fix: struct constructors on napi; boxed struct values on both engines

- napi namespaces resolve struct types to a constructor
  (`new Rect({...})`, `new Rect(x, y, w, h)`, `new Rect()`), returning
  the same plain object a struct return gives
- IPropertyValue holding Point/Size/Rect/TimeSpan/DateTime unboxes to
  a struct value instead of an empty wrapper
- plain objects shaped like those five types box back when passed to
  an Object parameter (PropertySet.Insert, settings values)
- missing struct fields serialize as zero instead of NaN
- napi struct String fields are written

Author: triniwiz

integration-tests/tests/boxed_structs.rs

@@ -0,0 +1,59 @@
+use runtime::Runtime;
+
+fn eval(rt: &mut Runtime, expr: &str) -> String {
+    rt.eval_script_to_string(expr)
+        .unwrap_or_else(|| "<exception>".to_string())
+}
+
+#[test]
+fn boxed_structs_unbox_and_box_by_shape() {
+    let mut rt = Runtime::new(".");
+    rt.run_script(
+        "const PV = Windows.Foundation.PropertyValue;
+         globalThis.ps = new Windows.Foundation.Collections.PropertySet();
+         ps.Insert('size', PV.CreateSize({ Width: 9, Height: 8 }));
+         ps.Insert('point', { X: 1, Y: 2 });
+         ps.Insert('rect', { X: 1, Y: 2, Width: 3, Height: 4 });
+         ps.Insert('span', { Duration: 10000000 });",
+        "setup.js",
+    );
+    assert_eq!(eval(&mut rt, "JSON.stringify(ps.Lookup('size'))"), r#"{"Width":9,"Height":8}"#);
+    assert_eq!(eval(&mut rt, "JSON.stringify(ps.Lookup('point'))"), r#"{"X":1,"Y":2}"#);
+    assert_eq!(
+        eval(&mut rt, "JSON.stringify(ps.Lookup('rect'))"),
+        r#"{"X":1,"Y":2,"Width":3,"Height":4}"#
+    );
+    assert_eq!(eval(&mut rt, "JSON.stringify(ps.Lookup('span'))"), r#"{"Duration":10000000}"#);
+    assert_eq!(
+        eval(&mut rt, "JSON.stringify(Windows.Foundation.PropertyValue.CreatePoint({ X: 1.5, Y: 2.5 }))"),
+        r#"{"X":1.5,"Y":2.5}"#
+    );
+}
+
+#[test]
+fn by_value_point_round_trips() {
+    let mut rt = Runtime::new(".");
+    assert_eq!(
+        eval(
+            &mut rt,
+            "JSON.stringify(new Windows.UI.Input.Inking.InkPoint({ X: 3, Y: 4 }, 0.5).Position)"
+        ),
+        r#"{"X":3,"Y":4}"#
+    );
+}
+
+#[test]
+fn missing_struct_fields_serialize_as_zero() {
+    let mut rt = Runtime::new(".");
+    let v = eval(
+        &mut rt,
+        "(() => { try {
+            const s = new Windows.Media.Core.TimedTextStyle();
+            s.Padding = { Before: 1, Unit: 1 };
+            return JSON.stringify(s.Padding);
+        } catch (e) { return 'skip'; } })()",
+    );
+    if v != "skip" {
+        assert_eq!(v, r#"{"Before":1,"After":0,"Start":0,"End":0,"Unit":1}"#);
+    }
+}

runtime/src/napi_engine/ns_proxy.rs

@@ -618,11 +618,49 @@ fn resolve_member(env: &Env, full_name: &str) -> napi::Result<JsUnknown> {
             create_ctor_proxy(env, full_name, declaration)?,
         )),
         DeclarationKind::Enum => Ok(as_unknown(env, create_enum_object(env, &declaration)?)),
-        // Interfaces / structs arrive with later slices.
+        DeclarationKind::Struct => Ok(as_unknown(env, create_struct_ctor(env, full_name, declaration)?)),
+        // Interfaces arrive with later slices.
         _ => undefined_js(env),
     }
 }
 
+/// `new Rect({ X, Y, Width, Height })`, `new Rect(x, y, w, h)` or `new Rect()`: a plain struct
+/// value, round-tripped through the struct's bytes so missing fields are zero and values match
+/// what native receives.
+fn create_struct_ctor(env: &Env, full_name: &str, declaration: Decl) -> napi::Result<JsFunction> {
+    use metadata::declarations::struct_declaration::StructDeclaration;
+
+    let simple_name = full_name.rsplit('.').next().unwrap_or(full_name);
+    env.create_function_from_closure(simple_name, move |ctx: CallContext| {
+        let env = &ctx.env;
+        let first = if ctx.length > 0 { Some(ctx.get::<JsUnknown>(0)?) } else { None };
+        let named = ctx.length == 1
+            && first.as_ref().is_some_and(|v| matches!(v.get_type(), Ok(ValueType::Object)));
+        let mut buf = Vec::new();
+        {
+            let lock = declaration.read();
+            let Some(sd) = lock.as_any().downcast_ref::<StructDeclaration>() else {
+                return undefined_js(env);
+            };
+            let source: JsObject = if named {
+                unsafe { first.unwrap().cast() }
+            } else {
+                let mut positional = env.create_object()?;
+                for (i, field) in sd.fields().iter().enumerate().take(ctx.length) {
+                    positional.set_named_property(field.name(), ctx.get::<JsUnknown>(i)?)?;
+                }
+                positional
+            };
+            crate::property_call::append_struct_object_bytes_napi(env, &mut buf, &source, sd);
+        }
+        if buf.is_empty() {
+            buf.push(0);
+        }
+        let value = create_struct_object_from_raw(env, &declaration, buf.as_ptr())?;
+        Ok(as_unknown(env, value))
+    })
+}
+
 /// A WinRT enum as a plain JS object of name → numeric value (Int32/UInt32, same
 /// representation the v8 interceptor produced).
 fn create_enum_object(env: &Env, declaration: &Decl) -> napi::Result<JsObject> {

runtime/src/napi_engine/value.rs

@@ -892,6 +892,43 @@ pub fn box_as_ireference(
 
 // 
 
+/// Boxes a plain object shaped like one of the struct types `IPropertyValue` supports
+/// (`{X,Y}`, `{Width,Height}`, `{X,Y,Width,Height}`, `{Duration}`, `{UniversalTime}`).
+fn box_struct_shape(env: &Env, obj: &JsObject) -> Option<windows::core::IInspectable> {
+    use windows::Foundation::{DateTime, Point, Rect, Size, TimeSpan};
+    let names = obj.get_property_names().ok()?;
+    let len = names.get_array_length().ok()?;
+    let mut keys: Vec<String> = Vec::with_capacity(len as usize);
+    for i in 0..len {
+        let k: JsString = names.get_element(i).ok()?;
+        keys.push(k.into_utf8().ok()?.as_str().ok()?.to_owned());
+    }
+    keys.sort();
+    let get = |name: &str| obj.get_named_property::<JsUnknown>(name).ok();
+    let f = |name: &str| {
+        get(name)
+            .and_then(|v| coerce_f64(env, &v))
+            .filter(|n| !n.is_nan())
+            .unwrap_or(0.0) as f32
+    };
+    let i = |name: &str| get(name).map(|v| js_to_i64(env, &v)).unwrap_or(0);
+    let keys: Vec<&str> = keys.iter().map(String::as_str).collect();
+    let boxed = match keys.as_slice() {
+        ["X", "Y"] => PropertyValue::CreatePoint(Point { X: f("X"), Y: f("Y") }),
+        ["Height", "Width"] => PropertyValue::CreateSize(Size { Width: f("Width"), Height: f("Height") }),
+        ["Height", "Width", "X", "Y"] => PropertyValue::CreateRect(Rect {
+            X: f("X"),
+            Y: f("Y"),
+            Width: f("Width"),
+            Height: f("Height"),
+        }),
+        ["Duration"] => PropertyValue::CreateTimeSpan(TimeSpan { Duration: i("Duration") }),
+        ["UniversalTime"] => PropertyValue::CreateDateTime(DateTime { UniversalTime: i("UniversalTime") }),
+        _ => return None,
+    };
+    boxed.ok()?.cast().ok()
+}
+
 pub fn napi_parse_pointer(env: &Env, arg: &JsUnknown) -> Result<NativeValue, AnyError> {
     let vt = value_type(arg)?;
 
@@ -941,6 +978,15 @@ pub fn napi_parse_pointer(env: &Env, arg: &JsUnknown) -> Result<NativeValue, Any
         }
     }
 
+    if vt == ValueType::Object {
+        let obj: JsObject = unsafe { arg.cast() };
+        if let Some(inspectable) = box_struct_shape(env, &obj) {
+            let ptr = inspectable.as_raw() as *mut c_void;
+            std::mem::forget(inspectable);
+            return Ok(NativeValue { pointer: ptr });
+        }
+    }
+
     let pointer = if vt == ValueType::External {
         ptr_from_external(env, arg).ok_or_else(|| {
             type_error("Invalid FFI pointer type, expected null, External, or { handle: External|null }")
@@ -1143,7 +1189,10 @@ pub fn append_struct_field_bytes(
     value: &JsUnknown,
     native_type: &NativeType,
 ) {
-    let num = coerce_f64(env, value).unwrap_or(0.0);
+    let num = match value.get_type() {
+        Ok(ValueType::Undefined | ValueType::Null) => 0.0,
+        _ => coerce_f64(env, value).unwrap_or(0.0),
+    };
     match native_type {
         NativeType::F64 => buf.extend_from_slice(&num.to_le_bytes()),
         NativeType::F32 => buf.extend_from_slice(&(num as f32).to_le_bytes()),
@@ -1157,6 +1206,12 @@ pub fn append_struct_field_bytes(
         NativeType::I8 => buf.extend_from_slice(&(num as i8).to_le_bytes()),
         NativeType::U8 => buf.push(num as u8),
         NativeType::Bool => buf.push(if coerce_bool(env, value) { 1u8 } else { 0u8 }),
+        // Ownership moves into the bytes; the struct reader releases it, call args leak it.
+        NativeType::String if matches!(value.get_type(), Ok(ValueType::String)) => {
+            let hstring = ManuallyDrop::new(hstring_from_js_value(env, value));
+            let raw: usize = unsafe { std::mem::transmute_copy(&*hstring) };
+            buf.extend_from_slice(&raw.to_le_bytes());
+        }
         _ => buf.extend(std::iter::repeat(0u8).take(native_type.size())),
     }
 }
@@ -1455,6 +1510,19 @@ pub fn try_unbox_property_value(env: &Env, raw: *mut c_void) -> Option<JsUnknown
             let g = unsafe { pv.GetGuid() }.ok()?;
             env.create_string(&format!("{g:?}")).ok().map(|v| as_unknown(env, v))
         }
+        PropertyType::Point => boxed_struct(env, "Windows.Foundation.Point", &unsafe { pv.GetPoint() }.ok()?),
+        PropertyType::Size => boxed_struct(env, "Windows.Foundation.Size", &unsafe { pv.GetSize() }.ok()?),
+        PropertyType::Rect => boxed_struct(env, "Windows.Foundation.Rect", &unsafe { pv.GetRect() }.ok()?),
+        PropertyType::TimeSpan => boxed_struct(env, "Windows.Foundation.TimeSpan", &unsafe { pv.GetTimeSpan() }.ok()?),
+        PropertyType::DateTime => boxed_struct(env, "Windows.Foundation.DateTime", &unsafe { pv.GetDateTime() }.ok()?),
         _ => None,
     }
 }
+
+/// A boxed struct value (`IReference<Point>` etc.) as the same plain object a struct return gives.
+fn boxed_struct<T>(env: &Env, type_name: &str, value: &T) -> Option<JsUnknown> {
+    let decl = metadata::meta_data_reader::MetadataReader::find_by_name(type_name)?;
+    crate::napi_engine::ns_proxy::create_struct_object_from_raw(env, &decl, value as *const T as *const u8)
+        .ok()
+        .map(|o| as_unknown(env, o))
+}

runtime/src/ns_proxy.rs

@@ -521,10 +521,25 @@ fn try_unbox_property_value<'a>(
             let g = pv.GetGuid().ok()?;
             v8::String::new(scope, &format!("{g:?}")).map(Into::into)
         }
+        PropertyType::Point => boxed_struct(scope, "Windows.Foundation.Point", &pv.GetPoint().ok()?),
+        PropertyType::Size => boxed_struct(scope, "Windows.Foundation.Size", &pv.GetSize().ok()?),
+        PropertyType::Rect => boxed_struct(scope, "Windows.Foundation.Rect", &pv.GetRect().ok()?),
+        PropertyType::TimeSpan => boxed_struct(scope, "Windows.Foundation.TimeSpan", &pv.GetTimeSpan().ok()?),
+        PropertyType::DateTime => boxed_struct(scope, "Windows.Foundation.DateTime", &pv.GetDateTime().ok()?),
         _ => None,
     }
 }
 
+/// A boxed struct value (`IReference<Point>` etc.) as the same object a struct return gives.
+fn boxed_struct<'a, T>(
+    scope: &mut v8::PinScope<'a, '_>,
+    type_name: &str,
+    value: &T,
+) -> Option<v8::Local<'a, v8::Value>> {
+    let decl = MetadataReader::find_by_name(type_name)?;
+    Some(crate::create_struct_object_from_raw(decl, value as *const T as *mut c_void, scope).into())
+}
+
 /// Sets a method/property return value, resolving `Object`/IInspectable returns to a full typed
 /// proxy via GetRuntimeClassName so property/event interceptors work (e.g. the WebView2 returned by
 /// `XamlReader.Load`). Any other signature defers to `set_ret_val`. A non-resolvable Object falls

runtime/src/value.rs

@@ -1248,6 +1248,17 @@ pub fn ffi_parse_pointer_arg(
         }
     }
 
+    if let Some(inspectable) = arg
+        .is_object()
+        .then(|| arg.to_object(scope))
+        .flatten()
+        .and_then(|obj| box_struct_shape(scope, obj))
+    {
+        let ptr = inspectable.as_raw() as *mut c_void;
+        std::mem::forget(inspectable);
+        return Ok(NativeValue { pointer: ptr });
+    }
+
     let pointer = if let Ok(value) = v8::Local::<v8::External>::try_from(arg) {
         value.value()
     } else if arg.is_null_or_undefined() {
@@ -1398,6 +1409,62 @@ pub fn ffi_parse_struct_arg(
     Ok(NativeValue { pointer })
 }
 
+/// Boxes a plain object shaped like one of the struct types `IPropertyValue` supports
+/// (`{X,Y}`, `{Width,Height}`, `{X,Y,Width,Height}`, `{Duration}`, `{UniversalTime}`).
+#[cfg(feature = "classic")]
+fn box_struct_shape(
+    scope: &mut v8::PinScope<'_, '_>,
+    obj: v8::Local<v8::Object>,
+) -> Option<windows::core::IInspectable> {
+    use windows::Foundation::{DateTime, Point, Rect, Size, TimeSpan};
+    let names = obj.get_own_property_names(scope, Default::default())?;
+    let mut keys: Vec<String> = (0..names.length())
+        .filter_map(|i| names.get_index(scope, i))
+        .map(|k| k.to_rust_string_lossy(scope))
+        .collect();
+    keys.sort();
+    let mut get = |name: &str| -> v8::Local<v8::Value> {
+        v8::String::new(scope, name)
+            .and_then(|k| obj.get(scope, k.into()))
+            .unwrap_or_else(|| v8::undefined(scope).into())
+    };
+    let keys: Vec<&str> = keys.iter().map(String::as_str).collect();
+    let boxed = match keys.as_slice() {
+        ["X", "Y"] => {
+            let (x, y) = (get("X"), get("Y"));
+            PropertyValue::CreatePoint(Point { X: f32_of(scope, x), Y: f32_of(scope, y) })
+        }
+        ["Height", "Width"] => {
+            let (w, h) = (get("Width"), get("Height"));
+            PropertyValue::CreateSize(Size { Width: f32_of(scope, w), Height: f32_of(scope, h) })
+        }
+        ["Height", "Width", "X", "Y"] => {
+            let (x, y, w, h) = (get("X"), get("Y"), get("Width"), get("Height"));
+            PropertyValue::CreateRect(Rect {
+                X: f32_of(scope, x),
+                Y: f32_of(scope, y),
+                Width: f32_of(scope, w),
+                Height: f32_of(scope, h),
+            })
+        }
+        ["Duration"] => {
+            let d = get("Duration");
+            PropertyValue::CreateTimeSpan(TimeSpan { Duration: v8_to_i64(scope, d) })
+        }
+        ["UniversalTime"] => {
+            let t = get("UniversalTime");
+            PropertyValue::CreateDateTime(DateTime { UniversalTime: v8_to_i64(scope, t) })
+        }
+        _ => return None,
+    };
+    boxed.ok()?.cast().ok()
+}
+
+#[cfg(feature = "classic")]
+fn f32_of(scope: &mut v8::PinScope<'_, '_>, v: v8::Local<v8::Value>) -> f32 {
+    v.number_value(scope).filter(|n| !n.is_nan()).unwrap_or(0.0) as f32
+}
+
 /// Write a single struct field value (from a V8 value) into a byte buffer in little-endian order.
 /// Used when converting a plain JS object like `{A:255, R:0, G:0, B:0}` to WinRT struct bytes.
 #[cfg(feature = "classic")]
@@ -1407,7 +1474,11 @@ pub(crate) fn append_struct_field_bytes(
     value: v8::Local<v8::Value>,
     native_type: &NativeType,
 ) {
-    let num = value.number_value(scope).unwrap_or(0.0);
+    let num = if value.is_null_or_undefined() {
+        0.0
+    } else {
+        value.number_value(scope).unwrap_or(0.0)
+    };
     match native_type {
         NativeType::F64 => buf.extend_from_slice(&num.to_le_bytes()),
         NativeType::F32 => buf.extend_from_slice(&(num as f32).to_le_bytes()),

windows-napi/test/struct-test.js

@@ -33,5 +33,30 @@ check('Colors.Red B', red.B, 0);
 check('struct spreads', JSON.stringify({ ...color }), '{"A":255,"R":128,"G":64,"B":32}');
 check('struct JSON', JSON.stringify(color), s => s.includes('"A":255'));
 
+// Struct constructors from namespaces; missing fields are zero.
+const F = Windows.Foundation;
+check('struct ctor named', JSON.stringify(new F.Rect({ X: 1, Y: 2, Width: 3, Height: 4 })), '{"X":1,"Y":2,"Width":3,"Height":4}');
+check('struct ctor positional', JSON.stringify(new F.Rect(5, 6, 7, 8)), '{"X":5,"Y":6,"Width":7,"Height":8}');
+check('struct ctor empty', JSON.stringify(new F.Rect()), '{"X":0,"Y":0,"Width":0,"Height":0}');
+check('struct ctor partial', JSON.stringify(new F.Rect({ X: 1 })), '{"X":1,"Y":0,"Width":0,"Height":0}');
+check('struct ctor nested', JSON.stringify(new Windows.UI.Xaml.Duration({ TimeSpan: { Duration: 5 }, Type: 1 })), '{"TimeSpan":{"Duration":5},"Type":1}');
+
+// Point passed by value round-trips.
+const inkPoint = new Windows.UI.Input.Inking.InkPoint(new F.Point(3, 4), 0.5);
+check('by-value Point', JSON.stringify(inkPoint.Position), '{"X":3,"Y":4}');
+
+// Boxed structs (IReference<Point> etc.) unbox to plain objects and box back by shape.
+const PV = F.PropertyValue;
+check('PropertyValue.CreatePoint', JSON.stringify(PV.CreatePoint({ X: 1.5, Y: 2.5 })), '{"X":1.5,"Y":2.5}');
+const ps = new F.Collections.PropertySet();
+ps.Insert('size', PV.CreateSize({ Width: 9, Height: 8 }));
+ps.Insert('point', { X: 1, Y: 2 });
+ps.Insert('rect', new F.Rect(1, 2, 3, 4));
+ps.Insert('span', { Duration: 10000000 });
+check('boxed Size', JSON.stringify(ps.Lookup('size')), '{"Width":9,"Height":8}');
+check('boxed Point', JSON.stringify(ps.Lookup('point')), '{"X":1,"Y":2}');
+check('boxed Rect', JSON.stringify(ps.Lookup('rect')), '{"X":1,"Y":2,"Width":3,"Height":4}');
+check('boxed TimeSpan', JSON.stringify(ps.Lookup('span')), '{"Duration":10000000}');
+
 console.log(`\n${pass} passed, ${fail} failed`);
 process.exit(fail ? 1 : 0);