Auto merge of #13453 - metajack:media-query-list, r=jdm

Implement matchMedia and MediaQueryList

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---

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #13376 (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Fixes #13376.

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This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13453)

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7 files changed, 204 insertions, 3 deletions

diff --git a/components/script/dom/bindings/codegen/Bindings.conf b/components/script/dom/bindings/codegen/Bindings.conf
index 434450d2bcc..5647679f446 100644
--- a/components/script/dom/bindings/codegen/Bindings.conf
+++ b/components/script/dom/bindings/codegen/Bindings.conf
@@ -14,12 +14,16 @@
 
 DOMInterfaces = {
 
+'MediaQueryList': {
+    'weakReferenceable': True,
+},
+
 'Promise': {
     'spiderMonkeyInterface': True,
 },
 
 'Range': {
-	'weakReferenceable': True,
+    'weakReferenceable': True,
 },
 
 #FIXME(jdm): This should be 'register': False, but then we don't generate enum types
diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 9ac91f7078c..e0f65d9f6e1 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -91,6 +91,7 @@ use std::time::{SystemTime, Instant};
 use string_cache::{Atom, Namespace, QualName};
 use style::attr::{AttrIdentifier, AttrValue, LengthOrPercentageOrAuto};
 use style::element_state::*;
+use style::media_queries::MediaQueryList;
 use style::properties::PropertyDeclarationBlock;
 use style::selector_impl::{ElementSnapshot, PseudoElement};
 use style::values::specified::Length;
@@ -367,7 +368,7 @@ no_jsmanaged_fields!(WebGLProgramId);
 no_jsmanaged_fields!(WebGLRenderbufferId);
 no_jsmanaged_fields!(WebGLShaderId);
 no_jsmanaged_fields!(WebGLTextureId);
-
+no_jsmanaged_fields!(MediaQueryList);
 
 impl JSTraceable for Box<ScriptChan + Send> {
     #[inline]
diff --git a/components/script/dom/mediaquerylist.rs b/components/script/dom/mediaquerylist.rs
new file mode 100644
index 00000000000..30e510171b4
--- /dev/null
+++ b/components/script/dom/mediaquerylist.rs
@@ -0,0 +1,156 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use cssparser::ToCss;
+use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
+use dom::bindings::codegen::Bindings::EventListenerBinding::EventListener;
+use dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetMethods;
+use dom::bindings::codegen::Bindings::MediaQueryListBinding::{self, MediaQueryListMethods};
+use dom::bindings::inheritance::Castable;
+use dom::bindings::js::{JS, Root};
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::bindings::trace::JSTraceable;
+use dom::bindings::weakref::{WeakRef, WeakRefVec};
+use dom::document::Document;
+use dom::eventtarget::EventTarget;
+use euclid::scale_factor::ScaleFactor;
+use js::jsapi::JSTracer;
+use std::cell::Cell;
+use std::rc::Rc;
+use style;
+use style::media_queries::{Device, MediaType};
+use style_traits::{PagePx, ViewportPx};
+
+pub enum MediaQueryListMatchState {
+    Same(bool),
+    Changed(bool),
+}
+
+#[dom_struct]
+pub struct MediaQueryList {
+    eventtarget: EventTarget,
+    document: JS<Document>,
+    media_query_list: style::media_queries::MediaQueryList,
+    last_match_state: Cell<Option<bool>>
+}
+
+impl MediaQueryList {
+    fn new_inherited(document: &Document,
+                     media_query_list: style::media_queries::MediaQueryList) -> MediaQueryList {
+        MediaQueryList {
+            eventtarget: EventTarget::new_inherited(),
+            document: JS::from_ref(document),
+            media_query_list: media_query_list,
+            last_match_state: Cell::new(None),
+        }
+    }
+
+    pub fn new(document: &Document,
+               media_query_list: style::media_queries::MediaQueryList) -> Root<MediaQueryList> {
+        reflect_dom_object(box MediaQueryList::new_inherited(document, media_query_list),
+                           document.window(),
+                           MediaQueryListBinding::Wrap)
+    }
+}
+
+impl MediaQueryList {
+    fn evaluate_changes(&self) -> MediaQueryListMatchState {
+        let matches = self.evaluate();
+
+        let result = if let Some(old_matches) = self.last_match_state.get() {
+            if old_matches == matches {
+                MediaQueryListMatchState::Same(matches)
+            } else {
+                MediaQueryListMatchState::Changed(matches)
+            }
+        } else {
+            MediaQueryListMatchState::Changed(matches)
+        };
+
+        self.last_match_state.set(Some(matches));
+        result
+    }
+
+    pub fn evaluate(&self) -> bool {
+        if let Some(window_size) = self.document.window().window_size() {
+            let viewport_size = window_size.visible_viewport;
+            // TODO: support real ViewportPx, including zoom level
+            // This information seems not to be tracked currently, so we assume
+            // ViewportPx == PagePx
+            let page_to_viewport: ScaleFactor<f32, PagePx, ViewportPx> = ScaleFactor::new(1.0);
+            let device = Device::new(MediaType::Screen, viewport_size * page_to_viewport);
+            self.media_query_list.evaluate(&device)
+        } else {
+            false
+        }
+    }
+}
+
+impl MediaQueryListMethods for MediaQueryList {
+    // https://drafts.csswg.org/cssom-view/#dom-mediaquerylist-media
+    fn Media(&self) -> DOMString {
+        let mut s = String::new();
+        self.media_query_list.to_css(&mut s).unwrap();
+        DOMString::from_string(s)
+    }
+
+    // https://drafts.csswg.org/cssom-view/#dom-mediaquerylist-matches
+    fn Matches(&self) -> bool {
+        match self.last_match_state.get() {
+            None => self.evaluate(),
+            Some(state) => state,
+        }
+    }
+
+    // https://drafts.csswg.org/cssom-view/#dom-mediaquerylist-addlistener
+    fn AddListener(&self, listener: Option<Rc<EventListener>>) {
+        self.upcast::<EventTarget>().AddEventListener(DOMString::from_string("change".to_owned()),
+                                                      listener, false);
+    }
+
+    // https://drafts.csswg.org/cssom-view/#dom-mediaquerylist-removelistener
+    fn RemoveListener(&self, listener: Option<Rc<EventListener>>) {
+        self.upcast::<EventTarget>().RemoveEventListener(DOMString::from_string("change".to_owned()),
+                                                         listener, false);
+    }
+
+    // https://drafts.csswg.org/cssom-view/#dom-mediaquerylist-onchange
+    event_handler!(change, GetOnchange, SetOnchange);
+}
+
+#[derive(HeapSizeOf)]
+pub struct WeakMediaQueryListVec {
+    cell: DOMRefCell<WeakRefVec<MediaQueryList>>,
+}
+
+#[allow(unsafe_code)]
+impl WeakMediaQueryListVec {
+    /// Create a new vector of weak references to MediaQueryList
+    pub fn new() -> Self {
+        WeakMediaQueryListVec { cell: DOMRefCell::new(WeakRefVec::new()) }
+    }
+
+    pub fn push(&self, mql: &MediaQueryList) {
+        self.cell.borrow_mut().push(WeakRef::new(mql));
+    }
+
+    /// Evaluate media query lists and report changes
+    /// https://drafts.csswg.org/cssom-view/#evaluate-media-queries-and-report-changes
+    pub fn evaluate_and_report_changes(&self) {
+        for mql in self.cell.borrow().iter() {
+            if let MediaQueryListMatchState::Changed(_) = mql.root().unwrap().evaluate_changes() {
+                mql.root().unwrap().upcast::<EventTarget>().fire_simple_event("change");
+            }
+        }
+    }
+}
+
+#[allow(unsafe_code)]
+impl JSTraceable for WeakMediaQueryListVec {
+    fn trace(&self, _: *mut JSTracer) {
+        self.cell.borrow_mut().retain_alive()
+    }
+}
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 4c6c7c941c4..14498823424 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -357,6 +357,7 @@ pub mod imagedata;
 pub mod keyboardevent;
 pub mod location;
 pub mod mediaerror;
+pub mod mediaquerylist;
 pub mod messageevent;
 pub mod mimetype;
 pub mod mimetypearray;
diff --git a/components/script/dom/webidls/MediaQueryList.webidl b/components/script/dom/webidls/MediaQueryList.webidl
new file mode 100644
index 00000000000..2991efa89a8
--- /dev/null
+++ b/components/script/dom/webidls/MediaQueryList.webidl
@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom-view/#mediaquerylist
+
+[Exposed=(Window)]
+interface MediaQueryList : EventTarget {
+  readonly attribute DOMString media;
+  readonly attribute boolean matches;
+  void addListener(EventListener? listener);
+  void removeListener(EventListener? listener);
+           attribute EventHandler onchange;
+};
diff --git a/components/script/dom/webidls/Window.webidl b/components/script/dom/webidls/Window.webidl
index 87cc3f3e486..ad3494b6f5f 100644
--- a/components/script/dom/webidls/Window.webidl
+++ b/components/script/dom/webidls/Window.webidl
@@ -120,7 +120,7 @@ dictionary ScrollToOptions : ScrollOptions {
 
 // http://dev.w3.org/csswg/cssom-view/#extensions-to-the-window-interface
 partial interface Window {
-  //MediaQueryList matchMedia(DOMString query);
+  [Exposed=(Window), NewObject] MediaQueryList matchMedia(DOMString query);
   [SameObject] readonly attribute Screen screen;
 
   // browsing context
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 5afbf475cc9..099e50f4820 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use app_units::Au;
+use cssparser::Parser;
 use devtools_traits::{ScriptToDevtoolsControlMsg, TimelineMarker, TimelineMarkerType};
 use dom::bindings::callback::ExceptionHandling;
 use dom::bindings::cell::DOMRefCell;
@@ -35,6 +36,7 @@ use dom::globalscope::GlobalScope;
 use dom::history::History;
 use dom::htmliframeelement::build_mozbrowser_custom_event;
 use dom::location::Location;
+use dom::mediaquerylist::{MediaQueryList, WeakMediaQueryListVec};
 use dom::messageevent::MessageEvent;
 use dom::navigator::Navigator;
 use dom::node::{Node, from_untrusted_node_address, window_from_node};
@@ -86,6 +88,7 @@ use std::sync::mpsc::TryRecvError::{Disconnected, Empty};
 use string_cache::Atom;
 use style::context::ReflowGoal;
 use style::error_reporting::ParseErrorReporter;
+use style::media_queries;
 use style::properties::longhands::overflow_x;
 use style::selector_impl::PseudoElement;
 use style::str::HTML_SPACE_CHARACTERS;
@@ -233,6 +236,9 @@ pub struct Window {
 
     /// A list of scroll offsets for each scrollable element.
     scroll_offsets: DOMRefCell<HashMap<UntrustedNodeAddress, Point2D<f32>>>,
+
+    /// All the MediaQueryLists we need to update
+    media_query_lists: WeakMediaQueryListVec,
 }
 
 impl Window {
@@ -309,6 +315,10 @@ impl Window {
     pub fn set_scroll_offsets(&self, offsets: HashMap<UntrustedNodeAddress, Point2D<f32>>) {
         *self.scroll_offsets.borrow_mut() = offsets
     }
+
+    pub fn current_viewport(&self) -> Rect<Au> {
+        self.current_viewport.clone().get()
+    }
 }
 
 #[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
@@ -856,6 +866,16 @@ impl WindowMethods for Window {
         }
     }
 
+    // https://drafts.csswg.org/cssom-view/#dom-window-matchmedia
+    fn MatchMedia(&self, query: DOMString) -> Root<MediaQueryList> {
+        let mut parser = Parser::new(&query);
+        let media_query_list = media_queries::parse_media_query_list(&mut parser);
+        let document = self.Document();
+        let mql = MediaQueryList::new(&document, media_query_list);
+        self.media_query_lists.push(&*mql);
+        mql
+    }
+
     #[allow(unrooted_must_root)]
     // https://fetch.spec.whatwg.org/#fetch-method
     fn Fetch(&self, input: RequestOrUSVString, init: &RequestInit) -> Rc<Promise> {
@@ -1477,6 +1497,10 @@ impl Window {
         let custom_event = build_mozbrowser_custom_event(&self, event);
         custom_event.upcast::<Event>().fire(self.upcast());
     }
+
+    pub fn evaluate_media_queries_and_report_changes(&self) {
+        self.media_query_lists.evaluate_and_report_changes();
+    }
 }
 
 impl Window {
@@ -1563,6 +1587,7 @@ impl Window {
             ignore_further_async_events: Arc::new(AtomicBool::new(false)),
             error_reporter: error_reporter,
             scroll_offsets: DOMRefCell::new(HashMap::new()),
+            media_query_lists: WeakMediaQueryListVec::new(),
         };
 
         WindowBinding::Wrap(runtime.cx(), win)