Create a solid rectangle display list entry for the page background.

3 files changed, 33 insertions, 7 deletions

diff --git a/components/layout/display_list/builder.rs b/components/layout/display_list/builder.rs
index 02bde1f6741..bb2bbe58b34 100644
--- a/components/layout/display_list/builder.rs
+++ b/components/layout/display_list/builder.rs
@@ -345,7 +345,7 @@ impl<'a> DisplayListBuildState<'a> {
         }
     }
 
-    fn add_display_item(&mut self, display_item: DisplayItem) {
+    pub fn add_display_item(&mut self, display_item: DisplayItem) {
         let items = self
             .items
             .entry(display_item.stacking_context_id())
@@ -374,7 +374,7 @@ impl<'a> DisplayListBuildState<'a> {
             self.processing_scrolling_overflow_element
     }
 
-    fn create_base_display_item(
+    pub fn create_base_display_item(
         &self,
         bounds: Rect<Au>,
         clip_rect: Rect<Au>,
diff --git a/components/layout/sequential.rs b/components/layout/sequential.rs
index dfa8fddd82c..6a0b99dab8c 100644
--- a/components/layout/sequential.rs
+++ b/components/layout/sequential.rs
@@ -6,6 +6,7 @@
 
 use crate::context::LayoutContext;
 use crate::display_list::{DisplayListBuildState, StackingContextCollectionState};
+use crate::display_list::items::{self, CommonDisplayItem, DisplayItem, DisplayListSection};
 use crate::floats::SpeculatedFloatPlacement;
 use crate::flow::{Flow, FlowFlags, GetBaseFlow, ImmutableFlowUtils};
 use crate::fragment::{CoordinateSystem, FragmentBorderBoxIterator};
@@ -14,7 +15,7 @@ use crate::incremental::RelayoutMode;
 use crate::traversal::{AssignBSizes, AssignISizes, BubbleISizes, BuildDisplayList};
 use crate::traversal::{InorderFlowTraversal, PostorderFlowTraversal, PreorderFlowTraversal};
 use app_units::Au;
-use euclid::{Point2D, Vector2D};
+use euclid::{Point2D, Rect, Size2D, Vector2D};
 use servo_config::opts;
 use style::servo::restyle_damage::ServoRestyleDamage;
 use webrender_api::units::LayoutPoint;
@@ -72,11 +73,31 @@ pub fn reflow(root: &mut dyn Flow, layout_context: &LayoutContext, relayout_mode
 pub fn build_display_list_for_subtree<'a>(
     flow_root: &mut dyn Flow,
     layout_context: &'a LayoutContext,
+    background_color: webrender_api::ColorF,
+    client_size: Size2D<Au>,
 ) -> DisplayListBuildState<'a> {
     let mut state = StackingContextCollectionState::new(layout_context.id);
     flow_root.collect_stacking_contexts(&mut state);
 
-    let state = DisplayListBuildState::new(layout_context, state);
+    let mut state = DisplayListBuildState::new(layout_context, state);
+
+    // Create a base rectangle for the page background based on the root
+    // background color.
+    let base = state.create_base_display_item(
+        Rect::new(Point2D::new(Au::new(0), Au::new(0)), client_size),
+        Rect::new(Point2D::new(Au::new(0), Au::new(0)), client_size),
+        flow_root.as_block().fragment.node,
+        None,
+        DisplayListSection::BackgroundAndBorders,
+    );
+    state.add_display_item(DisplayItem::Rectangle(CommonDisplayItem::new(
+        base,
+        webrender_api::RectangleDisplayItem {
+            color: background_color,
+            common: items::empty_common_item_properties(),
+        },
+    )));
+
     let mut build_display_list = BuildDisplayList { state: state };
     build_display_list.traverse(flow_root);
     build_display_list.state
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 1afe8e37e9f..1d8448c6e74 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1138,8 +1138,13 @@ impl LayoutThread {
                     rw_data.display_list.is_none()
                 {
                     if reflow_goal.needs_display_list() {
-                        let mut build_state =
-                            sequential::build_display_list_for_subtree(layout_root, layout_context);
+                        let background_color = get_root_flow_background_color(layout_root);
+                        let mut build_state = sequential::build_display_list_for_subtree(
+                            layout_root,
+                            layout_context,
+                            background_color,
+                            data.page_clip_rect.size,
+                        );
 
                         debug!("Done building display list.");
 
@@ -1255,7 +1260,7 @@ impl LayoutThread {
                 let mut txn = webrender_api::Transaction::new();
                 txn.set_display_list(
                     webrender_api::Epoch(epoch.0),
-                    Some(get_root_flow_background_color(layout_root)),
+                    None,
                     viewport_size,
                     builder.finalize(),
                     true,