Draft web platform structure

src/platform_impl/web/device.rs

@@ -0,0 +1,8 @@
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Id(pub i32);
+
+impl Id {
+    pub unsafe fn dummy() -> Self {
+        Id(0)
+    }
+}

src/platform_impl/web/error.rs

@@ -0,0 +1,10 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub struct OsError(pub String);
+
+impl fmt::Display for OsError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}

src/platform_impl/web/event_loop/mod.rs

@@ -0,0 +1,112 @@
+mod proxy;
+mod runner;
+mod state;
+mod window_target;
+
+pub use self::proxy::Proxy;
+pub use self::window_target::WindowTarget;
+
+use super::{backend, device, monitor, window};
+use crate::event::{DeviceId, ElementState, Event, KeyboardInput, WindowEvent};
+use crate::event_loop as root;
+use crate::window::WindowId;
+
+use std::collections::{vec_deque::IntoIter as VecDequeIter, VecDeque};
+use std::marker::PhantomData;
+
+pub struct EventLoop<T: 'static> {
+    elw: root::EventLoopWindowTarget<T>,
+}
+
+impl<T> EventLoop<T> {
+    pub fn new() -> Self {
+        EventLoop {
+            elw: root::EventLoopWindowTarget {
+                p: WindowTarget::new(),
+                _marker: PhantomData,
+            },
+        }
+    }
+
+    pub fn available_monitors(&self) -> VecDequeIter<monitor::Handle> {
+        VecDeque::new().into_iter()
+    }
+
+    pub fn primary_monitor(&self) -> monitor::Handle {
+        monitor::Handle
+    }
+
+    pub fn run<F>(self, mut event_handler: F) -> !
+    where
+        F: 'static + FnMut(Event<T>, &root::EventLoopWindowTarget<T>, &mut root::ControlFlow),
+    {
+        let target = root::EventLoopWindowTarget {
+            p: self.elw.p.clone(),
+            _marker: PhantomData,
+        };
+
+        let runner = self.elw.p.run(Box::new(move |event, flow| {
+            event_handler(event, &target, flow)
+        }));
+
+        backend::Document::on_blur(|| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::Focused(false),
+            });
+        });
+
+        backend::Document::on_focus(|| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::Focused(true),
+            });
+        });
+
+        backend::Document::on_key_down(|scancode, virtual_keycode, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::KeyboardInput {
+                    device_id: DeviceId(unsafe { device::Id::dummy() }),
+                    input: KeyboardInput {
+                        scancode,
+                        state: ElementState::Pressed,
+                        virtual_keycode,
+                        modifiers,
+                    },
+                },
+            });
+        });
+
+        backend::Document::on_key_up(|scancode, virtual_keycode, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::KeyboardInput {
+                    device_id: DeviceId(unsafe { device::Id::dummy() }),
+                    input: KeyboardInput {
+                        scancode,
+                        state: ElementState::Released,
+                        virtual_keycode,
+                        modifiers,
+                    },
+                },
+            });
+        });
+
+        // Throw an exception to break out of Rust exceution and use unreachable to tell the
+        // compiler this function won't return, giving it a return type of '!'
+        backend::throw(
+            "Using exceptions for control flow, don't mind me. This isn't actually an error!",
+        );
+
+        unreachable!();
+    }
+
+    pub fn create_proxy(&self) -> Proxy<T> {
+        self.elw.p.proxy()
+    }
+
+    pub fn window_target(&self) -> &root::EventLoopWindowTarget<T> {
+        &self.elw
+    }
+}

src/platform_impl/web/event_loop/proxy.rs

@@ -0,0 +1,19 @@
+use super::runner;
+use crate::event::Event;
+use crate::event_loop::EventLoopClosed;
+
+#[derive(Clone)]
+pub struct Proxy<T: 'static> {
+    runner: runner::Shared<T>,
+}
+
+impl<T: 'static> Proxy<T> {
+    pub fn new(runner: runner::Shared<T>) -> Self {
+        Proxy { runner }
+    }
+
+    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed> {
+        self.runner.send_event(Event::UserEvent(event));
+        Ok(())
+    }
+}

src/platform_impl/web/event_loop/runner.rs

@@ -0,0 +1,216 @@
+use super::{backend, state::State};
+use crate::event::{Event, StartCause};
+use crate::event_loop as root;
+
+use instant::{Duration, Instant};
+use std::{cell::RefCell, clone::Clone, collections::VecDeque, rc::Rc};
+
+pub struct Shared<T>(Rc<Execution<T>>);
+
+impl<T> Clone for Shared<T> {
+    fn clone(&self) -> Self {
+        Shared(self.0.clone())
+    }
+}
+
+pub struct Execution<T> {
+    runner: RefCell<Option<Runner<T>>>,
+    events: RefCell<VecDeque<Event<T>>>,
+}
+
+struct Runner<T> {
+    state: State,
+    is_busy: bool,
+    event_handler: Box<dyn FnMut(Event<T>, &mut root::ControlFlow)>,
+}
+
+impl<T: 'static> Runner<T> {
+    pub fn new(event_handler: Box<dyn FnMut(Event<T>, &mut root::ControlFlow)>) -> Self {
+        Runner {
+            state: State::Init,
+            is_busy: false,
+            event_handler,
+        }
+    }
+}
+
+impl<T: 'static> Shared<T> {
+    pub fn new() -> Self {
+        Shared(Rc::new(Execution {
+            runner: RefCell::new(None),
+            events: RefCell::new(VecDeque::new()),
+        }))
+    }
+
+    // Set the event callback to use for the event loop runner
+    // This the event callback is a fairly thin layer over the user-provided callback that closes
+    // over a RootEventLoopWindowTarget reference
+    pub fn set_listener(&self, event_handler: Box<dyn FnMut(Event<T>, &mut root::ControlFlow)>) {
+        self.0.runner.replace(Some(Runner::new(event_handler)));
+        self.send_event(Event::NewEvents(StartCause::Init));
+    }
+
+    // Add an event to the event loop runner
+    //
+    // It will determine if the event should be immediately sent to the user or buffered for later
+    pub fn send_event(&self, event: Event<T>) {
+        // If the event loop is closed, it should discard any new events
+        if self.closed() {
+            return;
+        }
+
+        // Determine if event handling is in process, and then release the borrow on the runner
+        let (start_cause, event_is_start) = match *self.0.runner.borrow() {
+            Some(ref runner) if !runner.is_busy => {
+                if let Event::NewEvents(cause) = event {
+                    (cause, true)
+                } else {
+                    (
+                        match runner.state {
+                            State::Init => StartCause::Init,
+                            State::Poll { .. } => StartCause::Poll,
+                            State::Wait { start } => StartCause::WaitCancelled {
+                                start,
+                                requested_resume: None,
+                            },
+                            State::WaitUntil { start, end, .. } => StartCause::WaitCancelled {
+                                start,
+                                requested_resume: Some(end),
+                            },
+                            State::Exit => {
+                                return;
+                            }
+                        },
+                        false,
+                    )
+                }
+            }
+            _ => {
+                // Events are currently being handled, so queue this one and don't try to
+                // double-process the event queue
+                self.0.events.borrow_mut().push_back(event);
+                return;
+            }
+        };
+        let mut control = self.current_control_flow();
+        // Handle starting a new batch of events
+        //
+        // The user is informed via Event::NewEvents that there is a batch of events to process
+        // However, there is only one of these per batch of events
+        self.handle_event(Event::NewEvents(start_cause), &mut control);
+        if !event_is_start {
+            self.handle_event(event, &mut control);
+        }
+        self.handle_event(Event::EventsCleared, &mut control);
+        self.apply_control_flow(control);
+        // If the event loop is closed, it has been closed this iteration and now the closing
+        // event should be emitted
+        if self.closed() {
+            self.handle_event(Event::LoopDestroyed, &mut control);
+        }
+    }
+
+    // handle_event takes in events and either queues them or applies a callback
+    //
+    // It should only ever be called from send_event
+    fn handle_event(&self, event: Event<T>, control: &mut root::ControlFlow) {
+        let closed = self.closed();
+
+        match *self.0.runner.borrow_mut() {
+            Some(ref mut runner) => {
+                // An event is being processed, so the runner should be marked busy
+                runner.is_busy = true;
+
+                (runner.event_handler)(event, control);
+
+                // Maintain closed state, even if the callback changes it
+                if closed {
+                    *control = root::ControlFlow::Exit;
+                }
+
+                // An event is no longer being processed
+                runner.is_busy = false;
+            }
+            // If an event is being handled without a runner somehow, add it to the event queue so
+            // it will eventually be processed
+            _ => self.0.events.borrow_mut().push_back(event),
+        }
+
+        // Don't take events out of the queue if the loop is closed or the runner doesn't exist
+        // If the runner doesn't exist and this method recurses, it will recurse infinitely
+        if !closed && self.0.runner.borrow().is_some() {
+            // Take an event out of the queue and handle it
+            if let Some(event) = self.0.events.borrow_mut().pop_front() {
+                self.handle_event(event, control);
+            }
+        }
+    }
+
+    // Apply the new ControlFlow that has been selected by the user
+    // Start any necessary timeouts etc
+    fn apply_control_flow(&self, control_flow: root::ControlFlow) {
+        let mut control_flow_status = match control_flow {
+            root::ControlFlow::Poll => {
+                let cloned = self.clone();
+                State::Poll {
+                    timeout: backend::Timeout::new(
+                        move || cloned.send_event(Event::NewEvents(StartCause::Poll)),
+                        Duration::from_millis(1),
+                    ),
+                }
+            }
+            root::ControlFlow::Wait => State::Wait {
+                start: Instant::now(),
+            },
+            root::ControlFlow::WaitUntil(end) => {
+                let cloned = self.clone();
+                let start = Instant::now();
+                let delay = if end <= start {
+                    Duration::from_millis(0)
+                } else {
+                    end - start
+                };
+                State::WaitUntil {
+                    start,
+                    end,
+                    timeout: backend::Timeout::new(
+                        move || cloned.send_event(Event::NewEvents(StartCause::Poll)),
+                        delay,
+                    ),
+                }
+            }
+            root::ControlFlow::Exit => State::Exit,
+        };
+
+        match *self.0.runner.borrow_mut() {
+            Some(ref mut runner) => {
+                // Put the new control flow status in the runner, and take out the old one
+                // This way we can safely take ownership of the TimeoutHandle and clear it,
+                // so that we don't get 'ghost' invocations of Poll or WaitUntil from earlier
+                // set_timeout invocations
+                std::mem::swap(&mut runner.state, &mut control_flow_status);
+                match control_flow_status {
+                    State::Poll { timeout } | State::WaitUntil { timeout, .. } => timeout.clear(),
+                    _ => (),
+                }
+            }
+            None => (),
+        }
+    }
+
+    // Check if the event loop is currntly closed
+    fn closed(&self) -> bool {
+        match *self.0.runner.borrow() {
+            Some(ref runner) => runner.state.is_exit(),
+            None => false, // If the event loop is None, it has not been intialised yet, so it cannot be closed
+        }
+    }
+
+    // Get the current control flow state
+    fn current_control_flow(&self) -> root::ControlFlow {
+        match *self.0.runner.borrow() {
+            Some(ref runner) => runner.state.into(),
+            None => root::ControlFlow::Poll,
+        }
+    }
+}

src/platform_impl/web/event_loop/state.rs

@@ -0,0 +1,42 @@
+use super::backend;
+use crate::event_loop::ControlFlow;
+
+use instant::Instant;
+
+#[derive(Debug, Clone, Copy)]
+pub enum State {
+    Init,
+    WaitUntil {
+        timeout: backend::Timeout,
+        start: Instant,
+        end: Instant,
+    },
+    Wait {
+        start: Instant,
+    },
+    Poll {
+        timeout: backend::Timeout,
+    },
+    Exit,
+}
+
+impl State {
+    pub fn is_exit(&self) -> bool {
+        match self {
+            State::Exit => true,
+            _ => false,
+        }
+    }
+}
+
+impl From<State> for ControlFlow {
+    fn from(state: State) -> ControlFlow {
+        match state {
+            State::Init => ControlFlow::Poll,
+            State::WaitUntil { end, .. } => ControlFlow::WaitUntil(end),
+            State::Wait { .. } => ControlFlow::Wait,
+            State::Poll { .. } => ControlFlow::Poll,
+            State::Exit => ControlFlow::Exit,
+        }
+    }
+}

src/platform_impl/web/event_loop/window_target.rs

@@ -0,0 +1,106 @@
+use super::{backend, device, proxy::Proxy, runner, window};
+use crate::event::{DeviceId, ElementState, Event, TouchPhase, WindowEvent};
+use crate::event_loop::ControlFlow;
+use crate::window::WindowId;
+use std::clone::Clone;
+
+pub struct WindowTarget<T: 'static> {
+    pub(crate) runner: runner::Shared<T>,
+}
+
+impl<T> Clone for WindowTarget<T> {
+    fn clone(&self) -> Self {
+        WindowTarget {
+            runner: self.runner.clone(),
+        }
+    }
+}
+
+impl<T> WindowTarget<T> {
+    pub fn new() -> Self {
+        WindowTarget {
+            runner: runner::Shared::new(),
+        }
+    }
+
+    pub fn proxy(&self) -> Proxy<T> {
+        Proxy::new(self.runner.clone())
+    }
+
+    pub fn run(
+        &self,
+        event_handler: Box<dyn FnMut(Event<T>, &mut ControlFlow)>,
+    ) -> &runner::Shared<T> {
+        self.runner.set_listener(event_handler);
+        &self.runner
+    }
+
+    pub fn register(&self, canvas: &backend::Canvas) {
+        let runner = &self.runner;
+
+        canvas.on_mouse_out(|pointer_id| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::CursorLeft {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                },
+            });
+        });
+
+        canvas.on_mouse_over(|pointer_id| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::CursorEntered {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                },
+            });
+        });
+
+        canvas.on_mouse_move(|pointer_id, position, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::CursorMoved {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                    position,
+                    modifiers,
+                },
+            });
+        });
+
+        canvas.on_mouse_up(|pointer_id, button, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::MouseInput {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                    state: ElementState::Released,
+                    button,
+                    modifiers,
+                },
+            });
+        });
+
+        canvas.on_mouse_down(|pointer_id, button, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::MouseInput {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                    state: ElementState::Pressed,
+                    button,
+                    modifiers,
+                },
+            });
+        });
+
+        canvas.on_mouse_scroll(|pointer_id, delta, modifiers| {
+            runner.send_event(Event::WindowEvent {
+                window_id: WindowId(window::Id),
+                event: WindowEvent::MouseWheel {
+                    device_id: DeviceId(device::Id(pointer_id)),
+                    delta,
+                    phase: TouchPhase::Moved,
+                    modifiers,
+                },
+            });
+        });
+    }
+}

src/platform_impl/web/mod.rs

@@ -0,0 +1,27 @@
+// TODO: dpi
+// TODO: close events (stdweb PR required)
+// TODO: pointer locking (stdweb PR required)
+// TODO: mouse wheel events (stdweb PR required)
+// TODO: key event: .which() (stdweb PR)
+// TODO: should there be a maximization / fullscreen API?
+
+mod device;
+mod error;
+mod event_loop;
+mod monitor;
+mod window;
+
+#[cfg(feature = "web_sys")]
+#[path = "web_sys/mod.rs"]
+mod backend;
+
+pub use self::device::Id as DeviceId;
+pub use self::error::OsError;
+pub use self::event_loop::{
+    EventLoop, Proxy as EventLoopProxy, WindowTarget as EventLoopWindowTarget,
+};
+pub use self::monitor::Handle as MonitorHandle;
+pub use self::window::{
+    Id as WindowId, PlatformSpecificBuilderAttributes as PlatformSpecificWindowBuilderAttributes,
+    Window,
+};

src/platform_impl/web/monitor.rs

@@ -0,0 +1,22 @@
+use crate::dpi::{PhysicalPosition, PhysicalSize};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Handle;
+
+impl Handle {
+    pub fn hidpi_factor(&self) -> f64 {
+        1.0
+    }
+
+    pub fn position(&self) -> PhysicalPosition {
+        unimplemented!();
+    }
+
+    pub fn dimensions(&self) -> PhysicalSize {
+        unimplemented!();
+    }
+
+    pub fn name(&self) -> Option<String> {
+        unimplemented!();
+    }
+}

src/platform_impl/web/stdweb/canvas.rs

@@ -0,0 +1,20 @@
+pub struct Canvas;
+
+impl Canvas {
+    pub fn new() -> Self {
+        let element = document()
+            .create_element("canvas")
+            .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?;
+
+        let canvas: CanvasElement = element
+            .try_into()
+            .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?;
+
+        document()
+            .body()
+            .ok_or_else(|| os_error!(OsError("Failed to find body node".to_owned())))?
+            .append_child(&canvas);
+
+        Canvas(canvas)
+    }
+}

src/platform_impl/web/web_sys/canvas.rs

@@ -0,0 +1,66 @@
+use crate::dpi::LogicalSize;
+use crate::error::OsError as RootOE;
+use crate::platform_impl::OsError;
+
+use wasm_bindgen::JsCast;
+use web_sys::HtmlCanvasElement;
+
+pub struct Canvas {
+    raw: HtmlCanvasElement,
+}
+
+impl Canvas {
+    pub fn create() -> Result<Self, RootOE> {
+        let window = web_sys::window().expect("Failed to obtain window");
+        let document = window.document().expect("Failed to obtain document");
+
+        let canvas: HtmlCanvasElement = document
+            .create_element("canvas")
+            .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?
+            .unchecked_into();
+
+        document
+            .body()
+            .ok_or_else(|| os_error!(OsError("Failed to find body node".to_owned())))?
+            .append_child(&canvas)
+            .map_err(|_| os_error!(OsError("Failed to append canvas".to_owned())))?;
+
+        Ok(Canvas { raw: canvas })
+    }
+
+    pub fn set_attribute(&self, attribute: &str, value: &str) {
+        self.raw
+            .set_attribute(attribute, value)
+            .expect(&format!("Set attribute: {}", attribute));
+    }
+
+    pub fn position(&self) -> (f64, f64) {
+        let bounds = self.raw.get_bounding_client_rect();
+
+        (bounds.x(), bounds.y())
+    }
+
+    pub fn width(&self) -> f64 {
+        self.raw.width() as f64
+    }
+
+    pub fn height(&self) -> f64 {
+        self.raw.height() as f64
+    }
+
+    pub fn set_size(&self, size: LogicalSize) {
+        self.raw.set_width(size.width as u32);
+        self.raw.set_height(size.height as u32);
+    }
+
+    pub fn raw(&self) -> HtmlCanvasElement {
+        self.raw.clone()
+    }
+
+    pub fn on_mouse_out<F>(&self, f: F) {}
+    pub fn on_mouse_over<F>(&self, f: F) {}
+    pub fn on_mouse_up<F>(&self, f: F) {}
+    pub fn on_mouse_down<F>(&self, f: F) {}
+    pub fn on_mouse_move<F>(&self, f: F) {}
+    pub fn on_mouse_scroll<F>(&self, f: F) {}
+}

src/platform_impl/web/web_sys/document.rs

@@ -0,0 +1,13 @@
+pub struct Document;
+
+impl Document {
+    pub fn set_title(title: &str) {}
+
+    pub fn on_blur<F>(f: F) {}
+
+    pub fn on_focus<F>(f: F) {}
+
+    pub fn on_key_up<F>(f: F) {}
+
+    pub fn on_key_down<F>(f: F) {}
+}

src/platform_impl/web/web_sys/mod.rs

@@ -0,0 +1,17 @@
+mod canvas;
+mod document;
+mod timeout;
+
+pub use self::canvas::Canvas;
+pub use self::document::Document;
+pub use self::timeout::Timeout;
+
+pub fn request_animation_frame<F>(f: F)
+where
+    F: Fn(),
+{
+}
+
+pub fn throw(msg: &str) {
+    wasm_bindgen::throw_str(msg);
+}

src/platform_impl/web/web_sys/timeout.rs

@@ -0,0 +1,12 @@
+use std::time::Duration;
+
+#[derive(Debug, Clone, Copy)]
+pub struct Timeout {}
+
+impl Timeout {
+    pub fn new<F>(f: F, duration: Duration) -> Timeout {
+        Timeout {}
+    }
+
+    pub fn clear(self) {}
+}

src/platform_impl/web/window.rs

@@ -0,0 +1,276 @@
+use crate::dpi::{LogicalPosition, LogicalSize};
+use crate::error::{ExternalError, NotSupportedError, OsError as RootOE};
+use crate::event::{Event, WindowEvent};
+use crate::icon::Icon;
+use crate::monitor::MonitorHandle as RootMH;
+use crate::window::{CursorIcon, WindowAttributes, WindowId as RootWI};
+
+use super::{backend, monitor, EventLoopWindowTarget};
+
+use std::cell::RefCell;
+use std::collections::vec_deque::IntoIter as VecDequeIter;
+use std::collections::VecDeque;
+
+pub struct Window {
+    canvas: backend::Canvas,
+    redraw: Box<dyn Fn()>,
+    previous_pointer: RefCell<&'static str>,
+    position: RefCell<LogicalPosition>,
+}
+
+impl Window {
+    pub fn new<T>(
+        target: &EventLoopWindowTarget<T>,
+        attr: WindowAttributes,
+        _: PlatformSpecificBuilderAttributes,
+    ) -> Result<Self, RootOE> {
+        let canvas = backend::Canvas::create()?;
+
+        target.register(&canvas);
+
+        let runner = target.runner.clone();
+        let redraw = Box::new(move || {
+            let runner = runner.clone();
+            backend::request_animation_frame(move || {
+                runner.send_event(Event::WindowEvent {
+                    window_id: RootWI(Id),
+                    event: WindowEvent::RedrawRequested,
+                })
+            });
+        });
+
+        let window = Window {
+            canvas,
+            redraw,
+            previous_pointer: RefCell::new("auto"),
+            position: RefCell::new(LogicalPosition { x: 0.0, y: 0.0 }),
+        };
+
+        window.set_inner_size(attr.inner_size.unwrap_or(LogicalSize {
+            width: 1024.0,
+            height: 768.0,
+        }));
+        window.set_title(&attr.title);
+        window.set_maximized(attr.maximized);
+        window.set_visible(attr.visible);
+        window.set_window_icon(attr.window_icon);
+
+        Ok(window)
+    }
+
+    pub fn set_title(&self, title: &str) {
+        backend::Document::set_title(title);
+    }
+
+    pub fn set_visible(&self, _visible: bool) {
+        // Intentionally a no-op
+    }
+
+    pub fn request_redraw(&self) {
+        (self.redraw)();
+    }
+
+    pub fn outer_position(&self) -> Result<LogicalPosition, NotSupportedError> {
+        let (x, y) = self.canvas.position();
+
+        Ok(LogicalPosition { x, y })
+    }
+
+    pub fn inner_position(&self) -> Result<LogicalPosition, NotSupportedError> {
+        Ok(*self.position.borrow())
+    }
+
+    pub fn set_outer_position(&self, position: LogicalPosition) {
+        *self.position.borrow_mut() = position;
+
+        self.canvas.set_attribute("position", "fixed");
+        self.canvas.set_attribute("left", &position.x.to_string());
+        self.canvas.set_attribute("top", &position.y.to_string());
+    }
+
+    #[inline]
+    pub fn inner_size(&self) -> LogicalSize {
+        LogicalSize {
+            width: self.canvas.width() as f64,
+            height: self.canvas.height() as f64,
+        }
+    }
+
+    #[inline]
+    pub fn outer_size(&self) -> LogicalSize {
+        LogicalSize {
+            width: self.canvas.width() as f64,
+            height: self.canvas.height() as f64,
+        }
+    }
+
+    #[inline]
+    pub fn set_inner_size(&self, size: LogicalSize) {
+        self.canvas.set_size(size);
+    }
+
+    #[inline]
+    pub fn set_min_inner_size(&self, _dimensions: Option<LogicalSize>) {
+        // Intentionally a no-op: users can't resize canvas elements
+    }
+
+    #[inline]
+    pub fn set_max_inner_size(&self, _dimensions: Option<LogicalSize>) {
+        // Intentionally a no-op: users can't resize canvas elements
+    }
+
+    #[inline]
+    pub fn set_resizable(&self, _resizable: bool) {
+        // Intentionally a no-op: users can't resize canvas elements
+    }
+
+    #[inline]
+    pub fn hidpi_factor(&self) -> f64 {
+        1.0
+    }
+
+    #[inline]
+    pub fn set_cursor_icon(&self, cursor: CursorIcon) {
+        let text = match cursor {
+            CursorIcon::Default => "auto",
+            CursorIcon::Crosshair => "crosshair",
+            CursorIcon::Hand => "pointer",
+            CursorIcon::Arrow => "default",
+            CursorIcon::Move => "move",
+            CursorIcon::Text => "text",
+            CursorIcon::Wait => "wait",
+            CursorIcon::Help => "help",
+            CursorIcon::Progress => "progress",
+
+            CursorIcon::NotAllowed => "not-allowed",
+            CursorIcon::ContextMenu => "context-menu",
+            CursorIcon::Cell => "cell",
+            CursorIcon::VerticalText => "vertical-text",
+            CursorIcon::Alias => "alias",
+            CursorIcon::Copy => "copy",
+            CursorIcon::NoDrop => "no-drop",
+            CursorIcon::Grab => "grab",
+            CursorIcon::Grabbing => "grabbing",
+            CursorIcon::AllScroll => "all-scroll",
+            CursorIcon::ZoomIn => "zoom-in",
+            CursorIcon::ZoomOut => "zoom-out",
+
+            CursorIcon::EResize => "e-resize",
+            CursorIcon::NResize => "n-resize",
+            CursorIcon::NeResize => "ne-resize",
+            CursorIcon::NwResize => "nw-resize",
+            CursorIcon::SResize => "s-resize",
+            CursorIcon::SeResize => "se-resize",
+            CursorIcon::SwResize => "sw-resize",
+            CursorIcon::WResize => "w-resize",
+            CursorIcon::EwResize => "ew-resize",
+            CursorIcon::NsResize => "ns-resize",
+            CursorIcon::NeswResize => "nesw-resize",
+            CursorIcon::NwseResize => "nwse-resize",
+            CursorIcon::ColResize => "col-resize",
+            CursorIcon::RowResize => "row-resize",
+        };
+        *self.previous_pointer.borrow_mut() = text;
+        self.canvas.set_attribute("cursor", text);
+    }
+
+    #[inline]
+    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), ExternalError> {
+        // TODO: pointer capture
+        Ok(())
+    }
+
+    #[inline]
+    pub fn set_cursor_grab(&self, _grab: bool) -> Result<(), ExternalError> {
+        // TODO: pointer capture
+        Ok(())
+    }
+
+    #[inline]
+    pub fn set_cursor_visible(&self, visible: bool) {
+        if !visible {
+            self.canvas.set_attribute("cursor", "none");
+        } else {
+            self.canvas
+                .set_attribute("cursor", *self.previous_pointer.borrow());
+        }
+    }
+
+    #[inline]
+    pub fn set_maximized(&self, _maximized: bool) {
+        // TODO: should there be a maximization / fullscreen API?
+    }
+
+    #[inline]
+    pub fn fullscreen(&self) -> Option<RootMH> {
+        // TODO: should there be a maximization / fullscreen API?
+        None
+    }
+
+    #[inline]
+    pub fn set_fullscreen(&self, _monitor: Option<RootMH>) {
+        // TODO: should there be a maximization / fullscreen API?
+    }
+
+    #[inline]
+    pub fn set_decorations(&self, _decorations: bool) {
+        // Intentionally a no-op, no canvas decorations
+    }
+
+    #[inline]
+    pub fn set_always_on_top(&self, _always_on_top: bool) {
+        // Intentionally a no-op, no window ordering
+    }
+
+    #[inline]
+    pub fn set_window_icon(&self, _window_icon: Option<Icon>) {
+        // Currently an intentional no-op
+    }
+
+    #[inline]
+    pub fn set_ime_position(&self, _position: LogicalPosition) {
+        // TODO: what is this?
+    }
+
+    #[inline]
+    pub fn current_monitor(&self) -> RootMH {
+        RootMH {
+            inner: monitor::Handle,
+        }
+    }
+
+    #[inline]
+    pub fn available_monitors(&self) -> VecDequeIter<monitor::Handle> {
+        VecDeque::new().into_iter()
+    }
+
+    #[inline]
+    pub fn primary_monitor(&self) -> monitor::Handle {
+        monitor::Handle
+    }
+
+    #[inline]
+    pub fn id(&self) -> Id {
+        // TODO ?
+        unsafe { Id::dummy() }
+    }
+}
+
+#[cfg(feature = "stdweb")]
+impl WindowExtStdweb for RootWindow {
+    fn canvas(&self) -> CanvasElement {
+        self.window.canvas.clone()
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Id;
+
+impl Id {
+    pub unsafe fn dummy() -> Id {
+        Id
+    }
+}
+
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct PlatformSpecificBuilderAttributes;