layout: Take into account the client point for fixed positioned stacking contexts.

7 files changed, 79 insertions, 45 deletions

diff --git a/components/gfx/display_list/mod.rs b/components/gfx/display_list/mod.rs
index c7143457db9..2942c75ac67 100644
--- a/components/gfx/display_list/mod.rs
+++ b/components/gfx/display_list/mod.rs
@@ -61,7 +61,7 @@ pub static BLUR_INFLATION_FACTOR: i32 = 3;
 /// LayerInfo is used to store PaintLayer metadata during DisplayList construction.
 /// It is also used for tracking LayerIds when creating layers to preserve ordering when
 /// layered DisplayItems should render underneath unlayered DisplayItems.
-#[derive(Clone, Copy, HeapSizeOf, Deserialize, Serialize)]
+#[derive(Clone, Copy, HeapSizeOf, Deserialize, Serialize, Debug)]
 pub struct LayerInfo {
     /// The base LayerId of this layer.
     pub layer_id: LayerId,
@@ -133,7 +133,7 @@ impl<'a> DisplayListTraversal<'a> {
     }
 }
 
-#[derive(HeapSizeOf, Deserialize, Serialize)]
+#[derive(HeapSizeOf, Deserialize, Serialize, Debug)]
 pub struct StackingContextOffsets {
     pub start: u32,
     pub block_backgrounds_and_borders: u32,
@@ -508,9 +508,12 @@ impl DisplayList {
             &draw_target, &stacking_context.filters, stacking_context.blend_mode);
     }
 
-    /// Return all nodes containing the point of interest, bottommost first,
-    /// and respecting the `pointer-events` CSS property.
-    pub fn hit_test(&self, point: &Point2D<Au>, scroll_offsets: &ScrollOffsetMap)
+    /// Return all nodes containing the point of interest, bottommost first, and
+    /// respecting the `pointer-events` CSS property.
+    pub fn hit_test(&self,
+                    translated_point: &Point2D<Au>,
+                    client_point: &Point2D<Au>,
+                    scroll_offsets: &ScrollOffsetMap)
                     -> Vec<DisplayItemMetadata> {
         let mut traversal = DisplayListTraversal {
             display_list: self,
@@ -518,7 +521,11 @@ impl DisplayList {
             last_item_index: self.list.len() - 1,
         };
         let mut result = Vec::new();
-        self.root_stacking_context.hit_test(&mut traversal, point, scroll_offsets, &mut result);
+        self.root_stacking_context.hit_test(&mut traversal,
+                                            translated_point,
+                                            client_point,
+                                            scroll_offsets,
+                                            &mut result);
         result
     }
 }
@@ -633,27 +640,35 @@ impl StackingContext {
 
     pub fn hit_test<'a>(&self,
                         traversal: &mut DisplayListTraversal<'a>,
-                        point: &Point2D<Au>,
+                        translated_point: &Point2D<Au>,
+                        client_point: &Point2D<Au>,
                         scroll_offsets: &ScrollOffsetMap,
                         result: &mut Vec<DisplayItemMetadata>) {
+        let is_fixed = match self.layer_info {
+            Some(ref layer_info) => layer_info.scroll_policy == ScrollPolicy::FixedPosition,
+            None => false,
+        };
+
+        let effective_point = if is_fixed { client_point } else { translated_point };
+
         // Convert the point into stacking context local transform space.
         let mut point = if self.context_type == StackingContextType::Real {
-            let point = *point - self.bounds.origin;
+            let point = *effective_point - self.bounds.origin;
             let inv_transform = self.transform.invert();
             let frac_point = inv_transform.transform_point(&Point2D::new(point.x.to_f32_px(),
                                                                          point.y.to_f32_px()));
             Point2D::new(Au::from_f32_px(frac_point.x), Au::from_f32_px(frac_point.y))
         } else {
-            *point
+            *effective_point
         };
 
-        // Adjust the point to account for the scroll offset if necessary. This can only happen
-        // when WebRender is in use.
+        // Adjust the translated point to account for the scroll offset if
+        // necessary. This can only happen when WebRender is in use.
         //
-        // We don't perform this adjustment on the root stacking context because the DOM-side code
-        // has already translated the point for us (e.g. in `Document::handle_mouse_move_event()`)
-        // by now.
-        if self.id != StackingContextId::root() {
+        // We don't perform this adjustment on the root stacking context because
+        // the DOM-side code has already translated the point for us (e.g. in
+        // `Window::hit_test_query()`) by now.
+        if !is_fixed && self.id != StackingContextId::root() {
             if let Some(scroll_offset) = scroll_offsets.get(&self.id) {
                 point.x -= Au::from_f32_px(scroll_offset.x);
                 point.y -= Au::from_f32_px(scroll_offset.y);
@@ -666,7 +681,7 @@ impl StackingContext {
                     result.push(meta);
                 }
             }
-            child.hit_test(traversal, &point, scroll_offsets, result);
+            child.hit_test(traversal, translated_point, client_point, scroll_offsets, result);
         }
 
         while let Some(item) = traversal.advance(self) {
@@ -1366,6 +1381,7 @@ impl DisplayItem {
         // TODO(pcwalton): Use a precise algorithm here. This will allow us to properly hit
         // test elements with `border-radius`, for example.
         let base_item = self.base();
+
         if !base_item.clip.might_intersect_point(&point) {
             // Clipped out.
             return None;
diff --git a/components/layout/query.rs b/components/layout/query.rs
index aed02a9392e..ee06f3865ba 100644
--- a/components/layout/query.rs
+++ b/components/layout/query.rs
@@ -133,15 +133,21 @@ impl LayoutRPC for LayoutRPCImpl {
         }
     }
 
-    fn nodes_from_point(&self, point: Point2D<f32>) -> Vec<UntrustedNodeAddress> {
-        let point = Point2D::new(Au::from_f32_px(point.x), Au::from_f32_px(point.y));
+    fn nodes_from_point(&self,
+                        page_point: Point2D<f32>,
+                        client_point: Point2D<f32>) -> Vec<UntrustedNodeAddress> {
+        let page_point = Point2D::new(Au::from_f32_px(page_point.x),
+                                      Au::from_f32_px(page_point.y));
+        let client_point = Point2D::new(Au::from_f32_px(client_point.x),
+                                        Au::from_f32_px(client_point.y));
+
         let nodes_from_point_list = {
             let &LayoutRPCImpl(ref rw_data) = self;
             let rw_data = rw_data.lock().unwrap();
             let result = match rw_data.display_list {
                 None => panic!("Tried to hit test without a DisplayList"),
                 Some(ref display_list) => {
-                    display_list.hit_test(&point, &rw_data.stacking_context_scroll_offsets)
+                    display_list.hit_test(&page_point, &client_point, &rw_data.stacking_context_scroll_offsets)
                 }
             };
 
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 958a2acc71e..c31e2de54ac 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1038,7 +1038,7 @@ impl LayoutThread {
                     ReflowQueryType::ContentBoxesQuery(_) => {
                         rw_data.content_boxes_response = Vec::new();
                     },
-                    ReflowQueryType::HitTestQuery(_, _) => {
+                    ReflowQueryType::HitTestQuery(..) => {
                         rw_data.hit_test_response = (None, false);
                     },
                     ReflowQueryType::NodeGeometryQuery(_) => {
@@ -1202,12 +1202,21 @@ impl LayoutThread {
                     let node = unsafe { ServoLayoutNode::new(&node) };
                     rw_data.content_boxes_response = process_content_boxes_request(node, &mut root_flow);
                 },
-                ReflowQueryType::HitTestQuery(point, update_cursor) => {
-                    let point = Point2D::new(Au::from_f32_px(point.x), Au::from_f32_px(point.y));
+                ReflowQueryType::HitTestQuery(translated_point, client_point, update_cursor) => {
+                    let translated_point =
+                        Point2D::new(Au::from_f32_px(translated_point.x),
+                                     Au::from_f32_px(translated_point.y));
+
+                    let client_point =
+                        Point2D::new(Au::from_f32_px(client_point.x),
+                                     Au::from_f32_px(client_point.y));
+
                     let result = rw_data.display_list
                                         .as_ref()
                                         .expect("Tried to hit test with no display list")
-                                        .hit_test(&point, &rw_data.stacking_context_scroll_offsets);
+                                        .hit_test(&translated_point,
+                                                  &client_point,
+                                                  &rw_data.stacking_context_scroll_offsets);
                     rw_data.hit_test_response = (result.last().cloned(), update_cursor);
                 },
                 ReflowQueryType::NodeGeometryQuery(node) => {
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 9366f9e18bb..5f1bf4c45cd 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -672,9 +672,7 @@ impl Document {
         };
         debug!("{}: at {:?}", mouse_event_type_string, client_point);
 
-        let page_point = Point2D::new(client_point.x + self.window.PageXOffset() as f32,
-                                      client_point.y + self.window.PageYOffset() as f32);
-        let node = match self.window.hit_test_query(page_point, false) {
+        let node = match self.window.hit_test_query(client_point, false) {
             Some(node_address) => {
                 debug!("node address is {:?}", node_address);
                 node::from_untrusted_node_address(js_runtime, node_address)
@@ -786,9 +784,7 @@ impl Document {
             return;
         }
 
-        let page_point = Point2D::new(client_point.x + self.window.PageXOffset() as f32,
-                                      client_point.y + self.window.PageYOffset() as f32);
-        let node = match self.window.hit_test_query(page_point, false) {
+        let node = match self.window.hit_test_query(client_point, false) {
             Some(node_address) => node::from_untrusted_node_address(js_runtime, node_address),
             None => return
         };
@@ -864,22 +860,17 @@ impl Document {
                                    js_runtime: *mut JSRuntime,
                                    client_point: Option<Point2D<f32>>,
                                    prev_mouse_over_target: &MutNullableHeap<JS<Element>>) {
-        let page_point = match client_point {
+        let client_point = match client_point {
             None => {
                 // If there's no point, there's no target under the mouse
                 // FIXME: dispatch mouseout here. We have no point.
                 prev_mouse_over_target.set(None);
                 return;
             }
-            Some(ref client_point) => {
-                Point2D::new(client_point.x + self.window.PageXOffset() as f32,
-                             client_point.y + self.window.PageYOffset() as f32)
-            }
+            Some(client_point) => client_point,
         };
 
-        let client_point = client_point.unwrap();
-
-        let maybe_new_target = self.window.hit_test_query(page_point, true).and_then(|address| {
+        let maybe_new_target = self.window.hit_test_query(client_point, true).and_then(|address| {
             let node = node::from_untrusted_node_address(js_runtime, address);
             node.inclusive_ancestors()
                 .filter_map(Root::downcast::<Element>)
@@ -1593,7 +1584,11 @@ impl Document {
     }
 
     pub fn nodes_from_point(&self, page_point: &Point2D<f32>) -> Vec<UntrustedNodeAddress> {
-        self.window.layout().nodes_from_point(*page_point)
+        let client_point =
+            Point2D::new(page_point.x - self.window.PageXOffset() as f32,
+                         page_point.y - self.window.PageYOffset() as f32);
+
+        self.window.layout().nodes_from_point(*page_point, client_point)
     }
 }
 
@@ -2824,10 +2819,10 @@ impl DocumentMethods for Document {
             return None;
         }
 
-        let js_runtime = unsafe { JS_GetRuntime(window.get_cx()) };
-
         match self.window.hit_test_query(*point, false) {
             Some(untrusted_node_address) => {
+                let js_runtime = unsafe { JS_GetRuntime(window.get_cx()) };
+
                 let node = node::from_untrusted_node_address(js_runtime, untrusted_node_address);
                 let parent_node = node.GetParentNode().unwrap();
                 let element_ref = node.downcast::<Element>().unwrap_or_else(|| {
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 8aaa0adcde3..e6e527aea9c 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -1271,10 +1271,18 @@ impl Window {
         self.layout_rpc.node_geometry().client_rect
     }
 
-    pub fn hit_test_query(&self, hit_test_request: Point2D<f32>, update_cursor: bool)
+    pub fn hit_test_query(&self,
+                          client_point: Point2D<f32>,
+                          update_cursor: bool)
                           -> Option<UntrustedNodeAddress> {
+        let translated_point =
+            Point2D::new(client_point.x + self.PageXOffset() as f32,
+                         client_point.y + self.PageYOffset() as f32);
+
         if !self.reflow(ReflowGoal::ForScriptQuery,
-                        ReflowQueryType::HitTestQuery(hit_test_request, update_cursor),
+                        ReflowQueryType::HitTestQuery(translated_point,
+                                                      client_point,
+                                                      update_cursor),
                         ReflowReason::Query) {
             return None
         }
@@ -1770,7 +1778,7 @@ fn debug_reflow_events(id: PipelineId, goal: &ReflowGoal, query_type: &ReflowQue
         ReflowQueryType::NoQuery => "\tNoQuery",
         ReflowQueryType::ContentBoxQuery(_n) => "\tContentBoxQuery",
         ReflowQueryType::ContentBoxesQuery(_n) => "\tContentBoxesQuery",
-        ReflowQueryType::HitTestQuery(_n, _o) => "\tHitTestQuery",
+        ReflowQueryType::HitTestQuery(..) => "\tHitTestQuery",
         ReflowQueryType::NodeGeometryQuery(_n) => "\tNodeGeometryQuery",
         ReflowQueryType::NodeLayerIdQuery(_n) => "\tNodeLayerIdQuery",
         ReflowQueryType::NodeOverflowQuery(_n) => "\tNodeOverFlowQuery",
diff --git a/components/script_layout_interface/message.rs b/components/script_layout_interface/message.rs
index 14580be4881..5d16aeffb0a 100644
--- a/components/script_layout_interface/message.rs
+++ b/components/script_layout_interface/message.rs
@@ -98,7 +98,7 @@ pub enum ReflowQueryType {
     ContentBoxQuery(TrustedNodeAddress),
     ContentBoxesQuery(TrustedNodeAddress),
     NodeOverflowQuery(TrustedNodeAddress),
-    HitTestQuery(Point2D<f32>, bool),
+    HitTestQuery(Point2D<f32>, Point2D<f32>, bool),
     NodeGeometryQuery(TrustedNodeAddress),
     NodeLayerIdQuery(TrustedNodeAddress),
     NodeScrollGeometryQuery(TrustedNodeAddress),
diff --git a/components/script_layout_interface/rpc.rs b/components/script_layout_interface/rpc.rs
index 21cac2a19c2..a470e76286e 100644
--- a/components/script_layout_interface/rpc.rs
+++ b/components/script_layout_interface/rpc.rs
@@ -38,7 +38,7 @@ pub trait LayoutRPC {
     /// Query layout for the resolve values of the margin properties for an element.
     fn margin_style(&self) -> MarginStyleResponse;
 
-    fn nodes_from_point(&self, point: Point2D<f32>) -> Vec<UntrustedNodeAddress>;
+    fn nodes_from_point(&self, page_point: Point2D<f32>, client_point: Point2D<f32>) -> Vec<UntrustedNodeAddress>;
 }
 
 pub struct ContentBoxResponse(pub Rect<Au>);