How to properly create a copy constructor containing a SDL_Texture?

[Haxses]

So I have created a Texture wrapper class for SDL_Texture (based off of Lazy Foo’s tutorials) and it has come to my attention that I really should have an explicit copy constructor and copy assignment operator to go with my destructor. My object attributes consist of a number of ints and a SDL_Texture pointer. My problem comes up when I try to properly copy the SDL_Texture struct in my copy constructor. I don’t want to just copy the pointer address, otherwise the compiler’s implicit copy constructor would do the job just fine. However as far as I can find, the SDL_Texture struct was made with the intention of not being copied, you can’t malloc(sizeof(SDL_Texture)) and there doesn’t seem to be any SDL function to copy a texture for you.

See:

Proper way to duplicate a SDL_Texture

Hello all, I’ve recently been porting my stuff to SDL2 and I still have doubts about Textures (but I will leave this to another post). My question is: how do you “properly” copy a SDL_Texture? With Sourfaces you just blit one into another, clipping the way you want. With Textures (from what I have understood) you have to define your target Texture with SDL_TEXTUREACCESS_TARGET, then bind it to a new SDL_Renderer(which has to be bound to a window) and the you can user SDL_RenderCopy() to copy …

Note that I don’t want to actually copy the texture in vram, that dosen’t make sense, I just want to copy the SDL_Texture struct contents which interacts with the graphics driver so that if I load a new texture to it, it wont overwrite anything for another object that was using that same texture.

So how exactly should I go about creating my copy constructor? Is there a proper way of doing this, am I just way off base and misunderstanding something, or is this one of the outlier cases where I need a destructor but not a copy constructor? Any help would be appreciated, thanks!

This question was prompted by my other question:

Weird texture rendering when not using object pointers

So i noticed in your link the example has a ‘&’ in the copy assignment operator. I did some googleing to refresh myself on the syntax of operator overloading and that doesn’t seem to just be the inherent syntax of overloading operators. So in that case does this mean we are overloading = to act on assigning pointers, Object* rather than Object? In that case what about assigning objects directly, should I have a version with the & and without it?

[es5804]

Your copy constructor should handle the SDL_Texture* in the same way it would handle any “raw” pointer.
Except that, as you said, you cannot copy the data of SDL_Texture. This solution only make sense for simple object anyway.

It depends on the behavior you want, but here some solutions:

• No copy = no problem
  Texture(Texture& that) = delete;
Texture& operator=(Texture& that) = delete;

• You could use “smart” pointer (unique_ptr, shared_ptr, …): http://en.cppreference.com/w/cpp/memory

• Use reference counting.

• Pass the SDL_Texture* to the ‘copied to’ object. With this solution, only one Texture object has the SDL_Texture* and the ‘copied from’ object has no SDL_Texture*.