Garbage collection capable wrappers for skia interop

kotlin-native/Interop/Runtime/src/native/kotlin/kotlinx/cinterop/ManagedType.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlinx.cinterop
+
+import kotlinx.cinterop.CStructVar
+
+interface SkiaRefCnt
+interface CPlusPlusClass
+
+abstract class ManagedType<T : CStructVar>(val cpp: T)
+
+val <T : CStructVar> ManagedType<T>.ptr: CPointer<T> get() = this.cpp.ptr

kotlin-native/Interop/Runtime/src/native/kotlin/kotlinx/cinterop/internal/Annotations.kt

@@ -24,6 +24,10 @@ annotation class CStruct(val spelling: String) {
     @Retention(AnnotationRetention.BINARY)
     annotation class VarType(val size: Long, val align: Int)
 
+    @Target(AnnotationTarget.CLASS)
+    @Retention(AnnotationRetention.BINARY)
+    annotation class CPlusPlusClass
+
     @Target(AnnotationTarget.CLASS)
     @Retention(AnnotationRetention.BINARY)
     annotation class ManagedType