avm2: Implement `Event.preventDefault` and `Event.isDefaultPrevented`

core/src/avm2/events.rs

@@ -103,6 +103,16 @@ impl<'gc> Event<'gc> {
         self.cancelable = cancelable;
     }
 
+    pub fn is_cancelled(&self) -> bool {
+        self.cancelled
+    }
+
+    pub fn cancel(&mut self) {
+        if self.cancelable {
+            self.cancelled = true;
+        }
+    }
+
     pub fn phase(&self) -> EventPhase {
         self.event_phase
     }

core/src/avm2/globals/flash/events/event.rs

@@ -191,6 +191,32 @@ pub fn format_to_string<'gc>(
     Ok(Value::Undefined)
 }
 
+/// Implements `isDefaultPrevented`
+pub fn is_default_prevented<'gc>(
+    _activation: &mut Activation<'_, 'gc, '_>,
+    this: Option<Object<'gc>>,
+    _args: &[Value<'gc>],
+) -> Result<Value<'gc>, Error> {
+    if let Some(evt) = this.unwrap().as_event() {
+        return Ok(evt.is_cancelled().into());
+    }
+
+    Ok(Value::Undefined)
+}
+
+/// Implements `preventDefault`
+pub fn prevent_default<'gc>(
+    activation: &mut Activation<'_, 'gc, '_>,
+    this: Option<Object<'gc>>,
+    _args: &[Value<'gc>],
+) -> Result<Value<'gc>, Error> {
+    if let Some(mut evt) = this.unwrap().as_event_mut(activation.context.gc_context) {
+        evt.cancel();
+    }
+
+    Ok(Value::Undefined)
+}
+
 /// Construct `Event`'s class.
 pub fn create_class<'gc>(mc: MutationContext<'gc, '_>) -> GcCell<'gc, Class<'gc>> {
     let class = Class::new(
@@ -235,6 +261,14 @@ pub fn create_class<'gc>(mc: MutationContext<'gc, '_>) -> GcCell<'gc, Class<'gc>
         QName::new(Namespace::public_namespace(), "formatToString"),
         Method::from_builtin(format_to_string),
     ));
+    write.define_instance_trait(Trait::from_method(
+        QName::new(Namespace::public_namespace(), "isDefaultPrevented"),
+        Method::from_builtin(is_default_prevented),
+    ));
+    write.define_instance_trait(Trait::from_method(
+        QName::new(Namespace::public_namespace(), "preventDefault"),
+        Method::from_builtin(prevent_default),
+    ));
 
     class
 }

core/tests/regression_tests.rs

@@ -451,6 +451,7 @@ swf_tests! {
     (as3_event_type, "avm2/event_type", 1),
     (as3_event_clone, "avm2/event_clone", 1),
     (as3_event_formattostring, "avm2/event_formattostring", 1),
+    (as3_event_isdefaultprevented, "avm2/event_isdefaultprevented", 1),
 }
 
 // TODO: These tests have some inaccuracies currently, so we use approx_eq to test that numeric values are close enough.

core/tests/swfs/avm2/event_isdefaultprevented/Test.as

@@ -0,0 +1,30 @@
+package {
+	public class Test {
+	}
+}
+
+import flash.events.Event;
+
+trace("//var e = new Event(\"test_event\", false, false);");
+var e = new Event("test_event", false, false);
+
+trace("//e.isDefaultPrevented();");
+trace(e.isDefaultPrevented());
+
+trace("//e.preventDefault()");
+e.preventDefault();
+
+trace("//e.isDefaultPrevented();");
+trace(e.isDefaultPrevented());
+
+trace("//var e = new Event(\"test_event\", true, true);");
+var e = new Event("test_event", true, true);
+
+trace("//e.isDefaultPrevented();");
+trace(e.isDefaultPrevented());
+
+trace("//e.preventDefault()");
+e.preventDefault();
+
+trace("//e.isDefaultPrevented();");
+trace(e.isDefaultPrevented());

core/tests/swfs/avm2/event_isdefaultprevented/output.txt

@@ -0,0 +1,12 @@
+//var e = new Event("test_event", false, false);
+//e.isDefaultPrevented();
+false
+//e.preventDefault()
+//e.isDefaultPrevented();
+false
+//var e = new Event("test_event", true, true);
+//e.isDefaultPrevented();
+false
+//e.preventDefault()
+//e.isDefaultPrevented();
+true