Split WindowHandle and add try_send_message method (#61)

* Add WindowHandle::try_send_message, implement it on macOS

* Add Send constraint to WindowHandler::Message

* Assert at compile-time that WindowHandle is Sync

* macOS: remove runtime timer, use frame timer instead

* Use wait-free spsc message chan; split off AppRunner from WindowHandle

* Add comment to WindowState static assertions code

* Clean up

* Split off AppRunner from WindowHandle on Windows and Linux

* README: add messages milestone row, add check mark to macOS column

* macOS: add and use MESSAGE_QUEUE_LEN constant

* macOS: clean up

Cargo.toml

@@ -17,6 +17,8 @@ license = "MIT OR Apache-2.0"
 log = "0.4.11"
 keyboard-types = { version = "0.5.0", default-features = false }
 raw-window-handle = "0.3.3"
+rtrb = "0.1.1"
+static_assertions = "1.1.0"
 
 [target.'cfg(target_os="linux")'.dependencies]
 xcb = { version = "0.9", features = ["thread", "xlib_xcb", "dri2"] }

README.md

@@ -18,6 +18,7 @@ Below is a proposed list of milestones (roughly in-order) and their status. Subj
 | Can find DPI scale factor                       |                    |                    | :heavy_check_mark: |
 | Basic event handling (mouse, keyboard)          | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | Parent window support                           | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
+| Send messages                                   |                    | :heavy_check_mark: |                    |
 | *(Converge on a common API for all platforms?)* |                    |                    |                    |
 
 ## Prerequisites

examples/open_window.rs

@@ -1,9 +1,19 @@
+use std::time::Duration;
+
 use baseview::{Event, Window, WindowHandler, WindowScalePolicy};
 
+
+#[derive(Debug, Clone)]
+enum Message {
+    Hello
+}
+
+
 struct OpenWindowExample;
 
+
 impl WindowHandler for OpenWindowExample {
-    type Message = ();
+    type Message = Message;
 
     fn on_frame(&mut self) {}
 
@@ -15,9 +25,12 @@ impl WindowHandler for OpenWindowExample {
         }
     }
 
-    fn on_message(&mut self, _window: &mut Window, _message: Self::Message) {}
+    fn on_message(&mut self, _window: &mut Window, message: Self::Message) {
+        println!("Message: {:?}", message);
+    }
 }
 
+
 fn main() {
     let window_open_options = baseview::WindowOpenOptions {
         title: "baseview".into(),
@@ -26,6 +39,20 @@ fn main() {
         parent: baseview::Parent::None,
     };
 
-    let handle = Window::open(window_open_options, |_| OpenWindowExample);
+    let (mut handle, opt_app_runner) = Window::open(
-    handle.app_run_blocking();
+        window_open_options,
+        |_| OpenWindowExample
+    );
+
+    ::std::thread::spawn(move || {
+        loop {
+            ::std::thread::sleep(Duration::from_secs(5));
+
+            if let Err(_) = handle.try_send_message(Message::Hello){
+                println!("Failed sending message");
+            }
+        }
+    });
+
+    opt_app_runner.unwrap().app_run_blocking();
 }

src/lib.rs

@@ -20,6 +20,8 @@ pub use window::*;
 pub use window_info::*;
 pub use window_open_options::*;
 
+const MESSAGE_QUEUE_LEN: usize = 128;
+
 #[derive(Debug)]
 pub enum Parent {
     None,
@@ -30,7 +32,7 @@ pub enum Parent {
 unsafe impl Send for Parent {}
 
 pub trait WindowHandler {
-    type Message;
+    type Message: Send;
 
     fn on_frame(&mut self);
     fn on_event(&mut self, window: &mut Window, event: Event);

src/macos/view.rs

@@ -20,7 +20,9 @@ use crate::{
 };
 use crate::MouseEvent::{ButtonPressed, ButtonReleased};
 
-use super::window::{WindowState, WINDOW_STATE_IVAR_NAME, FRAME_TIMER_IVAR_NAME};
+use super::window::{
+    WindowState, WINDOW_STATE_IVAR_NAME, FRAME_TIMER_IVAR_NAME
+};
 
 
 pub(super) unsafe fn create_view<H: WindowHandler>(
@@ -189,6 +191,7 @@ extern "C" fn trigger_on_frame<H: WindowHandler>(
         WindowState::from_field(this)
     };
 
+    state.handle_messages();
     state.trigger_frame();
 }
 

src/macos/window.rs

@@ -1,7 +1,3 @@
-/// macOS window handling
-///
-/// Inspired by implementation in https://github.com/antonok-edm/vst_window
-
 use std::ffi::c_void;
 use std::sync::Arc;
 
@@ -16,10 +12,11 @@ use keyboard_types::KeyboardEvent;
 use objc::{msg_send, runtime::Object, sel, sel_impl};
 
 use raw_window_handle::{macos::MacOSHandle, HasRawWindowHandle, RawWindowHandle};
+use rtrb::{RingBuffer, Producer, Consumer, PushError};
 
 use crate::{
     Event, Parent, WindowHandler, WindowOpenOptions,
-    WindowScalePolicy, WindowInfo
+    WindowScalePolicy, WindowInfo, MESSAGE_QUEUE_LEN
 };
 
 use super::view::create_view;
@@ -42,10 +39,10 @@ pub struct Window {
 }
 
 
-pub struct WindowHandle;
+pub struct AppRunner;
 
 
-impl WindowHandle {
+impl AppRunner {
     pub fn app_run_blocking(self) {
         unsafe {
             // Get reference to already created shared NSApplication object
@@ -55,18 +52,35 @@ impl WindowHandle {
     }
 }
 
+
+pub struct WindowHandle<H: WindowHandler> {
+    message_tx: Producer<H::Message>,
+}
+
+
+impl <H: WindowHandler>WindowHandle<H> {
+    pub fn try_send_message(
+        &mut self,
+        message: H::Message
+    ) -> Result<(), H::Message> {
+        self.message_tx.push(message)
+            .map_err(|PushError::Full(message)| message)
+    }
+}
+
+
 impl Window {
     pub fn open<H, B>(
         options: WindowOpenOptions,
         build: B
-    ) -> crate::WindowHandle
+    ) -> (crate::WindowHandle<H>, Option<crate::AppRunner>)
         where H: WindowHandler,
               B: FnOnce(&mut crate::Window) -> H,
               B: Send + 'static
     {
         let _pool = unsafe { NSAutoreleasePool::new(nil) };
 
-        let mut window = match options.parent {
+        let (mut window, opt_app_runner) = match options.parent {
             Parent::WithParent(parent) => {
                 if let RawWindowHandle::MacOS(handle) = parent {
                     let ns_view = handle.ns_view as *mut objc::runtime::Object;
@@ -76,10 +90,12 @@ impl Window {
 
                         let _: id = msg_send![ns_view, addSubview: subview];
 
-                        Window {
+                        let window = Window {
                             ns_window: None,
                             ns_view: subview,
-                        }
+                        };
+
+                        (window, None)
                     }
                 } else {
                     panic!("Not a macOS window");
@@ -90,10 +106,12 @@ impl Window {
                     create_view::<H>(&options)
                 };
 
-                Window {
+                let window = Window {
                     ns_window: None,
                     ns_view,
-                }
+                };
+
+                (window, None)
             },
             Parent::None => {
                 // It seems prudent to run NSApp() here before doing other
@@ -150,20 +168,26 @@ impl Window {
 
                     ns_window.setContentView_(subview);
 
-                    Window {
+                    let window = Window {
                         ns_window: Some(ns_window),
                         ns_view: subview,
-                    }
+                    };
+
+                    (window, Some(crate::AppRunner(AppRunner)))
                 }
             },
         };
 
         let window_handler = build(&mut crate::Window(&mut window));
 
+        let (message_tx, message_rx) = RingBuffer::new(MESSAGE_QUEUE_LEN)
+            .split();
+
         let window_state_arc = Arc::new(WindowState {
             window,
             window_handler,
             keyboard_state: KeyboardState::new(),
+            message_rx
         });
 
         let window_state_pointer = Arc::into_raw(
@@ -177,8 +201,7 @@ impl Window {
             );
         }
 
-        // Activate timer after window handler is setup and save a pointer to
+        // Setup frame timer once window state is stored
-        // it, so that it can be invalidated when view is released.
         unsafe {
             let timer_interval = 0.015;
             let selector = sel!(triggerOnFrame:);
@@ -192,13 +215,18 @@ impl Window {
                 repeats:YES
             ];
 
+            // Store pointer to timer for invalidation when view is released
             (*window_state_arc.window.ns_view).set_ivar(
                 FRAME_TIMER_IVAR_NAME,
                 timer as *mut c_void,
             )
         }
 
-        crate::WindowHandle(WindowHandle)
+        let window_handle = crate::WindowHandle(WindowHandle {
+            message_tx
+        });
+
+        (window_handle, opt_app_runner)
     }
 }
 
@@ -207,6 +235,7 @@ pub(super) struct WindowState<H: WindowHandler> {
     window: Window,
     window_handler: H,
     keyboard_state: KeyboardState,
+    message_rx: Consumer<H::Message>,
 }
 
 
@@ -222,6 +251,15 @@ impl <H: WindowHandler>WindowState<H> {
         &mut *(state_ptr as *mut Self)
     }
 
+    pub(super) fn handle_messages(&mut self){
+        while let Ok(message) = self.message_rx.pop(){
+            self.window_handler.on_message(
+                &mut crate::Window(&mut self.window),
+                message
+            )
+        }
+    }
+
     pub(super) fn trigger_event(&mut self, event: Event){
         self.window_handler.on_event(
             &mut crate::Window(&mut self.window),

src/win/window.rs

@@ -207,11 +207,25 @@ pub struct Window {
     hwnd: HWND,
 }
 
-pub struct WindowHandle {
+pub struct WindowHandle<H: WindowHandler> {
+    // FIXME: replace this with channel sender
+    phantom_data: std::marker::PhantomData<H::Message>,
+}
+
+impl <H: WindowHandler>WindowHandle<H> {
+    pub fn try_send_message(
+        &mut self,
+        message: H::Message
+    ) -> Result<(), H::Message> {
+        Err(message)
+    }
+}
+
+pub struct AppRunner {
     hwnd: HWND,
 }
 
-impl WindowHandle {
+impl AppRunner {
     pub fn app_run_blocking(self) {
         unsafe {
             let mut msg: MSG = std::mem::zeroed();
@@ -234,7 +248,7 @@ impl Window {
     pub fn open<H, B>(
         options: WindowOpenOptions,
         build: B
-    ) -> crate::WindowHandle
+    ) -> (crate::WindowHandle<H>, Option<crate::AppRunner>)
         where H: WindowHandler,
               B: FnOnce(&mut crate::Window) -> H,
               B: Send + 'static
@@ -311,7 +325,17 @@ impl Window {
             SetWindowLongPtrA(hwnd, GWLP_USERDATA, Box::into_raw(window_state) as *const _ as _);
             SetTimer(hwnd, 4242, 13, None);
 
-            crate::WindowHandle(WindowHandle { hwnd })
+            let window_handle = crate::WindowHandle(WindowHandle {
+                phantom_data: std::marker::PhantomData,
+            });
+
+            let opt_app_runner = if let crate::Parent::None = options.parent {
+                Some(crate::AppRunner(AppRunner { hwnd }))
+            } else {
+                None
+            };
+
+            (window_handle, opt_app_runner)
         }
     }
 }

src/window.rs

@@ -11,16 +11,31 @@ use crate::x11 as platform;
 use crate::macos as platform;
 
 
-pub struct WindowHandle(pub(crate) platform::WindowHandle);
+pub struct AppRunner(pub(crate) platform::AppRunner);
 
 
-impl WindowHandle {
+impl AppRunner {
     pub fn app_run_blocking(self){
         self.0.app_run_blocking();
     }
 }
 
 
+pub struct WindowHandle<H: WindowHandler>(
+    pub(crate) platform::WindowHandle<H>
+);
+
+
+impl <H: WindowHandler>WindowHandle<H> {
+    pub fn try_send_message(
+        &mut self,
+        message: H::Message
+    ) -> Result<(), H::Message> {
+        self.0.try_send_message(message)
+    }
+}
+
+
 pub struct Window<'a>(pub(crate) &'a mut platform::Window);
 
 
@@ -28,7 +43,7 @@ impl <'a>Window<'a> {
     pub fn open<H, B>(
         options: WindowOpenOptions,
         build: B
-    ) -> WindowHandle
+    ) -> (WindowHandle<H>, Option<AppRunner>)
         where H: WindowHandler,
               B: FnOnce(&mut Window) -> H,
               B: Send + 'static
@@ -43,3 +58,27 @@ unsafe impl <'a>HasRawWindowHandle for Window<'a> {
         self.0.raw_window_handle()
     }
 }
+
+
+// Compile-time API assertions
+#[doc(hidden)]
+mod assertions {
+    use crate::{WindowHandle, WindowHandler, Event, Window};
+
+    struct TestWindowHandler {
+        #[allow(dead_code)]
+        ptr: *mut ::std::ffi::c_void,
+    }
+
+    impl WindowHandler for TestWindowHandler {
+        type Message = ();
+
+        fn on_event(&mut self, _: &mut Window, _: Event) {}
+        fn on_message(&mut self, _: &mut Window, _: Self::Message) {}
+        fn on_frame(&mut self) {}
+    }
+
+    // Assert that WindowHandle is Send even if WindowHandler isn't
+    static_assertions::assert_not_impl_any!(TestWindowHandler: Send);
+    static_assertions::assert_impl_all!(WindowHandle<TestWindowHandler>: Send);
+}

src/x11/window.rs

@@ -30,12 +30,25 @@ pub struct Window {
     new_physical_size: Option<PhySize>
 }
 
-// FIXME: move to outer crate context
+pub struct WindowHandle<H: WindowHandler> {
-pub struct WindowHandle {
+    // FIXME: replace this with channel sender
+    phantom_data: std::marker::PhantomData<H::Message>,
+}
+
+impl <H: WindowHandler>WindowHandle<H> {
+    pub fn try_send_message(
+        &mut self,
+        message: H::Message
+    ) -> Result<(), H::Message> {
+        Err(message)
+    }
+}
+
+pub struct AppRunner {
     thread: std::thread::JoinHandle<()>,
 }
 
-impl WindowHandle {
+impl AppRunner {
     pub fn app_run_blocking(self) {
         let _ = self.thread.join();
     }
@@ -47,11 +60,13 @@ impl Window {
     pub fn open<H, B>(
         options: WindowOpenOptions,
         build: B
-    ) -> crate::WindowHandle
+    ) -> (crate::WindowHandle<H>, Option<crate::AppRunner>)
         where H: WindowHandler,
               B: FnOnce(&mut crate::Window) -> H,
               B: Send + 'static
     {
+        let is_not_parented = matches!(options.parent, Parent::None);
+
         let (tx, rx) = mpsc::sync_channel::<WindowOpenResult>(1);
 
         let thread = thread::spawn(move || {
@@ -63,7 +78,17 @@ impl Window {
         // FIXME: placeholder types for returning errors in the future
         let _ = rx.recv();
 
-        crate::WindowHandle(WindowHandle { thread })
+        let window_handle = crate::WindowHandle(WindowHandle {
+            phantom_data: std::marker::PhantomData
+        });
+
+        let opt_app_runner = if is_not_parented {
+            Some(crate::AppRunner(AppRunner { thread }))
+        } else {
+            None
+        };
+
+        (window_handle, opt_app_runner)
     }
 
     fn window_thread<H, B>(options: WindowOpenOptions, build: B,