feat: Add an owned display handle type

This was supposed to be rolled out with the rwh v0.6 update, but it
was left behind for some reason. I've added this type back.

Signed-off-by: John Nunley <dev@notgull.net>

CHANGELOG.md

@@ -30,6 +30,7 @@ Unreleased` header.
 - **Breaking:** Rename `VideoMode` to `VideoModeHandle` to represent that it doesn't hold static data.
 - **Breaking:** No longer export `platform::x11::XNotSupported`.
 - **Breaking:** Renamed `platform::x11::XWindowType` to `platform::x11::WindowType`.
+- Add the `OwnedDisplayHandle` type for allowing safe display handle usage outside of trivial cases.
 
 # 0.29.10
 

src/event_loop.rs

@@ -367,6 +367,15 @@ impl EventLoopWindowTarget {
     pub fn exiting(&self) -> bool {
         self.p.exiting()
     }
+
+    /// Gets a persistent reference to the underlying platform display.
+    ///
+    /// See the [`OwnedDisplayHandle`] type for more information.
+    pub fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle {
+            platform: self.p.owned_display_handle(),
+        }
+    }
 }
 
 #[cfg(feature = "rwh_06")]
@@ -386,6 +395,52 @@ unsafe impl rwh_05::HasRawDisplayHandle for EventLoopWindowTarget {
     }
 }
 
+/// A proxy for the underlying display handle.
+///
+/// The purpose of this type is to provide a cheaply clonable handle to the underlying
+/// display handle. This is often used by graphics APIs to connect to the underlying APIs.
+/// It is difficult to keep a handle to the [`EventLoop`] type or the [`EventLoopWindowTarget`]
+/// type. In contrast, this type involves no lifetimes and can be persisted for as long as
+/// needed.
+///
+/// For all platforms, this is one of the following:
+///
+/// - A zero-sized type that is likely optimized out.
+/// - A reference-counted pointer to the underlying type.
+#[derive(Clone)]
+pub struct OwnedDisplayHandle {
+    #[cfg_attr(not(any(feature = "rwh_05", feature = "rwh_06")), allow(dead_code))]
+    platform: platform_impl::OwnedDisplayHandle,
+}
+
+impl fmt::Debug for OwnedDisplayHandle {
+    #[inline]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OwnedDisplayHandle").finish_non_exhaustive()
+    }
+}
+
+#[cfg(feature = "rwh_06")]
+impl rwh_06::HasDisplayHandle for OwnedDisplayHandle {
+    #[inline]
+    fn display_handle(&self) -> Result<rwh_06::DisplayHandle<'_>, rwh_06::HandleError> {
+        let raw = self.platform.raw_display_handle_rwh_06()?;
+
+        // SAFETY: The underlying display handle should be safe.
+        let handle = unsafe { rwh_06::DisplayHandle::borrow_raw(raw) };
+
+        Ok(handle)
+    }
+}
+
+#[cfg(feature = "rwh_05")]
+unsafe impl rwh_05::HasRawDisplayHandle for OwnedDisplayHandle {
+    #[inline]
+    fn raw_display_handle(&self) -> rwh_05::RawDisplayHandle {
+        self.platform.raw_display_handle_rwh_05()
+    }
+}
+
 /// Used to send custom events to [`EventLoop`].
 pub struct EventLoopProxy<T: 'static> {
     event_loop_proxy: platform_impl::EventLoopProxy<T>,

src/platform_impl/android/mod.rs

@@ -721,6 +721,29 @@ impl EventLoopWindowTarget {
     pub(crate) fn exiting(&self) -> bool {
         self.exit.get()
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::AndroidDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::AndroidDisplayHandle::new().into())
+    }
 }
 
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]

src/platform_impl/ios/event_loop.rs

@@ -83,6 +83,29 @@ impl EventLoopWindowTarget {
     pub(crate) fn exiting(&self) -> bool {
         false
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::UiKitDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::UiKitDisplayHandle::new().into())
+    }
 }
 
 pub struct EventLoop<T: 'static> {

src/platform_impl/ios/mod.rs

@@ -70,7 +70,8 @@ use std::fmt;
 
 pub(crate) use self::{
     event_loop::{
-        EventLoop, EventLoopProxy, EventLoopWindowTarget, PlatformSpecificEventLoopAttributes,
+        EventLoop, EventLoopProxy, EventLoopWindowTarget, OwnedDisplayHandle,
+        PlatformSpecificEventLoopAttributes,
     },
     monitor::{MonitorHandle, VideoModeHandle},
     window::{PlatformSpecificWindowBuilderAttributes, Window, WindowId},

src/platform_impl/linux/mod.rs

@@ -902,6 +902,15 @@ impl EventLoopWindowTarget {
         x11_or_wayland!(match self; Self(evlp) => evlp.exiting())
     }
 
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        match self {
+            #[cfg(x11_platform)]
+            Self::X(conn) => OwnedDisplayHandle::X(conn.x_connection().clone()),
+            #[cfg(wayland_platform)]
+            Self::Wayland(conn) => OwnedDisplayHandle::Wayland(conn.connection.clone()),
+        }
+    }
+
     fn set_exit_code(&self, code: i32) {
         x11_or_wayland!(match self; Self(evlp) => evlp.set_exit_code(code))
     }
@@ -911,6 +920,67 @@ impl EventLoopWindowTarget {
     }
 }
 
+#[derive(Clone)]
+#[allow(dead_code)]
+pub(crate) enum OwnedDisplayHandle {
+    #[cfg(x11_platform)]
+    X(Arc<XConnection>),
+    #[cfg(wayland_platform)]
+    Wayland(wayland_client::Connection),
+}
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        match self {
+            #[cfg(x11_platform)]
+            Self::X(xconn) => {
+                let mut xlib_handle = rwh_05::XlibDisplayHandle::empty();
+                xlib_handle.display = xconn.display.cast();
+                xlib_handle.screen = xconn.default_screen_index() as _;
+                xlib_handle.into()
+            }
+
+            #[cfg(wayland_platform)]
+            Self::Wayland(conn) => {
+                use sctk::reexports::client::Proxy;
+
+                let mut wayland_handle = rwh_05::WaylandDisplayHandle::empty();
+                wayland_handle.display = conn.display().id().as_ptr() as *mut _;
+                wayland_handle.into()
+            }
+        }
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        use std::ptr::NonNull;
+
+        match self {
+            #[cfg(x11_platform)]
+            Self::X(xconn) => Ok(rwh_06::XlibDisplayHandle::new(
+                NonNull::new(xconn.display.cast()),
+                xconn.default_screen_index() as _,
+            )
+            .into()),
+
+            #[cfg(wayland_platform)]
+            Self::Wayland(conn) => {
+                use sctk::reexports::client::Proxy;
+
+                Ok(rwh_06::WaylandDisplayHandle::new(
+                    NonNull::new(conn.display().id().as_ptr().cast()).unwrap(),
+                )
+                .into())
+            }
+        }
+    }
+}
+
 /// Returns the minimum `Option<Duration>`, taking into account that `None`
 /// equates to an infinite timeout, not a zero timeout (so can't just use
 /// `Option::min`)

src/platform_impl/macos/event_loop.rs

@@ -128,6 +128,10 @@ impl EventLoopWindowTarget {
     pub(crate) fn exiting(&self) -> bool {
         self.delegate.exiting()
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
 }
 
 impl EventLoopWindowTarget {
@@ -460,6 +464,25 @@ impl<T> EventLoop<T> {
     }
 }
 
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::AppKitDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::AppKitDisplayHandle::new().into())
+    }
+}
+
 pub(super) fn stop_app_immediately(app: &NSApplication) {
     autoreleasepool(|_| {
         app.stop(None);

src/platform_impl/macos/mod.rs

@@ -19,7 +19,8 @@ use std::fmt;
 pub(crate) use self::{
     event::{physicalkey_to_scancode, scancode_to_physicalkey, KeyEventExtra},
     event_loop::{
-        EventLoop, EventLoopProxy, EventLoopWindowTarget, PlatformSpecificEventLoopAttributes,
+        EventLoop, EventLoopProxy, EventLoopWindowTarget, OwnedDisplayHandle,
+        PlatformSpecificEventLoopAttributes,
     },
     monitor::{MonitorHandle, VideoModeHandle},
     window::WindowId,

src/platform_impl/orbital/event_loop.rs

@@ -771,4 +771,27 @@ impl EventLoopWindowTarget {
     pub(crate) fn exiting(&self) -> bool {
         self.exit.get()
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::OrbitalDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::OrbitalDisplayHandle::new().into())
+    }
 }

src/platform_impl/orbital/mod.rs

@@ -6,7 +6,9 @@ use std::sync::Arc;
 
 use crate::dpi::{PhysicalPosition, PhysicalSize};
 
-pub use self::event_loop::{EventLoop, EventLoopProxy, EventLoopWindowTarget};
+pub(crate) use self::event_loop::{
+    EventLoop, EventLoopProxy, EventLoopWindowTarget, OwnedDisplayHandle,
+};
 mod event_loop;
 
 pub use self::window::Window;

src/platform_impl/web/event_loop/mod.rs

@@ -12,8 +12,8 @@ pub(crate) mod runner;
 mod state;
 mod window_target;
 
-pub use proxy::EventLoopProxy;
-pub use window_target::EventLoopWindowTarget;
+pub(crate) use proxy::EventLoopProxy;
+pub(crate) use window_target::{EventLoopWindowTarget, OwnedDisplayHandle};
 
 pub struct EventLoop<T: 'static> {
     elw: RootEventLoopWindowTarget,

src/platform_impl/web/event_loop/window_target.rs

@@ -704,4 +704,27 @@ impl EventLoopWindowTarget {
     pub(crate) fn waker(&self) -> Waker<Weak<Execution>> {
         self.runner.waker()
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::WebDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::WebDisplayHandle::new().into())
+    }
 }

src/platform_impl/web/mod.rs

@@ -33,7 +33,8 @@ mod backend;
 pub use self::device::DeviceId;
 pub use self::error::OsError;
 pub(crate) use self::event_loop::{
-    EventLoop, EventLoopProxy, EventLoopWindowTarget, PlatformSpecificEventLoopAttributes,
+    EventLoop, EventLoopProxy, EventLoopWindowTarget, OwnedDisplayHandle,
+    PlatformSpecificEventLoopAttributes,
 };
 pub use self::monitor::{MonitorHandle, VideoModeHandle};
 pub use self::window::{PlatformSpecificWindowBuilderAttributes, Window, WindowId};

src/platform_impl/windows/event_loop.rs

@@ -584,11 +584,34 @@ impl EventLoopWindowTarget {
         self.runner_shared.clear_exit();
     }
 
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+
     fn exit_code(&self) -> Option<i32> {
         self.runner_shared.exit_code()
     }
 }
 
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::WindowsDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::WindowsDisplayHandle::new().into())
+    }
+}
+
 /// Returns the id of the main thread.
 ///
 /// Windows has no real API to check if the current executing thread is the "main thread", unlike

src/platform_impl/windows/mod.rs

@@ -8,7 +8,8 @@ use windows_sys::Win32::{
 
 pub(crate) use self::{
     event_loop::{
-        EventLoop, EventLoopProxy, EventLoopWindowTarget, PlatformSpecificEventLoopAttributes,
+        EventLoop, EventLoopProxy, EventLoopWindowTarget, OwnedDisplayHandle,
+        PlatformSpecificEventLoopAttributes,
     },
     icon::{SelectedCursor, WinIcon},
     keyboard::{physicalkey_to_scancode, scancode_to_physicalkey},