Prevent crash in Lua bindings.

src/utils/SkLua.cpp

Index: src/utils/SkLua.cpp
===================================================================
--- src/utils/SkLua.cpp	(revision 12703)
+++ src/utils/SkLua.cpp	(working copy)
@@ -6,6 +6,7 @@
  */
 
 #include "SkLua.h"
+#include "SkAnnotation.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkDocument.h"
@@ -31,6 +32,7 @@
         return #T "_LuaMetaTableName";          \
     }
 
+DEF_MTNAME(SkAnnotation)
 DEF_MTNAME(SkCanvas)
 DEF_MTNAME(SkDocument)
 DEF_MTNAME(SkImage)
@@ -56,7 +58,7 @@
 }
 
 template <typename T> void push_ref(lua_State* L, T* ref) {
-    *(T**)lua_newuserdata(L, sizeof(T*)) = SkRef(ref);
+    *(T**)lua_newuserdata(L, sizeof(T*)) = SkSafeRef(ref);
     luaL_getmetatable(L, get_mtname<T>());
     lua_setmetatable(L, -2);
 }
@@ -635,6 +637,16 @@
     return 0;
 }
 
+static int lpaint_getAnnotation(lua_State* L) {
+    const SkPaint* paint = get_obj<SkPaint>(L, 1);
+    SkAnnotation* annotation = paint->getAnnotation();
+    if (annotation) {
+        push_ref(L, annotation);
+        return 1;
+    }
+    return 0;
+}
+
 static int lpaint_gc(lua_State* L) {
     get_obj<SkPaint>(L, 1)->~SkPaint();
     return 0;
@@ -660,6 +672,7 @@
     { "getFontMetrics", lpaint_getFontMetrics },
     { "getEffects", lpaint_getEffects },
     { "getShader", lpaint_getShader },
+    { "getAnnotation", lpaint_getAnnotation },
     { "__gc", lpaint_gc },
     { NULL, NULL }
 };
@@ -974,7 +987,7 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 static int ltypeface_gc(lua_State* L) {
-    get_ref<SkTypeface>(L, 1)->unref();
+    SkSafeUnref(get_ref<SkTypeface>(L, 1));

[reed1, 2013/12/17 16:31:50]

I believe you, but this just seems wrong. If we had no typeface, we should have
pushed a NULL up to lua, instead of a lua object wrapping null.

     return 0;
 }