1 files changed, 159 insertions, 0 deletions
diff --git a/components/script/dom/documentorshadowroot.rs b/components/script/dom/documentorshadowroot.rs
index c305afce1d6..91ce83af659 100644
--- a/components/script/dom/documentorshadowroot.rs
+++ b/components/script/dom/documentorshadowroot.rs
@@ -2,10 +2,22 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use crate::dom::bindings::codegen::Bindings::NodeBinding::NodeBinding::NodeMethods;
+use crate::dom::bindings::inheritance::Castable;
+use crate::dom::bindings::num::Finite;
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::cssstylesheet::CSSStyleSheet;
 use crate::dom::document::Document;
+use crate::dom::element::Element;
+use crate::dom::htmlelement::HTMLElement;
+use crate::dom::node;
 use crate::dom::shadowroot::ShadowRoot;
+use crate::dom::window::Window;
+use crate::dom::windowproxy::WindowProxy;
+use euclid::Point2D;
+use js::jsapi::JS_GetRuntime;
+use script_layout_interface::message::{NodesFromPointQueryType, QueryMsg};
+use script_traits::UntrustedNodeAddress;
 
 macro_rules! proxy_call(
     ($fn_name:ident, $return_type:ty) => (
@@ -38,3 +50,150 @@ impl DocumentOrShadowRoot {
     proxy_call!(stylesheet_count, usize);
     proxy_call!(stylesheet_at, index, usize, Option<DomRoot<CSSStyleSheet>>);
 }
+
+// https://w3c.github.io/webcomponents/spec/shadow/#extensions-to-the-documentorshadowroot-mixin
+#[must_root]
+#[derive(JSTraceable, MallocSizeOf)]
+pub struct DocumentOrShadowRootImpl {
+    has_browsing_context: bool,
+    window: Dom<Window>,
+}
+
+impl DocumentOrShadowRootImpl {
+    pub fn new(window: &Window, has_browsing_context: bool) -> Self {
+        Self {
+            has_browsing_context,
+            window: Dom::from_ref(window),
+        }
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#concept-document-bc>
+    #[inline]
+    pub fn browsing_context(&self) -> Option<DomRoot<WindowProxy>> {
+        if self.has_browsing_context {
+            self.window.undiscarded_window_proxy()
+        } else {
+            None
+        }
+    }
+
+    pub fn nodes_from_point(
+        &self,
+        client_point: &Point2D<f32>,
+        reflow_goal: NodesFromPointQueryType,
+    ) -> Vec<UntrustedNodeAddress> {
+        if !self
+            .window
+            .layout_reflow(QueryMsg::NodesFromPointQuery(*client_point, reflow_goal))
+        {
+            return vec![];
+        };
+
+        self.window.layout().nodes_from_point_response()
+    }
+
+    #[allow(unsafe_code)]
+    // https://drafts.csswg.org/cssom-view/#dom-document-elementfrompoint
+    pub fn element_from_point(
+        &self,
+        x: Finite<f64>,
+        y: Finite<f64>,
+        document_element: Option<DomRoot<Element>>,
+    ) -> Option<DomRoot<Element>> {
+        let x = *x as f32;
+        let y = *y as f32;
+        let point = &Point2D::new(x, y);
+        let viewport = self.window.window_size().initial_viewport;
+
+        if self.browsing_context().is_none() {
+            return None;
+        }
+
+        if x < 0.0 || y < 0.0 || x > viewport.width || y > viewport.height {
+            return None;
+        }
+
+        match self
+            .nodes_from_point(point, NodesFromPointQueryType::Topmost)
+            .first()
+        {
+            Some(address) => {
+                let js_runtime = unsafe { JS_GetRuntime(self.window.get_cx()) };
+                let node = unsafe { node::from_untrusted_node_address(js_runtime, *address) };
+                let parent_node = node.GetParentNode().unwrap();
+                let element_ref = node
+                    .downcast::<Element>()
+                    .unwrap_or_else(|| parent_node.downcast::<Element>().unwrap());
+
+                Some(DomRoot::from_ref(element_ref))
+            },
+            None => document_element,
+        }
+    }
+
+    #[allow(unsafe_code)]
+    // https://drafts.csswg.org/cssom-view/#dom-document-elementsfrompoint
+    pub fn elements_from_point(
+        &self,
+        x: Finite<f64>,
+        y: Finite<f64>,
+        document_element: Option<DomRoot<Element>>,
+    ) -> Vec<DomRoot<Element>> {
+        let x = *x as f32;
+        let y = *y as f32;
+        let point = &Point2D::new(x, y);
+        let viewport = self.window.window_size().initial_viewport;
+
+        if self.browsing_context().is_none() {
+            return vec![];
+        }
+
+        // Step 2
+        if x < 0.0 || y < 0.0 || x > viewport.width || y > viewport.height {
+            return vec![];
+        }
+
+        let js_runtime = unsafe { JS_GetRuntime(self.window.get_cx()) };
+
+        // Step 1 and Step 3
+        let nodes = self.nodes_from_point(point, NodesFromPointQueryType::All);
+        let mut elements: Vec<DomRoot<Element>> = nodes
+            .iter()
+            .flat_map(|&untrusted_node_address| {
+                let node = unsafe {
+                    node::from_untrusted_node_address(js_runtime, untrusted_node_address)
+                };
+                DomRoot::downcast::<Element>(node)
+            })
+            .collect();
+
+        // Step 4
+        if let Some(root_element) = document_element {
+            if elements.last() != Some(&root_element) {
+                elements.push(root_element);
+            }
+        }
+
+        // Step 5
+        elements
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-document-activeelement
+    pub fn get_active_element(
+        &self,
+        focused_element: Option<DomRoot<Element>>,
+        body: Option<DomRoot<HTMLElement>>,
+        document_element: Option<DomRoot<Element>>,
+    ) -> Option<DomRoot<Element>> {
+        // TODO: Step 2.
+
+        match focused_element {
+            Some(element) => Some(element), // Step 3. and 4.
+            None => match body {
+                // Step 5.
+                Some(body) => Some(DomRoot::upcast(body)),
+                None => document_element,
+            },
+        }
+    }
+}