Abstract a graphics sink to shield the renderer from the osmain thread

src/servo/gfx/renderer.rs

@@ -10,11 +10,20 @@ enum msg {
     exit(comm::chan<()>)
 }
 
-fn renderer(osmain: chan<osmain::msg>) -> chan<msg> {
+#[doc = "
+The interface used to by the renderer to aquire draw targets for
+each rendered frame and submit them to be drawn to the display
+"]
+iface sink {
+    fn begin_drawing(next_dt: chan<AzDrawTargetRef>);
+    fn draw(next_dt: chan<AzDrawTargetRef>, draw_me: AzDrawTargetRef);
+}
+
+fn renderer<S: sink send>(sink: S) -> chan<msg> {
     task::spawn_listener::<msg> {|po|
         listen {|draw_target_ch|
             #debug("renderer: beginning rendering loop");
-            osmain.send(osmain::begin_drawing(draw_target_ch));
+            sink.begin_drawing(draw_target_ch);
 
             loop {
                 alt po.recv() {
@@ -24,7 +33,7 @@ fn renderer(osmain: chan<osmain::msg>) -> chan<msg> {
                     #debug("renderer: rendering");
                     draw_display_list(draw_target, display_list);
                     #debug("renderer: returning surface");
-                    osmain.send(osmain::draw(draw_target_ch, draw_target));
+                    sink.draw(draw_target_ch, draw_target);
                   }
                   exit(response_ch) {
                     response_ch.send(());

src/servo/platform/osmain.rs

@@ -1,9 +1,12 @@
+export msg, osmain, gfxsink;
+
 import azure::*;
 import azure::bindgen::*;
 import azure::cairo;
 import azure::cairo::bindgen::*;
 import comm::*;
 import azure::cairo::cairo_surface_t;
+import gfx::renderer;
 
 enum msg {
     begin_drawing(chan<AzDrawTargetRef>),
@@ -81,6 +84,19 @@ fn mainloop(po: port<msg>) {
     sdl::quit();
 }
 
+#[doc = "
+Implementation to allow the osmain channel to be used as a graphics
+sink for the renderer
+"]
+impl gfxsink of renderer::sink for chan<msg> {
+    fn begin_drawing(next_dt: chan<AzDrawTargetRef>) {
+        self.send(begin_drawing(next_dt))
+    }
+    fn draw(next_dt: chan<AzDrawTargetRef>, draw_me: AzDrawTargetRef) {
+        self.send(draw(next_dt, draw_me))
+    }
+}
+
 type surface_set = {
     mut s1: {
         surf: surface,

src/servo/servo.rs

@@ -2,13 +2,19 @@ import comm::*;
 import parser::html;
 import parser::html::methods;
 import result::extensions;
+import gfx::renderer;
+import platform::osmain;
 
 fn main(args: [str]) {
     // The platform event handler thread
-    let osmain = platform::osmain::osmain();
+    let osmain = osmain::osmain();
 
     // The renderer
-    let renderer = gfx::renderer::renderer(osmain);
+    let renderer = {
+        // Use the platform thread as the renderer sink
+        import osmain::gfxsink;
+        renderer::renderer(osmain)
+    };
 
     // The layout task
     let layout = layout::layout::layout(renderer);