Fix winit backend on wayland

We were trying to swap_buffers while the xdg_surface had not been
configured yet, which is a protocol error.

Cargo.toml

@@ -13,9 +13,9 @@ slog = { version = "2.0.0" }
 slog-stdlog = "2.0.0-0.2"
 libloading = "0.4.0"
 wayland-client = { version = "0.9.9", optional = true }
-winit = { version = "0.8.0", optional = true }
-drm = { version = "0.2.1", optional = true }
-gbm = { version = "0.2.1", optional = true }
+winit = { version = "0.8.2", optional = true }
+drm = { version = "=0.2.1", optional = true }
+gbm = { version = "=0.2.1", optional = true }
 glium = { version = "0.17.1", optional = true, default-features = false }
 input = { version = "0.2.0", optional = true }
 clippy = { version = "*", optional = true }

examples/winit.rs

@@ -53,7 +53,7 @@ impl InputHandler<winit::WinitInputBackend> for WinitInputHandler {
         /* never happens with winit */
     }
     fn on_keyboard_key(&mut self, _: &input::Seat, evt: winit::WinitKeyboardInputEvent) {
-        let keycode = evt.key_code() - 8;
+        let keycode = evt.key_code();
         let state = evt.state();
         debug!(self.log, "key"; "keycode" => keycode, "state" => format!("{:?}", state));
         let serial = self.next_serial();

src/backend/winit.rs

@@ -10,12 +10,14 @@ use backend::input::{Axis, AxisSource, Event as BackendEvent, InputBackend, Inpu
                      TouchMotionEvent, TouchSlot, TouchUpEvent, UnusedEvent};
 use nix::c_void;
 use rental::TryNewError;
+use std::cell::Cell;
 use std::cmp;
 use std::error;
 use std::fmt;
 use std::rc::Rc;
 use winit::{ElementState, Event, EventsLoop, KeyboardInput, MouseButton as WinitMouseButton, MouseCursor,
             MouseScrollDelta, Touch, TouchPhase, WindowBuilder, WindowEvent};
+use winit::os::unix::WindowExt;
 
 rental! {
     mod rental {
@@ -61,6 +63,7 @@ impl<H> From<TryNewError<Error, H>> for Error {
 /// `EGLGraphicsBackend` graphics backend trait
 pub struct WinitGraphicsBackend {
     window: Rc<Window>,
+    ready: Cell<bool>,
     logger: ::slog::Logger,
 }
 
@@ -156,6 +159,7 @@ where
     Ok((
         WinitGraphicsBackend {
             window: window.clone(),
+            ready: Cell::new(false),
             logger: log.new(o!("smithay_winit_component" => "graphics")),
         },
         WinitInputBackend {
@@ -199,6 +203,15 @@ impl GraphicsBackend for WinitGraphicsBackend {
 impl EGLGraphicsBackend for WinitGraphicsBackend {
     fn swap_buffers(&self) -> ::std::result::Result<(), SwapBuffersError> {
         trace!(self.logger, "Swapping buffers");
+        if !self.ready.get() {
+            if self.window.head().is_ready() {
+                // avoid locking the mutex every time once the window is ready
+                self.ready.set(true);
+            } else {
+                // Not yet ready, just silently ignore the swap-buffers call
+                return Ok(());
+            }
+        }
         self.window
             .rent(|egl| egl.rent(|surface| surface.swap_buffers()))
     }