renderer/saver: enhanced safety

enhanced safety by taking into account the object reference counting.

src/renderer/tvgSaver.cpp

@@ -157,14 +157,17 @@ Result Saver::save(unique_ptr<Animation> animation, const string& path, uint32_t
     auto a = animation.release();
     if (!a) return Result::MemoryCorruption;
 
+    //animation holds the picture, it must be 1 at the bottom.
+    auto remove = PP(a->picture())->refCnt <= 1 ? true : false;
+
     if (mathZero(a->totalFrame())) {
-        delete(a);
+        if (remove) delete(a);
         return Result::InsufficientCondition;
     }
 
     //Already on saving an other resource.
     if (pImpl->saveModule) {
-        delete(a);
+        if (remove) delete(a);
         return Result::InsufficientCondition;
     }
 
@@ -173,12 +176,12 @@ Result Saver::save(unique_ptr<Animation> animation, const string& path, uint32_t
             pImpl->saveModule = saveModule;
             return Result::Success;
         } else {
-            delete(a);
+            if (remove) delete(a);
             delete(saveModule);
             return Result::Unknown;
         }
     }
-    delete(a);
+    if (remove) delete(a);
     return Result::NonSupport;
 }
 

src/savers/gif/tvgGifSaver.cpp

@@ -99,7 +99,8 @@ bool GifSaver::close()
     delete(bg);
     bg = nullptr;
 
-    delete(animation);
+    //animation holds the picture, it must be 1 at the bottom.
+    if (animation && PP(animation->picture())->refCnt <= 1) delete(animation);
     animation = nullptr;
 
     free(path);

src/savers/tvg/tvgTvgSaver.cpp

@@ -764,7 +764,7 @@ bool TvgSaver::close()
 {
     this->done();
 
-    delete(paint);
+    if (paint && P(paint)->refCnt == 0) delete(paint);
     paint = nullptr;
 
     free(path);