Initializing RenderWindow as class member

[nailuj]

Hi everybody,
I am using a RenderWindow as a class member in a class called DisplayManager. I want to initialize the RenderWindow with parameters from DisplayManager's constructor.
So I basically have this code:

DisplayManager.hpp

Code: [Select]


class DisplayManager {
public:
    DisplayManager(int screenWidth, int screenHeight);
private:
    void initDisplay();
    sf::RenderWindow mainWindow;
    int screenWidth, screenHeight;
};

DisplayManager.cpp

Code: [Select]


DisplayManager::DisplayManager(int screenWidth, int screenHeight) {
    screenWidth = screenWidth;
    screenHeight = screenHeight;
    initDisplay();
}
void DisplayManager::initDisplay() {
    // now this is where it becomes tricky
    // normally I would write
    // mainWindow = sf::RenderWindow(sf::VideoMode(screenWidth, screenHeight, 32), "FooBar"));
    // however, this doesn't work, because RenderWindows overload the assignment operator to make sure they're not being copied, as far as I understand
    // this is what I write instead
    sf::RenderWindow mainWindow(sf::VideoMode(screenWidth, screenHeight, 32), "FooBar"));
    // however, this seems to be a local variable, as the RenderWindow gets destructed as soon as I leave the initDisplay() function
}


My question is now, how do I initialize a RenderWindow member with parameters from the constructor? Maybe I'm missing something really obvious, but I can't seem to route around the copying check RenderWindow performs.
I'm not really familiar with the behaviour of C++ yet, so I don't really know whether the

Code: [Select]

sf::RenderWindow mainWindow(sf::VideoMode(screenWidth, screenHeight, 32), "FooBar"));
 is expected to create a local variable or not, or whether I'm missing some obvious C++ feature that does what I want (initializer lists give me the NonCopyable error as well).

I am using a git checkout of SFML2 by the way (commit b9b38887884fa9ad0b87e648dc16e27cad84d609) on Fedora 15 with g++ 4.6.0

Thanks for any help in advance

[Laurent]

Yes, declaring another variable with the same name creates a local variable which has nothing to do with your class member.

You can't "construct again" the window object, that's why the Create function exists...

[nailuj]

Yes, declaring another variable with the same name creates a local variable which has nothing to do with your class member.

You can't "construct again" the window object, that's why the Create function exists...

Alright, that works perfectly. Thanks very much for the help!
Next time I'll scan the API documentation a bit more carefully

[Nexus]

You can simplify your code a lot by using the initializer list.

Code: [Select]

DisplayManager::DisplayManager(int screenWidth, int screenHeight)
: screenWidth(screenWidth)
, screenHeight(screenHeight)
, mainWindow(sf::VideoMode(screenWidth, screenHeight, 32), "FooBar")
{
    // constructor body is empty
}
Do you even need to store the width and height? Recall that sf::RenderWindow has two methods GetWidth() and GetHeight(). Then you could just do it like this:

Code: [Select]

DisplayManager::DisplayManager(int screenWidth, int screenHeight)
: mainWindow(sf::VideoMode(screenWidth, screenHeight, 32), "FooBar")
{
}

[nailuj]

You can simplify your code a lot by using the initializer list.

Tthat did simplify it a lot indeed. I tried to construct with an initializer list before, but because I created a new instance of sf::RenderWindow to initialize mainWindow instead of just passing the arguments, I ran into problems. I didn't know you can just pass arguments in initializer lists.
I also saved myself saving the width and height now, thanks