wip: edit mode overlay

wlx-overlay-s/src/windowing/backend.rs

@@ -1,5 +1,5 @@
 use glam::{Affine2, Affine3A, Vec2};
-use std::sync::Arc;
+use std::{any::Any, sync::Arc};
 use vulkano::{format::Format, image::view::ImageView};
 
 use crate::{
@@ -25,7 +25,7 @@ pub enum ShouldRender {
     Unable,
 }
 
-pub trait OverlayBackend {
+pub trait OverlayBackend: Any {
     /// 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<()>;
@@ -46,7 +46,7 @@ pub trait OverlayBackend {
     /// Called to retrieve the effective extent of the image
     /// Used for creating swapchains.
     ///
-    /// Must be true if should_render was also true on the same frame.
+    /// Must be Some if should_render was Should or Can on the same frame.
     fn frame_meta(&mut self) -> Option<FrameMeta>;
 
     fn on_hover(&mut self, app: &mut AppState, hit: &PointerHit) -> HoverResult;
@@ -69,3 +69,42 @@ pub fn ui_transform(extent: [u32; 2]) -> Affine2 {
     let center = Vec2 { x: 0.5, y: 0.5 };
     Affine2::from_scale_angle_translation(scale, 0.0, center)
 }
+
+pub struct DummyBackend {}
+
+impl OverlayBackend for DummyBackend {
+    fn init(&mut self, _: &mut AppState) -> anyhow::Result<()> {
+        Ok(())
+    }
+    fn pause(&mut self, _: &mut AppState) -> anyhow::Result<()> {
+        Ok(())
+    }
+    fn resume(&mut self, _: &mut AppState) -> anyhow::Result<()> {
+        Ok(())
+    }
+    fn should_render(&mut self, _: &mut AppState) -> anyhow::Result<ShouldRender> {
+        Ok(ShouldRender::Unable)
+    }
+    fn render(
+        &mut self,
+        _: &mut AppState,
+        _: Arc<ImageView>,
+        _: &mut CommandBuffers,
+        _: f32,
+    ) -> anyhow::Result<bool> {
+        Ok(false)
+    }
+    fn frame_meta(&mut self) -> Option<FrameMeta> {
+        None
+    }
+
+    fn on_hover(&mut self, _: &mut AppState, _: &PointerHit) -> HoverResult {
+        HoverResult::default()
+    }
+    fn on_left(&mut self, _: &mut AppState, _: usize) {}
+    fn on_pointer(&mut self, _: &mut AppState, _: &PointerHit, _: bool) {}
+    fn on_scroll(&mut self, _: &mut AppState, _: &PointerHit, _: f32, _: f32) {}
+    fn get_interaction_transform(&mut self) -> Option<glam::Affine2> {
+        None
+    }
+}