Can't use low graphics in SDL

Question

When I scale the window, SDL simply ignores the resolution I set and draw diagonals on my pixels. It's SDL2, Im using SDL_RenderGeometry to draw my triangles.

Here's how I create the window:

static inline void canvas_init(Canvas* canvas) {
  SDL_CreateWindowAndRenderer(canvas->width * canvas->scale_x, canvas->height * canvas->scale_y, 0, &(canvas->window), &(canvas->renderer));
  SDL_RenderSetScale(canvas->renderer, canvas->scale_x, canvas->scale_y);
  SDL_Init(SDL_INIT_VIDEO);
}

I tried something about creating a backbuffer but I probably did it wrong and it didn't work with no errors.

Here is what I'm currently getting on a windows which were supposed to have 10 pixels clearly theres a diagonal on some pixels

Answer 1

Thank you comments guy, it's working by doing this

Creating a lowres texture, draw to it, but before displaying it, copy this to the window texture

static inline void canvas_init(Canvas* canvas) {
  SDL_CreateWindowAndRenderer(canvas->width * canvas->scale_x, canvas->height * canvas->scale_y, SDL_WINDOW_ALWAYS_ON_TOP, &(canvas->window), &(canvas->renderer));
  canvas->texture = SDL_CreateTexture(canvas->renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, canvas->width, canvas->height);
  SDL_Init(SDL_INIT_EVERYTHING);
}

static inline void canvas_update(Canvas canvas, uint16_t delay) {
  SDL_SetRenderTarget(canvas.renderer, NULL);
  SDL_RenderCopy(canvas.renderer, canvas.texture, NULL, NULL);
  canvas_display(canvas);

  SDL_SetRenderTarget(canvas.renderer, canvas.texture);
  canvas_color(canvas, (Color) {0, 0, 0, 255});
  canvas_clear(canvas);

  canvas_delay(delay);
}