Add sk_ref_sp helper function.

Review URL: https://codereview.chromium.org/1773943004

2 files changed, 31 insertions, 0 deletions

diff --git a/include/core/SkRefCnt.h b/include/core/SkRefCnt.h
index c3f724fa8d..f159e3b1b7 100644
--- a/include/core/SkRefCnt.h
+++ b/include/core/SkRefCnt.h
@@ -14,6 +14,8 @@
 #include <functional>
 #include <utility>
 
+#define SK_SUPPORT_TRANSITION_TO_SP_INTERFACES
+
 /** \class SkRefCntBase
 
     SkRefCntBase is the base class for objects that may be shared by multiple
@@ -430,4 +432,20 @@ sk_sp<T> sk_make_sp(Args&&... args) {
     return sk_sp<T>(new T(std::forward<Args>(args)...));
 }
 
+#ifdef SK_SUPPORT_TRANSITION_TO_SP_INTERFACES
+
+/*
+ *  Returns a sk_sp wrapping the provided ptr AND calls ref on it (if not null).
+ *
+ *  This is different than the semantics of the constructor for sk_sp, which just wraps the ptr,
+ *  effectively "adopting" it.
+ *
+ *  This function may be helpful while we convert callers from ptr-based to sk_sp-based parameters.
+ */
+template <typename T> sk_sp<T> sk_ref_sp(T* obj) {
+    return sk_sp<T>(SkSafeRef(obj));
+}
+
+#endif
+
 #endif
diff --git a/tests/RefCntTest.cpp b/tests/RefCntTest.cpp
index 2932913c3d..a9b461f352 100644
--- a/tests/RefCntTest.cpp
+++ b/tests/RefCntTest.cpp
@@ -385,3 +385,16 @@ DEF_TEST(sk_sp_reset, r) {
     sp.reset(rc);   // this should transfer our ownership over to sp
     REPORTER_ASSERT(r, rc->unique());
 }
+
+DEF_TEST(sk_sp_ref, r) {
+    SkRefCnt* rc = new SkRefCnt;
+    REPORTER_ASSERT(r, rc->unique());
+
+    {
+        sk_sp<SkRefCnt> sp = sk_ref_sp(rc);
+        REPORTER_ASSERT(r, !rc->unique());
+    }
+
+    REPORTER_ASSERT(r, rc->unique());
+    rc->unref();
+}