stylo: Implement scroll-snap-coordinate

MozReview-Commit-ID: 6mr4ktfeEGT

components/style/gecko_bindings/sugar/ns_t_array.rs

@@ -93,4 +93,13 @@ impl<T> nsTArray<T> {
         let mut header = self.header_mut();
         header.mLength = len;
     }
+
+    /// Resizes an array containing only POD elements
+    ///
+    /// This will not leak since it only works on POD types (and thus doesn't assert)
+    pub unsafe fn set_len_pod(&mut self, len: u32) where T: Copy {
+        self.ensure_capacity(len as usize);
+        let mut header = unsafe { self.header_mut() };
+        header.mLength = len;
+    }
 }

components/style/properties/gecko.mako.rs

@@ -1169,7 +1169,8 @@ fn static_assert() {
                           animation-iteration-count animation-timing-function
                           -moz-binding page-break-before page-break-after
                           scroll-snap-points-x scroll-snap-points-y transform
-                          scroll-snap-type-y scroll-snap-destination perspective-origin transform-origin""" %>
+                          scroll-snap-type-y scroll-snap-destination scroll-snap-coordinate
+                          perspective-origin transform-origin""" %>
 <%self:impl_trait style_struct_name="Box" skip_longhands="${skip_box_longhands}">
 
     // We manually-implement the |display| property until we get general
@@ -1347,6 +1348,34 @@ fn static_assert() {
 
     ${impl_simple_copy('scroll_snap_destination', 'mScrollSnapDestination')}
 
+    pub fn set_scroll_snap_coordinate(&mut self, v: longhands::scroll_snap_coordinate::computed_value::T) {
+        unsafe { self.gecko.mScrollSnapCoordinate.set_len_pod(v.0.len() as u32); }
+        for (gecko, servo) in self.gecko.mScrollSnapCoordinate
+                               .iter_mut()
+                               .zip(v.0.iter()) {
+            gecko.mXPosition = servo.horizontal.into();
+            gecko.mYPosition = servo.vertical.into();
+        }
+    }
+
+    pub fn copy_scroll_snap_coordinate_from(&mut self, other: &Self) {
+        unsafe {
+            self.gecko.mScrollSnapCoordinate
+                .set_len_pod(other.gecko.mScrollSnapCoordinate.len() as u32);
+        }
+
+        for (this, that) in self.gecko.mScrollSnapCoordinate
+                               .iter_mut()
+                               .zip(other.gecko.mScrollSnapCoordinate.iter()) {
+            *this = *that;
+        }
+    }
+
+    pub fn clone_scroll_snap_coordinate(&self) -> longhands::scroll_snap_coordinate::computed_value::T {
+        let vec = self.gecko.mScrollSnapCoordinate.iter().map(|f| f.into()).collect();
+        longhands::scroll_snap_coordinate::computed_value::T(vec)
+    }
+
     <%def name="transform_function_arm(name, keyword, items)">
         <%
             pattern = None

components/style/properties/helpers.mako.rs

@@ -21,8 +21,9 @@
     </%call>
 </%def>
 
-<%def name="predefined_type(name, type, initial_value, parse_method='parse', needs_context=True, **kwargs)">
-    <%call expr="longhand(name, predefined_type=type, **kwargs)">
+<%def name="predefined_type(name, type, initial_value, parse_method='parse',
+            needs_context=True, vector=False, **kwargs)">
+    <%def name="predefined_type_inner(name, type, initial_value, parse_method)">
         #[allow(unused_imports)]
         use app_units::Au;
         use cssparser::{Color as CSSParserColor, RGBA};
@@ -40,7 +41,16 @@
             specified::${type}::${parse_method}(input)
             % endif
         }
+    </%def>
+    % if vector:
+        <%call expr="vector_longhand(name, predefined_type=type, **kwargs)">
+            ${predefined_type_inner(name, type, initial_value, parse_method)}
         </%call>
+    % else:
+        <%call expr="longhand(name, predefined_type=type, **kwargs)">
+            ${predefined_type_inner(name, type, initial_value, parse_method)}
+        </%call>
+    % endif
 </%def>
 
 // FIXME (Manishearth): Add computed_value_as_specified argument

components/style/properties/longhand/box.mako.rs

@@ -1056,6 +1056,16 @@ ${helpers.predefined_type("scroll-snap-destination",
                           spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-destination)",
                           animatable=False)}
 
+${helpers.predefined_type("scroll-snap-coordinate",
+                          "Position",
+                          "computed::Position::zero()",
+                          vector=True,
+                          products="gecko",
+                          spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-snap-destination)",
+                          animatable=False,
+                          allow_empty=True)}
+
+
 <%helpers:longhand name="transform" products="gecko servo" extra_prefixes="webkit"
                    animatable="True"
                    spec="https://drafts.csswg.org/css-transforms/#propdef-transform">