Move a red square around with the arrow keys.

sdl-test.c

#include "SDL2/SDL.h"
#include <stdio.h>


void clear(SDL_Renderer * renderer) {
    SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);
    SDL_RenderClear(renderer);
    SDL_RenderPresent(renderer);
}

void draw(SDL_Renderer * renderer, SDL_Rect * rect) {
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
    SDL_RenderFillRect(renderer, rect);
    SDL_RenderPresent(renderer);
}

int main(int argc, char* argv[]) {

    SDL_Window *window;
    SDL_Renderer *renderer;

    SDL_Init(SDL_INIT_VIDEO);

    window = SDL_CreateWindow(
        "An SDL2 window",
        SDL_WINDOWPOS_UNDEFINED,
        SDL_WINDOWPOS_UNDEFINED,
        640,
        480,
        SDL_WINDOW_OPENGL
    );

    if (window == NULL) {
        printf("Could not create window: %s\n", SDL_GetError());
        return 1;
    }

    renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

    if (renderer == NULL) {
        printf("Could not create window: %s\n", SDL_GetError());
        return 1;
    }

    SDL_Rect rectangle = {
       .x = 10,
       .y = 10,
       .w = 10,
       .h = 10
    };

    clear(renderer);

    int quit = 0;
    while (!quit) {
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_KEYDOWN) {
                // Handle arrow keys
                switch(event.key.keysym.scancode) {
                    case SDL_SCANCODE_LEFT:
                        rectangle.x -= 10;
                        break;
                    case SDL_SCANCODE_RIGHT:
                        rectangle.x +=10;
                        break;
                    case SDL_SCANCODE_UP:
                        rectangle.y -= 10;
                        break;
                    case SDL_SCANCODE_DOWN:
                        rectangle.y += 10;
                        break;
                    default:
                        break;
                }

            } else if (event.type == SDL_QUIT) {
                quit = 1;
                puts("QUIT!");
                break;
            }
        }

        clear(renderer);
        draw(renderer, &rectangle);
    }

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();
    return 0;
}

Do you have any solution against the flickering square?

Do you have any solution against the flickering square?

Problem is about that rendering. Just 'draw' it every time when you change rectangle.x or y

Flickering was fixed after changing the clear function to call RenderPresent before RenderClear.

Quero passar este repositório para meu android para testar sua funcionalidade no meu app Cxx, posso?

The SDL_RenderPresent(renderer); call at line 8 causes the square to flicker. By removing that line, the flickering is also gone.