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//! The `message_loop` module provides a way to retreive keyboard and mouse //! input messages directly from the system. //! //! Internally, a [message-only window](https://docs.microsoft.com/en-us/windows/win32/winmsg/window-features#message-only-windows) //! is created to receive the messages. //! //! ## Examples //! //! ```rust, ignore //! use winput::{Vk, Action}; //! use winput::message_loop; //! //! let receiver = message_loop::start().unwrap(); //! //! loop { //! match receiver.next_event() { //! message_loop::Event::Keyboard { //! vk, //! action: Action::Press, //! .. //! } => { //! if vk == Vk::Escape { //! break; //! } else { //! println!("{:?} was pressed!", vk); //! } //! }, //! _ => (), //! } //! } //! ``` use std::ffi::OsStr; use std::mem::MaybeUninit; use std::os::windows::ffi::OsStrExt; use std::sync::atomic::{AtomicU8, Ordering}; use std::sync::mpsc; use std::time::Duration; use std::{iter, mem, ptr}; use winapi::shared::{hidusage, minwindef, windef}; use winapi::um::{libloaderapi, winuser}; use crate::input::{Action, Button}; use crate::vk::Vk; use crate::{WheelDirection, WindowsError}; /// The current state of the message loop. /// /// * 0 -> The message loop is not active. /// * 1 -> The `start` function has been called. /// The message loop is now starting. /// * 2 -> The message loop has successfully started. /// * 3 -> The message loop is now exiting. static STATE: AtomicU8 = AtomicU8::new(0); // This value initialized if `STATE` is `2`. It is uninitialized if `STATE` is `0`. // `SENDER` must only be used on the message loop's thread. static mut SENDER: MaybeUninit<mpsc::Sender<Event>> = MaybeUninit::uninit(); /// A buffer that must only be used on the message loop's thread. This buffer must /// be properly initialized when the message loop's thread is started. static mut BUFFER: MaybeUninit<Vec<u8>> = MaybeUninit::uninit(); /// Checks whether `short` contains all the bits of `mask`. #[inline] fn has_flags(short: u16, mask: u16) -> bool { short & mask == mask } /// A callback function called by the system on the message loop thread. unsafe extern "system" fn window_proc( hwnd: windef::HWND, msg: minwindef::UINT, w_param: minwindef::WPARAM, l_param: minwindef::LPARAM, ) -> minwindef::LRESULT { match msg { // Note: This loop is only here to break from the scope early. winuser::WM_INPUT => loop { // Determine how big should our buffer be. let mut size = 0; let mut result = winuser::GetRawInputData( l_param as winuser::HRAWINPUT, winuser::RID_INPUT, ptr::null_mut(), &mut size, mem::size_of::<winuser::RAWINPUTHEADER>() as _, ); if result == -1i32 as u32 { break; } // SAFETY: // The buffer must be initialized because we are on the message loop's // thread. let buffer = &mut *BUFFER.as_mut_ptr(); buffer.clear(); buffer.reserve(size as _); // Actually write to the buffer. result = winuser::GetRawInputData( l_param as winuser::HRAWINPUT, winuser::RID_INPUT, buffer.as_mut_ptr() as _, &mut size, mem::size_of::<winuser::RAWINPUTHEADER>() as _, ); if result != size { // We failed to write to the buffer. break; } // SAFETY: // The `GetRawInputData` function did not failed. let raw_input = &*(buffer.as_mut_ptr() as winuser::PRAWINPUT); // SAFETY: // We are on the message loop's thread, `SENDER` must be initialized. let sender = &mut *SENDER.as_mut_ptr(); match raw_input.header.dwType { winuser::RIM_TYPEMOUSE => { // Mouse event let data = raw_input.data.mouse(); if has_flags(data.usFlags, winuser::MOUSE_MOVE_RELATIVE) { sender .send(Event::MouseMoveRelative { x: data.lLastX, y: data.lLastY, }) .unwrap(); } if has_flags(data.usFlags, winuser::MOUSE_MOVE_ABSOLUTE) { sender .send(Event::MouseMoveAbsolute { x: data.lLastX as f32 / 65535.0, y: data.lLastY as f32 / 65535.0, virtual_desk: data.usFlags & winuser::MOUSE_VIRTUAL_DESKTOP == winuser::MOUSE_VIRTUAL_DESKTOP, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_LEFT_BUTTON_DOWN) { sender .send(Event::MouseButton { action: Action::Press, button: Button::Left, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_LEFT_BUTTON_UP) { sender .send(Event::MouseButton { action: Action::Release, button: Button::Left, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_RIGHT_BUTTON_DOWN) { sender .send(Event::MouseButton { action: Action::Press, button: Button::Right, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_RIGHT_BUTTON_UP) { sender .send(Event::MouseButton { action: Action::Release, button: Button::Right, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_MIDDLE_BUTTON_DOWN) { sender .send(Event::MouseButton { action: Action::Press, button: Button::Middle, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_MIDDLE_BUTTON_UP) { sender .send(Event::MouseButton { action: Action::Release, button: Button::Middle, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_BUTTON_4_DOWN) { sender .send(Event::MouseButton { action: Action::Press, button: Button::X1, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_BUTTON_4_UP) { sender .send(Event::MouseButton { action: Action::Release, button: Button::X1, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_BUTTON_5_DOWN) { sender .send(Event::MouseButton { action: Action::Press, button: Button::X2, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_BUTTON_5_UP) { sender .send(Event::MouseButton { action: Action::Release, button: Button::X2, }) .unwrap(); } if has_flags(data.usButtonFlags, winuser::RI_MOUSE_WHEEL) { sender .send(Event::MouseWheel { delta: data.usButtonData as i16 as f32 / 120.0, direction: WheelDirection::Vertical, }) .unwrap(); } if has_flags(data.usButtonFlags, 0x0800) { sender .send(Event::MouseWheel { delta: data.usButtonData as i16 as f32 / 120.0, direction: WheelDirection::Horizontal, }) .unwrap(); } } winuser::RIM_TYPEKEYBOARD => { // Keyboard event let data = raw_input.data.keyboard(); sender .send(Event::Keyboard { vk: Vk::from_u8(data.VKey as u8), scan_code: data.MakeCode as u32, action: Action::from_press(data.Flags & 1 == 0), }) .unwrap(); } 2 => (), _ => unreachable!("Invalid message"), } break; }, _ => (), } winuser::DefWindowProcW(hwnd, msg, w_param, l_param) } /// An error that can be produced by the [`start`] function. /// /// [`start`]: fn.start.html #[derive(Clone, Debug)] pub enum MessageLoopError { /// Only one message loop can be created at any given time. This error /// is produced when [`start`] is called even though the message loop /// was already active. AlreadyActive, /// Windows raised an error. OsError(WindowsError), } /// Checks if the message loop is currently active. When this function returns /// `true`, calling `start` always produces an error. /// /// ## Examples /// /// ```rust, ignore /// let _ = winput::messgage_loop::start(); /// assert!(winput::message_loop::is_active()); /// /// ``` #[inline] pub fn is_active() -> bool { STATE.load(Ordering::Acquire) != 0 } /// Starts the message loop on a new thread. /// /// ## Returns /// /// This function returns an error if the message loop is already active: only one /// message loop can be started at any given time. Be carfull if another library is /// also using the message loop. /// /// You can check if the message loop is currently active by calling [`is_active`]. /// /// ## Example /// /// ```rust, ignore /// use winput::message_loop; /// /// let receiver = message_loop::start().unwrap(); /// /// loop { /// println!("{:?}", receiver.next_event()); /// } /// ``` /// /// [`is_active`]: fn.is_active.html pub fn start() -> Result<EventReceiver, MessageLoopError> { loop { match STATE.compare_exchange(0, 1, Ordering::SeqCst, Ordering::SeqCst) { Ok(0) => break, // If the message loop is shutting down, we can just wait // a bit until we can start it again. Err(3) => (), _ => return Err(MessageLoopError::AlreadyActive), } std::hint::spin_loop(); } // The message loop is now starting. // This channel is used to receive the messages of the message loop. let (s, r) = mpsc::channel(); // We have to initialize `SENDER` and `BUFFER`. unsafe { SENDER = MaybeUninit::new(s); BUFFER = MaybeUninit::new(Vec::new()); } // This channel is used to retreive a potential error from the message loop's // thread. let (error_s, error_r) = mpsc::channel(); std::thread::spawn(move || { unsafe { // Retreives the module handle of the application. let h_instance = libloaderapi::GetModuleHandleW(ptr::null()); // Create the window. let class_name = OsStr::new("winput_message_loop") .encode_wide() .chain(iter::once(0)) .collect::<Vec<_>>(); let mut wnd_class: winuser::WNDCLASSW = mem::zeroed(); wnd_class.hInstance = h_instance; wnd_class.lpszClassName = class_name.as_ptr(); wnd_class.lpfnWndProc = Some(window_proc); let class = winuser::RegisterClassW(&wnd_class); if class == 0 { error_s .send(Err(MessageLoopError::OsError( WindowsError::from_last_error(), ))) .unwrap(); return; } let h_wnd = winuser::CreateWindowExW( 0, class_name.as_ptr(), class_name.as_ptr(), 0, 0, 0, 0, 0, winuser::HWND_MESSAGE, ptr::null_mut(), h_instance, ptr::null_mut(), ); if h_wnd.is_null() { error_s .send(Err(MessageLoopError::OsError( WindowsError::from_last_error(), ))) .unwrap(); return; } // Tell the system we want to receive inputs. let mut rid: [winuser::RAWINPUTDEVICE; 2] = mem::zeroed(); // Keyboard rid[0].dwFlags = winuser::RIDEV_NOLEGACY | winuser::RIDEV_INPUTSINK; rid[0].usUsagePage = hidusage::HID_USAGE_PAGE_GENERIC; rid[0].usUsage = hidusage::HID_USAGE_GENERIC_KEYBOARD; rid[0].hwndTarget = h_wnd; // Mouse rid[1].dwFlags = winuser::RIDEV_NOLEGACY | winuser::RIDEV_INPUTSINK; rid[1].usUsagePage = hidusage::HID_USAGE_PAGE_GENERIC; rid[1].usUsage = hidusage::HID_USAGE_GENERIC_MOUSE; rid[1].hwndTarget = h_wnd; let result = winuser::RegisterRawInputDevices( rid.as_ptr(), rid.len() as _, mem::size_of::<winuser::RAWINPUTDEVICE>() as _, ); if result == 0 { error_s .send(Err(MessageLoopError::OsError( WindowsError::from_last_error(), ))) .unwrap(); return; } // The message loop has now started. // It is ready to receive events. STATE.store(2, Ordering::SeqCst); // Notify the main thread that the initialisation is a success. error_s.send(Ok(())).unwrap(); // After this point, the `start` function will return and the receiver // will be dropped. Using the `error_s` after this will always return an error. drop(error_s); // Start the message loop. let mut msg = mem::zeroed(); while STATE.load(Ordering::SeqCst) == 2 { let result = winuser::GetMessageW(&mut msg, h_wnd, 0, 0); if result == -1 { // An error occured in the message loop. break; } else { winuser::TranslateMessage(&msg); winuser::DispatchMessageW(&msg); } } // The message loop is now exiting. // Deinitialize the sender and the buffer. // TODO: Use `MaybeUninit::assume_init_drop` when stable. ptr::drop_in_place(SENDER.as_mut_ptr()); ptr::drop_in_place(BUFFER.as_mut_ptr()); // The message loop is now shut down. STATE.store(0, Ordering::SeqCst); } }); error_r .recv() .unwrap() .map(|()| EventReceiver { receiver: r }) } /// An event of any kind. #[derive(Clone, Copy, Debug)] pub enum Event { Keyboard { /// The virtual keycode of the key that was pressed. vk: Vk, /// The scan code of that key. scan_code: u32, /// The action that was taken on the key. action: Action, }, MouseMoveRelative { /// The x coordinate of the mouse, in [per-monitor-aware] screen coordinates. /// /// [per-monitor-aware]: https://docs.microsoft.com/en-us/windows/desktop/api/shellscalingapi/ne-shellscalingapi-process_dpi_awareness x: i32, /// The y coordinate of the mouse, in [per-monitor-aware] screen coordinates. /// /// [per-monitor-aware]: https://docs.microsoft.com/en-us/windows/desktop/api/shellscalingapi/ne-shellscalingapi-process_dpi_awareness y: i32, }, MouseMoveAbsolute { /// The x coordinate of the mouse in screen coordinates. x: f32, /// The y coordinate of the mouse in screen coordinates. y: f32, /// If this flag is set to `true`, the `x` and `y` coordinates map to the entier /// virtual desktop (this is relevent if multiple monitors are used). virtual_desk: bool, }, MouseButton { /// The action that was taken on the mouse button. action: Action, /// The mouse button involved in the event. button: Button, }, MouseWheel { /// The amount of rotation of the wheel. Positive values indicate that the wheel /// was rotated forward, away from the user; a negative value means that the wheel /// was rotated backward, toward the user. delta: f32, /// The direction of the wheel. direction: WheelDirection, }, } // Only one instance of `EventReceiver` can be created at any given time. // That only instance relies on `STATE` and `SENDER` that is only initialized // when `STATE` is `2`. // /// The result of the [`start`] function. This structure receives the messages /// received by the message loop. /// /// The message loop is automatically stopped when this structure is dropped. /// /// [`start`]: fn.start.html pub struct EventReceiver { receiver: mpsc::Receiver<Event>, } impl EventReceiver { /// Discard all the events stored in the receiver. #[inline] pub fn clear(&self) { if is_active() { while let Some(_) = self.try_next_event() {} } } /// Blocks the current thread until an event is received. #[inline] pub fn next_event(&self) -> Event { self.receiver .recv() .expect("The message loop is not active") } /// Blocks the current thread until an event is received or the given /// duration is reached. #[inline] pub fn next_event_timeout(&self, timeout: Duration) -> Option<Event> { match self.receiver.recv_timeout(timeout) { Ok(val) => Some(val), Err(mpsc::RecvTimeoutError::Timeout) => None, Err(mpsc::RecvTimeoutError::Disconnected) => { panic!("The message loop is not active") } } } /// Tries to receive an event without blocking the thread. #[inline] pub fn try_next_event(&self) -> Option<Event> { match self.receiver.try_recv() { Ok(val) => Some(val), Err(mpsc::TryRecvError::Empty) => None, Err(mpsc::TryRecvError::Disconnected) => { panic!("The message loop is not active") } } } // TODO: add `next_event_deadline` when `Reciever::recv_deadline` is stable. } impl Drop for EventReceiver { fn drop(&mut self) { // Stop the message loop. stop(); } } /// Stops the message loop. /// /// After calling this function, using the `EventReceiver` will always result /// in a panic. /// /// Be careful, if another libary already created a message loop, this function will /// still stop it. pub fn stop() { if !is_active() { return; } // If the `EventReceiver` was able to be constructed, // that means that `STATE` is currently `2`. STATE.store(3, Ordering::SeqCst); // Cleaning up the static variables is up to the message loop thread. // We just have to wait until it finishes. while STATE.load(Ordering::Acquire) != 0 { std::hint::spin_loop(); } }