+			</description>
+		</signal>
+	</signals>
+	<constants>
+	</constants>
+</class>
diff --git a/editor/editor_node.cpp b/editor/editor_node.cpp
index 61b17a7247..40ad23ef65 100644
--- a/editor/editor_node.cpp
+++ b/editor/editor_node.cpp
@@ -82,6 +82,7 @@
 #include "editor/editor_log.h"
 #include "editor/editor_plugin.h"
 #include "editor/editor_properties.h"
+#include "editor/editor_resource_picker.h"
 #include "editor/editor_resource_preview.h"
 #include "editor/editor_run_native.h"
 #include "editor/editor_run_script.h"
@@ -3757,6 +3758,7 @@ void EditorNode::register_editor_types() {
 	ClassDB::register_class<ScriptCreateDialog>();
 	ClassDB::register_class<EditorFeatureProfile>();
 	ClassDB::register_class<EditorSpinSlider>();
+	ClassDB::register_class<EditorResourcePicker>();
 	ClassDB::register_class<EditorSceneImporterMesh>();
 	ClassDB::register_class<EditorSceneImporterMeshNode3D>();
 
diff --git a/editor/editor_resource_picker.cpp b/editor/editor_resource_picker.cpp
new file mode 100644
index 0000000000..c72d240962
--- /dev/null
+++ b/editor/editor_resource_picker.cpp
@@ -0,0 +1,764 @@
+/*************************************************************************/
+/*  editor_resource_picker.cpp                                           */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "editor_resource_picker.h"
+
+#include "editor/editor_resource_preview.h"
+#include "editor_node.h"
+#include "editor_scale.h"
+#include "editor_settings.h"
+#include "filesystem_dock.h"
+
+void EditorResourcePicker::_update_resource() {
+	preview_rect->set_texture(Ref<Texture2D>());
+	assign_button->set_custom_minimum_size(Size2(1, 1));
+
+	if (edited_resource == RES()) {
+		assign_button->set_icon(Ref<Texture2D>());
+		assign_button->set_text(TTR("[empty]"));
+	} else {
+		assign_button->set_icon(EditorNode::get_singleton()->get_object_icon(edited_resource.operator->(), "Object"));
+
+		if (edited_resource->get_name() != String()) {
+			assign_button->set_text(edited_resource->get_name());
+		} else if (edited_resource->get_path().is_resource_file()) {
+			assign_button->set_text(edited_resource->get_path().get_file());
+			assign_button->set_tooltip(edited_resource->get_path());
+		} else {
+			assign_button->set_text(edited_resource->get_class());
+		}
+
+		if (edited_resource->get_path().is_resource_file()) {
+			assign_button->set_tooltip(edited_resource->get_path());
+		}
+
+		// Preview will override the above, so called at the end.
+		EditorResourcePreview::get_singleton()->queue_edited_resource_preview(edited_resource, this, "_update_resource_preview", edited_resource->get_instance_id());
+	}
+}
+
+void EditorResourcePicker::_update_resource_preview(const String &p_path, const Ref<Texture2D> &p_preview, const Ref<Texture2D> &p_small_preview, ObjectID p_obj) {
+	if (!edited_resource.is_valid() || edited_resource->get_instance_id() != p_obj) {
+		return;
+	}
+
+	String type = edited_resource->get_class_name();
+	if (ClassDB::is_parent_class(type, "Script")) {
+		assign_button->set_text(edited_resource->get_path().get_file());
+		return;
+	}
+
+	if (p_preview.is_valid()) {
+		preview_rect->set_offset(SIDE_LEFT, assign_button->get_icon()->get_width() + assign_button->get_theme_stylebox("normal")->get_default_margin(SIDE_LEFT) + get_theme_constant("hseparation", "Button"));
+
+		if (type == "GradientTexture") {
+			preview_rect->set_stretch_mode(TextureRect::STRETCH_SCALE);
+			assign_button->set_custom_minimum_size(Size2(1, 1));
+		} else {
+			preview_rect->set_stretch_mode(TextureRect::STRETCH_KEEP_ASPECT_CENTERED);
+			int thumbnail_size = EditorSettings::get_singleton()->get("filesystem/file_dialog/thumbnail_size");
+			thumbnail_size *= EDSCALE;
+			assign_button->set_custom_minimum_size(Size2(1, thumbnail_size));
+		}
+
+		preview_rect->set_texture(p_preview);
+		assign_button->set_text("");
+	}
+}
+
+void EditorResourcePicker::_resource_selected() {
+	if (edited_resource.is_null()) {
+		edit_button->set_pressed(true);
+		_update_menu();
+		return;
+	}
+
+	emit_signal("resource_selected", edited_resource);
+}
+
+void EditorResourcePicker::_file_selected(const String &p_path) {
+	RES loaded_resource = ResourceLoader::load(p_path);
+	ERR_FAIL_COND_MSG(loaded_resource.is_null(), "Cannot load resource from path '" + p_path + "'.");
+
+	if (base_type != "") {
+		bool any_type_matches = false;
+
+		for (int i = 0; i < base_type.get_slice_count(","); i++) {
+			String base = base_type.get_slice(",", i);
+			if (loaded_resource->is_class(base)) {
+				any_type_matches = true;
+				break;
+			}
+		}
+
+		if (!any_type_matches) {
+			EditorNode::get_singleton()->show_warning(vformat(TTR("The selected resource (%s) does not match any type expected for this property (%s)."), loaded_resource->get_class(), base_type));
+			return;
+		}
+	}
+
+	edited_resource = loaded_resource;
+	emit_signal("resource_changed", edited_resource);
+	_update_resource();
+}
+
+void EditorResourcePicker::_update_menu() {
+	_update_menu_items();
+
+	Rect2 gt = edit_button->get_screen_rect();
+	edit_menu->set_as_minsize();
+	int ms = edit_menu->get_contents_minimum_size().width;
+	Vector2 popup_pos = gt.position + gt.size - Vector2(ms, 0);
+	edit_menu->set_position(popup_pos);
+	edit_menu->popup();
+}
+
+void EditorResourcePicker::_update_menu_items() {
+	edit_menu->clear();
+
+	// Add options for creating specific subtypes of the base resource type.
+	if (base_type != "") {
+		int idx = 0;
+
+		Set<String> allowed_types;
+		_get_allowed_types(false, &allowed_types);
+
+		Vector<EditorData::CustomType> custom_resources;
+		if (EditorNode::get_editor_data().get_custom_types().has("Resource")) {
+			custom_resources = EditorNode::get_editor_data().get_custom_types()["Resource"];
+		}
+
+		for (Set<String>::Element *E = allowed_types.front(); E; E = E->next()) {
+			const String &t = E->get();
+
+			bool is_custom_resource = false;
+			Ref<Texture2D> icon;
+			if (!custom_resources.is_empty()) {
+				for (int j = 0; j < custom_resources.size(); j++) {
+					if (custom_resources[j].name == t) {
+						is_custom_resource = true;
+						if (custom_resources[j].icon.is_valid()) {
+							icon = custom_resources[j].icon;
+						}
+						break;
+					}
+				}
+			}
+
+			if (!is_custom_resource && !(ScriptServer::is_global_class(t) || ClassDB::can_instance(t))) {
+				continue;
+			}
+
+			inheritors_array.push_back(t);
+
+			if (!icon.is_valid()) {
+				icon = get_theme_icon(has_theme_icon(t, "EditorIcons") ? t : "Object", "EditorIcons");
+			}
+
+			int id = TYPE_BASE_ID + idx;
+			edit_menu->add_icon_item(icon, vformat(TTR("New %s"), t), id);
+
+			idx++;
+		}
+
+		if (edit_menu->get_item_count()) {
+			edit_menu->add_separator();
+		}
+	}
+
+	// Add an option to load a resource from a file.
+	edit_menu->add_icon_item(get_theme_icon("Load", "EditorIcons"), TTR("Load"), OBJ_MENU_LOAD);
+
+	// Add options for changing existing value of the resource.
+	if (edited_resource.is_valid()) {
+		edit_menu->add_icon_item(get_theme_icon("Edit", "EditorIcons"), TTR("Edit"), OBJ_MENU_EDIT);
+		edit_menu->add_icon_item(get_theme_icon("Clear", "EditorIcons"), TTR("Clear"), OBJ_MENU_CLEAR);
+		edit_menu->add_icon_item(get_theme_icon("Duplicate", "EditorIcons"), TTR("Make Unique"), OBJ_MENU_MAKE_UNIQUE);
+		edit_menu->add_icon_item(get_theme_icon("Save", "EditorIcons"), TTR("Save"), OBJ_MENU_SAVE);
+
+		if (edited_resource->get_path().is_resource_file()) {
+			edit_menu->add_separator();
+			edit_menu->add_item(TTR("Show in FileSystem"), OBJ_MENU_SHOW_IN_FILE_SYSTEM);
+		}
+	}
+
+	// Add options to copy/paste resource.
+	RES cb = EditorSettings::get_singleton()->get_resource_clipboard();
+	bool paste_valid = false;
+	if (cb.is_valid()) {
+		if (base_type == "") {
+			paste_valid = true;
+		} else {
+			for (int i = 0; i < base_type.get_slice_count(","); i++) {
+				if (ClassDB::is_parent_class(cb->get_class(), base_type.get_slice(",", i))) {
+					paste_valid = true;
+					break;
+				}
+			}
+		}
+	}
+
+	if (edited_resource.is_valid() || paste_valid) {
+		edit_menu->add_separator();
+
+		if (edited_resource.is_valid()) {
+			edit_menu->add_item(TTR("Copy"), OBJ_MENU_COPY);
+		}
+
+		if (paste_valid) {
+			edit_menu->add_item(TTR("Paste"), OBJ_MENU_PASTE);
+		}
+	}
+
+	// Add options to convert existing resource to another type of resource.
+	if (edited_resource.is_valid()) {
+		Vector<Ref<EditorResourceConversionPlugin>> conversions = EditorNode::get_singleton()->find_resource_conversion_plugin(edited_resource);
+		if (conversions.size()) {
+			edit_menu->add_separator();
+		}
+		for (int i = 0; i < conversions.size(); i++) {
+			String what = conversions[i]->converts_to();
+			Ref<Texture2D> icon;
+			if (has_theme_icon(what, "EditorIcons")) {
+				icon = get_theme_icon(what, "EditorIcons");
+			} else {
+				icon = get_theme_icon(what, "Resource");
+			}
+
+			edit_menu->add_icon_item(icon, vformat(TTR("Convert To %s"), what), CONVERT_BASE_ID + i);
+		}
+	}
+}
+
+void EditorResourcePicker::_edit_menu_cbk(int p_which) {
+	switch (p_which) {
+		case OBJ_MENU_LOAD: {
+			List<String> extensions;
+			for (int i = 0; i < base_type.get_slice_count(","); i++) {
+				String base = base_type.get_slice(",", i);
+				ResourceLoader::get_recognized_extensions_for_type(base, &extensions);
+			}
+
+			Set<String> valid_extensions;
+			for (List<String>::Element *E = extensions.front(); E; E = E->next()) {
+				valid_extensions.insert(E->get());
+			}
+
+			file_dialog->clear_filters();
+			for (Set<String>::Element *E = valid_extensions.front(); E; E = E->next()) {
+				file_dialog->add_filter("*." + E->get() + " ; " + E->get().to_upper());
+			}
+
+			file_dialog->popup_file_dialog();
+		} break;
+
+		case OBJ_MENU_EDIT: {
+			if (edited_resource.is_valid()) {
+				emit_signal("resource_selected", edited_resource);
+			}
+		} break;
+
+		case OBJ_MENU_CLEAR: {
+			edited_resource = RES();
+			emit_signal("resource_changed", edited_resource);
+			_update_resource();
+		} break;
+
+		case OBJ_MENU_MAKE_UNIQUE: {
+			if (edited_resource.is_null()) {
+				return;
+			}
+
+			List<PropertyInfo> property_list;
+			edited_resource->get_property_list(&property_list);
+			List<Pair<String, Variant>> propvalues;
+			for (List<PropertyInfo>::Element *E = property_list.front(); E; E = E->next()) {
+				Pair<String, Variant> p;
+				PropertyInfo &pi = E->get();
+				if (pi.usage & PROPERTY_USAGE_STORAGE) {
+					p.first = pi.name;
+					p.second = edited_resource->get(pi.name);
+				}
+
+				propvalues.push_back(p);
+			}
+
+			String orig_type = edited_resource->get_class();
+			Object *inst = ClassDB::instance(orig_type);
+			Ref<Resource> unique_resource = Ref<Resource>(Object::cast_to<Resource>(inst));
+			ERR_FAIL_COND(unique_resource.is_null());
+
+			for (List<Pair<String, Variant>>::Element *E = propvalues.front(); E; E = E->next()) {
+				Pair<String, Variant> &p = E->get();
+				unique_resource->set(p.first, p.second);
+			}
+
+			edited_resource = unique_resource;
+			emit_signal("resource_changed", edited_resource);
+			_update_resource();
+		} break;
+
+		case OBJ_MENU_SAVE: {
+			if (edited_resource.is_null()) {
+				return;
+			}
+			EditorNode::get_singleton()->save_resource(edited_resource);
+		} break;
+
+		case OBJ_MENU_COPY: {
+			EditorSettings::get_singleton()->set_resource_clipboard(edited_resource);
+		} break;
+
+		case OBJ_MENU_PASTE: {
+			edited_resource = EditorSettings::get_singleton()->get_resource_clipboard();
+			emit_signal("resource_changed", edited_resource);
+			_update_resource();
+		} break;
+
+		case OBJ_MENU_SHOW_IN_FILE_SYSTEM: {
+			FileSystemDock *file_system_dock = EditorNode::get_singleton()->get_filesystem_dock();
+			file_system_dock->navigate_to_path(edited_resource->get_path());
+
+			// Ensure that the FileSystem dock is visible.
+			TabContainer *tab_container = (TabContainer *)file_system_dock->get_parent_control();
+			tab_container->set_current_tab(file_system_dock->get_index());
+		} break;
+
+		default: {
+			if (p_which >= CONVERT_BASE_ID) {
+				int to_type = p_which - CONVERT_BASE_ID;
+				Vector<Ref<EditorResourceConversionPlugin>> conversions = EditorNode::get_singleton()->find_resource_conversion_plugin(edited_resource);
+				ERR_FAIL_INDEX(to_type, conversions.size());
+
+				edited_resource = conversions[to_type]->convert(edited_resource);
+				emit_signal("resource_changed", edited_resource);
+				_update_resource();
+				break;
+			}
+
+			ERR_FAIL_COND(inheritors_array.is_empty());
+
+			String intype = inheritors_array[p_which - TYPE_BASE_ID];
+			Variant obj;
+
+			if (ScriptServer::is_global_class(intype)) {
+				obj = ClassDB::instance(ScriptServer::get_global_class_native_base(intype));
+				if (obj) {
+					Ref<Script> script = ResourceLoader::load(ScriptServer::get_global_class_path(intype));
+					if (script.is_valid()) {
+						((Object *)obj)->set_script(script);
+					}
+				}
+			} else {
+				obj = ClassDB::instance(intype);
+			}
+
+			if (!obj) {
+				obj = EditorNode::get_editor_data().instance_custom_type(intype, "Resource");
+			}
+
+			Resource *resp = Object::cast_to<Resource>(obj);
+			ERR_BREAK(!resp);
+
+			edited_resource = RES(resp);
+			emit_signal("resource_changed", edited_resource);
+			_update_resource();
+		} break;
+	}
+}
+
+void EditorResourcePicker::_button_draw() {
+	if (dropping) {
+		Color color = get_theme_color("accent_color", "Editor");
+		assign_button->draw_rect(Rect2(Point2(), assign_button->get_size()), color, false);
+	}
+}
+
+void EditorResourcePicker::_button_input(const Ref<InputEvent> &p_event) {
+	if (!editable) {
+		return;
+	}
+
+	Ref<InputEventMouseButton> mb = p_event;
+
+	if (mb.is_valid()) {
+		if (mb->is_pressed() && mb->get_button_index() == MOUSE_BUTTON_RIGHT) {
+			_update_menu_items();
+
+			Vector2 pos = get_screen_position() + mb->get_position();
+			edit_menu->set_as_minsize();
+			edit_menu->set_position(pos);
+			edit_menu->popup();
+		}
+	}
+}
+
+void EditorResourcePicker::_get_allowed_types(bool p_with_convert, Set<String> *p_vector) const {
+	Vector<String> allowed_types = base_type.split(",");
+	int size = allowed_types.size();
+
+	List<StringName> global_classes;
+	ScriptServer::get_global_class_list(&global_classes);
+
+	for (int i = 0; i < size; i++) {
+		String base = allowed_types[i].strip_edges();
+		p_vector->insert(base);
+
+		List<StringName> inheriters;
+
+		ClassDB::get_inheriters_from_class(base, &inheriters);
+		for (List<StringName>::Element *E = inheriters.front(); E; E = E->next()) {
+			p_vector->insert(E->get());
+		}
+
+		for (List<StringName>::Element *E = global_classes.front(); E; E = E->next()) {
+			if (EditorNode::get_editor_data().script_class_is_parent(E->get(), base)) {
+				p_vector->insert(E->get());
+			}
+		}
+
+		if (p_with_convert) {
+			if (base == "StandardMaterial3D") {
+				p_vector->insert("Texture2D");
+			} else if (base == "ShaderMaterial") {
+				p_vector->insert("Shader");
+			} else if (base == "Font") {
+				p_vector->insert("FontData");
+			}
+		}
+	}
+
+	if (EditorNode::get_editor_data().get_custom_types().has("Resource")) {
+		Vector<EditorData::CustomType> custom_resources = EditorNode::get_editor_data().get_custom_types()["Resource"];
+
+		for (int i = 0; i < custom_resources.size(); i++) {
+			p_vector->insert(custom_resources[i].name);
+		}
+	}
+}
+
+bool EditorResourcePicker::_is_drop_valid(const Dictionary &p_drag_data) const {
+	if (base_type.is_empty()) {
+		return true;
+	}
+
+	Dictionary drag_data = p_drag_data;
+
+	Ref<Resource> res;
+	if (drag_data.has("type") && String(drag_data["type"]) == "script_list_element") {
+		ScriptEditorBase *se = Object::cast_to<ScriptEditorBase>(drag_data["script_list_element"]);
+		res = se->get_edited_resource();
+	} else if (drag_data.has("type") && String(drag_data["type"]) == "resource") {
+		res = drag_data["resource"];
+	}
+
+	Set<String> allowed_types;
+	_get_allowed_types(true, &allowed_types);
+
+	if (res.is_valid() && _is_type_valid(res->get_class(), allowed_types)) {
+		return true;
+	}
+
+	if (res.is_valid() && res->get_script()) {
+		StringName custom_class = EditorNode::get_singleton()->get_object_custom_type_name(res->get_script());
+		if (_is_type_valid(custom_class, allowed_types)) {
+			return true;
+		}
+	}
+
+	if (drag_data.has("type") && String(drag_data["type"]) == "files") {
+		Vector<String> files = drag_data["files"];
+
+		if (files.size() == 1) {
+			String file = files[0];
+
+			String file_type = EditorFileSystem::get_singleton()->get_file_type(file);
+			if (file_type != "" && _is_type_valid(file_type, allowed_types)) {
+				return true;
+			}
+		}
+	}
+
+	return false;
+}
+
+bool EditorResourcePicker::_is_type_valid(const String p_type_name, Set<String> p_allowed_types) const {
+	for (Set<String>::Element *E = p_allowed_types.front(); E; E = E->next()) {
+		String at = E->get().strip_edges();
+		if (p_type_name == at || ClassDB::is_parent_class(p_type_name, at) || EditorNode::get_editor_data().script_class_is_parent(p_type_name, at)) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+Variant EditorResourcePicker::get_drag_data_fw(const Point2 &p_point, Control *p_from) {
+	if (edited_resource.is_valid()) {
+		return EditorNode::get_singleton()->drag_resource(edited_resource, p_from);
+	}
+
+	return Variant();
+}
+
+bool EditorResourcePicker::can_drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from) const {
+	return editable && _is_drop_valid(p_data);
+}
+
+void EditorResourcePicker::drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from) {
+	ERR_FAIL_COND(!_is_drop_valid(p_data));
+
+	Dictionary drag_data = p_data;
+
+	Ref<Resource> dropped_resource;
+	if (drag_data.has("type") && String(drag_data["type"]) == "script_list_element") {
+		ScriptEditorBase *se = Object::cast_to<ScriptEditorBase>(drag_data["script_list_element"]);
+		dropped_resource = se->get_edited_resource();
+	} else if (drag_data.has("type") && String(drag_data["type"]) == "resource") {
+		dropped_resource = drag_data["resource"];
+	}
+
+	if (!dropped_resource.is_valid() && drag_data.has("type") && String(drag_data["type"]) == "files") {
+		Vector<String> files = drag_data["files"];
+
+		if (files.size() == 1) {
+			String file = files[0];
+			dropped_resource = ResourceLoader::load(file);
+		}
+	}
+
+	if (dropped_resource.is_valid()) {
+		Set<String> allowed_types;
+		_get_allowed_types(false, &allowed_types);
+
+		// If the accepted dropped resource is from the extended list, it requires conversion.
+		if (!_is_type_valid(dropped_resource->get_class(), allowed_types)) {
+			for (Set<String>::Element *E = allowed_types.front(); E; E = E->next()) {
+				String at = E->get().strip_edges();
+
+				if (at == "StandardMaterial3D" && ClassDB::is_parent_class(dropped_resource->get_class(), "Texture2D")) {
+					Ref<StandardMaterial3D> mat = memnew(StandardMaterial3D);
+					mat->set_texture(StandardMaterial3D::TextureParam::TEXTURE_ALBEDO, dropped_resource);
+					dropped_resource = mat;
+					break;
+				}
+
+				if (at == "ShaderMaterial" && ClassDB::is_parent_class(dropped_resource->get_class(), "Shader")) {
+					Ref<ShaderMaterial> mat = memnew(ShaderMaterial);
+					mat->set_shader(dropped_resource);
+					dropped_resource = mat;
+					break;
+				}
+
+				if (at == "Font" && ClassDB::is_parent_class(dropped_resource->get_class(), "FontData")) {
+					Ref<Font> font = memnew(Font);
+					font->add_data(dropped_resource);
+					dropped_resource = font;
+					break;
+				}
+			}
+		}
+
+		edited_resource = dropped_resource;
+		emit_signal("resource_changed", edited_resource);
+		_update_resource();
+	}
+}
+
+void EditorResourcePicker::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("_update_resource_preview"), &EditorResourcePicker::_update_resource_preview);
+	ClassDB::bind_method(D_METHOD("get_drag_data_fw", "position", "from"), &EditorResourcePicker::get_drag_data_fw);
+	ClassDB::bind_method(D_METHOD("can_drop_data_fw", "position", "data", "from"), &EditorResourcePicker::can_drop_data_fw);
+	ClassDB::bind_method(D_METHOD("drop_data_fw", "position", "data", "from"), &EditorResourcePicker::drop_data_fw);
+
+	ClassDB::bind_method(D_METHOD("set_base_type", "base_type"), &EditorResourcePicker::set_base_type);
+	ClassDB::bind_method(D_METHOD("get_base_type"), &EditorResourcePicker::get_base_type);
+	ClassDB::bind_method(D_METHOD("get_allowed_types"), &EditorResourcePicker::get_allowed_types);
+	ClassDB::bind_method(D_METHOD("set_edited_resource", "resource"), &EditorResourcePicker::set_edited_resource);
+	ClassDB::bind_method(D_METHOD("get_edited_resource"), &EditorResourcePicker::get_edited_resource);
+	ClassDB::bind_method(D_METHOD("set_editable", "enable"), &EditorResourcePicker::set_editable);
+	ClassDB::bind_method(D_METHOD("is_editable"), &EditorResourcePicker::is_editable);
+
+	ADD_PROPERTY(PropertyInfo(Variant::STRING, "base_type"), "set_base_type", "get_base_type");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "edited_resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource", 0), "set_edited_resource", "get_edited_resource");
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "editable"), "set_editable", "is_editable");
+
+	ADD_SIGNAL(MethodInfo("resource_selected", PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource")));
+	ADD_SIGNAL(MethodInfo("resource_changed", PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource")));
+}
+
+void EditorResourcePicker::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_ENTER_TREE: {
+			_update_resource();
+			[[fallthrough]];
+		}
+		case NOTIFICATION_THEME_CHANGED: {
+			edit_button->set_icon(get_theme_icon("select_arrow", "Tree"));
+		} break;
+
+		case NOTIFICATION_DRAW: {
+			draw_style_box(get_theme_stylebox("bg", "Tree"), Rect2(Point2(), get_size()));
+		} break;
+
+		case NOTIFICATION_DRAG_BEGIN: {
+			if (editable && _is_drop_valid(get_viewport()->gui_get_drag_data())) {
+				dropping = true;
+				assign_button->update();
+			}
+		} break;
+
+		case NOTIFICATION_DRAG_END: {
+			if (dropping) {
+				dropping = false;
+				assign_button->update();
+			}
+		} break;
+	}
+}
+
+void EditorResourcePicker::set_base_type(const String &p_base_type) {
+	base_type = p_base_type;
+
+	// There is a possibility that the new base type is conflicting with the existing value.
+	// Keep the value, but warn the user that there is a potential mistake.
+	if (!base_type.is_empty() && edited_resource.is_valid()) {
+		Set<String> allowed_types;
+		_get_allowed_types(true, &allowed_types);
+
+		StringName custom_class;
+		bool is_custom = false;
+		if (edited_resource->get_script()) {
+			custom_class = EditorNode::get_singleton()->get_object_custom_type_name(edited_resource->get_script());
+			is_custom = _is_type_valid(custom_class, allowed_types);
+		}
+
+		if (!is_custom && !_is_type_valid(edited_resource->get_class(), allowed_types)) {
+			String class_str = (custom_class == StringName() ? edited_resource->get_class() : vformat("%s (%s)", custom_class, edited_resource->get_class()));
+			WARN_PRINT(vformat("Value mismatch between the new base type of this EditorResourcePicker, '%s', and the type of the value it already has, '%s'.", base_type, class_str));
+		}
+	}
+}
+
+String EditorResourcePicker::get_base_type() const {
+	return base_type;
+}
+
+Vector<String> EditorResourcePicker::get_allowed_types() const {
+	Set<String> allowed_types;
+	_get_allowed_types(false, &allowed_types);
+
+	Vector<String> types;
+	types.resize(allowed_types.size());
+
+	int i = 0;
+	String *w = types.ptrw();
+	for (Set<String>::Element *E = allowed_types.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+
+	return types;
+}
+
+void EditorResourcePicker::set_edited_resource(RES p_resource) {
+	if (!p_resource.is_valid()) {
+		return;
+	}
+
+	if (!base_type.is_empty()) {
+		Set<String> allowed_types;
+		_get_allowed_types(true, &allowed_types);
+
+		StringName custom_class;
+		bool is_custom = false;
+		if (p_resource->get_script()) {
+			custom_class = EditorNode::get_singleton()->get_object_custom_type_name(p_resource->get_script());
+			is_custom = _is_type_valid(custom_class, allowed_types);
+		}
+
+		if (!is_custom && !_is_type_valid(p_resource->get_class(), allowed_types)) {
+			String class_str = (custom_class == StringName() ? p_resource->get_class() : vformat("%s (%s)", custom_class, p_resource->get_class()));
+			ERR_FAIL_MSG(vformat("Failed to set a resource of the type '%s' because this EditorResourcePicker only accepts '%s' and its derivatives.", class_str, base_type));
+		}
+	}
+
+	edited_resource = p_resource;
+	_update_resource();
+}
+
+RES EditorResourcePicker::get_edited_resource() {
+	return edited_resource;
+}
+
+void EditorResourcePicker::set_editable(bool p_editable) {
+	editable = p_editable;
+	assign_button->set_disabled(!editable);
+	edit_button->set_visible(editable);
+}
+
+bool EditorResourcePicker::is_editable() const {
+	return editable;
+}
+
+EditorResourcePicker::EditorResourcePicker() {
+	assign_button = memnew(Button);
+	assign_button->set_flat(true);
+	assign_button->set_h_size_flags(SIZE_EXPAND_FILL);
+	assign_button->set_clip_text(true);
+	assign_button->connect("pressed", callable_mp(this, &EditorResourcePicker::_resource_selected));
+	assign_button->set_drag_forwarding(this);
+	assign_button->connect("draw", callable_mp(this, &EditorResourcePicker::_button_draw));
+	add_child(assign_button);
+
+	preview_rect = memnew(TextureRect);
+	preview_rect->set_expand(true);
+	preview_rect->set_anchors_and_offsets_preset(PRESET_WIDE);
+	preview_rect->set_offset(SIDE_TOP, 1);
+	preview_rect->set_offset(SIDE_BOTTOM, -1);
+	preview_rect->set_offset(SIDE_RIGHT, -1);
+	assign_button->add_child(preview_rect);
+	assign_button->connect("gui_input", callable_mp(this, &EditorResourcePicker::_button_input));
+
+	edit_menu = memnew(PopupMenu);
+	add_child(edit_menu);
+	edit_button = memnew(Button);
+	edit_button->set_flat(true);
+	edit_button->set_toggle_mode(true);
+	edit_menu->connect("id_pressed", callable_mp(this, &EditorResourcePicker::_edit_menu_cbk));
+	edit_menu->connect("popup_hide", callable_mp((BaseButton *)edit_button, &BaseButton::set_pressed), varray(false));
+	edit_button->connect("pressed", callable_mp(this, &EditorResourcePicker::_update_menu));
+	add_child(edit_button);
+	edit_button->connect("gui_input", callable_mp(this, &EditorResourcePicker::_button_input));
+
+	file_dialog = memnew(EditorFileDialog);
+	file_dialog->set_file_mode(EditorFileDialog::FILE_MODE_OPEN_FILE);
+	add_child(file_dialog);
+	file_dialog->connect("file_selected", callable_mp(this, &EditorResourcePicker::_file_selected));
+}
diff --git a/editor/editor_resource_picker.h b/editor/editor_resource_picker.h
new file mode 100644
index 0000000000..8123b5e966
--- /dev/null
+++ b/editor/editor_resource_picker.h
@@ -0,0 +1,110 @@
+/*************************************************************************/
+/*  editor_resource_picker.h                                             */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef EDITOR_RESOURCE_PICKER_H
+#define EDITOR_RESOURCE_PICKER_H
+
+#include "editor_file_dialog.h"
+#include "scene/gui/box_container.h"
+#include "scene/gui/button.h"
+#include "scene/gui/popup_menu.h"
+#include "scene/gui/texture_rect.h"
+
+class EditorResourcePicker : public HBoxContainer {
+	GDCLASS(EditorResourcePicker, HBoxContainer);
+
+	String base_type;
+	RES edited_resource;
+
+	bool editable = true;
+	bool dropping = false;
+
+	Vector<String> inheritors_array;
+
+	Button *assign_button;
+	TextureRect *preview_rect;
+	Button *edit_button;
+	EditorFileDialog *file_dialog;
+
+	enum MenuOption {
+		OBJ_MENU_LOAD,
+		OBJ_MENU_EDIT,
+		OBJ_MENU_CLEAR,
+		OBJ_MENU_MAKE_UNIQUE,
+		OBJ_MENU_SAVE,
+		OBJ_MENU_COPY,
+		OBJ_MENU_PASTE,
+		OBJ_MENU_SHOW_IN_FILE_SYSTEM,
+
+		TYPE_BASE_ID = 100,
+		CONVERT_BASE_ID = 1000,
+	};
+
+	PopupMenu *edit_menu;
+
+	void _update_resource();
+	void _update_resource_preview(const String &p_path, const Ref<Texture2D> &p_preview, const Ref<Texture2D> &p_small_preview, ObjectID p_obj);
+
+	void _resource_selected();
+	void _file_selected(const String &p_path);
+
+	void _update_menu();
+	void _update_menu_items();
+	void _edit_menu_cbk(int p_which);
+
+	void _button_draw();
+	void _button_input(const Ref<InputEvent> &p_event);
+
+	void _get_allowed_types(bool p_with_convert, Set<String> *p_vector) const;
+	bool _is_drop_valid(const Dictionary &p_drag_data) const;
+	bool _is_type_valid(const String p_type_name, Set<String> p_allowed_types) const;
+
+	Variant get_drag_data_fw(const Point2 &p_point, Control *p_from);
+	bool can_drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from) const;
+	void drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from);
+
+protected:
+	static void _bind_methods();
+	void _notification(int p_what);
+
+public:
+	void set_base_type(const String &p_base_type);
+	String get_base_type() const;
+	Vector<String> get_allowed_types() const;
+	void set_edited_resource(RES p_resource);
+	RES get_edited_resource();
+
+	void set_editable(bool p_editable);
+	bool is_editable() const;
+
+	EditorResourcePicker();
+};
+
+#endif // EDITOR_RESOURCE_PICKER_H