WayVR: External process support, various tweaks and bugfixes

- Support for foreign wayland clients, WayVR process is now separated into
  managed and external one
- Add `run_compositor_at_start` global param
- Add `primary` display param
- Export WAYLAND_DISPLAY number into XDG_RUNTIME_DIR directory
- Bugfix: Redraw event is not triggered after despawning a process
- Sanitization in WayVRConfig::post_load()

src/config_wayvr.rs

@@ -2,7 +2,9 @@
 compile_error!("WayVR feature is not enabled");
 
 use std::{
+    cell::RefCell,
     collections::{BTreeMap, HashMap},
+    rc::Rc,
     sync::Arc,
 };
 
@@ -12,6 +14,7 @@ use crate::{
     backend::{
         overlay::RelativeTo,
         task::{TaskContainer, TaskType},
+        wayvr,
     },
     config::{load_known_yaml, ConfigType},
     overlays::wayvr::WayVRAction,
@@ -63,6 +66,7 @@ pub struct WayVRDisplay {
     pub rotation: Option<Rotation>,
     pub pos: Option<[f32; 3]>,
     pub attach_to: Option<AttachTo>,
+    pub primary: Option<bool>,
 }
 
 #[derive(Clone, Deserialize, Serialize)]
@@ -79,6 +83,7 @@ impl WayVRCatalog {
 #[derive(Deserialize, Serialize)]
 pub struct WayVRConfig {
     pub version: u32,
+    pub run_compositor_at_start: bool,
     pub catalogs: HashMap<String, WayVRCatalog>,
     pub displays: BTreeMap<String, WayVRDisplay>, // sorted alphabetically
 }
@@ -92,7 +97,31 @@ impl WayVRConfig {
         self.displays.get(name)
     }
 
-    pub fn post_load(&self, tasks: &mut TaskContainer) {
+    pub fn get_default_display(&self) -> Option<(String, &WayVRDisplay)> {
+        for (disp_name, disp) in &self.displays {
+            if disp.primary.unwrap_or(false) {
+                return Some((disp_name.clone(), disp));
+            }
+        }
+        None
+    }
+
+    pub fn post_load(
+        &self,
+        tasks: &mut TaskContainer,
+    ) -> anyhow::Result<Option<Rc<RefCell<wayvr::WayVR>>>> {
+        let primary_count = self
+            .displays
+            .iter()
+            .filter(|d| d.1.primary.unwrap_or(false))
+            .count();
+
+        if primary_count > 1 {
+            anyhow::bail!("Number of primary displays is more than 1")
+        } else if primary_count == 0 {
+            log::warn!("No primary display specified");
+        }
+
         for (catalog_name, catalog) in &self.catalogs {
             for app in &catalog.apps {
                 if let Some(b) = app.shown_at_start {
@@ -105,6 +134,14 @@ impl WayVRConfig {
                 }
             }
         }
+
+        if self.run_compositor_at_start {
+            // Start Wayland server instantly
+            Ok(Some(Rc::new(RefCell::new(wayvr::WayVR::new()?))))
+        } else {
+            // Lazy-init WayVR later if the user requested
+            Ok(None)
+        }
     }
 }