internal/pipewire: implement Core::CreateObject

Nothing uses this right now, this would have to be called by wrapper methods on Registry that would search the objects

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pipewire/core.go

@@ -572,6 +572,58 @@ func (ctx *Context) GetRegistry() (*Registry, error) {
 	)
 }
 
+// CoreCreateObject is sent when the client requests to create a
+// new object from a factory of a certain type.
+//
+// The client allocates a new_id for the proxy. The server will
+// allocate a new resource with the same new_id and from then on,
+// Methods and Events will be exchanged between the new object of
+// the given type.
+type CoreCreateObject struct {
+	// The name of a server factory object to use.
+	FactoryName String `json:"factory_name"`
+	// The type of the object to create, this is also the type of
+	// the interface of the new_id proxy.
+	Type String `json:"type"`
+	// Undocumented, assumed to be the local version of the proxy.
+	Version Int `json:"version"`
+	// Extra properties to create the object.
+	Properties *SPADict `json:"props"`
+	// The proxy id of the new object.
+	NewID Int `json:"new_id"`
+}
+
+// Opcode satisfies [Message] with a constant value.
+func (c *CoreCreateObject) Opcode() byte { return PW_CORE_METHOD_CREATE_OBJECT }
+
+// FileCount satisfies [Message] with a constant value.
+func (c *CoreCreateObject) FileCount() Int { return 0 }
+
+// Size satisfies [KnownSize] with a value computed at runtime.
+func (c *CoreCreateObject) Size() Word {
+	return SizePrefix +
+		SizeString[Word](c.FactoryName) +
+		SizeString[Word](c.Type) +
+		Size(SizeInt) +
+		c.Properties.Size() +
+		Size(SizeInt)
+}
+
+// MarshalBinary satisfies [encoding.BinaryMarshaler] via [Marshal].
+func (c *CoreCreateObject) MarshalBinary() ([]byte, error) { return Marshal(c) }
+
+// UnmarshalBinary satisfies [encoding.BinaryUnmarshaler] via [Unmarshal].
+func (c *CoreCreateObject) UnmarshalBinary(data []byte) error { return Unmarshal(data, c) }
+
+// createObject queues a [CoreCreateObject] message for the PipeWire server.
+// This is not safe to use directly, callers should use typed wrapper methods on [Registry] instead.
+func (core *Core) createObject(factoryName, typeName String, version Int, props SPADict, newId Int) error {
+	return core.ctx.writeMessage(
+		PW_ID_CORE,
+		&CoreCreateObject{factoryName, typeName, version, &props, newId},
+	)
+}
+
 // A RegistryGlobal event is emitted to notify a client about a new global object.
 type RegistryGlobal struct {
 	// The global id.