TexLock should be movable and not copyable

libswan/include/swan/gfxutil.h

@@ -15,6 +15,8 @@ inline std::ostream &operator<<(std::ostream &os, const SDL_Rect &rect) {
 class TexLock {
 public:
 	TexLock(SDL_Texture *tex, SDL_Rect *rect = nullptr);
+	TexLock(const TexLock &) = delete;
+	TexLock(TexLock &&lock) noexcept;
 	~TexLock();
 
 	int blit(SDL_Rect *destrect, SDL_Surface *srcsurf, SDL_Rect *srcrect = nullptr) {

libswan/src/gfxutil.cc

@@ -42,8 +42,15 @@ TexLock::TexLock(SDL_Texture *tex, SDL_Rect *rect): tex_(tex) {
 		32, pitch, rmask, gmask, bmask, amask));
 }
 
+TexLock::TexLock(TexLock &&lock) noexcept {
+	tex_ = lock.tex_;
+	surf_ = std::move(lock.surf_);
+	lock.tex_ = nullptr;
+}
+
 TexLock::~TexLock() {
-	SDL_UnlockTexture(tex_);
+	if (tex_ != nullptr)
+		SDL_UnlockTexture(tex_);
 }
 
 }