core: Add `DisplayObject::scaling_grid`

core/src/display_object.rs

@@ -252,6 +252,10 @@ pub struct DisplayObjectBase<'gc> {
     #[collect(require_static)]
     next_scroll_rect: Rectangle<Twips>,
 
+    /// Rectangle used for 9-slice scaling (`DislayObject.scale9grid`).
+    #[collect(require_static)]
+    scaling_grid: Rectangle<Twips>,
+
     /// If this Display Object should cacheAsBitmap - and if so, the cache itself.
     /// None means not cached, Some means cached.
     #[collect(require_static)]
@@ -282,6 +286,7 @@ impl<'gc> Default for DisplayObjectBase<'gc> {
             flags: DisplayObjectFlags::VISIBLE,
             scroll_rect: None,
             next_scroll_rect: Default::default(),
+            scaling_grid: Default::default(),
             cache: None,
         }
     }
@@ -1616,6 +1621,14 @@ pub trait TDisplayObject<'gc>:
         }
     }
 
+    fn scaling_grid(&self) -> Rectangle<Twips> {
+        self.base().scaling_grid.clone()
+    }
+
+    fn set_scaling_grid(&self, gc_context: &Mutation<'gc>, rect: Rectangle<Twips>) {
+        self.base_mut(gc_context).scaling_grid = rect;
+    }
+
     /// Whether this object has been removed. Only applies to AVM1.
     fn avm1_removed(&self) -> bool {
         self.base().avm1_removed()

core/src/display_object/movie_clip.rs

@@ -598,6 +598,10 @@ impl<'gc> MovieClip<'gc> {
                     .0
                     .write(context.gc_context)
                     .define_morph_shape(context, reader, 2),
+                TagCode::DefineScalingGrid => self
+                    .0
+                    .write(context.gc_context)
+                    .define_scaling_grid(context, reader),
                 TagCode::DefineShape => self
                     .0
                     .write(context.gc_context)
@@ -3473,6 +3477,25 @@ impl<'gc, 'a> MovieClipData<'gc> {
         Ok(())
     }
 
+    #[inline]
+    fn define_scaling_grid(
+        &mut self,
+        context: &mut UpdateContext<'_, 'gc>,
+        reader: &mut SwfStream<'a>,
+    ) -> Result<(), Error> {
+        let id = reader.read_u16()?;
+        let rect = reader.read_rectangle()?;
+        let library = context.library.library_for_movie_mut(self.movie());
+        if let Some(character) = library.character_by_id(id) {
+            if let Character::MovieClip(clip) = character {
+                clip.set_scaling_grid(context.gc_context, rect);
+            } else {
+                tracing::warn!("DefineScalingGrid for invalid ID {}", id);
+            }
+        }
+        Ok(())
+    }
+
     #[inline]
     fn define_morph_shape(
         &mut self,