Web: Updates the canvas to disable the contextmenu event and double click text selection

.gitignore

@@ -8,3 +8,4 @@ rls/
 *.js
 #*#
 .DS_Store
+.idea/

CHANGELOG.md

@@ -11,6 +11,8 @@ And please only add new entries to the top of this list, right below the `# Unre
 - **Breaking:** `CursorIcon` is now used from the `cursor-icon` crate.
 - **Breaking:** `CursorIcon::Hand` is now named `CursorIcon::Pointer`.
 - **Breaking:** `CursorIcon::Arrow` was removed.
+- **Breaking:** Web: Canvases will now capture the contextmenu if prevent_default is enabled so they don't interfere with right click pointer events.
+- **Breaking:** Web: Canvases will now have `user-select: none` to prevent double clicks from selecting text outside the canvas.
 - On Wayland, fix maximized startup not taking full size on GNOME.
 - On Wayland, fix initial window size not restored for maximized/fullscreened on startup window.
 - On Wayland, `Window::outer_size` now accounts for **client side** decorations.

src/platform_impl/web/event_loop/window_target.rs

@@ -85,6 +85,8 @@ impl<T> EventLoopWindowTarget<T> {
             });
         });
 
+        canvas.on_contextmenu(prevent_default);
+
         let runner = self.runner.clone();
         canvas.on_keyboard_press(
             move |scancode, virtual_keycode, modifiers| {

src/platform_impl/web/web_sys/canvas.rs

@@ -27,6 +27,7 @@ pub struct Canvas {
     on_touch_end: Option<EventListenerHandle<dyn FnMut(Event)>>,
     on_focus: Option<EventListenerHandle<dyn FnMut(FocusEvent)>>,
     on_blur: Option<EventListenerHandle<dyn FnMut(FocusEvent)>>,
+    on_contextmenu: Option<EventListenerHandle<dyn FnMut(Event)>>,
     on_keyboard_release: Option<EventListenerHandle<dyn FnMut(KeyboardEvent)>>,
     on_keyboard_press: Option<EventListenerHandle<dyn FnMut(KeyboardEvent)>>,
     on_received_character: Option<EventListenerHandle<dyn FnMut(KeyboardEvent)>>,
@@ -72,6 +73,12 @@ impl Canvas {
                 .map_err(|_| os_error!(OsError("Failed to set a tabindex".to_owned())))?;
         }
 
+        // Prevent double clicks on the canvas from causing text selections elsewhere on the page
+        // Calling preventDefault within a dblclick/pointerdown handler on the canvas does not work.
+        for prefix in ["", "-webkit-", "-moz-", "-ms-"] {
+            super::set_canvas_style_property(&canvas, &format!("{}user-select", prefix), "none");
+        }
+
         let mouse_state = if has_pointer_event() {
             MouseState::HasPointerEvent(pointer_handler::PointerHandler::new())
         } else {
@@ -87,6 +94,7 @@ impl Canvas {
             on_touch_end: None,
             on_blur: None,
             on_focus: None,
+            on_contextmenu: None,
             on_keyboard_release: None,
             on_keyboard_press: None,
             on_received_character: None,
@@ -172,6 +180,19 @@ impl Canvas {
         }));
     }
 
+    pub fn on_contextmenu(&mut self, prevent_default: bool) {
+        // Setup a handler to prevent the default context menu from appearing.
+        //
+        // contextmenu events normally occur on right click and can interfere with the sequence of
+        // pointer events, e.g. https://github.com/rust-windowing/winit/issues/2608.
+        self.on_contextmenu = Some(self.common.add_event("contextmenu", move |event: Event| {
+            if prevent_default {
+                trace!("contextmenu event ignored because prevent_default is true");
+                event.prevent_default();
+            }
+        }));
+    }
+
     pub fn on_keyboard_release<F>(&mut self, mut handler: F, prevent_default: bool)
     where
         F: 'static + FnMut(ScanCode, Option<VirtualKeyCode>, ModifiersState),
@@ -364,6 +385,7 @@ impl Canvas {
     pub fn remove_listeners(&mut self) {
         self.on_focus = None;
         self.on_blur = None;
+        self.on_contextmenu = None;
         self.on_keyboard_release = None;
         self.on_keyboard_press = None;
         self.on_received_character = None;