Hello, recently I've tried to make a simple menu system in SFML. To implement it correctly, I've decided to use State Pattern. However, some exception is thrown, and I don't know what's the source of problem. My code looks like that:
#include <SFML/Graphics.hpp>
#include <iostream>
#include <vector>
class Context;
class Menu
{
protected:
Context* m_context{ nullptr };
int currentPosition{ 0 };
std::vector<sf::Text> buttons;
public:
virtual void draw(sf::RenderWindow& window) = 0;
virtual void clickButton() = 0;
virtual void moveUp() = 0;
virtual void moveDown() = 0;
};
class Context
{
private:
Menu* m_menu;
public:
Context();
void setMenu(Menu* menu)
{
m_menu = menu;
}
void draw(sf::RenderWindow& window)
{
m_menu->draw(window);
}
void clickButton()
{
m_menu->clickButton();
}
void moveUp()
{
m_menu->moveUp();
}
void moveDown()
{
m_menu->moveDown();
}
};
class FirstMenu: public Menu
{
public:
FirstMenu(Context* context)
{
this->m_context = context;
sf::Font font;
if (!font.loadFromFile("arial.ttf"))
{
std::cout << "Error occured. \n";
}
sf::Text text;
sf::Text text1;
sf::Text text2;
text.setFont(font);
text1.setFont(font);
text2.setFont(font);
text.setFillColor(sf::Color::Red);
text.setPosition(250, 150);
text1.setFillColor(sf::Color::White);
text1.setPosition(250, 250);
text2.setFillColor(sf::Color::White);
text2.setPosition(250, 350);
this->buttons.push_back(text);
this->buttons.push_back(text1);
this->buttons.push_back(text2);
}
virtual void moveUp()
{
for (int i = 0; i < this->buttons.size(); i++)
{
if (i == currentPosition)
{
this->buttons[i].setFillColor(sf::Color::White);
currentPosition--;
this->buttons[i-1].setFillColor(sf::Color::Red);
break;
}
}
}
virtual void moveDown()
{
for (int i = 0; i < this->buttons.size(); i++)
{
if (i == currentPosition)
{
this->buttons[i].setFillColor(sf::Color::White);
currentPosition++;
this->buttons[i+1].setFillColor(sf::Color::Red);
break;
}
}
}
virtual void draw(sf::RenderWindow& window)
{
for (auto i : this->buttons)
{
window.draw(i); //Exception thrown here
}
}
virtual void clickButton()
{
std::cout << "Button clicked. \n";
}
};
class SecondMenu: public Menu
{
};
Context::Context()
{
this->m_menu = new FirstMenu(this);
}
int main()
{
sf::RenderWindow window(sf::VideoMode(500, 500), "SFML works!");
Context context;
while (window.isOpen())
{
sf::Event event;
while (window.pollEvent(event))
{
if (event.type == sf::Event::KeyPressed)
{
if (event.key.code == sf::Keyboard::Up)
{
context.moveUp();
}
if (event.key.code == sf::Keyboard::Down)
{
context.moveDown();
}
if (event.key.code == sf::Keyboard::Return)
{
context.clickButton();
}
}
}
window.clear();
context.draw(window);
window.display();
}
return 0;
}
Exception thrown:
Exception thrown at 0x7A5B35BE (sfml-graphics-2.dll) in SFF.exe: 0xC0000005: Access violation reading location 0x00000010.
The problem is that you're setting the fonts as local varibales:
void someFunc()
{
sf::Font font;
if (!font.loadFromFile("arial.ttf"))
{
std::cout << "Error occured. \n";
}
} //font will delete itself here
So when the window tries to draw your text, it doesn't find its font, because it was deleted when it got out of scope. To fix this issue, I'd suggest adding the font to your class or main function so it doesn't get deleted.