webgl: Refactor implementation to move logic inside the DOM interfaces

This improves the encapsulation and consistency in our WebGL
implementation.

Also allows to implement new methods such as `getShaderSource()`.

It will also allow us to use `delete()` in the destructors of them (note
that we will want to keep track of them from the context).

components/script/dom/webglrenderbuffer.rs

@@ -9,31 +9,59 @@ use dom::bindings::js::Root;
 use dom::bindings::utils::reflect_dom_object;
 use dom::webglobject::WebGLObject;
 
+use canvas_traits::{CanvasMsg, CanvasWebGLMsg};
+use std::sync::mpsc::{channel, Sender};
+use std::cell::Cell;
+
 #[dom_struct]
 pub struct WebGLRenderbuffer {
     webgl_object: WebGLObject,
     id: u32,
+    is_deleted: Cell<bool>,
+    renderer: Sender<CanvasMsg>,
 }
 
 impl WebGLRenderbuffer {
-    fn new_inherited(id: u32) -> WebGLRenderbuffer {
+    fn new_inherited(renderer: Sender<CanvasMsg>, id: u32) -> WebGLRenderbuffer {
         WebGLRenderbuffer {
             webgl_object: WebGLObject::new_inherited(),
             id: id,
+            is_deleted: Cell::new(false),
+            renderer: renderer,
         }
     }
 
-    pub fn new(global: GlobalRef, id: u32) -> Root<WebGLRenderbuffer> {
-        reflect_dom_object(box WebGLRenderbuffer::new_inherited(id), global, WebGLRenderbufferBinding::Wrap)
+    pub fn maybe_new(global: GlobalRef, renderer: Sender<CanvasMsg>) -> Option<Root<WebGLRenderbuffer>> {
+        let (sender, receiver) = channel();
+        renderer.send(CanvasMsg::WebGL(CanvasWebGLMsg::CreateRenderbuffer(sender))).unwrap();
+        receiver.recv().unwrap()
+            .map(|renderbuffer_id| WebGLRenderbuffer::new(global, renderer, *renderbuffer_id))
+    }
+
+    pub fn new(global: GlobalRef, renderer: Sender<CanvasMsg>, id: u32) -> Root<WebGLRenderbuffer> {
+        reflect_dom_object(box WebGLRenderbuffer::new_inherited(renderer, id), global, WebGLRenderbufferBinding::Wrap)
     }
 }
 
 pub trait WebGLRenderbufferHelpers {
-    fn get_id(self) -> u32;
+    fn id(self) -> u32;
+    fn bind(self, target: u32);
+    fn delete(self);
 }
 
 impl<'a> WebGLRenderbufferHelpers for &'a WebGLRenderbuffer {
-    fn get_id(self) -> u32 {
+    fn id(self) -> u32 {
         self.id
     }
+
+    fn bind(self, target: u32) {
+        self.renderer.send(CanvasMsg::WebGL(CanvasWebGLMsg::BindRenderbuffer(target, self.id))).unwrap();
+    }
+
+    fn delete(self) {
+        if !self.is_deleted.get() {
+            self.is_deleted.set(true);
+            self.renderer.send(CanvasMsg::WebGL(CanvasWebGLMsg::DeleteRenderbuffer(self.id))).unwrap();
+        }
+    }
 }