Auto merge of #9824 - danlrobertson:element1, r=asajeffrey

Add the scrollWidth and scrollHeight extensions to the element interface

Add the `scrollWidth` and `scrollHeight` extensions to the element interface. My goal was to create a method that encompassed getting `scrollWidth`, `scrollHeight`, `scrollTop`, and `scrollLeft`.

I also noted that `clientHeight` and `clientWidth` to not handle the root element and the body element correctly.

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components/script/dom/element.rs

@@ -1421,6 +1421,16 @@ impl ElementMethods for Element {
                      rect.size.height.to_f64_px())
     }
 
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrollwidth
+    fn ScrollWidth(&self) -> i32 {
+        self.upcast::<Node>().get_scroll_area().size.width
+    }
+
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrollheight
+    fn ScrollHeight(&self) -> i32 {
+        self.upcast::<Node>().get_scroll_area().size.height
+    }
+
     // https://drafts.csswg.org/cssom-view/#dom-element-clienttop
     fn ClientTop(&self) -> i32 {
         self.upcast::<Node>().get_client_rect().origin.y

components/script/dom/node.rs

@@ -18,6 +18,7 @@ use dom::bindings::codegen::Bindings::NamedNodeMapBinding::NamedNodeMapMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::{NodeConstants, NodeMethods};
 use dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use dom::bindings::codegen::Bindings::ProcessingInstructionBinding::ProcessingInstructionMethods;
+use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::codegen::UnionTypes::NodeOrString;
 use dom::bindings::conversions::{self, DerivedFrom};
 use dom::bindings::error::{Error, ErrorResult, Fallible};
@@ -37,6 +38,7 @@ use dom::documentfragment::DocumentFragment;
 use dom::documenttype::DocumentType;
 use dom::element::{Element, ElementCreator};
 use dom::eventtarget::EventTarget;
+use dom::htmlbodyelement::HTMLBodyElement;
 use dom::htmlcollection::HTMLCollection;
 use dom::htmlelement::HTMLElement;
 use dom::nodelist::NodeList;
@@ -45,8 +47,11 @@ use dom::range::WeakRangeVec;
 use dom::text::Text;
 use dom::virtualmethods::{VirtualMethods, vtable_for};
 use dom::window::Window;
+use euclid::point::Point2D;
 use euclid::rect::Rect;
+use euclid::size::Size2D;
 use heapsize::{HeapSizeOf, heap_size_of};
+use html5ever::tree_builder::QuirksMode;
 use js::jsapi::{JSContext, JSObject, JSRuntime};
 use layout_interface::{LayoutChan, Msg};
 use libc::{self, c_void, uintptr_t};
@@ -577,6 +582,42 @@ impl Node {
         window_from_node(self).client_rect_query(self.to_trusted_node_address())
     }
 
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrollwidth
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrollheight
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrolltop
+    // https://drafts.csswg.org/cssom-view/#dom-element-scrollleft
+    pub fn get_scroll_area(&self) -> Rect<i32> {
+        // Step 1
+        let document = self.owner_doc();
+        // Step 3
+        let window = document.window();
+
+        let html_element = document.GetDocumentElement();
+
+        let is_body_element = html_element.r().and_then(|root| {
+            let node = root.upcast::<Node>();
+            node.children().find(|child| { child.is::<HTMLBodyElement>() }).map(|node| {
+                *node.r() == *self
+            })
+        }).unwrap_or(false);
+
+        let scroll_area = window.scroll_area_query(self.to_trusted_node_address());
+
+        match (document != window.Document(), is_body_element, document.quirks_mode(),
+               html_element.r() == self.downcast::<Element>()) {
+            // Step 2 && Step 5
+            (true, _, _, _) | (_, false, QuirksMode::Quirks, true) => Rect::zero(),
+            // Step 6 && Step 7
+            (false, false, _, true) | (false, true, QuirksMode::Quirks, _) => {
+                Rect::new(Point2D::new(window.ScrollX(), window.ScrollY()),
+                                       Size2D::new(max(window.InnerWidth(), scroll_area.size.width),
+                                                   max(window.InnerHeight(), scroll_area.size.height)))
+            },
+            // Step 9
+            _ => scroll_area
+        }
+    }
+
     // https://dom.spec.whatwg.org/#dom-childnode-before
     pub fn before(&self, nodes: Vec<NodeOrString>) -> ErrorResult {
         // Step 1.

components/script/dom/webidls/Element.webidl

@@ -77,6 +77,9 @@ partial interface Element {
   DOMRectList getClientRects();
   DOMRect getBoundingClientRect();
 
+  readonly attribute long scrollWidth;
+  readonly attribute long scrollHeight;
+
   readonly attribute long clientTop;
   readonly attribute long clientLeft;
   readonly attribute long clientWidth;

components/script/dom/window.rs

@@ -1110,6 +1110,13 @@ impl Window {
         self.layout_rpc.hit_test().node_address
     }
 
+    pub fn scroll_area_query(&self, node: TrustedNodeAddress) -> Rect<i32> {
+        self.reflow(ReflowGoal::ForScriptQuery,
+                    ReflowQueryType::NodeScrollGeometryQuery(node),
+                    ReflowReason::Query);
+        self.layout_rpc.node_scroll_area().client_rect
+    }
+
     pub fn resolved_style_query(&self,
                             element: TrustedNodeAddress,
                             pseudo: Option<PseudoElement>,
@@ -1463,6 +1470,7 @@ fn debug_reflow_events(id: PipelineId, goal: &ReflowGoal, query_type: &ReflowQue
         ReflowQueryType::ContentBoxesQuery(_n) => "\tContentBoxesQuery",
         ReflowQueryType::HitTestQuery(_n, _o) => "\tHitTestQuery",
         ReflowQueryType::NodeGeometryQuery(_n) => "\tNodeGeometryQuery",
+        ReflowQueryType::NodeScrollGeometryQuery(_n) => "\tNodeScrollGeometryQuery",
         ReflowQueryType::ResolvedStyleQuery(_, _, _) => "\tResolvedStyleQuery",
         ReflowQueryType::OffsetParentQuery(_n) => "\tOffsetParentQuery",
         ReflowQueryType::MarginStyleQuery(_n) => "\tMarginStyleQuery",

components/script/layout_interface.rs

@@ -104,6 +104,8 @@ 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 scroll geometry of this node. Used by APIs such as `scrollTop`.
+    fn node_scroll_area(&self) -> NodeGeometryResponse;
     /// Requests the node containing the point of interest
     fn hit_test(&self) -> HitTestResponse;
     /// Query layout for the resolved value of a given CSS property
@@ -165,6 +167,7 @@ pub enum ReflowQueryType {
     ContentBoxesQuery(TrustedNodeAddress),
     HitTestQuery(Point2D<f32>, bool),
     NodeGeometryQuery(TrustedNodeAddress),
+    NodeScrollGeometryQuery(TrustedNodeAddress),
     ResolvedStyleQuery(TrustedNodeAddress, Option<PseudoElement>, Atom),
     OffsetParentQuery(TrustedNodeAddress),
     MarginStyleQuery(TrustedNodeAddress),