Why the rendered squares duplicate? - c++

Question

My problem is that when i run programm it runs normally for around 10-20 seconds, and then it glitch out. You can see further what's happening on the video.
https://youtu.be/YOlhjQFTzZc
This error is hunting me for over a month, First i thought this was some mistake in making shorter Render function. But not.
You can see it here.
void Render(char * image_place, int object_x, int object_y)
{
SDL_Surface * object_image = IMG_Load(image_place);
SDL_Rect object_position;
object_position.x=object_x;
object_position.y=object_y;
SDL_BlitSurface(object_image, NULL, ekran, &object_position);
}
But when i started "researching" on this topic more, i discovered that it happen even without using this function!
Here is code from the video:
#include <iostream>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_mixer.h>
#include <SDL2/SDL_ttf.h>
#include <windows.h>
#include <time.h>
using namespace std;
//SDL
SDL_Window * okno;
SDL_Surface * ekran;
SDL_Rect pozycja_obramowki;
SDL_Event zdarzenie;
SDL_Rect tlo_pos;
//zmienne
int x_obraz=0;
int y_obraz=0;
int main(int argc, char*args[])
{
SDL_Init(SDL_INIT_EVERYTHING);
okno = SDL_CreateWindow("LevelEditor",SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED, 1280, 720, NULL);
ekran = SDL_GetWindowSurface(okno);
while(true)
{
{//render
SDL_Surface * tlo = IMG_Load("biel.png");
tlo_pos.x=0;
tlo_pos.y=0;
SDL_BlitSurface(tlo,NULL, ekran, &tlo_pos);
SDL_Surface * obramowka = IMG_Load("obramowka.png");
pozycja_obramowki.x=x_obraz;
pozycja_obramowki.y=y_obraz;
SDL_BlitSurface(obramowka,NULL, ekran, &pozycja_obramowki);
}
{//zdarzenia
if(SDL_PollEvent(&zdarzenie))
{
if(zdarzenie.type==SDL_QUIT)
{
return 0;
}
}
}
{//sterowanie
if(GetAsyncKeyState(VK_RIGHT)) {x_obraz=x_obraz+5;}
if(GetAsyncKeyState(VK_LEFT)) {x_obraz=x_obraz-5;}
if(GetAsyncKeyState(VK_UP)) {y_obraz=y_obraz-5;}
if(GetAsyncKeyState(VK_DOWN)) {y_obraz=y_obraz+5;}
}
{//fps end & odswiezanie ekranu
SDL_UpdateWindowSurface(okno);
}
}
}
If i wrote something wrong or explained anything wrong, feel free to comment on this post. Any help will be useful, thanks ; )

Answer 1

You shouldn't call IMG_Load repeatedly. (I suspect that you're running out of memory pretty quickly.)
Load all images at startup and store pointers to the resulting surfaces.
// Moved out of the loop
SDL_Surface * tlo = IMG_Load("biel.png");
SDL_Surface * obramowka = IMG_Load("obramowka.png");
while(true)
{
// As before, but without declaring the variables mentioned above.
}