Remove the "headless" feature

src/api/caca/mod.rs

@@ -1,7 +1,7 @@
-#![cfg(all(any(target_os = "linux", target_os = "freebsd"), feature="headless"))]
+#![cfg(any(target_os = "linux", target_os = "freebsd"))]
 
 use libc;
-use api::osmesa::OsMesaContext;
+use api::osmesa::{OsMesaContext, OsMesaCreationError};
 
 use Api;
 use BuilderAttribs;
@@ -83,7 +83,12 @@ impl<'a> Iterator for WaitEventsIterator<'a> {
 
 impl Window {
     pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
-        let opengl = try!(OsMesaContext::new(builder));
+        let opengl = match OsMesaContext::new(builder) {
+            Err(OsMesaCreationError::NotSupported) => return Err(CreationError::NotSupported),
+            Err(OsMesaCreationError::CreationError(e)) => return Err(e),
+            Ok(c) => c
+        };
+
         let opengl_dimensions = opengl.get_dimensions();
 
         let libcaca = match ffi::LibCaca::open(&Path::new("libcaca.so.0")) {

src/api/cocoa/mod.rs

@@ -1,6 +1,5 @@
 #![cfg(target_os = "macos")]
 
-#[cfg(feature = "headless")]
 pub use self::headless::HeadlessContext;
 
 use {CreationError, Event, MouseCursor, CursorState};
@@ -48,8 +47,6 @@ pub use self::monitor::{MonitorID, get_available_monitors, get_primary_monitor};
 
 mod monitor;
 mod event;
-
-#[cfg(feature = "headless")]
 mod headless;
 
 static mut shift_pressed: bool = false;

src/api/osmesa/mod.rs

@@ -1,11 +1,10 @@
-#![cfg(all(any(target_os = "linux", target_os = "freebsd"), feature="headless"))]
+#![cfg(any(target_os = "linux", target_os = "freebsd"))]
 
 extern crate osmesa_sys;
 
 use Api;
 use BuilderAttribs;
 use CreationError;
-use CreationError::OsError;
 use GlContext;
 use PixelFormat;
 use libc;
@@ -19,8 +18,23 @@ pub struct OsMesaContext {
     height: u32,
 }
 
+pub enum OsMesaCreationError {
+    CreationError(CreationError),
+    NotSupported,
+}
+
+impl From<CreationError> for OsMesaCreationError {
+    fn from(e: CreationError) -> OsMesaCreationError {
+        OsMesaCreationError::CreationError(e)
+    }
+}
+
 impl OsMesaContext {
-    pub fn new(builder: BuilderAttribs) -> Result<OsMesaContext, CreationError> {
+    pub fn new(builder: BuilderAttribs) -> Result<OsMesaContext, OsMesaCreationError> {
+        if let Err(_) = osmesa_sys::OsMesa::try_loading() {
+            return Err(OsMesaCreationError::NotSupported);
+        }
+
         let dimensions = builder.dimensions.unwrap();
 
         Ok(OsMesaContext {
@@ -31,7 +45,7 @@ impl OsMesaContext {
             context: unsafe {
                 let ctxt = osmesa_sys::OSMesaCreateContext(0x1908, ptr::null_mut());
                 if ctxt.is_null() {
-                    return Err(OsError("OSMesaCreateContext failed".to_string()));
+                    return Err(CreationError::OsError("OSMesaCreateContext failed".to_string()).into());
                 }
                 ctxt
             }