Expose FastTransform so that it can be used in Servo

Also derive Deserialize and Serialize for serde, not just for the
capture and replay features.

Co-authored-by: Martin Robinson <mrobinson@igalia.com>
Signed-off-by: Oriol Brufau <obrufau@igalia.com>

Author: Loirooriol

webrender/src/lib.rs

@@ -192,6 +192,7 @@ pub use crate::picture::{TileNode, TileNodeKind, TileOffset};
 pub use crate::intern::ItemUid;
 pub use crate::render_api::*;
 pub use crate::tile_cache::{PictureCacheDebugInfo, DirtyTileDebugInfo, TileDebugInfo, SliceDebugInfo};
+pub use crate::util::FastTransform;
 pub use glyph_rasterizer;
 pub use bump_allocator::ChunkPool;
 

webrender/src/util.rs

@@ -1002,8 +1002,7 @@ impl<U> MaxRect for Box2D<f32, U> {
 /// An enum that tries to avoid expensive transformation matrix calculations
 /// when possible when dealing with non-perspective axis-aligned transformations.
 #[derive(Debug, MallocSizeOf)]
-#[cfg_attr(feature = "capture", derive(Serialize))]
-#[cfg_attr(feature = "replay", derive(Deserialize))]
+#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
 pub enum FastTransform<Src, Dst> {
     /// A simple offset, which can be used without doing any matrix math.
     Offset(Vector2D<f32, Src>),
@@ -1024,6 +1023,12 @@ impl<Src, Dst> Clone for FastTransform<Src, Dst> {
 
 impl<Src, Dst> Copy for FastTransform<Src, Dst> { }
 
+impl<Src, Dst> Default for FastTransform<Src, Dst> {
+    fn default() -> Self {
+        Self::identity()
+    }
+}
+
 impl<Src, Dst> FastTransform<Src, Dst> {
     pub fn identity() -> Self {
         FastTransform::Offset(Vector2D::zero())