Add window camera handlers

src/window/window.rs

@@ -2,7 +2,9 @@
 /*
  * FIXME: this file is too big. Some heavy refactoring need to be done here.
  */
+use std::cell::Ref;
 use std::cell::RefCell;
+use std::cell::RefMut;
 use std::iter::repeat;
 use std::path::Path;
 use std::rc::Rc;
@@ -631,6 +633,16 @@ impl Window {
         self.canvas.cursor_pos()
     }
 
+    /// Gets a handle to the window camera.
+    pub fn camera(&self) -> Ref<'_, ArcBall> {
+        self.camera.borrow()
+    }
+
+    /// Gets a mutable handle to the window camera.
+    pub fn camera_mut(&self) -> RefMut<'_, ArcBall> {
+        self.camera.borrow_mut()
+    }
+
     #[inline]
     fn handle_events(
         &mut self,