Implement matchMedia and MediaQueryList

Fixes #13376.

1 files changed, 156 insertions, 0 deletions

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()
+    }
+}