Change the representation of the Property to be more FFI friendly

api/sixtyfps-cpp/include/sixtyfps_properties.h

@@ -0,0 +1,51 @@
+#pragma once
+#include <string_view>
+#include "sixtyfps_properties_internal.h"
+
+namespace sixtyfps {
+
+template<typename T>
+struct Property
+{
+    Property() {
+        internal::sixtyfps_property_init(&inner);
+    }
+    ~Property() {
+        internal::sixtyfps_property_drop(&inner);
+    }
+    Property(const Property&) = delete;
+    Property(Property&&) = delete;
+    Property &operator=(const Property&) = delete;
+
+    void operator=(const T &value) {
+        set(value);
+    }
+
+    void set(const T &value) const {
+        this->value = value;
+    }
+
+    const T &get() const {
+        internal::sixtyfps_property_update(&inner, &value);
+        return value;
+    }
+
+    template <typename F>
+    void set_binding(F binding) const {
+        internal::sixtyfps_property_set_binding(
+            &inner,
+            [](const void *user_data, const void *value) {
+                *reinterpret_cast<T*>(value) = (*reinterpret_cast<F*>(user_data))();
+            },
+            new F(binding),
+            [](const void *user_data) {
+                delete reinterpret_cast<F*>(user_data);
+            }
+        );
+    }
+
+private:
+    internal::PropertyHandleOpaque inner;
+    mutable T value;
+};
+}