Web: Fullscreen Overhaul (#3063)

CHANGELOG.md

@@ -15,6 +15,8 @@ And please only add new entries to the top of this list, right below the `# Unre
 - **Breaking:** Move `Event::RedrawRequested` to `WindowEvent::RedrawRequested`.
 - On macOS, fix crash in `window.set_minimized(false)`.
 - On Web, enable event propagation and let `DeviceEvent`s appear after `WindowEvent`s.
+- On Web, take all transient activations on the canvas and window into account to queue a fullscreen request.
+- On Web, remove any fullscreen requests from the queue when an external fullscreen activation was detected.
 
 # 0.29.1-beta
 

examples/web.rs

@@ -65,7 +65,10 @@ mod wasm {
 
     use softbuffer::{Surface, SurfaceExtWeb};
     use wasm_bindgen::prelude::*;
-    use winit::{event::Event, window::Window};
+    use winit::{
+        event::{Event, WindowEvent},
+        window::Window,
+    };
 
     #[wasm_bindgen(start)]
     pub fn run() {
@@ -116,6 +119,10 @@ mod wasm {
         // So we implement this basic logging system into the page to give developers an easy alternative.
         // As a bonus its also kind of handy on desktop.
         let event = match event {
+            Event::WindowEvent {
+                event: WindowEvent::RedrawRequested,
+                ..
+            } => None,
             Event::WindowEvent { event, .. } => Some(format!("{event:?}")),
             Event::Resumed | Event::Suspended => Some(format!("{event:?}")),
             _ => None,

src/platform_impl/web/event_loop/runner.rs

@@ -54,6 +54,7 @@ pub struct Execution<T: 'static> {
     on_key_press: OnEventHandle<KeyboardEvent>,
     on_key_release: OnEventHandle<KeyboardEvent>,
     on_visibility_change: OnEventHandle<web_sys::Event>,
+    on_touch_end: OnEventHandle<web_sys::Event>,
 }
 
 enum RunnerEnum<T: 'static> {
@@ -167,6 +168,7 @@ impl<T: 'static> Shared<T> {
             on_key_press: RefCell::new(None),
             on_key_release: RefCell::new(None),
             on_visibility_change: RefCell::new(None),
+            on_touch_end: RefCell::new(None),
         }))
     }
 
@@ -324,6 +326,8 @@ impl<T: 'static> Shared<T> {
             self.window().clone(),
             "pointerdown",
             Closure::new(move |event: PointerEvent| {
+                runner.transient_activation();
+
                 if !runner.device_events() {
                     return;
                 }
@@ -347,6 +351,8 @@ impl<T: 'static> Shared<T> {
             self.window().clone(),
             "pointerup",
             Closure::new(move |event: PointerEvent| {
+                runner.transient_activation();
+
                 if !runner.device_events() {
                     return;
                 }
@@ -370,6 +376,8 @@ impl<T: 'static> Shared<T> {
             self.window().clone(),
             "keydown",
             Closure::new(move |event: KeyboardEvent| {
+                runner.transient_activation();
+
                 if !runner.device_events() {
                     return;
                 }
@@ -428,6 +436,14 @@ impl<T: 'static> Shared<T> {
                 }
             }),
         ));
+        let runner = self.clone();
+        *self.0.on_touch_end.borrow_mut() = Some(EventListenerHandle::new(
+            self.window().clone(),
+            "touchend",
+            Closure::new(move |_| {
+                runner.transient_activation();
+            }),
+        ));
     }
 
     // Generate a strictly increasing ID
@@ -736,7 +752,7 @@ impl<T: 'static> Shared<T> {
         self.0.device_events.set(allowed)
     }
 
-    pub fn device_events(&self) -> bool {
+    fn device_events(&self) -> bool {
         match self.0.device_events.get() {
             DeviceEvents::Always => true,
             DeviceEvents::WhenFocused => self.0.all_canvases.borrow().iter().any(|(_, canvas)| {
@@ -750,6 +766,14 @@ impl<T: 'static> Shared<T> {
         }
     }
 
+    fn transient_activation(&self) {
+        self.0.all_canvases.borrow().iter().for_each(|(_, canvas)| {
+            if let Some(canvas) = canvas.upgrade() {
+                canvas.borrow().transient_activation();
+            }
+        });
+    }
+
     pub fn event_loop_recreation(&self, allow: bool) {
         self.0.event_loop_recreation.set(allow)
     }

src/platform_impl/web/event_loop/window_target.rs

@@ -660,6 +660,8 @@ impl<T> EventLoopWindowTarget<T> {
 
         let runner = self.runner.clone();
         canvas.on_animation_frame(move || runner.request_redraw(RootWindowId(id)));
+
+        canvas.on_touch_end();
     }
 
     pub fn available_monitors(&self) -> VecDequeIter<MonitorHandle> {

src/platform_impl/web/web_sys/animation_frame.rs

@@ -49,6 +49,14 @@ impl AnimationFrameHandler {
 
         self.handle.set(Some(handle));
     }
+
+    pub fn cancel(&mut self) {
+        if let Some(handle) = self.handle.take() {
+            self.window
+                .cancel_animation_frame(handle)
+                .expect("Failed to cancel animation frame");
+        }
+    }
 }
 
 impl Drop for AnimationFrameHandler {

src/platform_impl/web/web_sys/canvas.rs

@@ -1,12 +1,10 @@
-use std::cell::{Cell, RefCell};
+use std::cell::Cell;
-use std::rc::Rc;
+use std::rc::{Rc, Weak};
 use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Mutex};
 
-use js_sys::Promise;
 use smol_str::SmolStr;
 use wasm_bindgen::{closure::Closure, JsCast};
-use wasm_bindgen_futures::JsFuture;
 use web_sys::{
     CssStyleDeclaration, Document, Event, FocusEvent, HtmlCanvasElement, KeyboardEvent, WheelEvent,
 };
@@ -21,10 +19,11 @@ use crate::window::{WindowAttributes, WindowId as RootWindowId};
 use super::super::WindowId;
 use super::animation_frame::AnimationFrameHandler;
 use super::event_handle::EventListenerHandle;
+use super::fullscreen::FullscreenHandler;
 use super::intersection_handle::IntersectionObserverHandle;
 use super::media_query_handle::MediaQueryListHandle;
 use super::pointer::PointerHandler;
-use super::{event, fullscreen, ButtonsState, ResizeScaleHandle};
+use super::{event, ButtonsState, ResizeScaleHandle};
 
 #[allow(dead_code)]
 pub struct Canvas {
@@ -33,7 +32,6 @@ pub struct Canvas {
     pub has_focus: Arc<AtomicBool>,
     pub is_intersecting: Option<bool>,
     on_touch_start: Option<EventListenerHandle<dyn FnMut(Event)>>,
-    on_touch_end: Option<EventListenerHandle<dyn FnMut(Event)>>,
     on_focus: Option<EventListenerHandle<dyn FnMut(FocusEvent)>>,
     on_blur: Option<EventListenerHandle<dyn FnMut(FocusEvent)>>,
     on_keyboard_release: Option<EventListenerHandle<dyn FnMut(KeyboardEvent)>>,
@@ -44,6 +42,7 @@ pub struct Canvas {
     on_resize_scale: Option<ResizeScaleHandle>,
     on_intersect: Option<IntersectionObserverHandle>,
     animation_frame_handler: AnimationFrameHandler,
+    on_touch_end: Option<EventListenerHandle<dyn FnMut(Event)>>,
 }
 
 pub struct Common {
@@ -54,7 +53,7 @@ pub struct Common {
     style: CssStyleDeclaration,
     old_size: Rc<Cell<PhysicalSize<u32>>>,
     current_size: Rc<Cell<PhysicalSize<u32>>>,
-    wants_fullscreen: Rc<RefCell<bool>>,
+    fullscreen_handler: Rc<FullscreenHandler>,
 }
 
 impl Canvas {
@@ -101,12 +100,12 @@ impl Canvas {
 
         let common = Common {
             window: window.clone(),
-            document,
+            document: document.clone(),
-            raw: canvas,
+            raw: canvas.clone(),
             style,
             old_size: Rc::default(),
             current_size: Rc::default(),
-            wants_fullscreen: Rc::new(RefCell::new(false)),
+            fullscreen_handler: Rc::new(FullscreenHandler::new(document.clone(), canvas.clone())),
         };
 
         if let Some(size) = attr.inner_size {
@@ -130,7 +129,7 @@ impl Canvas {
         }
 
         if attr.fullscreen.is_some() {
-            common.request_fullscreen();
+            common.fullscreen_handler.request_fullscreen();
         }
 
         if attr.active {
@@ -143,7 +142,6 @@ impl Canvas {
             has_focus: Arc::new(AtomicBool::new(false)),
             is_intersecting: None,
             on_touch_start: None,
-            on_touch_end: None,
             on_blur: None,
             on_focus: None,
             on_keyboard_release: None,
@@ -154,6 +152,7 @@ impl Canvas {
             on_resize_scale: None,
             on_intersect: None,
             animation_frame_handler: AnimationFrameHandler::new(window),
+            on_touch_end: None,
         })
     }
 
@@ -262,9 +261,8 @@ impl Canvas {
     where
         F: 'static + FnMut(KeyCode, Key, Option<SmolStr>, KeyLocation, bool, ModifiersState),
     {
-        self.on_keyboard_release = Some(self.common.add_user_event(
+        self.on_keyboard_release =
-            "keyup",
+            Some(self.common.add_event("keyup", move |event: KeyboardEvent| {
-            move |event: KeyboardEvent| {
                 if prevent_default {
                     event.prevent_default();
                 }
@@ -278,15 +276,14 @@ impl Canvas {
                     event.repeat(),
                     modifiers,
                 );
-            },
+            }));
-        ));
     }
 
     pub fn on_keyboard_press<F>(&mut self, mut handler: F, prevent_default: bool)
     where
         F: 'static + FnMut(KeyCode, Key, Option<SmolStr>, KeyLocation, bool, ModifiersState),
     {
-        self.on_keyboard_press = Some(self.common.add_user_event(
+        self.on_keyboard_press = Some(self.common.add_transient_event(
             "keydown",
             move |event: KeyboardEvent| {
                 if prevent_default {
@@ -446,12 +443,20 @@ impl Canvas {
         self.animation_frame_handler.on_animation_frame(f)
     }
 
+    pub(crate) fn on_touch_end(&mut self) {
+        self.on_touch_end = Some(self.common.add_transient_event("touchend", |_| {}));
+    }
+
     pub fn request_fullscreen(&self) {
-        self.common.request_fullscreen()
+        self.common.fullscreen_handler.request_fullscreen()
+    }
+
+    pub fn exit_fullscreen(&self) {
+        self.common.fullscreen_handler.exit_fullscreen()
     }
 
     pub fn is_fullscreen(&self) -> bool {
-        self.common.is_fullscreen()
+        self.common.fullscreen_handler.is_fullscreen()
     }
 
     pub fn request_animation_frame(&self) {
@@ -502,7 +507,12 @@ impl Canvas {
         }
     }
 
+    pub(crate) fn transient_activation(&self) {
+        self.common.fullscreen_handler.transient_activation()
+    }
+
     pub fn remove_listeners(&mut self) {
+        self.on_touch_start = None;
         self.on_focus = None;
         self.on_blur = None;
         self.on_keyboard_release = None;
@@ -512,6 +522,9 @@ impl Canvas {
         self.pointer_handler.remove_listeners();
         self.on_resize_scale = None;
         self.on_intersect = None;
+        self.animation_frame_handler.cancel();
+        self.on_touch_end = None;
+        self.common.fullscreen_handler.cancel();
     }
 }
 
@@ -531,7 +544,7 @@ impl Common {
     // The difference between add_event and add_user_event is that the latter has a special meaning
     // for browser security. A user event is a deliberate action by the user (like a mouse or key
     // press) and is the only time things like a fullscreen request may be successfully completed.)
-    pub fn add_user_event<E, F>(
+    pub fn add_transient_event<E, F>(
         &self,
         event_name: &'static str,
         mut handler: F,
@@ -540,37 +553,14 @@ impl Common {
         E: 'static + AsRef<web_sys::Event> + wasm_bindgen::convert::FromWasmAbi,
         F: 'static + FnMut(E),
     {
-        let wants_fullscreen = self.wants_fullscreen.clone();
+        let fullscreen_handler = Rc::downgrade(&self.fullscreen_handler);
-        let canvas = self.raw.clone();
 
         self.add_event(event_name, move |event: E| {
             handler(event);
 
-            if *wants_fullscreen.borrow() {
+            if let Some(fullscreen_handler) = Weak::upgrade(&fullscreen_handler) {
-                fullscreen::request_fullscreen(&canvas).expect("Failed to enter fullscreen");
+                fullscreen_handler.transient_activation()
-                *wants_fullscreen.borrow_mut() = false;
             }
         })
     }
-
-    pub fn request_fullscreen(&self) {
-        // This should return a `Promise`, but Safari v<16.4 is not up-to-date with the spec.
-        match fullscreen::request_fullscreen(&self.raw) {
-            Ok(value) if !value.is_undefined() => {
-                let promise: Promise = value.unchecked_into();
-                let wants_fullscreen = self.wants_fullscreen.clone();
-                wasm_bindgen_futures::spawn_local(async move {
-                    if JsFuture::from(promise).await.is_err() {
-                        *wants_fullscreen.borrow_mut() = true
-                    }
-                });
-            }
-            // We are on Safari v<16.4, let's try again on the next transient activation.
-            _ => *self.wants_fullscreen.borrow_mut() = true,
-        }
-    }
-
-    pub fn is_fullscreen(&self) -> bool {
-        super::is_fullscreen(&self.document, &self.raw)
-    }
 }

src/platform_impl/web/web_sys/fullscreen.rs

@@ -1,13 +1,145 @@
-use once_cell::unsync::OnceCell;
+use std::cell::Cell;
+use std::rc::Rc;
+
+use js_sys::Promise;
+use once_cell::unsync::{Lazy, OnceCell};
+use wasm_bindgen::closure::Closure;
 use wasm_bindgen::prelude::wasm_bindgen;
 use wasm_bindgen::{JsCast, JsValue};
 use web_sys::{Document, Element, HtmlCanvasElement};
 
+use super::EventListenerHandle;
+
 thread_local! {
     static FULLSCREEN_API_SUPPORT: OnceCell<bool> = OnceCell::new();
 }
 
-fn canvas_has_fullscreen_api_support(canvas: &HtmlCanvasElement) -> bool {
+pub struct FullscreenHandler {
+    document: Document,
+    canvas: HtmlCanvasElement,
+    fullscreen_requested: Rc<Cell<bool>>,
+    _fullscreen_change: EventListenerHandle<dyn FnMut()>,
+}
+
+impl FullscreenHandler {
+    pub fn new(document: Document, canvas: HtmlCanvasElement) -> Self {
+        let fullscreen_requested = Rc::new(Cell::new(false));
+        let fullscreen_change = EventListenerHandle::new(
+            canvas.clone(),
+            if has_fullscreen_api_support(&canvas) {
+                "fullscreenchange"
+            } else {
+                "webkitfullscreenchange"
+            },
+            Closure::new({
+                let fullscreen_requested = fullscreen_requested.clone();
+                move || {
+                    // It doesn't matter if the canvas entered or exitted fullscreen mode,
+                    // we don't want to request it again later.
+                    fullscreen_requested.set(false);
+                }
+            }),
+        );
+
+        Self {
+            document,
+            canvas,
+            fullscreen_requested,
+            _fullscreen_change: fullscreen_change,
+        }
+    }
+
+    fn internal_request_fullscreen(&self) {
+        #[wasm_bindgen]
+        extern "C" {
+            type RequestFullscreen;
+
+            #[wasm_bindgen(method, js_name = requestFullscreen)]
+            fn request_fullscreen(this: &RequestFullscreen) -> Promise;
+
+            #[wasm_bindgen(method, js_name = webkitRequestFullscreen)]
+            fn webkit_request_fullscreen(this: &RequestFullscreen);
+        }
+
+        let canvas: &RequestFullscreen = self.canvas.unchecked_ref();
+
+        if has_fullscreen_api_support(&self.canvas) {
+            thread_local! {
+                static REJECT_HANDLER: Lazy<Closure<dyn FnMut(JsValue)>> = Lazy::new(|| Closure::new(|_| ()));
+            }
+            REJECT_HANDLER.with(|handler| {
+                let _ = canvas.request_fullscreen().catch(handler);
+            });
+        } else {
+            canvas.webkit_request_fullscreen();
+        }
+    }
+
+    pub fn request_fullscreen(&self) {
+        if !self.is_fullscreen() {
+            self.internal_request_fullscreen();
+            self.fullscreen_requested.set(true);
+        }
+    }
+
+    pub fn transient_activation(&self) {
+        if self.fullscreen_requested.get() {
+            self.internal_request_fullscreen()
+        }
+    }
+
+    pub fn is_fullscreen(&self) -> bool {
+        #[wasm_bindgen]
+        extern "C" {
+            type FullscreenElement;
+
+            #[wasm_bindgen(method, getter, js_name = webkitFullscreenElement)]
+            fn webkit_fullscreen_element(this: &FullscreenElement) -> Option<Element>;
+        }
+
+        let element = if has_fullscreen_api_support(&self.canvas) {
+            #[allow(clippy::disallowed_methods)]
+            self.document.fullscreen_element()
+        } else {
+            let document: &FullscreenElement = self.document.unchecked_ref();
+            document.webkit_fullscreen_element()
+        };
+
+        match element {
+            Some(element) => {
+                let canvas: &Element = &self.canvas;
+                canvas == &element
+            }
+            None => false,
+        }
+    }
+
+    pub fn exit_fullscreen(&self) {
+        #[wasm_bindgen]
+        extern "C" {
+            type ExitFullscreen;
+
+            #[wasm_bindgen(method, js_name = webkitExitFullscreen)]
+            fn webkit_exit_fullscreen(this: &ExitFullscreen);
+        }
+
+        if has_fullscreen_api_support(&self.canvas) {
+            #[allow(clippy::disallowed_methods)]
+            self.document.exit_fullscreen()
+        } else {
+            let document: &ExitFullscreen = self.document.unchecked_ref();
+            document.webkit_exit_fullscreen()
+        }
+
+        self.fullscreen_requested.set(false);
+    }
+
+    pub fn cancel(&self) {
+        self.fullscreen_requested.set(false);
+    }
+}
+
+fn has_fullscreen_api_support(canvas: &HtmlCanvasElement) -> bool {
     FULLSCREEN_API_SUPPORT.with(|support| {
         *support.get_or_init(|| {
             #[wasm_bindgen]
@@ -23,77 +155,3 @@ fn canvas_has_fullscreen_api_support(canvas: &HtmlCanvasElement) -> bool {
         })
     })
 }
-
-fn document_has_fullscreen_api_support(document: &Document) -> bool {
-    FULLSCREEN_API_SUPPORT.with(|support| {
-        *support.get_or_init(|| {
-            #[wasm_bindgen]
-            extern "C" {
-                type DocumentFullScreenApiSupport;
-
-                #[wasm_bindgen(method, getter, js_name = exitFullscreen)]
-                fn has_exit_fullscreen(this: &DocumentFullScreenApiSupport) -> JsValue;
-            }
-
-            let support: &DocumentFullScreenApiSupport = document.unchecked_ref();
-            !support.has_exit_fullscreen().is_undefined()
-        })
-    })
-}
-
-pub fn request_fullscreen(canvas: &HtmlCanvasElement) -> Result<JsValue, JsValue> {
-    #[wasm_bindgen]
-    extern "C" {
-        type RequestFullscreen;
-
-        #[wasm_bindgen(catch, method, js_name = requestFullscreen)]
-        fn request_fullscreen(this: &RequestFullscreen) -> Result<JsValue, JsValue>;
-
-        #[wasm_bindgen(catch, method, js_name = webkitRequestFullscreen)]
-        fn webkit_request_fullscreen(this: &RequestFullscreen) -> Result<JsValue, JsValue>;
-    }
-
-    let element: &RequestFullscreen = canvas.unchecked_ref();
-
-    if canvas_has_fullscreen_api_support(canvas) {
-        element.request_fullscreen()
-    } else {
-        element.webkit_request_fullscreen()
-    }
-}
-
-pub fn exit_fullscreen(document: &Document) {
-    #[wasm_bindgen]
-    extern "C" {
-        type ExitFullscreen;
-
-        #[wasm_bindgen(method, js_name = webkitExitFullscreen)]
-        fn webkit_exit_fullscreen(this: &ExitFullscreen);
-    }
-
-    if document_has_fullscreen_api_support(document) {
-        #[allow(clippy::disallowed_methods)]
-        document.exit_fullscreen()
-    } else {
-        let document: &ExitFullscreen = document.unchecked_ref();
-        document.webkit_exit_fullscreen()
-    }
-}
-
-pub fn fullscreen_element(document: &Document) -> Option<Element> {
-    #[wasm_bindgen]
-    extern "C" {
-        type FullscreenElement;
-
-        #[wasm_bindgen(method, getter, js_name = webkitFullscreenElement)]
-        fn webkit_fullscreen_element(this: &FullscreenElement) -> Option<Element>;
-    }
-
-    if document_has_fullscreen_api_support(document) {
-        #[allow(clippy::disallowed_methods)]
-        document.fullscreen_element()
-    } else {
-        let document: &FullscreenElement = document.unchecked_ref();
-        document.webkit_fullscreen_element()
-    }
-}

src/platform_impl/web/web_sys/mod.rs

@@ -18,17 +18,13 @@ pub use self::schedule::Schedule;
 use crate::dpi::{LogicalPosition, LogicalSize};
 use wasm_bindgen::closure::Closure;
 use web_sys::{
-    CssStyleDeclaration, Document, Element, HtmlCanvasElement, PageTransitionEvent, VisibilityState,
+    CssStyleDeclaration, Document, HtmlCanvasElement, PageTransitionEvent, VisibilityState,
 };
 
 pub fn throw(msg: &str) {
     wasm_bindgen::throw_str(msg);
 }
 
-pub fn exit_fullscreen(document: &Document) {
-    fullscreen::exit_fullscreen(document);
-}
-
 pub struct PageTransitionEventHandle {
     _show_listener: event_handle::EventListenerHandle<dyn FnMut(PageTransitionEvent)>,
     _hide_listener: event_handle::EventListenerHandle<dyn FnMut(PageTransitionEvent)>,
@@ -175,16 +171,6 @@ pub fn set_canvas_style_property(raw: &HtmlCanvasElement, property: &str, value:
         .unwrap_or_else(|err| panic!("error: {err:?}\nFailed to set {property}"))
 }
 
-pub fn is_fullscreen(document: &Document, canvas: &HtmlCanvasElement) -> bool {
-    match fullscreen::fullscreen_element(document) {
-        Some(elem) => {
-            let canvas: &Element = canvas;
-            canvas == &elem
-        }
-        None => false,
-    }
-}
-
 pub fn is_dark_mode(window: &web_sys::Window) -> Option<bool> {
     window
         .match_media("(prefers-color-scheme: dark)")

src/platform_impl/web/web_sys/pointer.rs

@@ -80,7 +80,7 @@ impl PointerHandler {
         T: 'static + FnMut(ModifiersState, i32, PhysicalPosition<f64>, Force),
     {
         let window = canvas_common.window.clone();
-        self.on_pointer_release = Some(canvas_common.add_user_event(
+        self.on_pointer_release = Some(canvas_common.add_transient_event(
             "pointerup",
             move |event: PointerEvent| {
                 let modifiers = event::mouse_modifiers(&event);
@@ -118,7 +118,7 @@ impl PointerHandler {
     {
         let window = canvas_common.window.clone();
         let canvas = canvas_common.raw.clone();
-        self.on_pointer_press = Some(canvas_common.add_user_event(
+        self.on_pointer_press = Some(canvas_common.add_transient_event(
             "pointerdown",
             move |event: PointerEvent| {
                 if prevent_default {

src/platform_impl/web/window.rs

@@ -7,7 +7,7 @@ use crate::window::{
 };
 
 use raw_window_handle::{RawDisplayHandle, RawWindowHandle, WebDisplayHandle, WebWindowHandle};
-use web_sys::{Document, HtmlCanvasElement};
+use web_sys::HtmlCanvasElement;
 
 use super::r#async::Dispatcher;
 use super::{backend, monitor::MonitorHandle, EventLoopWindowTarget, Fullscreen};
@@ -25,7 +25,6 @@ pub struct Window {
 pub struct Inner {
     id: WindowId,
     pub window: web_sys::Window,
-    document: Document,
     canvas: Rc<RefCell<backend::Canvas>>,
     previous_pointer: RefCell<&'static str>,
     destroy_fn: Option<Box<dyn FnOnce()>>,
@@ -57,7 +56,6 @@ impl Window {
         let inner = Inner {
             id,
             window: window.clone(),
-            document: document.clone(),
             canvas,
             previous_pointer: RefCell::new("auto"),
             destroy_fn: Some(destroy_fn),
@@ -282,10 +280,12 @@ impl Inner {
 
     #[inline]
     pub(crate) fn set_fullscreen(&self, fullscreen: Option<Fullscreen>) {
+        let canvas = &self.canvas.borrow();
+
         if fullscreen.is_some() {
-            self.canvas.borrow().request_fullscreen();
+            canvas.request_fullscreen();
-        } else if self.canvas.borrow().is_fullscreen() {
+        } else {
-            backend::exit_fullscreen(&self.document);
+            canvas.exit_fullscreen()
         }
     }