Refactor BorderRadius and move it to the border modules

BorderRadius now parses itself reusing Rect<T>.

components/style/values/generics/border.rs

@@ -4,6 +4,7 @@
 
 //! Generic types for CSS values related to borders.
 
+use euclid::Size2D;
 use std::fmt;
 use style_traits::ToCss;
 use values::generics::rect::Rect;
@@ -30,6 +31,27 @@ pub struct BorderImageSlice<NumberOrPercentage> {
     pub fill: bool,
 }
 
+/// A generic value for `border-radius`, `outline-radius` and `inset()`.
+///
+/// https://drafts.csswg.org/css-backgrounds-3/#border-radius
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
+pub struct BorderRadius<LengthOrPercentage> {
+    /// The top left radius.
+    pub top_left: BorderRadiusSize<LengthOrPercentage>,
+    /// The top right radius.
+    pub top_right: BorderRadiusSize<LengthOrPercentage>,
+    /// The bottom right radius.
+    pub bottom_right: BorderRadiusSize<LengthOrPercentage>,
+    /// The bottom left radius.
+    pub bottom_left: BorderRadiusSize<LengthOrPercentage>,
+}
+
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Clone, Copy, Debug, HasViewportPercentage, PartialEq, ToComputedValue)]
+/// A generic value for `border-*-radius` longhand properties.
+pub struct BorderRadiusSize<L>(pub Size2D<L>);
+
 impl<L, N> ToCss for BorderImageWidthSide<L, N>
     where L: ToCss, N: ToCss,
 {
@@ -69,3 +91,81 @@ impl<N> ToCss for BorderImageSlice<N>
         Ok(())
     }
 }
+
+impl<L> BorderRadius<L> {
+    /// Returns a new `BorderRadius<L>`.
+    #[inline]
+    pub fn new(tl: BorderRadiusSize<L>,
+               tr: BorderRadiusSize<L>,
+               br: BorderRadiusSize<L>,
+               bl: BorderRadiusSize<L>)
+               -> Self {
+        BorderRadius {
+            top_left: tl,
+            top_right: tr,
+            bottom_right: br,
+            bottom_left: bl,
+        }
+    }
+}
+
+impl<L> BorderRadius<L>
+    where L: PartialEq + ToCss
+{
+    /// Serialises two given rects following the syntax of the `border-radius``
+    /// property.
+    pub fn serialize_rects<W>(widths: Rect<&L>, heights: Rect<&L>, dest: &mut W) -> fmt::Result
+        where W: fmt::Write,
+    {
+        widths.to_css(dest)?;
+        if widths.0 != heights.0 || widths.1 != heights.1 || widths.2 != heights.2 || widths.3 != heights.3 {
+            dest.write_str(" / ")?;
+            heights.to_css(dest)?;
+        }
+        Ok(())
+    }
+}
+
+impl<L> ToCss for BorderRadius<L>
+    where L: PartialEq + ToCss
+{
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        let BorderRadius {
+            top_left: ref tl,
+            top_right: ref tr,
+            bottom_right: ref br,
+            bottom_left: ref bl,
+        } = *self;
+
+        let widths = Rect::new(&tl.0.width, &tr.0.width, &br.0.width, &bl.0.width);
+        let heights = Rect::new(&tl.0.height, &tr.0.height, &br.0.height, &bl.0.height);
+
+        Self::serialize_rects(widths, heights, dest)
+    }
+}
+
+impl<L> BorderRadiusSize<L> {
+    #[inline]
+    /// Create a new `BorderRadiusSize` for an area of given width and height.
+    pub fn new(width: L, height: L) -> BorderRadiusSize<L> {
+        BorderRadiusSize(Size2D::new(width, height))
+    }
+}
+
+impl<L: Clone> From<L> for BorderRadiusSize<L> {
+    fn from(radius: L) -> Self {
+        Self::new(radius.clone(), radius)
+    }
+}
+
+impl<L> ToCss for BorderRadiusSize<L>
+    where L: ToCss,
+{
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+        where W: fmt::Write
+    {
+        self.0.width.to_css(dest)?;
+        dest.write_str(" ")?;
+        self.0.height.to_css(dest)
+    }
+}