Add support for raw-window-handle

Add a `rwh_06` feature to the Rust API crates, which adds support for version 0.6 of rwh to slint::Window, by delegation to the backend.

HasDisplayHandle could also be provided on the backend, but that can be
done separately if needed.

Fixes #877

Cargo.toml

@@ -140,6 +140,8 @@ strum = { version = "0.26.1", default-features = false, features = ["derive"] }
 toml_edit = { version = "0.22.7" }
 cfg_aliases = { version = "0.2.0" }
 
+rwh_06 = { package = "raw-window-handle", version = "0.6", features = ["alloc"] }
+
 [profile.release]
 lto = true
 panic = "abort"

api/rs/slint/Cargo.toml

@@ -78,6 +78,10 @@ unsafe-single-threaded = ["i-slint-core/unsafe-single-threaded"]
 ## APIs to support screen readers and other assistive technologies.
 accessibility = ["i-slint-backend-selector/accessibility"]
 
+### Enable integration with raw-window-handle version 0.6. This provides a HasWindowHandle implementation
+### for slint::Window.
+rwh_06 = ["i-slint-core/rwh_06", "i-slint-backend-selector/rwh_06"]
+
 #! ### Backends
 
 #! Slint needs a backend that will act as liaison between Slint and the OS.

internal/backends/selector/Cargo.toml

@@ -32,6 +32,8 @@ renderer-software = ["i-slint-backend-winit?/renderer-software", "i-slint-core/s
 rtti = ["i-slint-core/rtti", "i-slint-backend-qt?/rtti"]
 accessibility = ["i-slint-backend-winit?/accessibility"]
 
+rwh_06 = ["i-slint-backend-winit?/rwh_06"]
+
 # note that default enable the i-slint-backend-qt, but not its enable feature
 default = ["i-slint-backend-qt", "backend-winit"]
 

internal/backends/winit/Cargo.toml

@@ -27,6 +27,7 @@ renderer-skia-opengl = ["renderer-skia", "i-slint-renderer-skia/opengl"]
 renderer-skia-vulkan = ["renderer-skia", "i-slint-renderer-skia/vulkan"]
 renderer-software = ["dep:softbuffer", "dep:imgref", "dep:rgb", "i-slint-core/software-renderer-systemfonts", "dep:bytemuck", "winit/rwh_05"]
 accessibility = ["dep:accesskit", "dep:accesskit_winit"]
+rwh_06 = ["dep:rwh_06", "winit/rwh_06"]
 default = []
 
 [dependencies]
@@ -58,6 +59,8 @@ imgref = { version = "1.6.1", optional = true }
 rgb = { version = "0.8.27", optional = true }
 bytemuck = { workspace = true, optional = true, features = ["derive"] }
 
+rwh_06 = { workspace = true, optional = true }
+
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 web-sys = { version = "0.3", features=["HtmlInputElement", "HtmlCanvasElement", "Window", "Document", "Event", "KeyboardEvent", "InputEvent", "CompositionEvent", "DomStringMap", "ClipboardEvent", "DataTransfer"] }
 wasm-bindgen = { version = "0.2" }
@@ -77,7 +80,7 @@ cocoa = { version = "0.25.0" }
 cfg_aliases = { workspace = true }
 
 [dev-dependencies]
-slint = { path = "../../../api/rs/slint", default-features = false, features = ["std", "compat-1-2", "backend-winit", "renderer-software"] }
+slint = { path = "../../../api/rs/slint", default-features = false, features = ["std", "compat-1-2", "backend-winit", "renderer-software", "rwh_06"] }
 
 [package.metadata.docs.rs]
 features = ["wayland", "renderer-software"]

internal/backends/winit/lib.rs

@@ -416,3 +416,17 @@ fn test_window_accessor() {
     let slint_window = app.window();
     assert!(slint_window.has_winit_window());
 }
+
+// Sorry, can't test with rust test harness and multiple threads.
+#[cfg(not(any(target_arch = "wasm32", target_os = "macos", target_os = "ios")))]
+#[test]
+fn test_rwh() {
+    slint::platform::set_platform(Box::new(crate::Backend::new().unwrap())).unwrap();
+
+    use testui::*;
+    let app = App::new().unwrap();
+    let slint_window = app.window();
+    use rwh_06::{HasDisplayHandle, HasWindowHandle};
+    assert!(slint_window.window_handle().is_ok());
+    assert!(slint_window.display_handle().is_ok());
+}

internal/backends/winit/winitwindowadapter.rs

@@ -617,6 +617,16 @@ impl WindowAdapter for WinitWindowAdapter {
     fn internal(&self, _: corelib::InternalToken) -> Option<&dyn WindowAdapterInternal> {
         Some(self)
     }
+
+    #[cfg(feature = "rwh_06")]
+    fn window_handle_06(&self) -> Result<rwh_06::WindowHandle<'_>, rwh_06::HandleError> {
+        rwh_06::HasWindowHandle::window_handle(&self.winit_window)
+    }
+
+    #[cfg(feature = "rwh_06")]
+    fn display_handle_06(&self) -> Result<rwh_06::DisplayHandle<'_>, rwh_06::HandleError> {
+        rwh_06::HasDisplayHandle::display_handle(&self.winit_window)
+    }
 }
 
 impl WindowAdapterInternal for WinitWindowAdapter {

internal/core/Cargo.toml

@@ -24,7 +24,7 @@ libm = ["num-traits/libm", "euclid/libm"]
 # Allow the viewer to query at runtime information about item types
 rtti = []
 # Use the standard library
-std = ["euclid/std", "once_cell/std", "scoped-tls-hkt", "lyon_path", "lyon_algorithms", "lyon_geom", "lyon_extra", "dep:web-time", "image-decoders", "svg"]
+std = ["euclid/std", "once_cell/std", "scoped-tls-hkt", "lyon_path", "lyon_algorithms", "lyon_geom", "lyon_extra", "dep:web-time", "image-decoders", "svg", "rwh_06?/std"]
 # Unsafe feature meaning that there is only one core running and all thread_local are static.
 # You can only enable this feature if you are sure that any API of this crate is only called
 # from a single core, and not in a interrupt or signal handler.
@@ -44,6 +44,8 @@ box-shadow-cache = []
 
 shared-fontdb = ["i-slint-common/shared-fontdb"]
 
+rwh_06 = ["dep:rwh_06"]
+
 default = ["std", "unicode"]
 
 [dependencies]
@@ -86,6 +88,8 @@ resvg = { workspace = true, optional = true }
 fontdb = { workspace = true, optional = true }
 serde = { version = "1.0.163", features = ["derive"], optional = true }
 
+rwh_06 = { workspace = true, optional = true }
+
 [target.'cfg(target_family = "unix")'.dependencies]
 gettext-rs = { version = "0.7", optional = true, features = ["gettext-system"] }
 
@@ -107,4 +111,4 @@ ttf-parser = "0.20.0"
 fontdb = { workspace = true, default-features = true }
 serde_json = "1.0.96"
 tiny-skia = "0.11.0"
-tokio = { version = "1.35", features = ["rt-multi-thread"] }
+tokio = { version = "1.35", features = ["rt-multi-thread"] }

internal/core/api.rs

@@ -573,6 +573,36 @@ impl Window {
     }
 }
 
+#[cfg(feature = "rwh_06")]
+impl rwh_06::HasWindowHandle for Window {
+    fn window_handle<'a>(&'a self) -> Result<rwh_06::WindowHandle<'a>, rwh_06::HandleError> {
+        let adapter = self.0.window_adapter();
+        let wh = adapter.window_handle_06()?;
+        // Safety: The Rc<dyn WindowAdapter> owns this slint::Window (&self). Therefore the caller of
+        // this function must also have a strong reference to the window adapter. The adapter above
+        // was created from a self weak and is the same as the Rc<dyn WindowAdapter> of the caller.
+        #[allow(unsafe_code)]
+        Ok(unsafe {
+            core::mem::transmute::<rwh_06::WindowHandle<'_>, rwh_06::WindowHandle<'a>>(wh)
+        })
+    }
+}
+
+#[cfg(feature = "rwh_06")]
+impl rwh_06::HasDisplayHandle for Window {
+    fn display_handle<'a>(&'a self) -> Result<rwh_06::DisplayHandle<'a>, rwh_06::HandleError> {
+        let adapter = self.0.window_adapter();
+        let wh = adapter.display_handle_06()?;
+        // Safety: The Rc<dyn WindowAdapter> owns this slint::Window (&self). Therefore the caller of
+        // this function must also have a strong reference to the window adapter. The adapter above
+        // was created from a self weak and is the same as the Rc<dyn WindowAdapter> of the caller.
+        #[allow(unsafe_code)]
+        Ok(unsafe {
+            core::mem::transmute::<rwh_06::DisplayHandle<'_>, rwh_06::DisplayHandle<'a>>(wh)
+        })
+    }
+}
+
 pub use crate::SharedString;
 
 /// This trait is used to obtain references to global singletons exported in `.slint`

internal/core/window.rs

@@ -137,6 +137,18 @@ pub trait WindowAdapter {
     fn internal(&self, _: crate::InternalToken) -> Option<&dyn WindowAdapterInternal> {
         None
     }
+
+    /// Re-implement this to support exposing raw window handles (version 0.6).
+    #[cfg(feature = "rwh_06")]
+    fn window_handle_06(&self) -> Result<rwh_06::WindowHandle<'_>, rwh_06::HandleError> {
+        Err(rwh_06::HandleError::NotSupported)
+    }
+
+    /// Re-implement this to support exposing raw display handles (version 0.6).
+    #[cfg(feature = "rwh_06")]
+    fn display_handle_06(&self) -> Result<rwh_06::DisplayHandle<'_>, rwh_06::HandleError> {
+        Err(rwh_06::HandleError::NotSupported)
+    }
 }
 
 /// Implementation details behind [`WindowAdapter`], but since this

internal/interpreter/Cargo.toml

@@ -107,6 +107,10 @@ renderer-winit-software = ["renderer-software"]
 ## APIs to support screen readers and other assistive technologies.
 accessibility = ["i-slint-backend-selector/accessibility"]
 
+### Enable integration with raw-window-handle version 0.6. This provides a HasWindowHandle implementation
+### for slint::Window.
+rwh_06 = ["i-slint-core/rwh_06", "i-slint-backend-selector/rwh_06"]
+
 ## Features used internally by Slint tooling that are not stable and come without
 ## any stability guarantees whatsoever.
 internal = []