Copy/Paste property paths/values in inspector.

Resolves godotengine/godot-proposals#106.

Adds the following property menu options with default bindings:

- Copy Property (ctrl+c)
- Paste Property (ctrl+v)
- Copy Property Path (ctrl+shift+c)

If you hover over a property label in the inspector dock, you can copy
either the property value or the property path to the system clipboard
using the shortcuts above This is especially useful for the
`AnimationTree`, where code might reference properties like
"parameters/state/aim/move/blend_position".

One issue is that if you click a property, then click on the node you
currently have selected in the node tree, then press ctrl+shift+c, it
will still copy the selected property path rather than the node path. If
you click on a different node in the nodetree, however, ctrl+shift+c
will return to copying the nodepath.

The property value copy/paste was implemented by KoBeWi at #39398 and
merged into this PR due to their similarity.

Backport of 0205fffbf3ebf03cf974802f07368a5d18326893 from master.

editor/editor_inspector.cpp

@@ -32,10 +32,12 @@
 
 #include "array_property_edit.h"
 #include "core/os/input.h"
+#include "core/os/keyboard.h"
 #include "dictionary_property_edit.h"
 #include "editor_feature_profile.h"
 #include "editor_node.h"
 #include "editor_scale.h"
+#include "editor_settings.h"
 #include "multi_node_edit.h"
 #include "scene/property_utils.h"
 #include "scene/resources/packed_scene.h"
@@ -543,6 +545,27 @@ void EditorProperty::_gui_input(const Ref<InputEvent> &p_event) {
 	}
 }
 
+void EditorProperty::_unhandled_key_input(const Ref<InputEvent> &p_event) {
+	if (!selected) {
+		return;
+	}
+
+	const Ref<InputEventKey> k = p_event;
+
+	if (k.is_valid() && k->is_pressed()) {
+		if (ED_IS_SHORTCUT("property_editor/copy_property", p_event)) {
+			_menu_option(MENU_COPY_PROPERTY);
+			accept_event();
+		} else if (ED_IS_SHORTCUT("property_editor/paste_property", p_event) && !is_read_only()) {
+			_menu_option(MENU_PASTE_PROPERTY);
+			accept_event();
+		} else if (ED_IS_SHORTCUT("property_editor/copy_property_path", p_event)) {
+			_menu_option(MENU_COPY_PROPERTY_PATH);
+			accept_event();
+		}
+	}
+}
+
 void EditorProperty::set_label_reference(Control *p_control) {
 	label_reference = p_control;
 }
@@ -702,6 +725,7 @@ void EditorProperty::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("_gui_input"), &EditorProperty::_gui_input);
 	ClassDB::bind_method(D_METHOD("_menu_option", "option"), &EditorProperty::_menu_option);
+	ClassDB::bind_method(D_METHOD("_unhandled_key_input"), &EditorProperty::_unhandled_key_input);
 	ClassDB::bind_method(D_METHOD("_focusable_focused"), &EditorProperty::_focusable_focused);
 
 	ClassDB::bind_method(D_METHOD("get_tooltip_text"), &EditorProperty::get_tooltip_text);
@@ -759,6 +783,8 @@ EditorProperty::EditorProperty() {
 	label_reference = nullptr;
 	bottom_editor = nullptr;
 	menu = nullptr;
+
+	set_process_unhandled_key_input(true);
 }
 
 void EditorProperty::_update_popup() {
@@ -769,7 +795,14 @@ void EditorProperty::_update_popup() {
 		add_child(menu);
 		menu->connect("id_pressed", this, "_menu_option");
 	}
+
+	menu->add_shortcut(ED_GET_SHORTCUT("property_editor/copy_property"), MENU_COPY_PROPERTY);
+	menu->add_shortcut(ED_GET_SHORTCUT("property_editor/paste_property"), MENU_PASTE_PROPERTY);
+	menu->add_shortcut(ED_GET_SHORTCUT("property_editor/copy_property_path"), MENU_COPY_PROPERTY_PATH);
+	menu->set_item_disabled(MENU_PASTE_PROPERTY, is_read_only());
+
 	if (!pin_hidden) {
+		menu->add_separator();
 		if (can_pin) {
 			menu->add_check_item(TTR("Pin value"), MENU_PIN_VALUE);
 			menu->set_item_checked(menu->get_item_index(MENU_PIN_VALUE), is_pinned);
@@ -787,6 +820,15 @@ void EditorProperty::_menu_option(int p_option) {
 			emit_signal("property_pinned", property, !is_pinned);
 			update();
 		} break;
+		case MENU_COPY_PROPERTY: {
+			EditorNode::get_singleton()->get_inspector()->set_property_clipboard(object->get(property));
+		} break;
+		case MENU_PASTE_PROPERTY: {
+			emit_changed(property, EditorNode::get_singleton()->get_inspector()->get_property_clipboard());
+		} break;
+		case MENU_COPY_PROPERTY_PATH: {
+			OS::get_singleton()->set_clipboard(property);
+		} break;
 	}
 }
 
@@ -1899,6 +1941,14 @@ void EditorInspector::set_sub_inspector(bool p_enable) {
 	_update_inspector_bg();
 }
 
+void EditorInspector::set_property_clipboard(const Variant &p_value) {
+	property_clipboard = p_value;
+}
+
+Variant EditorInspector::get_property_clipboard() const {
+	return property_clipboard;
+}
+
 void EditorInspector::_edit_request_change(Object *p_object, const String &p_property) {
 	if (object != p_object) { //may be undoing/redoing for a non edited object, so ignore
 		return;
@@ -2292,7 +2342,12 @@ EditorInspector::EditorInspector() {
 	set_process(true);
 	property_focusable = -1;
 	sub_inspector = false;
+	property_clipboard = Variant();
 
 	get_v_scrollbar()->connect("value_changed", this, "_vscroll_changed");
 	update_scroll_request = -1;
+
+	ED_SHORTCUT("property_editor/copy_property", TTR("Copy Property"), KEY_MASK_CMD | KEY_C);
+	ED_SHORTCUT("property_editor/paste_property", TTR("Paste Property"), KEY_MASK_CMD | KEY_V);
+	ED_SHORTCUT("property_editor/copy_property_path", TTR("Copy Property Path"), KEY_MASK_CMD | KEY_MASK_SHIFT | KEY_C);
 }

editor/editor_inspector.h

@@ -53,6 +53,9 @@ class EditorProperty : public Container {
 public:
 	enum MenuItems {
 		MENU_PIN_VALUE,
+		MENU_COPY_PROPERTY,
+		MENU_PASTE_PROPERTY,
+		MENU_COPY_PROPERTY_PATH,
 	};
 
 private:
@@ -112,6 +115,7 @@ protected:
 	static void _bind_methods();
 
 	void _gui_input(const Ref<InputEvent> &p_event);
+	void _unhandled_key_input(const Ref<InputEvent> &p_event);
 
 public:
 	void emit_changed(const StringName &p_property, const Variant &p_value, const StringName &p_field = StringName(), bool p_changing = false);
@@ -308,6 +312,7 @@ class EditorInspector : public ScrollContainer {
 
 	String property_prefix; //used for sectioned inspector
 	String object_class;
+	Variant property_clipboard;
 
 	void _edit_set(const String &p_name, const Variant &p_value, bool p_refresh_all, const String &p_changed_field);
 
@@ -394,6 +399,9 @@ public:
 	void set_sub_inspector(bool p_enable);
 	bool is_sub_inspector() const { return sub_inspector; }
 
+	void set_property_clipboard(const Variant &p_value);
+	Variant get_property_clipboard() const;
+
 	EditorInspector();
 };