refactor overlay windowing

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

@@ -0,0 +1,70 @@
+use glam::{Affine2, Affine3A, Vec2};
+use std::sync::Arc;
+use vulkano::{format::Format, image::view::ImageView};
+
+use crate::{
+    backend::input::{Haptics, PointerHit},
+    graphics::CommandBuffers,
+    state::AppState,
+};
+
+#[derive(Default, Clone, Copy)]
+pub struct FrameMeta {
+    pub extent: [u32; 3],
+    pub transform: Affine3A,
+    pub format: Format,
+}
+
+pub enum ShouldRender {
+    /// The overlay is dirty and needs to be rendered.
+    Should,
+    /// The overlay is not dirty but is ready to be rendered.
+    Can,
+    /// The overlay is not ready to be rendered.
+    Unable,
+}
+
+pub trait OverlayBackend {
+    /// 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 should_render(&mut self, app: &mut AppState) -> anyhow::Result<ShouldRender>;
+
+    /// Called when the contents need to be rendered to the swapchain
+    fn render(
+        &mut self,
+        app: &mut AppState,
+        tgt: Arc<ImageView>,
+        buf: &mut CommandBuffers,
+        alpha: f32,
+    ) -> anyhow::Result<bool>;
+
+    /// 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.
+    fn frame_meta(&mut self) -> Option<FrameMeta>;
+
+    fn on_hover(&mut self, app: &mut AppState, hit: &PointerHit) -> Option<Haptics>;
+    fn on_left(&mut self, app: &mut AppState, pointer: usize);
+    fn on_pointer(&mut self, app: &mut AppState, hit: &PointerHit, pressed: bool);
+    fn on_scroll(&mut self, app: &mut AppState, hit: &PointerHit, delta_y: f32, delta_x: f32);
+    fn get_interaction_transform(&mut self) -> Option<Affine2>;
+}
+
+pub fn ui_transform(extent: [u32; 2]) -> Affine2 {
+    let aspect = extent[0] as f32 / extent[1] as f32;
+    let scale = if aspect < 1.0 {
+        Vec2 {
+            x: 1.0 / aspect,
+            y: -1.0,
+        }
+    } else {
+        Vec2 { x: 1.0, y: -aspect }
+    };
+    let center = Vec2 { x: 0.5, y: 0.5 };
+    Affine2::from_scale_angle_translation(scale, 0.0, center)
+}