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Author Topic: *Solved* Unable to draw a sf::Text Object  (Read 2759 times)

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SFMLNewbie

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*Solved* Unable to draw a sf::Text Object
« on: May 15, 2014, 06:20:57 am »
I'm trying to make a Menu object. So far I've only added the buttons, which contain a RectangleShape body and Text. When trying to draw the text portion of a button to the window I get errors.


//MenuTest.h
#include <SFML/Graphics.hpp>
#include <string>
#include <vector>

class Menu1
{
        class Button1
        {
                sf::RectangleShape body;
                sf::Text text;
                void create(float x, float y);//sets button postion
                void setText();//ensures text is centered inside the button
        public:
                void setPosition(float x, float y);
                void drawButton(sf::RenderWindow &window);

                Button1(float w, float h, float x, float y, sf::Font f, std::string s="Button")
                    : body(sf::Vector2f(w,h)), text(s,f) {create(x,y);}
               
        };

        std::vector<Button1> MenuButtons;
public:
        void draw(sf::RenderWindow &window);
        void addButton(float w, float h, float x, float y, sf::Font f, std::string s="Button");
};
 
#include "MenuTest.h"

//Button1---
void Menu1::Button1::create(float x, float y)
{
        body.setOutlineThickness(-2);
        body.setFillColor(sf::Color::Black);
        body.setOutlineColor(sf::Color::White);
        setPosition(x,y);
}

void Menu1::Button1::setText()
{
//lot of code that makes sure text is aligned inside the button
//confirmed that this has no effect on the issue
}
void Menu1::Button1::setPosition(float x, float y)
{
        body.setPosition(x,y);
        setText();
}
void Menu1::Button1::drawButton(sf::RenderWindow &window)
{
        window.draw(body);
        window.draw(text);//<--- Error comes from here
}

//Menu1----
void Menu1::addButton(float w, float h, float x, float y, sf::Font f, std::string s)
{
        MenuButtons.push_back(Button1(w,h,x,y,f,s));
}
void Menu1::draw(sf::RenderWindow &window)
{
        for(int i=0;i<MenuButtons.size();i++)
                MenuButtons[i].drawButton(window);
}
 
#include "MenuTest.h"
#include <iostream>
void createMenu(sf::RenderWindow &window)
{
        Menu1 main;
        sf::Font font;
        if(!font.loadFromFile("Terminal.ttf"))
                std::cout<<"Font error\n";
        main.addButton(100,50,20,20,font);
        main.draw(window);
}


int main()
{
        sf::RenderWindow window(sf::VideoMode(1000,800),"Window");
        window.clear();
        createMenu(window);
       
        window.display();
        char a;
        std::cin>>a;
        window.close();
    return 0;
}
 

This causes an error at the line
Code: [Select]
window.draw(text); in Menu::Button::drawButton(). With the error "Access violation reading location (some memory address)"

I have confirmed that everything works up until the draw text line. I have also confirmed that the neither the setText function nor the vector are causing the problem by having Menu1 store just one button by itself and setting the text to some arbitrary point. The error still occurs. I've been looking a this for awhile and I'm at a loss as to what is happening.

Thanks for any help/suggestions.
« Last Edit: May 15, 2014, 08:08:36 am by SFMLNewbie »

binary1248

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Re: Unable to draw a sf::Text Object
« Reply #1 on: May 15, 2014, 07:43:25 am »
Quote from: SFML Documentation
The font argument refers to a font that must exist as long as the text uses it. Indeed, the text doesn't store its own copy of the font, but rather keeps a pointer to the one that you passed to this function. If the font is destroyed and the text tries to use it, the behaviour is undefined.

You are copying your font more times than I would want to even count. When the functions return, they are destroyed. Pass your font by reference and heed this warning in the documentation and the crash should disappear.
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SFMLNewbie

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Re: Unable to draw a sf::Text Object
« Reply #2 on: May 15, 2014, 08:08:11 am »
Problem solved!

Guess I should read the documentation more carefully.

 

anything