Add layout RPC query for getting an element's style

This enables us to implement Element::has_css_layout_box() in a more
direct way, and also enables us to remove some of the existing more
specific queries.

Fixes #19811.

2 files changed, 12 insertions, 28 deletions

diff --git a/components/script_layout_interface/message.rs b/components/script_layout_interface/message.rs
index 7a1cb7e5316..6f2ab91420d 100644
--- a/components/script_layout_interface/message.rs
+++ b/components/script_layout_interface/message.rs
@@ -113,13 +113,12 @@ pub enum ReflowGoal {
     TickAnimations,
     ContentBoxQuery(TrustedNodeAddress),
     ContentBoxesQuery(TrustedNodeAddress),
-    NodeOverflowQuery(TrustedNodeAddress),
     NodeScrollRootIdQuery(TrustedNodeAddress),
     NodeGeometryQuery(TrustedNodeAddress),
     NodeScrollGeometryQuery(TrustedNodeAddress),
     ResolvedStyleQuery(TrustedNodeAddress, Option<PseudoElement>, PropertyId),
     OffsetParentQuery(TrustedNodeAddress),
-    MarginStyleQuery(TrustedNodeAddress),
+    StyleQuery(TrustedNodeAddress),
     TextIndexQuery(TrustedNodeAddress, Point2D<f32>),
     NodesFromPointQuery(Point2D<f32>, NodesFromPointQueryType),
 }
@@ -133,9 +132,9 @@ impl ReflowGoal {
             ReflowGoal::TickAnimations | ReflowGoal::Full => true,
             ReflowGoal::ContentBoxQuery(_) | ReflowGoal::ContentBoxesQuery(_) |
             ReflowGoal::NodeGeometryQuery(_) | ReflowGoal::NodeScrollGeometryQuery(_) |
-            ReflowGoal::NodeOverflowQuery(_) | ReflowGoal::NodeScrollRootIdQuery(_) |
+            ReflowGoal::NodeScrollRootIdQuery(_) |
             ReflowGoal::ResolvedStyleQuery(..) | ReflowGoal::OffsetParentQuery(_) |
-            ReflowGoal::MarginStyleQuery(_)  => false,
+            ReflowGoal::StyleQuery(_)  => false,
         }
     }
 
@@ -143,10 +142,10 @@ impl ReflowGoal {
     /// false if a layout_thread display list is sufficient.
     pub fn needs_display(&self) -> bool {
         match *self {
-            ReflowGoal::MarginStyleQuery(_)  | ReflowGoal::TextIndexQuery(..) |
+            ReflowGoal::StyleQuery(_)  | ReflowGoal::TextIndexQuery(..) |
             ReflowGoal::ContentBoxQuery(_) | ReflowGoal::ContentBoxesQuery(_) |
             ReflowGoal::NodeGeometryQuery(_) | ReflowGoal::NodeScrollGeometryQuery(_) |
-            ReflowGoal::NodeOverflowQuery(_) | ReflowGoal::NodeScrollRootIdQuery(_) |
+            ReflowGoal::NodeScrollRootIdQuery(_) |
             ReflowGoal::ResolvedStyleQuery(..) |
             ReflowGoal::OffsetParentQuery(_) => false,
             ReflowGoal::NodesFromPointQuery(..) | ReflowGoal::Full |
diff --git a/components/script_layout_interface/rpc.rs b/components/script_layout_interface/rpc.rs
index 5702c8cce9d..3988711eeaa 100644
--- a/components/script_layout_interface/rpc.rs
+++ b/components/script_layout_interface/rpc.rs
@@ -5,7 +5,9 @@
 use app_units::Au;
 use euclid::{Point2D, Rect};
 use script_traits::UntrustedNodeAddress;
-use style::properties::longhands::{margin_top, margin_right, margin_bottom, margin_left, overflow_x};
+use servo_arc::Arc;
+use style::properties::ComputedValues;
+use style::properties::longhands::overflow_x;
 use webrender_api::ClipId;
 
 /// Synchronous messages that script can send to layout.
@@ -23,8 +25,6 @@ pub trait LayoutRPC {
     fn content_boxes(&self) -> ContentBoxesResponse;
     /// Requests the geometry of this node. Used by APIs such as `clientTop`.
     fn node_geometry(&self) -> NodeGeometryResponse;
-    /// Requests the overflow-x and overflow-y of this node. Used by `scrollTop` etc.
-    fn node_overflow(&self) -> NodeOverflowResponse;
     /// Requests the scroll geometry of this node. Used by APIs such as `scrollTop`.
     fn node_scroll_area(&self) -> NodeGeometryResponse;
     /// Requests the scroll root id of this node. Used by APIs such as `scrollTop`
@@ -32,8 +32,9 @@ pub trait LayoutRPC {
     /// Query layout for the resolved value of a given CSS property
     fn resolved_style(&self) -> ResolvedStyleResponse;
     fn offset_parent(&self) -> OffsetParentResponse;
-    /// Query layout for the resolve values of the margin properties for an element.
-    fn margin_style(&self) -> MarginStyleResponse;
+    /// Requests the styles for an element. Contains a `None` value if the element is in a `display:
+    /// none` subtree.
+    fn style(&self) -> StyleResponse;
     fn text_index(&self) -> TextIndexResponse;
     /// Requests the list of nodes from the given point.
     fn nodes_from_point_response(&self) -> Vec<UntrustedNodeAddress>;
@@ -70,23 +71,7 @@ impl OffsetParentResponse {
 }
 
 #[derive(Clone)]
-pub struct MarginStyleResponse {
-    pub top: margin_top::computed_value::T,
-    pub right: margin_right::computed_value::T,
-    pub bottom: margin_bottom::computed_value::T,
-    pub left: margin_left::computed_value::T,
-}
-
-impl MarginStyleResponse {
-    pub fn empty() -> MarginStyleResponse {
-        MarginStyleResponse {
-            top: margin_top::computed_value::T::Auto,
-            right: margin_right::computed_value::T::Auto,
-            bottom: margin_bottom::computed_value::T::Auto,
-            left: margin_left::computed_value::T::Auto,
-        }
-    }
-}
+pub struct StyleResponse(pub Option<Arc<ComputedValues>>);
 
 #[derive(Clone)]
 pub struct TextIndexResponse(pub Option<usize>);