Add a GlContext trait

src/lib.rs

@@ -70,6 +70,34 @@ mod headless;
 #[cfg(feature = "window")]
 mod window;
 
+/// Trait that describes objects that have access to an OpenGL context.
+pub trait GlContext {
+    /// Sets the context as the current context.
+    unsafe fn make_current(&self);
+
+    /// Returns true if this context is the current one in this thread.
+    fn is_current(&self) -> bool;
+
+    /// Returns the address of an OpenGL function.
+    fn get_proc_address(&self, addr: &str) -> *const libc::c_void;
+
+    /// Swaps the buffers in case of double or triple buffering.
+    ///
+    /// You should call this function every time you have finished rendering, or the image
+    ///  may not be displayed on the screen.
+    ///
+    /// **Warning**: if you enabled vsync, this function will block until the next time the screen
+    /// is refreshed. However drivers can choose to override your vsync settings, which means that
+    /// you can't know in advance whether `swap_buffers` will block or not.
+    fn swap_buffers(&self);
+
+    /// Returns the OpenGL API being used.
+    fn get_api(&self) -> Api;
+
+    /// Returns the pixel format of the main framebuffer of the context.
+    fn get_pixel_format(&self) -> PixelFormat;
+}
+
 /// Error that can happen while creating a window or a headless renderer.
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum CreationError {