Add a way to embed the X11 window into another

Signed-off-by: John Nunley <dev@notgull.net>
Tested-by: Kirill Chibisov <contact@kchibisov.com>

CHANGELOG.md

@@ -60,6 +60,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 - **Breaking** `MainEventsCleared` removed ([#2900](https://github.com/rust-windowing/winit/issues/2900))
 - Added `AboutToWait` event which is emitted when the event loop is about to block and wait for new events ([#2900](https://github.com/rust-windowing/winit/issues/2900))
 - **Breaking:** `with_x11_visual` now takes the visual ID instead of the bare pointer.
+- On X11, add a `with_embedded_parent_window` function to the window builder to allow embedding a window into another window.
 
 # 0.29.0-beta.0
 

examples/x11_embed.rs

@@ -0,0 +1,69 @@
+//! A demonstration of embedding a winit window in an existing X11 application.
+
+#[cfg(x11_platform)]
+#[path = "util/fill.rs"]
+mod fill;
+
+#[cfg(x11_platform)]
+mod imple {
+    use super::fill;
+    use simple_logger::SimpleLogger;
+    use winit::{
+        event::{Event, WindowEvent},
+        event_loop::EventLoop,
+        platform::x11::WindowBuilderExtX11,
+        window::WindowBuilder,
+    };
+
+    pub(super) fn entry() -> Result<(), Box<dyn std::error::Error>> {
+        // First argument should be a 32-bit X11 window ID.
+        let parent_window_id = std::env::args()
+            .nth(1)
+            .ok_or("Expected a 32-bit X11 window ID as the first argument.")?
+            .parse::<u32>()?;
+
+        SimpleLogger::new().init().unwrap();
+        let event_loop = EventLoop::new();
+
+        let window = WindowBuilder::new()
+            .with_title("An embedded window!")
+            .with_inner_size(winit::dpi::LogicalSize::new(128.0, 128.0))
+            .with_embed_parent_window(parent_window_id)
+            .build(&event_loop)
+            .unwrap();
+
+        event_loop.run(move |event, _, control_flow| {
+            control_flow.set_wait();
+
+            match event {
+                Event::WindowEvent {
+                    event: WindowEvent::CloseRequested,
+                    window_id,
+                } if window_id == window.id() => control_flow.set_exit(),
+                Event::AboutToWait => {
+                    window.request_redraw();
+                }
+                Event::RedrawRequested(_) => {
+                    // Notify the windowing system that we'll be presenting to the window.
+                    window.pre_present_notify();
+                    fill::fill_window(&window);
+                }
+                _ => (),
+            }
+        })?;
+
+        Ok(())
+    }
+}
+
+#[cfg(not(x11_platform))]
+mod imple {
+    pub(super) fn entry() -> Result<(), Box<dyn std::error::Error>> {
+        println!("This example is only supported on X11 platforms.");
+        Ok(())
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    imple::entry()
+}

src/platform/x11.rs

@@ -20,6 +20,9 @@ pub type XlibErrorHook =
 /// A unique identifer for an X11 visual.
 pub type XVisualID = u32;
 
+/// A unique identifier for an X11 window.
+pub type XWindow = u32;
+
 /// Hook to winit's xlib error handling callback.
 ///
 /// This method is provided as a safe way to handle the errors comming from X11
@@ -118,18 +121,35 @@ pub trait WindowBuilderExtX11 {
     /// WindowBuilder::new().with_base_size(PhysicalSize::new(400, 200));
     /// ```
     fn with_base_size<S: Into<Size>>(self, base_size: S) -> Self;
+
+    /// Embed this window into another parent window.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use winit::window::WindowBuilder;
+    /// use winit::platform::x11::{XWindow, WindowBuilderExtX11};
+    /// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+    /// let event_loop = winit::event_loop::EventLoop::new();
+    /// let parent_window_id = std::env::args().nth(1).unwrap().parse::<XWindow>()?;
+    /// let window = WindowBuilder::new()
+    ///     .with_embed_parent_window(parent_window_id)
+    ///     .build(&event_loop)?;
+    /// # Ok(()) }
+    /// ```
+    fn with_embed_parent_window(self, parent_window_id: XWindow) -> Self;
 }
 
 impl WindowBuilderExtX11 for WindowBuilder {
     #[inline]
     fn with_x11_visual(mut self, visual_id: XVisualID) -> Self {
-        self.platform_specific.visual_id = Some(visual_id);
+        self.platform_specific.x11.visual_id = Some(visual_id);
         self
     }
 
     #[inline]
     fn with_x11_screen(mut self, screen_id: i32) -> Self {
-        self.platform_specific.screen_id = Some(screen_id);
+        self.platform_specific.x11.screen_id = Some(screen_id);
         self
     }
 
@@ -141,19 +161,25 @@ impl WindowBuilderExtX11 for WindowBuilder {
 
     #[inline]
     fn with_override_redirect(mut self, override_redirect: bool) -> Self {
-        self.platform_specific.override_redirect = override_redirect;
+        self.platform_specific.x11.override_redirect = override_redirect;
         self
     }
 
     #[inline]
     fn with_x11_window_type(mut self, x11_window_types: Vec<XWindowType>) -> Self {
-        self.platform_specific.x11_window_types = x11_window_types;
+        self.platform_specific.x11.x11_window_types = x11_window_types;
         self
     }
 
     #[inline]
     fn with_base_size<S: Into<Size>>(mut self, base_size: S) -> Self {
-        self.platform_specific.base_size = Some(base_size.into());
+        self.platform_specific.x11.base_size = Some(base_size.into());
+        self
+    }
+
+    #[inline]
+    fn with_embed_parent_window(mut self, parent_window_id: XWindow) -> Self {
+        self.platform_specific.x11.embed_window = Some(parent_window_id);
         self
     }
 }

src/platform_impl/linux/mod.rs

@@ -96,15 +96,20 @@ pub struct PlatformSpecificWindowBuilderAttributes {
     pub name: Option<ApplicationName>,
     pub activation_token: Option<ActivationToken>,
     #[cfg(x11_platform)]
+    pub x11: X11WindowBuilderAttributes,
+}
+
+#[derive(Clone)]
+#[cfg(x11_platform)]
+pub struct X11WindowBuilderAttributes {
     pub visual_id: Option<x11rb::protocol::xproto::Visualid>,
-    #[cfg(x11_platform)]
     pub screen_id: Option<i32>,
-    #[cfg(x11_platform)]
     pub base_size: Option<Size>,
-    #[cfg(x11_platform)]
     pub override_redirect: bool,
-    #[cfg(x11_platform)]
     pub x11_window_types: Vec<XWindowType>,
+
+    /// The parent window to embed this window into.
+    pub embed_window: Option<x11rb::protocol::xproto::Window>,
 }
 
 impl Default for PlatformSpecificWindowBuilderAttributes {
@@ -113,15 +118,14 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
             name: None,
             activation_token: None,
             #[cfg(x11_platform)]
-            visual_id: None,
+            x11: X11WindowBuilderAttributes {
-            #[cfg(x11_platform)]
+                visual_id: None,
-            screen_id: None,
+                screen_id: None,
-            #[cfg(x11_platform)]
+                base_size: None,
-            base_size: None,
+                override_redirect: false,
-            #[cfg(x11_platform)]
+                x11_window_types: vec![XWindowType::Normal],
-            override_redirect: false,
+                embed_window: None,
-            #[cfg(x11_platform)]
+            },
-            x11_window_types: vec![XWindowType::Normal],
         }
     }
 }

src/platform_impl/linux/x11/atoms.rs

@@ -99,7 +99,8 @@ atom_manager! {
     _NET_CLIENT_LIST,
     _NET_FRAME_EXTENTS,
     _NET_SUPPORTED,
-    _NET_SUPPORTING_WM_CHECK
+    _NET_SUPPORTING_WM_CHECK,
+    _XEMBED
 }
 
 impl Index<AtomName> for Atoms {

src/platform_impl/linux/x11/window.rs

@@ -126,6 +126,15 @@ pub(crate) struct UnownedWindow {
     activation_sender: WakeSender<super::ActivationToken>,
 }
 
+macro_rules! leap {
+    ($e:expr) => {
+        match $e {
+            Ok(x) => x,
+            Err(err) => return Err(os_error!(OsError::XError(X11Error::from(err).into()))),
+        }
+    };
+}
+
 impl UnownedWindow {
     #[allow(clippy::unnecessary_cast)]
     pub(crate) fn new<T>(
@@ -133,15 +142,6 @@ impl UnownedWindow {
         window_attrs: WindowAttributes,
         pl_attribs: PlatformSpecificWindowBuilderAttributes,
     ) -> Result<UnownedWindow, RootOsError> {
-        macro_rules! leap {
-            ($e:expr) => {
-                match $e {
-                    Ok(x) => x,
-                    Err(err) => return Err(os_error!(OsError::XError(X11Error::from(err).into()))),
-                }
-            };
-        }
-
         let xconn = &event_loop.xconn;
         let atoms = xconn.atoms();
         let root = match window_attrs.parent_window {
@@ -210,7 +210,7 @@ impl UnownedWindow {
             dimensions
         };
 
-        let screen_id = match pl_attribs.screen_id {
+        let screen_id = match pl_attribs.x11.screen_id {
             Some(id) => id,
             None => xconn.default_screen_index() as c_int,
         };
@@ -230,7 +230,7 @@ impl UnownedWindow {
             });
 
         // creating
-        let (visualtype, depth, require_colormap) = match pl_attribs.visual_id {
+        let (visualtype, depth, require_colormap) = match pl_attribs.x11.visual_id {
             Some(vi) => {
                 // Find this specific visual.
                 let (visualtype, depth) = all_visuals
@@ -271,12 +271,12 @@ impl UnownedWindow {
 
             aux = aux.event_mask(event_mask).border_pixel(0);
 
-            if pl_attribs.override_redirect {
+            if pl_attribs.x11.override_redirect {
                 aux = aux.override_redirect(true as u32);
             }
 
             // Add a colormap if needed.
-            let colormap_visual = match pl_attribs.visual_id {
+            let colormap_visual = match pl_attribs.x11.visual_id {
                 Some(vi) => Some(vi),
                 None if require_colormap => Some(visual),
                 _ => None,
@@ -298,6 +298,9 @@ impl UnownedWindow {
             aux
         };
 
+        // Figure out the window's parent.
+        let parent = pl_attribs.x11.embed_window.unwrap_or(root);
+
         // finally creating the window
         let xwindow = {
             let (x, y) = position.map_or((0, 0), Into::into);
@@ -305,7 +308,7 @@ impl UnownedWindow {
             let result = xconn.xcb_connection().create_window(
                 depth,
                 wid,
-                root,
+                parent,
                 x,
                 y,
                 dimensions.0.try_into().unwrap(),
@@ -357,6 +360,11 @@ impl UnownedWindow {
             leap!(window.set_theme_inner(Some(theme))).ignore_error();
         }
 
+        // Embed the window if needed.
+        if pl_attribs.x11.embed_window.is_some() {
+            window.embed_window()?;
+        }
+
         {
             // Enable drag and drop (TODO: extend API to make this toggleable)
             {
@@ -407,7 +415,7 @@ impl UnownedWindow {
                 flusher.ignore_error()
             }
 
-            leap!(window.set_window_types(pl_attribs.x11_window_types)).ignore_error();
+            leap!(window.set_window_types(pl_attribs.x11.x11_window_types)).ignore_error();
 
             // Set size hints.
             let mut min_inner_size = window_attrs
@@ -430,7 +438,7 @@ impl UnownedWindow {
             shared_state.min_inner_size = min_inner_size.map(Into::into);
             shared_state.max_inner_size = max_inner_size.map(Into::into);
             shared_state.resize_increments = window_attrs.resize_increments;
-            shared_state.base_size = pl_attribs.base_size;
+            shared_state.base_size = pl_attribs.x11.base_size;
 
             let normal_hints = WmSizeHints {
                 position: position.map(|PhysicalPosition { x, y }| {
@@ -447,6 +455,7 @@ impl UnownedWindow {
                     .resize_increments
                     .map(|size| cast_size_to_hint(size, scale_factor)),
                 base_size: pl_attribs
+                    .x11
                     .base_size
                     .map(|size| cast_size_to_hint(size, scale_factor)),
                 aspect: None,
@@ -559,6 +568,21 @@ impl UnownedWindow {
         Ok(window)
     }
 
+    /// Embed this window into a parent window.
+    pub(super) fn embed_window(&self) -> Result<(), RootOsError> {
+        let atoms = self.xconn.atoms();
+        leap!(leap!(self.xconn.change_property(
+            self.xwindow,
+            atoms[_XEMBED],
+            atoms[_XEMBED],
+            xproto::PropMode::REPLACE,
+            &[0u32, 1u32],
+        ))
+        .check());
+
+        Ok(())
+    }
+
     pub(super) fn shared_state_lock(&self) -> MutexGuard<'_, SharedState> {
         self.shared_state.lock().unwrap()
     }