Passing in an SDL_Event* into a method - c++

Question

I want to time text input in SDL2 to not spam it at 1000 key presses per second, rather the standard which is like ~33kps.
main.cpp
#include <iostream>
#include <SDL2/SDL.h>
#include "main.h"
void Main::Init()
{
std::cout << "Main Init called\n";
SDL_Init(SDL_INIT_VIDEO);
Get_Instance().window = SDL_CreateWindow("Program", 0, 30, 1280, 720, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE );
Get_Instance().renderer = SDL_CreateRenderer(Get_Instance().window, -1, SDL_RENDERER_ACCELERATED );
Get_Instance().running = true;
}
void Main::Free()
{
SDL_DestroyRenderer(Get_Instance().renderer);
SDL_DestroyWindow(Get_Instance().window);
SDL_Quit();
std::cout << "Main Free called\n";
}
void Main::Mainloop()
{
Get_Instance(); ///To initialize constructor
if (Get_Instance().mainloopInstanceBlocker == 'C')
{
Get_Instance().mainloopInstanceBlocker = 'B'; ///Begins at I (initialized), then C (constructed) then B (began)
///It works as it begins as constructed, then does the main loop, after set to B, won't enter again.
Get_Instance().Init();
SDL_Event event;
SDL_StartTextInput();
while (Get_Instance().running)
{
///Poll events
SDL_PollEvent(&event);
///To quit program
if ( event.type == SDL_QUIT ){
Get_Instance().running = false;
break;
}
///Clear display to color
SDL_SetRenderDrawColor(Get_Instance().renderer, 0,255,0,255);
SDL_RenderClear(Get_Instance().renderer);
Get_Instance().m_Main_Loop.Mainloop( Get_Instance().window, Get_Instance().renderer, &event );
SDL_RenderPresent(Get_Instance().renderer);
}
SDL_StopTextInput();
Get_Instance().Free();
}
}
int main(int argc, char* argv[])
{
Main::Mainloop();
return 0;
}
main.h
#ifndef MAIN_H
#define MAIN_H
#include "main_loop.h"
class Main
{
public:
Main(const Main&) = delete;
Main(Main&&) = delete;
Main& operator=(const Main&) = delete;
Main& operator=(Main&&) = delete;
static void Mainloop();
private:
Main()
{
std::cout << "Main constructor called\n";
mainloopInstanceBlocker = 'C';
}
static Main& Get_Instance()
{
static Main instance;
return instance;
}
static void Init();
static void Free();
Main_Loop m_Main_Loop;
SDL_Window* window = nullptr;
SDL_Renderer* renderer = nullptr;
bool running = false;
char mainloopInstanceBlocker = 'I';
};
#endif // MAIN_H
main_loop.h
#ifndef MAIN_LOOP_H
#define MAIN_LOOP_H
#include <iostream>
#include <string>
#include <SDL2/SDL.h>
class Main_Loop
{
public:
Main_Loop();
~Main_Loop();
void Mainloop(SDL_Window* window, SDL_Renderer* renderer, SDL_Event* event);
};
#endif // MAIN_LOOP_H
main_loop.cpp
#include "main_loop.h"
Main_Loop::Main_Loop()
{
}
void Main_Loop::Mainloop(SDL_Window* window, SDL_Renderer* renderer, SDL_Event* event)
{
if (event->type == SDL_TEXTINPUT)
{
std::cout << event->text.text << std::endl;
}
}
Main_Loop::~Main_Loop()
{
}

Answer 1

Your problem is
SDL_PollEvent(&event);
SDL_PollEvent returns 0 if there are no more events in the queue, but in that case it doesn't write anything into passed event structure. Since you no longer check return value of PollEvent, you operate on stale data left by last event you've had. At the very least do something like
if(!SDL_PollEvent(&event)) event.type = 0;
Your Mainloop function is questionable - does it imply there could be only one event per frame? What'd you do if there are multiple events happened in single frame? I'd suggest separating event processing and rendering - i.e. make event processing function that handles entire event queue and reacts to events by modifying your data, and separate rendering function that only does rendering.