Implement hidpi for web platform (#1233)

* fix: use a 'static lifetime for the web backend's `Event` types

* implement hidpi for stdweb (web-sys wip?)

* fix: make all canvas resizes go through backend::set_canvas_size

* update Window docs for web, make `inner/outer_position` return the position in the viewport

Cargo.toml

@@ -90,6 +90,7 @@ version = "0.3.22"
 optional = true
 features = [
     'console',
+    'CssStyleDeclaration',
     'BeforeUnloadEvent',
     'Document',
     'DomRect',

src/platform_impl/web/event_loop/mod.rs

@@ -37,7 +37,8 @@ impl<T> EventLoop<T> {
 
     pub fn run<F>(self, mut event_handler: F) -> !
     where
-        F: 'static + FnMut(Event<T>, &root::EventLoopWindowTarget<T>, &mut root::ControlFlow),
+        F: 'static
+            + FnMut(Event<'static, T>, &root::EventLoopWindowTarget<T>, &mut root::ControlFlow),
     {
         let target = root::EventLoopWindowTarget {
             p: self.elw.p.clone(),

src/platform_impl/web/event_loop/runner.rs

@@ -11,7 +11,7 @@ use std::{
     rc::Rc,
 };
 
-pub struct Shared<T>(Rc<Execution<T>>);
+pub struct Shared<T: 'static>(Rc<Execution<T>>);
 
 impl<T> Clone for Shared<T> {
     fn clone(&self) -> Self {
@@ -19,21 +19,21 @@ impl<T> Clone for Shared<T> {
     }
 }
 
-pub struct Execution<T> {
+pub struct Execution<T: 'static> {
     runner: RefCell<Option<Runner<T>>>,
-    events: RefCell<VecDeque<Event<T>>>,
+    events: RefCell<VecDeque<Event<'static, T>>>,
     id: RefCell<u32>,
     redraw_pending: RefCell<HashSet<WindowId>>,
 }
 
-struct Runner<T> {
+struct Runner<T: 'static> {
     state: State,
     is_busy: bool,
-    event_handler: Box<dyn FnMut(Event<T>, &mut root::ControlFlow)>,
+    event_handler: Box<dyn FnMut(Event<'static, T>, &mut root::ControlFlow)>,
 }
 
 impl<T: 'static> Runner<T> {
-    pub fn new(event_handler: Box<dyn FnMut(Event<T>, &mut root::ControlFlow)>) -> Self {
+    pub fn new(event_handler: Box<dyn FnMut(Event<'static, T>, &mut root::ControlFlow)>) -> Self {
         Runner {
             state: State::Init,
             is_busy: false,
@@ -55,7 +55,10 @@ impl<T: 'static> Shared<T> {
     // 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)>) {
+    pub fn set_listener(
+        &self,
+        event_handler: Box<dyn FnMut(Event<'static, T>, &mut root::ControlFlow)>,
+    ) {
         self.0.runner.replace(Some(Runner::new(event_handler)));
         self.send_event(Event::NewEvents(StartCause::Init));
 
@@ -79,7 +82,7 @@ impl<T: 'static> Shared<T> {
     // 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>) {
+    pub fn send_event(&self, event: Event<'static, T>) {
         // If the event loop is closed, it should discard any new events
         if self.is_closed() {
             return;
@@ -153,7 +156,7 @@ impl<T: 'static> Shared<T> {
     // 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) {
+    fn handle_event(&self, event: Event<'static, T>, control: &mut root::ControlFlow) {
         let is_closed = self.is_closed();
 
         match *self.0.runner.borrow_mut() {

src/platform_impl/web/event_loop/window_target.rs

@@ -1,5 +1,5 @@
 use super::{backend, device, proxy::Proxy, runner, window};
-use crate::dpi::LogicalSize;
+use crate::dpi::{PhysicalSize, Size};
 use crate::event::{DeviceId, ElementState, Event, KeyboardInput, TouchPhase, WindowEvent};
 use crate::event_loop::ControlFlow;
 use crate::window::WindowId;
@@ -28,7 +28,7 @@ impl<T> WindowTarget<T> {
         Proxy::new(self.runner.clone())
     }
 
-    pub fn run(&self, event_handler: Box<dyn FnMut(Event<T>, &mut ControlFlow)>) {
+    pub fn run(&self, event_handler: Box<dyn FnMut(Event<'static, T>, &mut ControlFlow)>) {
         self.runner.set_listener(event_handler);
     }
 
@@ -170,25 +170,27 @@ impl<T> WindowTarget<T> {
 
         let runner = self.runner.clone();
         let raw = canvas.raw().clone();
-        let mut intended_size = LogicalSize {
+
-            width: raw.width() as f64,
+        // The size to restore to after exiting fullscreen.
-            height: raw.height() as f64,
+        let mut intended_size = PhysicalSize {
+            width: raw.width() as u32,
+            height: raw.height() as u32,
         };
         canvas.on_fullscreen_change(move || {
             // If the canvas is marked as fullscreen, it is moving *into* fullscreen
             // If it is not, it is moving *out of* fullscreen
             let new_size = if backend::is_fullscreen(&raw) {
-                intended_size = LogicalSize {
+                intended_size = PhysicalSize {
-                    width: raw.width() as f64,
+                    width: raw.width() as u32,
-                    height: raw.height() as f64,
+                    height: raw.height() as u32,
                 };
 
-                backend::window_size()
+                backend::window_size().to_physical(backend::hidpi_factor())
             } else {
                 intended_size
             };
-            raw.set_width(new_size.width as u32);
+
-            raw.set_height(new_size.height as u32);
+            backend::set_canvas_size(&raw, Size::Physical(new_size));
             runner.send_event(Event::WindowEvent {
                 window_id: WindowId(id),
                 event: WindowEvent::Resized(new_size),

src/platform_impl/web/monitor.rs

@@ -10,7 +10,7 @@ impl Handle {
     }
 
     pub fn position(&self) -> PhysicalPosition<i32> {
-        PhysicalPosition { x: 0.0, y: 0.0 }
+        PhysicalPosition { x: 0, y: 0 }
     }
 
     pub fn name(&self) -> Option<String> {
@@ -19,8 +19,8 @@ impl Handle {
 
     pub fn size(&self) -> PhysicalSize<u32> {
         PhysicalSize {
-            width: 0.0,
+            width: 0,
-            height: 0.0,
+            height: 0,
         }
     }
 

src/platform_impl/web/stdweb/canvas.rs

@@ -1,5 +1,5 @@
 use super::event;
-use crate::dpi::{LogicalPosition, LogicalSize};
+use crate::dpi::{LogicalPosition, PhysicalPosition, PhysicalSize};
 use crate::error::OsError as RootOE;
 use crate::event::{ModifiersState, MouseButton, MouseScrollDelta, ScanCode, VirtualKeyCode};
 use crate::platform_impl::OsError;
@@ -19,6 +19,7 @@ use stdweb::web::{
 };
 
 pub struct Canvas {
+    /// Note: resizing the CanvasElement should go through `backend::set_canvas_size` to ensure the DPI factor is maintained.
     raw: CanvasElement,
     on_focus: Option<EventListenerHandle>,
     on_blur: Option<EventListenerHandle>,
@@ -82,23 +83,20 @@ impl Canvas {
             .expect(&format!("Set attribute: {}", attribute));
     }
 
-    pub fn position(&self) -> (f64, f64) {
+    pub fn position(&self) -> LogicalPosition<f64> {
         let bounds = self.raw.get_bounding_client_rect();
 
-        (bounds.get_x(), bounds.get_y())
+        LogicalPosition {
+            x: bounds.get_x(),
+            y: bounds.get_y(),
+        }
     }
 
-    pub fn width(&self) -> f64 {
+    pub fn size(&self) -> PhysicalSize<u32> {
-        self.raw.width() as f64
+        PhysicalSize {
+            width: self.raw.width() as u32,
+            height: self.raw.height() as u32,
         }
-
-    pub fn height(&self) -> f64 {
-        self.raw.height() as f64
-    }
-
-    pub fn set_size(&self, size: LogicalSize<f64>) {
-        self.raw.set_width(size.width as u32);
-        self.raw.set_height(size.height as u32);
     }
 
     pub fn raw(&self) -> &CanvasElement {
@@ -209,12 +207,13 @@ impl Canvas {
 
     pub fn on_cursor_move<F>(&mut self, mut handler: F)
     where
-        F: 'static + FnMut(i32, LogicalPosition, ModifiersState),
+        F: 'static + FnMut(i32, PhysicalPosition<i32>, ModifiersState),
     {
+        // todo
         self.on_cursor_move = Some(self.add_event(move |event: PointerMoveEvent| {
             handler(
                 event.pointer_id(),
-                event::mouse_position(&event),
+                event::mouse_position(&event).to_physical(super::hidpi_factor()),
                 event::mouse_modifiers(&event),
             );
         }));

src/platform_impl/web/stdweb/mod.rs

@@ -5,7 +5,7 @@ mod timeout;
 pub use self::canvas::Canvas;
 pub use self::timeout::Timeout;
 
-use crate::dpi::LogicalSize;
+use crate::dpi::{LogicalSize, Size};
 use crate::platform::web::WindowExtStdweb;
 use crate::window::Window;
 
@@ -41,6 +41,28 @@ pub fn window_size() -> LogicalSize<f64> {
     LogicalSize { width, height }
 }
 
+pub fn hidpi_factor() -> f64 {
+    let window = window();
+    window.device_pixel_ratio()
+}
+
+pub fn set_canvas_size(raw: &CanvasElement, size: Size) {
+    use stdweb::*;
+
+    let hidpi_factor = hidpi_factor();
+
+    let physical_size = size.to_physical::<u32>(hidpi_factor);
+    let logical_size = size.to_logical::<f64>(hidpi_factor);
+
+    raw.set_width(physical_size.width);
+    raw.set_height(physical_size.height);
+
+    js! {
+        @{raw.as_ref()}.style.width = @{logical_size.width} + "px";
+        @{raw.as_ref()}.style.height = @{logical_size.height} + "px";
+    }
+}
+
 pub fn is_fullscreen(canvas: &CanvasElement) -> bool {
     match document().fullscreen_element() {
         Some(elem) => {

src/platform_impl/web/web_sys/canvas.rs

@@ -1,5 +1,5 @@
 use super::event;
-use crate::dpi::{LogicalPosition, LogicalSize};
+use crate::dpi::{LogicalPosition, PhysicalPosition, PhysicalSize};
 use crate::error::OsError as RootOE;
 use crate::event::{ModifiersState, MouseButton, MouseScrollDelta, ScanCode, VirtualKeyCode};
 use crate::platform_impl::OsError;
@@ -11,6 +11,7 @@ use wasm_bindgen::{closure::Closure, JsCast};
 use web_sys::{Event, FocusEvent, HtmlCanvasElement, KeyboardEvent, PointerEvent, WheelEvent};
 
 pub struct Canvas {
+    /// Note: resizing the HTMLCanvasElement should go through `backend::set_canvas_size` to ensure the DPI factor is maintained.
     raw: HtmlCanvasElement,
     on_focus: Option<Closure<dyn FnMut(FocusEvent)>>,
     on_blur: Option<Closure<dyn FnMut(FocusEvent)>>,
@@ -80,23 +81,20 @@ impl Canvas {
             .expect(&format!("Set attribute: {}", attribute));
     }
 
-    pub fn position(&self) -> (f64, f64) {
+    pub fn position(&self) -> LogicalPosition<f64> {
         let bounds = self.raw.get_bounding_client_rect();
 
-        (bounds.x(), bounds.y())
+        LogicalPosition {
+            x: bounds.x(),
+            y: bounds.y(),
+        }
     }
 
-    pub fn width(&self) -> f64 {
+    pub fn size(&self) -> PhysicalSize<u32> {
-        self.raw.width() as f64
+        PhysicalSize {
+            width: self.raw.width(),
+            height: self.raw.height(),
         }
-
-    pub fn height(&self) -> f64 {
-        self.raw.height() as f64
-    }
-
-    pub fn set_size(&self, size: LogicalSize<f64>) {
-        self.raw.set_width(size.width as u32);
-        self.raw.set_height(size.height as u32);
     }
 
     pub fn raw(&self) -> &HtmlCanvasElement {
@@ -218,12 +216,12 @@ impl Canvas {
 
     pub fn on_cursor_move<F>(&mut self, mut handler: F)
     where
-        F: 'static + FnMut(i32, LogicalPosition, ModifiersState),
+        F: 'static + FnMut(i32, PhysicalPosition<i32>, ModifiersState),
     {
         self.on_cursor_move = Some(self.add_event("pointermove", move |event: PointerEvent| {
             handler(
                 event.pointer_id(),
-                event::mouse_position(&event),
+                event::mouse_position(&event).to_physical(super::hidpi_factor()),
                 event::mouse_modifiers(&event),
             );
         }));

src/platform_impl/web/web_sys/mod.rs

@@ -5,7 +5,7 @@ mod timeout;
 pub use self::canvas::Canvas;
 pub use self::timeout::Timeout;
 
-use crate::dpi::LogicalSize;
+use crate::dpi::{LogicalSize, Size};
 use crate::platform::web::WindowExtWebSys;
 use crate::window::Window;
 use wasm_bindgen::{closure::Closure, JsCast};
@@ -56,6 +56,29 @@ pub fn window_size() -> LogicalSize<f64> {
     LogicalSize { width, height }
 }
 
+pub fn hidpi_factor() -> f64 {
+    let window = web_sys::window().expect("Failed to obtain window");
+    window.device_pixel_ratio()
+}
+
+pub fn set_canvas_size(raw: &HtmlCanvasElement, size: Size) {
+    let hidpi_factor = hidpi_factor();
+
+    let physical_size = size.to_physical::<u32>(hidpi_factor);
+    let logical_size = size.to_logical::<f64>(hidpi_factor);
+
+    raw.set_width(physical_size.width);
+    raw.set_height(physical_size.height);
+
+    let style = raw.style();
+    style
+        .set_property("width", &format!("{}px", logical_size.width))
+        .expect("Failed to set canvas width");
+    style
+        .set_property("height", &format!("{}px", logical_size.height))
+        .expect("Failed to set canvas height");
+}
+
 pub fn is_fullscreen(canvas: &HtmlCanvasElement) -> bool {
     let window = window().expect("Failed to obtain window");
     let document = window.document().expect("Failed to obtain document");

src/platform_impl/web/window.rs

@@ -1,4 +1,4 @@
-use crate::dpi::{LogicalPosition, LogicalSize};
+use crate::dpi::{LogicalSize, PhysicalPosition, PhysicalSize, Position, Size};
 use crate::error::{ExternalError, NotSupportedError, OsError as RootOE};
 use crate::icon::Icon;
 use crate::monitor::MonitorHandle as RootMH;
@@ -15,7 +15,6 @@ use std::collections::VecDeque;
 pub struct Window {
     canvas: backend::Canvas,
     previous_pointer: RefCell<&'static str>,
-    position: RefCell<LogicalPosition<f64>>,
     id: Id,
     register_redraw_request: Box<dyn Fn()>,
 }
@@ -39,15 +38,14 @@ impl Window {
         let window = Window {
             canvas,
             previous_pointer: RefCell::new("auto"),
-            position: RefCell::new(LogicalPosition { x: 0.0, y: 0.0 }),
             id,
             register_redraw_request,
         };
 
-        window.set_inner_size(attr.inner_size.unwrap_or(LogicalSize {
+        window.set_inner_size(attr.inner_size.unwrap_or(Size::Logical(LogicalSize {
             width: 1024.0,
             height: 768.0,
-        }));
+        })));
         window.set_title(&attr.title);
         window.set_maximized(attr.maximized);
         window.set_visible(attr.visible);
@@ -72,18 +70,17 @@ impl Window {
         (self.register_redraw_request)();
     }
 
-    pub fn outer_position(&self) -> Result<LogicalPosition<f64>, NotSupportedError> {
+    pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
-        let (x, y) = self.canvas.position();
+        Ok(self.canvas.position().to_physical(self.hidpi_factor()))
-
-        Ok(LogicalPosition { x, y })
     }
 
-    pub fn inner_position(&self) -> Result<LogicalPosition<f64>, NotSupportedError> {
+    pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
-        Ok(*self.position.borrow())
+        // Note: the canvas element has no window decorations, so this is equal to `outer_position`.
+        self.outer_position()
     }
 
-    pub fn set_outer_position(&self, position: LogicalPosition<f64>) {
+    pub fn set_outer_position(&self, position: Position) {
-        *self.position.borrow_mut() = position;
+        let position = position.to_logical::<f64>(self.hidpi_factor());
 
         self.canvas.set_attribute("position", "fixed");
         self.canvas.set_attribute("left", &position.x.to_string());
@@ -91,33 +88,28 @@ impl Window {
     }
 
     #[inline]
-    pub fn inner_size(&self) -> LogicalSize<f64> {
+    pub fn inner_size(&self) -> PhysicalSize<u32> {
-        LogicalSize {
+        self.canvas.size()
-            width: self.canvas.width() as f64,
-            height: self.canvas.height() as f64,
-        }
     }
 
     #[inline]
-    pub fn outer_size(&self) -> LogicalSize<f64> {
+    pub fn outer_size(&self) -> PhysicalSize<u32> {
-        LogicalSize {
+        // Note: the canvas element has no window decorations, so this is equal to `inner_size`.
-            width: self.canvas.width() as f64,
+        self.inner_size()
-            height: self.canvas.height() as f64,
-        }
     }
 
     #[inline]
-    pub fn set_inner_size(&self, size: LogicalSize<f64>) {
+    pub fn set_inner_size(&self, size: Size) {
-        self.canvas.set_size(size);
+        backend::set_canvas_size(self.canvas.raw(), size);
     }
 
     #[inline]
-    pub fn set_min_inner_size(&self, _dimensions: Option<LogicalSize<f64>>) {
+    pub fn set_min_inner_size(&self, _dimensions: Option<Size>) {
         // Intentionally a no-op: users can't resize canvas elements
     }
 
     #[inline]
-    pub fn set_max_inner_size(&self, _dimensions: Option<LogicalSize<f64>>) {
+    pub fn set_max_inner_size(&self, _dimensions: Option<Size>) {
         // Intentionally a no-op: users can't resize canvas elements
     }
 
@@ -128,7 +120,7 @@ impl Window {
 
     #[inline]
     pub fn hidpi_factor(&self) -> f64 {
-        1.0
+        super::backend::hidpi_factor()
     }
 
     #[inline]
@@ -178,10 +170,7 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(
+    pub fn set_cursor_position(&self, _position: Position) -> Result<(), ExternalError> {
-        &self,
-        _position: LogicalPosition<f64>,
-    ) -> Result<(), ExternalError> {
         // Intentionally a no-op, as the web does not support setting cursor positions
         Ok(())
     }
@@ -246,7 +235,7 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, _position: LogicalPosition<f64>) {
+    pub fn set_ime_position(&self, _position: Position) {
         // Currently a no-op as it does not seem there is good support for this on web
     }
 

src/window.rs

@@ -419,6 +419,8 @@ impl Window {
     ///
     /// - **iOS:** Can only be called on the main thread. Returns the top left coordinates of the
     ///   window's [safe area] in the screen space coordinate system.
+    /// - **Web:** Returns the top-left coordinates relative to the viewport. _Note: this returns the
+    ///    same value as `outer_position`._
     ///
     /// [safe area]: https://developer.apple.com/documentation/uikit/uiview/2891103-safeareainsets?language=objc
     #[inline]
@@ -440,6 +442,7 @@ impl Window {
     ///
     /// - **iOS:** Can only be called on the main thread. Returns the top left coordinates of the
     ///   window in the screen space coordinate system.
+    /// - **Web:** Returns the top-left coordinates relative to the viewport.
     #[inline]
     pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
         self.window.outer_position()
@@ -454,6 +457,7 @@ impl Window {
     ///
     /// - **iOS:** Can only be called on the main thread. Sets the top left coordinates of the
     ///   window in the screen space coordinate system.
+    /// - **Web:** Sets the top-left coordinates relative to the viewport.
     #[inline]
     pub fn set_outer_position<P: Into<Position>>(&self, position: P) {
         self.window.set_outer_position(position.into())
@@ -467,6 +471,7 @@ impl Window {
     ///
     /// - **iOS:** Can only be called on the main thread. Returns the `PhysicalSize` of the window's
     ///   [safe area] in screen space coordinates.
+    /// - **Web:** Returns the size of the canvas element.
     ///
     /// [safe area]: https://developer.apple.com/documentation/uikit/uiview/2891103-safeareainsets?language=objc
     #[inline]
@@ -483,6 +488,7 @@ impl Window {
     ///
     /// - **iOS:** Unimplemented. Currently this panics, as it's not clear what `set_inner_size`
     ///   would mean for iOS.
+    /// - **Web:** Sets the size of the canvas element.
     #[inline]
     pub fn set_inner_size<S: Into<Size>>(&self, size: S) {
         self.window.set_inner_size(size.into())
@@ -497,6 +503,8 @@ impl Window {
     ///
     /// - **iOS:** Can only be called on the main thread. Returns the `PhysicalSize` of the window in
     ///   screen space coordinates.
+    /// - **Web:** Returns the size of the canvas element. _Note: this returns the same value as
+    ///   `inner_size`._
     #[inline]
     pub fn outer_size(&self) -> PhysicalSize<u32> {
         self.window.outer_size()