Messages

1

General / Re: sf::Text application crash

« on: June 18, 2020, 08:55:56 pm »

Many thanks!

The specification is very clear, indeed.

I tought that the text object would store a copy of the font, that seemed intuitive to me, for the convenience of not having to manage a separate object, and it would prevent the application crash, that in VS debugs into a misterious "Access violation reading location".
Exception thrown at 0x00007FF6020939E3 in Example.exe: 0xC0000005: Access violation reading location 0x0000000000000008.
In general, I worry about these "Access violation" problems, wondering if they could be a security concern (exploitable). Of course, they depend on a bug in the code, as always... in my case, to let the font object get out of scope. But the point is if that bug is a fairly common mistake, then we have a risk.

Anyway, I understand that was a design choice, and I'm sure for good reasons (memory... if one font and many texts; perhaps performance also for the copy).

2

General / [SOLVED] sf::Text application crash

« on: June 18, 2020, 05:07:19 pm »

Hi,

Little help please...

The following simple example shows a reproducible crash with no compiler warnings.

1/ Example.cpp

#include <SFML/Graphics.hpp>
#include "MyClass.h"

int main()
{
    // create a graphical text
    sf::Font font;
    font.loadFromFile("c:\\windows\\fonts\\arial.ttf");
    sf::Text txt("sample text", font, 24);

    // create a MyClass object
    MyClass myObject;

    sf::RenderWindow window(sf::VideoMode(800, 600), "");
    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }
        window.clear();
       
        window.draw(txt);                   // this works fine (if we comment out the next line)
        window.draw(myObject.objectText);   // this crashes application!
       
        window.display();
    }
}

2/ MyClass.h

#pragma once
#include <SFML/Graphics.hpp>

class MyClass
{
public:
        MyClass();
        sf::Text objectText;
};

3/ MyClass.cpp

#include "MyClass.h"

MyClass::MyClass()
{
        sf::Font font;
        font.loadFromFile("c:\\windows\\fonts\\arial.ttf");
        objectText.setFont(font);
        objectText.setString("object text");
        objectText.setCharacterSize(24);
        objectText.setPosition(25, 50);
}

Environment is VS 16.6.2 (latest), x64, SFML 2.5.1, Preprocessor SFML_STATIC, additional dependencies sfml-main.lib;sfml-graphics-s.lib;sfml-window-s.lib;sfml-system-s.lib;opengl32.lib;winmm.lib;freetype.lib;

I'm a bit fuzzy why this crashes... can you help?
Thanks!