WindowServer: Implement partial window resizing

This patch adds support for client side resizing, so clients can request
the server to resize their windows. WindowServer will respond with
resize event when and if the resizing is complete.

userspace/libraries/LibGUI/Window.cpp

@@ -59,7 +59,7 @@ namespace LibGUI
 
 	Window::~Window()
 	{
-		clear();
+		cleanup();
 	}
 
 	BAN::ErrorOr<BAN::UniqPtr<Window>> Window::create(uint32_t width, uint32_t height, BAN::StringView title)
@@ -101,27 +101,13 @@ namespace LibGUI
 		TRY(create_packet.title.append(title));
 		TRY(create_packet.send_serialized(server_fd));
 
-		const auto [response_type, response_data ] = TRY(recv_packet(server_fd));
-		if (response_type != PacketType::WindowCreateResponse)
-			return BAN::Error::from_literal("Server responded with invalid packet");
+		auto window = TRY(BAN::UniqPtr<Window>::create(server_fd));
 
-		const auto create_response = TRY(WindowPacket::WindowCreateResponse::deserialize(response_data.span()));
-		void* framebuffer_addr = smo_map(create_response.smo_key);
-		if (framebuffer_addr == nullptr)
-			return BAN::Error::from_errno(errno);
-		width = create_response.width;
-		height = create_response.height;
-
-		BAN::Vector<uint32_t> framebuffer;
-		TRY(framebuffer.resize(width * height, 0xFFFFFFFF));
-
-		auto window = TRY(BAN::UniqPtr<Window>::create(
-			server_fd,
-			static_cast<uint32_t*>(framebuffer_addr),
-			BAN::move(framebuffer),
-			width,
-			height
-		));
+		bool resized = false;
+		window->set_resize_window_event_callback([&]() { resized = true; });
+		while (!resized)
+			window->poll_events();
+		window->set_resize_window_event_callback({});
 
 		server_closer.disable();
 
@@ -291,6 +277,16 @@ namespace LibGUI
 		m_attributes = attributes;
 	}
 
+	void Window::request_resize(uint32_t width, uint32_t height)
+	{
+		WindowPacket::WindowSetSize packet;
+		packet.width = width;
+		packet.height = height;
+
+		if (auto ret = packet.send_serialized(m_server_fd); ret.is_error())
+			return on_socket_error(__FUNCTION__);
+	}
+
 	void Window::on_socket_error(BAN::StringView function)
 	{
 		if (m_handling_socket_error)
@@ -303,14 +299,42 @@ namespace LibGUI
 			exit(1);
 
 		m_socket_error_callback();
-		clear();
+		cleanup();
 	}
 
-	void Window::clear()
+	void Window::cleanup()
 	{
 		munmap(m_framebuffer_smo, m_width * m_height * 4);
 		close(m_server_fd);
-		m_server_fd = -1;
+	}
+
+	BAN::ErrorOr<void> Window::handle_resize_event(const EventPacket::ResizeWindowEvent& event)
+	{
+		if (m_framebuffer_smo)
+			munmap(m_framebuffer_smo, m_width * m_height * 4);
+		m_framebuffer_smo = nullptr;
+
+		BAN::Vector<uint32_t> framebuffer;
+		TRY(framebuffer.resize(event.width * event.height, 0xFFFFFFFF));
+
+		void* framebuffer_addr = smo_map(event.smo_key);
+		if (framebuffer_addr == nullptr)
+			return BAN::Error::from_errno(errno);
+
+		const uint32_t min_x = BAN::Math::min(m_width, event.width);
+		const uint32_t min_y = BAN::Math::min(m_height, event.height);
+		for (uint32_t y = 0; y < min_y; y++)
+			for (uint32_t x = 0; x < min_x; x++)
+				framebuffer[y * event.width + x] = m_framebuffer[y * m_width + x];
+
+		m_framebuffer_smo = static_cast<uint32_t*>(framebuffer_addr);
+		m_framebuffer = BAN::move(framebuffer);
+		m_width = event.width;
+		m_height = event.height;
+
+		invalidate();
+
+		return {};
 	}
 
 #define TRY_OR_BREAK(...) ({ auto&& e = (__VA_ARGS__); if (e.is_error()) break; e.release_value(); })
@@ -343,6 +367,13 @@ namespace LibGUI
 					else
 						exit(0);
 					break;
+				case PacketType::ResizeWindowEvent:
+				{
+					MUST(handle_resize_event(TRY_OR_BREAK(EventPacket::ResizeWindowEvent::deserialize(packet_data.span()))));
+					if (m_resize_window_event_callback)
+						m_resize_window_event_callback();
+					break;
+				}
 				case PacketType::KeyEvent:
 					if (m_key_event_callback)
 						m_key_event_callback(TRY_OR_BREAK(EventPacket::KeyEvent::deserialize(packet_data.span())).event);