Allow any surface to create its own SDL software (surface) renderer

The surface object is in charge of the life of the renderer.

src/gui/core/canvas.cpp

@@ -1407,8 +1407,6 @@ tcanvas::tcanvas()
 
 tcanvas::~tcanvas()
 {
-	SDL_DestroyRenderer(renderer_);
-
 }
 
 void tcanvas::draw(const bool force)
@@ -1429,9 +1427,7 @@ void tcanvas::draw(const bool force)
 	DBG_GUI_D << "Canvas: create new empty canvas.\n";
 	canvas_.assign(create_neutral_surface(w_, h_));
 
-	SDL_DestroyRenderer(renderer_);
-
-	renderer_ = SDL_CreateSoftwareRenderer(canvas_);
+	renderer_ = canvas_.create_renderer();
 	SDL_SetRenderDrawBlendMode(renderer_, SDL_BLENDMODE_BLEND);
 
 	// draw items

src/sdl/utils.hpp

@@ -52,20 +52,21 @@ SDLKey sdl_keysym_from_name(std::string const &keyname);
 class surface
 {
 public:
-	surface() : surface_(nullptr)
+	surface() : surface_(nullptr), renderer_(nullptr)
 	{}
 
-	surface(SDL_Surface* surf) : surface_(surf)
+	surface(SDL_Surface* surf) : surface_(surf), renderer_(nullptr)
 	{}
 
-	surface(const surface& s) : surface_(s.get())
+	surface(const surface& s) : surface_(s.get()), renderer_(nullptr)
 	{
 		add_surface_ref(surface_);
 	}
 
 	~surface()
 	{
 		free_surface();
+		destroy_renderer();
 	}
 
 	void assign(SDL_Surface* surf)
@@ -84,6 +85,12 @@ class surface
 		return *this;
 	}
 
+	SDL_Renderer* create_renderer()
+	{
+		renderer_ = SDL_CreateSoftwareRenderer(surface_);
+		return renderer_;
+	}
+
 	operator SDL_Surface*() const { return surface_; }
 
 	SDL_Surface* get() const { return surface_; }
@@ -105,6 +112,12 @@ class surface
 		add_surface_ref(surf); // Needs to be done before assignment to avoid corruption on "a = a;"
 		free_surface();
 		surface_ = surf;
+
+		// Reassign renderer if it exists
+		if(renderer_) {
+			destroy_renderer();
+			create_renderer();
+		}
 	}
 
 	void free_surface()
@@ -114,7 +127,15 @@ class surface
 		}
 	}
 
+	void destroy_renderer()
+	{
+		if(renderer_) {
+			SDL_DestroyRenderer(renderer_);
+		}
+	}
+
 	SDL_Surface* surface_;
+	SDL_Renderer* renderer_;
 };
 
 bool operator<(const surface& a, const surface& b);