style: Use cbindgen for cursors.

Pretty straight-forward.

Differential Revision: https://phabricator.services.mozilla.com/D63777

components/style/values/computed/ui.rs

@@ -13,10 +13,10 @@ pub use crate::values::specified::ui::CursorKind;
 pub use crate::values::specified::ui::{MozForceBrokenImageIcon, UserSelect};
 
 /// A computed value for the `cursor` property.
-pub type Cursor = generics::Cursor<CursorImage>;
+pub type Cursor = generics::GenericCursor<CursorImage>;
 
 /// A computed value for item of `image cursors`.
-pub type CursorImage = generics::CursorImage<ComputedImageUrl, Number>;
+pub type CursorImage = generics::GenericCursorImage<ComputedImageUrl, Number>;
 
 /// A computed value for `scrollbar-color` property.
 pub type ScrollbarColor = generics::GenericScrollbarColor<Color>;

components/style/values/generics/ui.rs

@@ -21,19 +21,22 @@ use values::specified::ui::CursorKind;
     ToResolvedValue,
     ToShmem,
 )]
-pub struct Cursor<Image> {
+#[repr(C)]
+pub struct GenericCursor<Image> {
     /// The parsed images for the cursor.
-    pub images: Box<[Image]>,
+    pub images: crate::OwnedSlice<Image>,
     /// The kind of the cursor [default | help | ...].
     pub keyword: CursorKind,
 }
 
+pub use self::GenericCursor as Cursor;
+
 impl<Image> Cursor<Image> {
     /// Set `cursor` to `auto`
     #[inline]
     pub fn auto() -> Self {
         Self {
-            images: vec![].into_boxed_slice(),
+            images: Default::default(),
             keyword: CursorKind::Auto,
         }
     }
@@ -63,24 +66,31 @@ impl<Image: ToCss> ToCss for Cursor<Image> {
     ToResolvedValue,
     ToShmem,
 )]
-pub struct CursorImage<ImageUrl, Number> {
+#[repr(C)]
+pub struct GenericCursorImage<ImageUrl, Number> {
     /// The url to parse images from.
     pub url: ImageUrl,
-    /// The <x> and <y> coordinates.
-    pub hotspot: Option<(Number, Number)>,
+    /// Whether the image has a hotspot or not.
+    pub has_hotspot: bool,
+    /// The x coordinate.
+    pub hotspot_x: Number,
+    /// The y coordinate.
+    pub hotspot_y: Number,
 }
 
+pub use self::GenericCursorImage as CursorImage;
+
 impl<ImageUrl: ToCss, Number: ToCss> ToCss for CursorImage<ImageUrl, Number> {
     fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
     where
         W: Write,
     {
         self.url.to_css(dest)?;
-        if let Some((ref x, ref y)) = self.hotspot {
+        if self.has_hotspot {
             dest.write_str(" ")?;
-            x.to_css(dest)?;
+            self.hotspot_x.to_css(dest)?;
             dest.write_str(" ")?;
-            y.to_css(dest)?;
+            self.hotspot_y.to_css(dest)?;
         }
         Ok(())
     }

components/style/values/specified/ui.rs

@@ -14,10 +14,10 @@ use std::fmt::{self, Write};
 use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 
 /// A specified value for the `cursor` property.
-pub type Cursor = generics::Cursor<CursorImage>;
+pub type Cursor = generics::GenericCursor<CursorImage>;
 
 /// A specified value for item of `image cursors`.
-pub type CursorImage = generics::CursorImage<SpecifiedImageUrl, Number>;
+pub type CursorImage = generics::GenericCursorImage<SpecifiedImageUrl, Number>;
 
 impl Parse for Cursor {
     /// cursor: [<url> [<number> <number>]?]# [auto | default | ...]
@@ -34,7 +34,7 @@ impl Parse for Cursor {
             input.expect_comma()?;
         }
         Ok(Self {
-            images: images.into_boxed_slice(),
+            images: images.into(),
             keyword: CursorKind::parse(input)?,
         })
     }
@@ -45,13 +45,20 @@ impl Parse for CursorImage {
         context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<Self, ParseError<'i>> {
-        Ok(Self {
-            url: SpecifiedImageUrl::parse(context, input)?,
-            hotspot: match input.try(|input| Number::parse(context, input)) {
-                Ok(number) => Some((number, Number::parse(context, input)?)),
-                Err(_) => None,
-            },
-        })
+        use crate::Zero;
+
+        let url = SpecifiedImageUrl::parse(context, input)?;
+        let mut has_hotspot = false;
+        let mut hotspot_x = Number::zero();
+        let mut hotspot_y = Number::zero();
+
+        if let Ok(x) = input.try(|input| Number::parse(context, input)) {
+            has_hotspot = true;
+            hotspot_x = x;
+            hotspot_y = Number::parse(context, input)?;
+        }
+
+        Ok(Self { url, has_hotspot, hotspot_x, hotspot_y })
     }
 }