bug whith Text class

[Sanatostin]

Hi!
First of all I want to say thanks for such a wonderful and simple graphicks libruary. I had a trouble whith Text class while coding. Hear two simplyfied code fragments:

this works properly:

#include <SFML/Graphics.hpp>
using namespace sf;

class A
{

public:
    void draw_on(RenderTarget & target)
    {
        Text text;
        Font font;
        font.loadFromFile("arial.ttf");
        text.setCharacterSize(100);
        text.setColor(Color::Red);
        text.setFont(font);
        text.setString("Experiment");
        target.draw(text);
    }
};


int main()
{
    sf::RenderWindow app(sf::VideoMode(800, 600), "SFML window");
    A a;
    while (app.isOpen())
    {
        sf::Event event;
        while (app.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                app.close();
        }
        app.clear();
        a.draw_on(app);
        app.display();
    }
    return 0;
}
 

and shows red word "Experiment"

this one shows nothing:

#include <SFML/Graphics.hpp>
using namespace sf;

class A
{
    Text text;
public:
    void draw_on(RenderTarget & target)
    {
        Font font;
        font.loadFromFile("arial.ttf");
        text.setCharacterSize(100);
        text.setColor(Color::Red);
        text.setFont(font);
        text.setString("Experiment");
        target.draw(text);
    }
};


int main()
{
    sf::RenderWindow app(sf::VideoMode(800, 600), "SFML window");
    A a;
    while (app.isOpen())
    {
        sf::Event event;
        while (app.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                app.close();
        }
        app.clear();
        a.draw_on(app);
        app.display();
    }
    return 0;
}
 

the difference is in place of declaration of Text text

Please, answer if you know why this happens.

[Gleade]

In your first example, text is in the same scope as the font, both being re-created on every draw call. In your second example, text is now a class member; therefore, it's on a different scope level compared to the font.

I'm thinking that this must be the problem. As the font goes out of scope (therefore destroyed), the text would still have a reference to it. I believe the general rule is, to keep an object alive for as long as it is being referenced / pointed to. So in your case, you would want to make font a class member also - I'd also recommend loading the font before you render it (you're currently loading the font every draw call).