Multiple display list support

src/components/gfx/display_list.rs

@@ -27,11 +27,62 @@ use std::cast::transmute_region;
 use std::vec::VecIterator;
 use style::computed_values::border_style;
 
+pub struct DisplayListCollection<E> {
+    lists: ~[DisplayList<E>]
+}
+
+impl<E> DisplayListCollection<E> {
+    pub fn new() -> DisplayListCollection<E> {
+        DisplayListCollection {
+            lists: ~[]
+        }
+    }
+
+    pub fn iter<'a>(&'a self) -> DisplayListIterator<'a,E> {
+        ParentDisplayListIterator(self.lists.iter())
+    }
+
+    pub fn add_list(&mut self, list: DisplayList<E>) {
+        self.lists.push(list);
+    }
+
+    pub fn draw_lists_into_context(&self, render_context: &mut RenderContext) {
+        for list in self.lists.iter() {
+            list.draw_into_context(render_context);
+        }
+        debug!("{:?}", self.dump());
+    }
+
+    fn dump(&self) {
+        let mut index = 0;
+        for list in self.lists.iter() {
+            debug!("dumping display list {:d}:", index);
+            list.dump();
+            index = index + 1;
+        }
+    }
+}
+
 /// A list of rendering operations to be performed.
 pub struct DisplayList<E> {
     list: ~[DisplayItem<E>]
 }
 
+pub enum DisplayListIterator<'a,E> {
+    EmptyDisplayListIterator,
+    ParentDisplayListIterator(VecIterator<'a,DisplayList<E>>),
+}
+
+impl<'a,E> Iterator<&'a DisplayList<E>> for DisplayListIterator<'a,E> {
+    #[inline]
+    fn next(&mut self) -> Option<&'a DisplayList<E>> {
+        match *self {
+            EmptyDisplayListIterator => None,
+            ParentDisplayListIterator(ref mut subiterator) => subiterator.next(),
+        }
+    }
+}
+
 impl<E> DisplayList<E> {
     /// Creates a new display list.
     pub fn new() -> DisplayList<E> {
@@ -62,7 +113,6 @@ impl<E> DisplayList<E> {
             item.draw_into_context(render_context)
         }
         debug!("Ending display list.");
-        debug!("{:?}", self.dump());
     }
 
     /// Returns a preorder iterator over the given display list.

src/components/gfx/render_task.rs

@@ -24,13 +24,14 @@ use std::comm::{Chan, Port, SharedChan};
 use extra::arc::Arc;
 
 use buffer_map::BufferMap;
-use display_list::DisplayList;
+use font_context::{FontContext, FontContextInfo};
+use display_list::DisplayListCollection;
 use font_context::{FontContext, FontContextInfo};
 use opts::Opts;
 use render_context::RenderContext;
 
 pub struct RenderLayer<T> {
-    display_list: Arc<DisplayList<T>>,
+    display_list_collection: Arc<DisplayListCollection<T>>,
     size: Size2D<uint>,
     color: Color
 }
@@ -305,7 +306,7 @@ impl<C: RenderListener + Send,T:Send+Freeze> RenderTask<C,T> {
                         
                         // Draw the display list.
                         profile(time::RenderingDrawingCategory, self.profiler_chan.clone(), || {
-                            render_layer.display_list.get().draw_into_context(&mut ctx);
+                            render_layer.display_list_collection.get().draw_lists_into_context(&mut ctx);
                             ctx.draw_target.flush();
                         });
                     }