Formspec: Show a player inventory using core.show_formspec (#15963)

'core.show_formspec' now shows and updates the inventory formspec as if
it was opened using the hotkey on client-side.

src/client/game.cpp

@@ -1925,7 +1925,7 @@ void Game::processKeyInput()
 		if (g_settings->getBool("continuous_forward"))
 			toggleAutoforward();
 	} else if (wasKeyDown(KeyType::INVENTORY)) {
-		m_game_formspec.showPlayerInventory();
+		m_game_formspec.showPlayerInventory(nullptr);
 	} else if (input->cancelPressed()) {
 #ifdef __ANDROID__
 		m_android_chat_open = false;
@@ -2714,11 +2714,16 @@ void Game::handleClientEvent_DeathscreenLegacy(ClientEvent *event, CameraOrienta
 
 void Game::handleClientEvent_ShowFormSpec(ClientEvent *event, CameraOrientation *cam)
 {
-	m_game_formspec.showFormSpec(*event->show_formspec.formspec,
-		*event->show_formspec.formname);
+	auto &fs = event->show_formspec;
 
-	delete event->show_formspec.formspec;
-	delete event->show_formspec.formname;
+	if (fs.formname->empty() && !fs.formspec->empty()) {
+		m_game_formspec.showPlayerInventory(fs.formspec);
+	} else {
+		m_game_formspec.showFormSpec(*fs.formspec, *fs.formname);
+	}
+
+	delete fs.formspec;
+	delete fs.formname;
 }
 
 void Game::handleClientEvent_ShowCSMFormSpec(ClientEvent *event, CameraOrientation *cam)

src/client/game_formspec.cpp

@@ -178,6 +178,10 @@ public:
 	const std::string &getForm() const
 	{
 		LocalPlayer *player = m_client->getEnv().getLocalPlayer();
+
+		if (!player->inventory_formspec_override.empty())
+			return player->inventory_formspec_override;
+
 		return player->inventory_formspec;
 	}
 
@@ -304,7 +308,7 @@ void GameFormSpec::showNodeFormspec(const std::string &formspec, const v3s16 &no
 	m_formspec->setFormSpec(formspec, inventoryloc);
 }
 
-void GameFormSpec::showPlayerInventory()
+void GameFormSpec::showPlayerInventory(const std::string *fs_override)
 {
 	/*
 	 * Don't permit to open inventory is CAO or player doesn't exists.
@@ -317,28 +321,35 @@ void GameFormSpec::showPlayerInventory()
 
 	infostream << "Game: Launching inventory" << std::endl;
 
-	PlayerInventoryFormSource *fs_src = new PlayerInventoryFormSource(m_client);
+	auto fs_src = std::make_unique<PlayerInventoryFormSource>(m_client);
 
 	InventoryLocation inventoryloc;
 	inventoryloc.setCurrentPlayer();
 
-	if (m_client->modsLoaded() && m_client->getScript()->on_inventory_open(m_client->getInventory(inventoryloc))) {
-		delete fs_src;
-		return;
+	if (fs_override) {
+		// Temporary overwrite for this specific formspec.
+		player->inventory_formspec_override = *fs_override;
+	} else {
+		// Show the regular inventory formspec
+		player->inventory_formspec_override.clear();
 	}
 
-	if (fs_src->getForm().empty()) {
-		delete fs_src;
+	// If prevented by Client-Side Mods
+	if (m_client->modsLoaded() && m_client->getScript()->on_inventory_open(m_client->getInventory(inventoryloc)))
+		return;
+
+	// Empty formspec -> do not show.
+	if (fs_src->getForm().empty())
 		return;
-	}
 
 	TextDest *txt_dst = new TextDestPlayerInventory(m_client);
 
 	GUIFormSpecMenu::create(m_formspec, m_client, m_rendering_engine->get_gui_env(),
-		&m_input->joystick, fs_src, txt_dst, m_client->getFormspecPrepend(),
+		&m_input->joystick, fs_src.get(), txt_dst, m_client->getFormspecPrepend(),
 		m_client->getSoundManager());
 
 	m_formspec->setFormSpec(fs_src->getForm(), inventoryloc);
+	fs_src.release(); // owned by GUIFormSpecMenu
 }
 
 #define SIZE_TAG "size[11,5.5,true]" // Fixed size (ignored in touchscreen mode)

src/client/game_formspec.h

@@ -34,7 +34,9 @@ struct GameFormSpec
 	// Currently only used for the in-game settings menu.
 	void showPauseMenuFormSpec(const std::string &formspec, const std::string &formname);
 	void showNodeFormspec(const std::string &formspec, const v3s16 &nodepos);
-	void showPlayerInventory();
+	/// If `!fs_override`: Uses `player->inventory_formspec`.
+	/// If ` fs_override`: Uses a temporary formspec until an update is received.
+	void showPlayerInventory(const std::string *fs_override);
 	void showDeathFormspecLegacy();
 	// Shows the hardcoded "main" pause menu.
 	void showPauseMenu();

src/client/localplayer.h

@@ -99,6 +99,8 @@ public:
 
 	std::string hotbar_image = "";
 	std::string hotbar_selected_image = "";
+	/// Temporary player inventory formspec. Empty value = feature inactive.
+	std::string inventory_formspec_override;
 
 	video::SColor light_color = video::SColor(255, 255, 255, 255);