Passing class member object - SFML draw() - c++

Question

It seems like a very weird situation. I just want to draw a sf::Text object that is handle outside the main loop (in another class).
I show you only the essential. This code works (it draws other things that are handle directly in the main) and so it compiles.
Main :
int main()
{
//we handle the creation of the window //
//...
//Example where the sf::Text is handle in the main (it works)
sf::Font font;
font.loadFromFile("arial.ttf");
sf::Text mainTxt("It works !!",font);
mainTxt.setPosition(sf::Vector2f(64,"It works !!"));
mainTxt.setCharacterSize(25);
mainTxt.setFillColor(sf::Color::Blue);
TextManager textManager(); //My class that don't work...
sf::Event event;
while (window.isOpen())
{
// We handle event (we don't care here)
// ...
window.draw(mainTxt); // it works
window.draw(textManager.getMyText()); // do nothing
window.display();
window.clear();
}
return 0;
}
TextManager header :
#ifndef TEXTMANAGER_H
#define TEXTMANAGER_H
#include <SFML/Graphics.hpp>
class TextManager
{
public:
TextManager();
virtual ~TextManager();
sf::Text getMyText();
private:
sf::Text myText;
};
#endif // TEXTMANAGER_H
TextManager cpp
#include "TextManager.h"
TextManager::TextManager()
{
sf::Font font;
font.loadFromFile("arial.ttf");
sf::Text myText("Not drawn on the screen :-(",font);
myText.setPosition(sf::Vector2f(164,0));
myText.setCharacterSize(25);
myText.setFillColor(sf::Color::Blue);
}
// in this example (that do not work) I do not change fspText. But, I want to update it at each call of the get function. So, it is not a constant class member.
sf::Text TextManager::getMyText() {
return myText;
}
TextManager::~TextManager()
{
//dtor
}
What I really do not understand, is the fact that with a custom class of mine, I can access a class member object with this type of getter. I also did some research, and I think It should return a copy of the sf::Text object.
I try lot of things, like return reference or const reference etc... I do not understand.
I hope my problem is well displayed.
Thank you for your help ;-)
And have a nice day !

Answer 1

This
TextManager textManager(); //My class that don't work...
is function declaration, not construction of object.
Should be:
TextManager textManager; //My class that don't work...
By
sf::Text myText("Not drawn on the screen :-(",font);
you define a local variable called myText the same as your data member. So, myText returned by getMyText is just not affected.
Read the docs before coding:
It is important to note that the sf::Text instance doesn't copy the
font that it uses, it only keeps a reference to it. Thus, a sf::Font
must not be destructed while it is used by a sf::Text (i.e. never
write a function that uses a local sf::Font instance for creating a
text).
taken from SFML reference.
class TextManager
{
public:
TextManager();
virtual ~TextManager();
sf::Text& getMyText(); // <- pass by reference
private:
sf::Font myFont;
sf::Text myText;
};
and
TextManager::TextManager()
{
myFont.loadFromFile("arial.ttf");
myText.setString("Not drawn on the screen :-(");
myText.setFont(myFont);
myText.setPosition(sf::Vector2f(164,0));
myText.setCharacterSize(25);
myText.setFillColor(sf::Color::Blue);
}
might work.