WayVR: Redraw only if needed

src/backend/wayvr/comp.rs

@@ -1,13 +1,15 @@
 use smithay::backend::renderer::utils::on_commit_buffer_handler;
 use smithay::input::{Seat, SeatHandler, SeatState};
 use smithay::reexports::wayland_protocols::xdg::shell::server::xdg_toplevel;
+use smithay::reexports::wayland_server;
 use smithay::reexports::wayland_server::protocol::{wl_buffer, wl_seat, wl_surface};
-use smithay::reexports::wayland_server::{self, Resource};
+use smithay::reexports::wayland_server::Resource;
 use smithay::wayland::buffer::BufferHandler;
 use smithay::wayland::shm::{ShmHandler, ShmState};
 use smithay::{
     delegate_compositor, delegate_data_device, delegate_seat, delegate_shm, delegate_xdg_shell,
 };
+use std::collections::HashSet;
 use std::os::fd::OwnedFd;
 
 use smithay::utils::Serial;
@@ -35,8 +37,14 @@ pub struct Application {
     pub seat_state: SeatState<Application>,
     pub shm: ShmState,
     pub data_device: DataDeviceState,
-
     pub wayvr_tasks: SyncEventQueue<WayVRTask>,
+    pub redraw_requests: HashSet<wayland_server::backend::ObjectId>,
+}
+
+impl Application {
+    pub fn check_redraw(&mut self, surface: &WlSurface) -> bool {
+        self.redraw_requests.remove(&surface.id())
+    }
 }
 
 impl compositor::CompositorHandler for Application {
@@ -53,6 +61,7 @@ impl compositor::CompositorHandler for Application {
 
     fn commit(&mut self, surface: &WlSurface) {
         on_commit_buffer_handler::<Self>(surface);
+        self.redraw_requests.insert(surface.id());
     }
 }
 

src/backend/wayvr/display.rs

@@ -27,10 +27,10 @@ fn generate_auth_key() -> String {
     uuid.to_string()
 }
 
-struct DisplayWindow {
-    window_handle: window::WindowHandle,
+pub struct DisplayWindow {
+    pub window_handle: window::WindowHandle,
+    pub toplevel: ToplevelSurface,
     process_handle: process::ProcessHandle,
-    toplevel: ToplevelSurface,
 }
 
 pub struct SpawnProcessResult {
@@ -49,8 +49,9 @@ pub struct Display {
     pub name: String,
     pub visible: bool,
     pub overlay_id: Option<OverlayID>,
+    pub wants_redraw: bool,
     wm: Rc<RefCell<window::WindowManager>>,
-    displayed_windows: Vec<DisplayWindow>,
+    pub displayed_windows: Vec<DisplayWindow>,
     wayland_env: super::WaylandEnv,
 
     // Render data stuff
@@ -108,6 +109,7 @@ impl Display {
             height,
             name: String::from(name),
             displayed_windows: Vec::new(),
+            wants_redraw: true,
             egl_data,
             dmabuf_data,
             egl_image,

src/backend/wayvr/mod.rs

@@ -10,7 +10,7 @@ mod smithay_wrapper;
 mod time;
 mod window;
 
-use std::{cell::RefCell, rc::Rc};
+use std::{cell::RefCell, collections::HashSet, rc::Rc};
 
 use comp::Application;
 use display::DisplayVec;
@@ -94,6 +94,7 @@ impl WayVR {
             shm,
             data_device,
             wayvr_tasks: tasks.clone(),
+            redraw_requests: HashSet::new(),
         };
 
         let time_start = get_millis();
@@ -118,22 +119,41 @@ impl WayVR {
         // millis since the start of wayvr
         let display = self
             .displays
-            .get(&display)
+            .get_mut(&display)
             .ok_or(anyhow::anyhow!(STR_INVALID_HANDLE_DISP))?;
 
-        let time_ms = get_millis() - self.time_start;
+        if !display.wants_redraw {
+            // Nothing changed, do not render
+            return Ok(());
+        }
 
         if !display.visible {
             // Display is invisible, do not render
             return Ok(());
         }
 
+        let time_ms = get_millis() - self.time_start;
+
         display.tick_render(&mut self.gles_renderer, time_ms)?;
+        display.wants_redraw = false;
 
         Ok(())
     }
 
     pub fn tick_events(&mut self) -> anyhow::Result<()> {
+        // Check for redraw events
+        self.displays.iter_mut(&mut |_, disp| {
+            for disp_window in &disp.displayed_windows {
+                if self
+                    .manager
+                    .state
+                    .check_redraw(disp_window.toplevel.wl_surface())
+                {
+                    disp.wants_redraw = true;
+                }
+            }
+        });
+
         // Tick all child processes
         let mut to_remove: SmallVec<[(process::ProcessHandle, display::DisplayHandle); 2]> =
             SmallVec::new();