avm1: Implement `Object.registerClass`

core/src/avm1/globals.rs

@@ -179,12 +179,7 @@ pub fn create_globals<'gc>(
         boolean::create_proto(gc_context, object_proto, function_proto);
 
     //TODO: These need to be constructors and should also set `.prototype` on each one
-    let object = FunctionObject::function(
-        gc_context,
-        Executable::Native(object::constructor),
-        Some(function_proto),
-        Some(object_proto),
-    );
+    let object = object::create_object_object(gc_context, object_proto, function_proto);
 
     let color = FunctionObject::function(
         gc_context,

core/src/avm1/globals/object.rs

@@ -1,7 +1,9 @@
 //! Object prototype
+use crate::avm1::function::{Executable, FunctionObject};
 use crate::avm1::property::Attribute::{self, *};
 use crate::avm1::return_value::ReturnValue;
 use crate::avm1::{Avm1, Error, Object, TObject, UpdateContext, Value};
+use crate::character::Character;
 use enumset::EnumSet;
 use gc_arena::MutationContext;
 
@@ -129,6 +131,32 @@ fn value_of<'gc>(
     Ok(ReturnValue::Immediate(this.into()))
 }
 
+/// Implements `Object.registerClass`
+pub fn register_class<'gc>(
+    avm: &mut Avm1<'gc>,
+    context: &mut UpdateContext<'_, 'gc, '_>,
+    _this: Object<'gc>,
+    args: &[Value<'gc>],
+) -> Result<ReturnValue<'gc>, Error> {
+    if let Some(class_name) = args
+        .get(0)
+        .and_then(|v| v.clone().coerce_to_string(avm, context).ok())
+    {
+        if let Some(Character::MovieClip(movie_clip)) = context
+            .library
+            .library_for_movie_mut(context.swf.clone())
+            .get_character_by_export_name(&class_name)
+        {
+            if let Some(constructor) = args.get(1).and_then(|v| v.as_object().ok()) {
+                movie_clip.set_avm1_constructor(context.gc_context, Some(constructor));
+            } else {
+                movie_clip.set_avm1_constructor(context.gc_context, None);
+            }
+        }
+    }
+    Ok(Value::Undefined.into())
+}
+
 /// Partially construct `Object.prototype`.
 ///
 /// `__proto__` and other cross-linked properties of this object will *not*
@@ -259,3 +287,27 @@ pub fn as_set_prop_flags<'gc>(
 
     Ok(Value::Undefined.into())
 }
+
+pub fn create_object_object<'gc>(
+    gc_context: MutationContext<'gc, '_>,
+    proto: Object<'gc>,
+    fn_proto: Object<'gc>,
+) -> Object<'gc> {
+    let object_function = FunctionObject::function(
+        gc_context,
+        Executable::Native(constructor),
+        Some(fn_proto),
+        Some(proto),
+    );
+    let mut object = object_function.as_script_object().unwrap();
+
+    object.force_set_function(
+        "registerClass",
+        register_class,
+        gc_context,
+        Attribute::DontEnum | Attribute::DontDelete | Attribute::ReadOnly,
+        Some(fn_proto),
+    );
+
+    object_function
+}

core/src/display_object/movie_clip.rs

@@ -1,5 +1,5 @@
 //! `MovieClip` display object and support code.
-use crate::avm1::{Avm1, Object, StageObject, Value};
+use crate::avm1::{Avm1, Object, StageObject, TObject, Value};
 use crate::backend::audio::AudioStreamHandle;
 use crate::character::Character;
 use crate::context::{ActionType, RenderContext, UpdateContext};
@@ -41,6 +41,7 @@ pub struct MovieClipData<'gc> {
     object: Option<Object<'gc>>,
     clip_actions: SmallVec<[ClipAction; 2]>,
     flags: EnumSet<MovieClipFlags>,
+    avm1_constructor: Option<Object<'gc>>,
 }
 
 impl<'gc> MovieClip<'gc> {
@@ -58,6 +59,7 @@ impl<'gc> MovieClip<'gc> {
                 object: None,
                 clip_actions: SmallVec::new(),
                 flags: EnumSet::empty(),
+                avm1_constructor: None,
             },
         ))
     }
@@ -89,6 +91,7 @@ impl<'gc> MovieClip<'gc> {
                 object: None,
                 clip_actions: SmallVec::new(),
                 flags: MovieClipFlags::Playing.into(),
+                avm1_constructor: None,
             },
         ))
     }
@@ -180,6 +183,14 @@ impl<'gc> MovieClip<'gc> {
         self.0.read().static_data.total_frames
     }
 
+    pub fn set_avm1_constructor(
+        self,
+        gc_context: MutationContext<'gc, '_>,
+        prototype: Option<Object<'gc>>,
+    ) {
+        self.0.write(gc_context).avm1_constructor = prototype;
+    }
+
     pub fn frame_label_to_number(self, frame_label: &str) -> Option<FrameNumber> {
         // Frame labels are case insensitive.
         let label = frame_label.to_ascii_lowercase();
@@ -386,12 +397,32 @@ impl<'gc> TDisplayObject<'gc> for MovieClip<'gc> {
 
     fn post_instantiation(
         &mut self,
-        _avm: &mut Avm1<'gc>,
+        avm: &mut Avm1<'gc>,
         context: &mut UpdateContext<'_, 'gc, '_>,
         display_object: DisplayObject<'gc>,
     ) {
         let mut mc = self.0.write(context.gc_context);
         if mc.object.is_none() {
+            if let Some(constructor) = mc.avm1_constructor {
+                if let Ok(prototype) = constructor
+                    .get("prototype", avm, context)
+                    .and_then(|v| v.resolve(avm, context))
+                    .and_then(|v| v.as_object())
+                {
+                    let object: Object<'gc> = StageObject::for_display_object(
+                        context.gc_context,
+                        display_object,
+                        Some(prototype),
+                    )
+                    .into();
+                    mc.object = Some(object);
+                    if let Ok(result) = constructor.call(avm, context, object, &[]) {
+                        let _ = result.resolve(avm, context);
+                    }
+                    return;
+                }
+            };
+
             let object = StageObject::for_display_object(
                 context.gc_context,
                 display_object,
@@ -432,6 +463,7 @@ unsafe impl<'gc> Collect for MovieClipData<'gc> {
         self.base.trace(cc);
         self.static_data.trace(cc);
         self.object.trace(cc);
+        self.avm1_constructor.trace(cc);
     }
 }
 

core/tests/regression_tests.rs

@@ -126,6 +126,7 @@ swf_tests! {
     (equals2_swf5, "avm1/equals2_swf5", 1),
     (equals2_swf6, "avm1/equals2_swf6", 1),
     (equals2_swf7, "avm1/equals2_swf7", 1),
+    (register_class, "avm1/register_class", 1),
     (set_variable_scope, "avm1/set_variable_scope", 1),
     (slash_syntax, "avm1/slash_syntax", 2),
     (strictequals_swf6, "avm1/strictequals_swf6", 1),

core/tests/swfs/avm1/register_class/output.txt

@@ -0,0 +1,18 @@
+Custom movieclip!
+// typeof custom_movieclip
+movieclip
+// custom_movieclip.__proto__ == custom_mc.prototype
+true
+// custom_movieclip.__proto__ == MovieClip.prototype
+false
+// custom_movieclip.isCustom()
+true
+
+// typeof normal_movieclip
+movieclip
+// normal_movieclip.__proto__ == custom_mc.prototype
+false
+// normal_movieclip.__proto__ == MovieClip.prototype
+true
+// normal_movieclip.isCustom()
+undefined