2 files changed, 115 insertions, 19 deletions

diff --git a/src/osx/headless.rs b/src/osx/headless.rs
new file mode 100644
index 0000000..bbe3d9f
--- /dev/null
+++ b/src/osx/headless.rs
@@ -0,0 +1,109 @@
+use CreationError;
+use CreationError::OsError;
+use HeadlessRendererBuilder;
+use libc;
+use std::ptr;
+
+use core_foundation::base::TCFType;
+use core_foundation::string::CFString;
+use core_foundation::bundle::{CFBundleGetBundleWithIdentifier, CFBundleGetFunctionPointerForName};
+use cocoa::base::{id, nil};
+use cocoa::appkit::*;
+
+mod gl {
+    generate_gl_bindings! {
+        api: "gl",
+        profile: "core",
+        version: "3.2",
+        generator: "global",
+        extensions: ["GL_EXT_framebuffer_object"],
+    }
+}
+
+static mut framebuffer: u32 = 0;
+static mut texture: u32 = 0;
+
+pub struct HeadlessContext {
+    width: uint,
+    height: uint,
+    context: id,
+}
+
+impl HeadlessContext {
+    pub fn new(builder: HeadlessRendererBuilder) -> Result<HeadlessContext, CreationError> {
+        let (width, height) = builder.dimensions;
+        let context = unsafe {
+            let attributes = [
+                NSOpenGLPFADoubleBuffer as uint,
+                NSOpenGLPFAClosestPolicy as uint,
+                NSOpenGLPFAColorSize as uint, 24,
+                NSOpenGLPFAAlphaSize as uint, 8,
+                NSOpenGLPFADepthSize as uint, 24,
+                NSOpenGLPFAStencilSize as uint, 8,
+                NSOpenGLPFAOffScreen as uint,
+                0
+            ];
+
+            let pixelformat = NSOpenGLPixelFormat::alloc(nil).initWithAttributes_(&attributes);
+            if pixelformat == nil {
+                return Err(OsError(format!("Could not create the pixel format")));
+            }
+            let context = NSOpenGLContext::alloc(nil).initWithFormat_shareContext_(pixelformat, nil);
+            if context == nil {
+                return Err(OsError(format!("Could not create the rendering context")));
+            }
+            context
+        };
+
+        let headless = HeadlessContext {
+            width: width,
+            height: height,
+            context: context,
+        };
+
+        // Load the function pointers as we need them to create the FBO
+        gl::load_with(|s| headless.get_proc_address(s) as *const libc::c_void);
+
+        Ok(headless)
+    }
+
+    pub unsafe fn make_current(&self) {
+        self.context.makeCurrentContext();
+
+        gl::GenFramebuffersEXT(1, &mut framebuffer);
+        gl::BindFramebufferEXT(gl::FRAMEBUFFER_EXT, framebuffer);
+        gl::GenTextures(1, &mut texture);
+        gl::BindTexture(gl::TEXTURE_2D, texture);
+        gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MAG_FILTER, gl::LINEAR as i32);
+        gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR as i32);
+        gl::TexImage2D(gl::TEXTURE_2D, 0, gl::RGBA8 as i32, self.width as i32, self.height as i32,
+                       0, gl::RGBA, gl::UNSIGNED_BYTE, ptr::null());
+        gl::FramebufferTexture2DEXT(gl::FRAMEBUFFER_EXT, gl::COLOR_ATTACHMENT0_EXT,
+                                    gl::TEXTURE_2D, texture, 0);
+        let status = gl::CheckFramebufferStatusEXT(gl::FRAMEBUFFER_EXT);
+        if status != gl::FRAMEBUFFER_COMPLETE_EXT {
+            panic!("Error while creating the framebuffer");
+        }
+    }
+
+    pub fn get_proc_address(&self, _addr: &str) -> *const () {
+        let symbol_name: CFString = from_str(_addr).unwrap();
+        let framework_name: CFString = from_str("com.apple.opengl").unwrap();
+        let framework = unsafe {
+            CFBundleGetBundleWithIdentifier(framework_name.as_concrete_TypeRef())
+        };
+        let symbol = unsafe {
+            CFBundleGetFunctionPointerForName(framework, symbol_name.as_concrete_TypeRef())
+        };
+        symbol as *const ()
+    }
+}
+
+impl Drop for HeadlessContext {
+    fn drop(&mut self) {
+        unsafe {
+            gl::DeleteTextures(1, &texture);
+            gl::DeleteFramebuffersEXT(1, &framebuffer);
+        }
+    }
+}
diff --git a/src/osx/mod.rs b/src/osx/mod.rs
index 8ab3efd..0cb4553 100644
--- a/src/osx/mod.rs
+++ b/src/osx/mod.rs
@@ -1,3 +1,6 @@
+#[cfg(feature = "headless")]
+pub use self::headless::HeadlessContext;
+
 use {CreationError, Event};
 use CreationError::OsError;
 use libc;
@@ -5,9 +8,6 @@ use libc;
 #[cfg(feature = "window")]
 use WindowBuilder;
 
-#[cfg(feature = "headless")]
-use HeadlessRendererBuilder;
-
 use cocoa::base::{id, NSUInteger, nil, objc_allocateClassPair, class, objc_registerClassPair};
 use cocoa::base::{selector, msg_send, class_addMethod, class_addIvar};
 use cocoa::base::{object_setInstanceVariable, object_getInstanceVariable};
@@ -33,6 +33,9 @@ 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;
 static mut ctrl_pressed: bool = false;
 static mut win_pressed: bool = false;
@@ -60,14 +63,6 @@ pub struct Window {
     state: Box<InternalState>,
 }
 
-pub struct HeadlessContext(Window);
-
-impl Deref<Window> for HeadlessContext {
-    fn deref(&self) -> &Window {
-        &self.0
-    }
-}
-
 #[cfg(feature = "window")]
 impl Window {
     pub fn new(builder: WindowBuilder) -> Result<Window, CreationError> {
@@ -79,14 +74,6 @@ impl Window {
     }
 }
 
-#[cfg(feature = "headless")]
-impl HeadlessContext {
-    pub fn new(builder: HeadlessRendererBuilder) -> Result<HeadlessContext, CreationError> {
-        Window::new_impl(Some(builder.dimensions), "", None, false)
-            .map(|w| HeadlessContext(w))
-    }
-}
-
 extern fn window_should_close(this: id, _: id) -> id {
     unsafe {
         let mut stored_value = ptr::null_mut();