Is there a way to copy CCMenuItem... objects? may be this is a bug.

cocos2d-x C++
#1

Hello.
I try create copy of CCMenuItem, CCMenuItemImage, CCMenuItemSprite and etc… All of this classes produce an crash if I try add their to CCMenu.

My code looked like this:

CCMenuItemImage* close_item = CCMenuItemImage::itemFromNormalImage(
      "CloseNormal.png",
      "CloseSelected.png",
      this,
      menu_selector(MenuScene::menuCloseCallback));
close_item->setPosition(CCPointZero);
CCMenuItemImage* copy_item(close_item);
CCMenu* menu_1 = CCMenu::menuWithItems(close_item, copy_item, NULL);

crashed at - CCAssert( child~~>m_pParent == NULL, “child already added. It can’t be added again”);
I looked classes CCMenuItem, CCMenuItemImage, CCMenuItemSprite…
and found that all classes don’t have copy constructor~~ declaration, definition or
explicit prohibition copying (something like this:

class T { 
private:
    Т( const T& );  // without definition
    Т& operator=( const T& );  // without definition
};

)

This look like a bug. Maybe i’m wrong? Maybe correct way to copy MenuItems objects exist?

#2

Sorry, the copy method has not been implemented so far.
You had to create the item twice here.

#3

Quick question, can you not reference instance members in the callback function of another class?

void OtherClass::init()
{
CCMenuItemImage* close_item = CCMenuItemImage::itemFromNormalImage(
“normal.png”, “selected.png”,this, menu_selector(MenuScene::menuCloseCallback));
}

…
void MenuScene::menuCloseCallback(CCObject* sender)
{
member~~>DoStuff;
}
It makes sense, since the callback is referring to class method instead of the method of an instance. But is there any way to reference the object’s member? I tried wrapping with another class function:
void MenuScene::DoStuff
{
member~~>DoStuff();
}

void MenuScene::menuCloseCallback(CCObject* sender)
{
DoStuff();
}

It doesn’t work because when I break at the code the member pointer has corrupt data. It seems that the only solution would be to use a static member.

#4

Sorry, I don’t know what you want to do.

#5

I setup a callback to: MenuScene::menuCloseCallback

it’s referring to a class method, not an object method.

It’s fine, I just have to reimplement MenuScene as a singleton and maybe do something like this:
void MenuScene::menuCloseCallback(CCObject* sender)
{
sharedInstance()>member>DoStuff();
}

#6

I don’t know if I catch your idea.
Callback of MenuScene::menuCloseCallback is not a class method. You can refer HelloWorld, menuCloseCallback is not a class method.

#7

Okay, well I setup the callback from a different class (not HelloWorld).

void OtherClass::init()
{
CCMenuItemImage* close_item = CCMenuItemImage::itemFromNormalImage(
“CloseNormal.png”,
“CloseSelected.png”,
this,
menu_selector(MenuScene::menuCloseCallback));
}

How does it know which “MenuScene::menuCloseCallback” to call? For example, say I had two instances (not that I would). So if I had two instances, would I get two calls to MenuScene::menuCloseCallback? One for each instance?

If I break inside of MenuScene::menuCloseCallback and take a look at ‘member’, which is a pointer to a derived class of CCSprite, it’s a bad pointer.

#8

It can not used in this way. As fact, only the classes that inherit from SelectorProtocol can use it. And it points the object that use the menu_selector.

#9

Just to verify, this is not possible?

class Menu: public cocos2d::CCLayer
{
public:
…
CCSprite* sprite;

void aCallback(cocos2d::CCObject* sender)
{
sprite->Something();
}
};

class OtherClass: public cocos2d::CCLayer
{
public:
…
void init() {
CCMenuItemImage* close_item = CCMenuItemImage::itemFromNormalImage(“n.png”,“s.png”,this,menu_selector(Menu::aCallback));
…
}
};

#10

Yeap. It is impossible.

#11

Okay, well if anyone has a similar problem in the future, this is what I did.

class UI: public cocos2d::CCLayer
{
public:
//…
bool init()
{
CCMenuItemImage* item = CCMenuItemImage::itemFromNormalImage( … , menu_selector(UI::callback));
//…
}

void callback(cocos2d::CCObject* sender)
{
MainLayer* ml = (MainLayer*)getParent();
ml->FunctionToCall();
}
};

#12

If at the now many classes don’t have copy constructors

  • May be it’s good idea to explicitly disallow copying ( for detect copying errors at compile time.)?
    Like in my sample above.
#13

I think that’s a good idea for the next patch.

#14

#699 is created for it.