openxr: configurable screen downscale

src/backend/openvr/lines.rs

@@ -189,4 +189,7 @@ impl OverlayRenderer for StaticRenderer {
     fn view(&mut self) -> Option<Arc<ImageView>> {
         Some(self.view.clone())
     }
+    fn extent(&mut self) -> Option<[u32; 3]> {
+        Some(self.view.image().extent())
+    }
 }

src/backend/openxr/overlay.rs

@@ -38,7 +38,8 @@ impl OverlayData<OpenXrOverlayData> {
             log::warn!("{}: Will not show - image not ready", self.state.name);
             return Ok(CompositionLayer::None);
         };
-        let extent = my_view.image().extent();
+
+        let extent = self.extent().unwrap(); // want panic
 
         let data = match self.data.swapchain {
             Some(ref mut data) => data,

src/backend/overlay.rs

@@ -224,6 +224,9 @@ where
     pub fn view(&mut self) -> Option<Arc<ImageView>> {
         self.backend.view()
     }
+    pub fn extent(&mut self) -> Option<[u32; 3]> {
+        self.backend.extent()
+    }
     pub fn set_visible(&mut self, app: &mut AppState, visible: bool) -> anyhow::Result<()> {
         let old_visible = self.state.want_visible;
         self.state.want_visible = visible;
@@ -239,11 +242,19 @@ where
 }
 
 pub trait OverlayRenderer {
+    /// Called once, before the first frame is rendered
     fn init(&mut self, app: &mut AppState) -> anyhow::Result<()>;
     fn pause(&mut self, app: &mut AppState) -> anyhow::Result<()>;
     fn resume(&mut self, app: &mut AppState) -> anyhow::Result<()>;
+    /// Called when the presentation layer is ready to present a new frame
     fn render(&mut self, app: &mut AppState) -> anyhow::Result<()>;
+    /// Called to retrieve the current image to be displayed
     fn view(&mut self) -> Option<Arc<ImageView>>;
+    /// Called to retrieve the effective extent of the image
+    /// Used for creating swapchains.
+    ///
+    /// Muse not be None if view() is also not None
+    fn extent(&mut self) -> Option<[u32; 3]>;
 }
 
 pub struct FallbackRenderer;
@@ -264,6 +275,9 @@ impl OverlayRenderer for FallbackRenderer {
     fn view(&mut self) -> Option<Arc<ImageView>> {
         None
     }
+    fn extent(&mut self) -> Option<[u32; 3]> {
+        None
+    }
 }
 // Boilerplate and dummies
 
@@ -318,6 +332,9 @@ impl OverlayRenderer for SplitOverlayBackend {
     fn view(&mut self) -> Option<Arc<ImageView>> {
         self.renderer.view()
     }
+    fn extent(&mut self) -> Option<[u32; 3]> {
+        self.renderer.extent()
+    }
 }
 impl InteractionHandler for SplitOverlayBackend {
     fn on_left(&mut self, app: &mut AppState, pointer: usize) {