How to draw pixels in SDL 2.0?

How does one draw with pixels in SDL2.0?

I'm trying to get familiar with C++, but this is very difficult to do without pretty pictures, so I'm trying to get a very basic graphics display thing running. All I really want it to do is give me a window, let me draw rgbα pixels on it, and access information about those pixels. There may be other things I want that I'm not aware of, but that's all that's on my list right now. My research on this has lead me to try using SDL, the current version being 2.0.

Almost all my graphics experience comes from using JavaScript on a <canvas>. Most of the other bit comes from my calculator, which has this really awesome Pxl-On() command, so easy.

I'm using MinGW for my C++, if it matters. Also, if there's something better** out there than SDL2.0 for what I need, advice welcome.

** "better" means "contains what functionality I need, but less total functionality than SDL2.0, and/or has a more intuitive/less complex*** API than SDL2.0."

*** Less lines of code to accomplish the same task.

Solution

I don't know how your code is structured. Assuming you have a SDL_Window and a SDL_Renderer, you just have to call SDL_RenderDrawPoint(renderer, x, y).

If you don't have a renderer nor window, you can create both with SDL_CreateWindowAndRenderer(). For example:

SDL_Window *window;
SDL_Renderer *renderer;
SDL_CreateWindowAndRenderer(800, 600, 0, &window, &renderer);

//Probably on a loop
  SDL_RenderDrawPoint(renderer, 400, 300); //Renders on middle of screen.
  SDL_RenderPresent(renderer);

This should draw a pixel on the middle of screen. To read a pixel is a little more complicated. You can use SDL_RenderReadPixels(), it is made for read an area, but you can always specify an area of 1x1. Read the wiki page if you really need it.

If you are having much trouble with SDL2 a recommend you to read the Lazy Foo tutorials. The SDL2 section still a work in progress, but there is enough material to begin learning.