Implement headless rendering

src/x11/headless.rs

@@ -0,0 +1,47 @@
+use HeadlessRendererBuilder;
+use libc;
+use std::{mem, ptr};
+use super::ffi;
+
+pub struct HeadlessContext {
+    context: ffi::OSMesaContext,
+    buffer: Vec<u32>,
+    width: uint,
+    height: uint,
+}
+
+impl HeadlessContext {
+    pub fn new(builder: HeadlessRendererBuilder) -> Result<HeadlessContext, String> {
+        Ok(HeadlessContext {
+            width: builder.dimensions.0,
+            height: builder.dimensions.1,
+            buffer: Vec::from_elem(builder.dimensions.0 * builder.dimensions.1, unsafe { mem::uninitialized() }),
+            context: unsafe {
+                // TODO: check errors
+                ffi::OSMesaCreateContext(0x1908, ptr::null())
+            }
+        })
+    }
+
+    pub unsafe fn make_current(&self) {
+        ffi::OSMesaMakeCurrent(self.context,
+            self.buffer.as_ptr() as *mut libc::c_void,
+            0x1401, self.width as libc::c_int, self.height as libc::c_int);
+    }
+
+    pub fn get_proc_address(&self, addr: &str) -> *const () {
+        use std::c_str::ToCStr;
+
+        unsafe {
+            addr.with_c_str(|s| {
+                ffi::OSMesaGetProcAddress(mem::transmute(s)) as *const ()
+            })
+        }
+    }
+}
+
+impl Drop for HeadlessContext {
+    fn drop(&mut self) {
+        unsafe { ffi::OSMesaDestroyContext(self.context) }
+    }
+}