Events loop backend (#269)

* Don't use UNIX_BACKEND in Window2::new

* Move get_available_monitors and get_primary_monitor to EventsLoop

* Remove UNIX_BACKEND

* Restore choosing the Linux backend

* Return a XNotSupported for new_x11()

* Fix fullscreen example

src/os/unix.rs

@@ -3,21 +3,42 @@
 use std::sync::Arc;
 use std::ptr;
 use libc;
+use EventsLoop;
 use MonitorId;
 use Window;
+use platform::EventsLoop as LinuxEventsLoop;
 use platform::Window2 as LinuxWindow;
-use platform::{UnixBackend, UNIX_BACKEND};
 use WindowBuilder;
 use platform::x11::XConnection;
 use platform::x11::ffi::XVisualInfo;
 
-pub use platform::x11;
+pub use platform::XNotSupported;
 
-// TODO: do not expose XConnection
-pub fn get_x11_xconnection() -> Option<Arc<XConnection>> {
-    match *UNIX_BACKEND {
-        UnixBackend::X(ref connec) => Some(connec.clone()),
-        _ => None,
+/// Additional methods on `EventsLoop` that are specific to Linux.
+pub trait EventsLoopExt {
+    /// Builds a new `EventsLoop` that is forced to use X11.
+    fn new_x11() -> Result<Self, XNotSupported>
+        where Self: Sized;
+
+    /// Builds a new `EventsLoop` that is forced to use Wayland.
+    fn new_wayland() -> Self
+        where Self: Sized;
+}
+
+impl EventsLoopExt for EventsLoop {
+    #[inline]
+    fn new_x11() -> Result<Self, XNotSupported> {
+        LinuxEventsLoop::new_x11().map(|ev| EventsLoop { events_loop: ev })
+    }
+
+    #[inline]
+    fn new_wayland() -> Self {
+        EventsLoop {
+            events_loop: match LinuxEventsLoop::new_wayland() {
+                Ok(e) => e,
+                Err(_) => panic!()      // TODO: propagate
+            }
+        }
     }
 }