C or C++ library for putting pixel on the screen

Question

For a fullfledge GUI I can use Qt or GTK. If I want OpenGL or Vulkan, GLFW will do. What is the most appropriate choice if all I want to do is

1. Open a window
2. Read image dimensions from stdin
3. Read pixel data from stdin (until EOF), and put to the window.

A reasonable way of doing it would be to use GLFW + Cairo, but then I will have a hard dependency towards the display server anyways.

Answer 1

I suggest looking into CImg. It is

• open source, CeCILL-C license (like GNU GPL)
• easy to use, because you just need to include a single header. No complex setup.

Bad news:

• AFAIK, you need to publish the source code of your software if someone asks you for it. Make sure you understand the impact of the license.

Here's code that creates an image of specific size in memory and draws some pixels:

#include "CImg.h"
using namespace cimg_library;

int main()
{
    CImg<unsigned char> imgDrawPixel(100,200,1,3, false);
    const unsigned char color[] = { 255,0,255 };
    for (int i = 0; i < 50; i++)
    {
        imgDrawPixel.draw_point(i + 20, i + 20, color);
    }

    CImgDisplay main_disp(imgDrawPixel, "This is an image");
    while (!main_disp.is_closed()) {
        main_disp.wait();
    }
    return 0;
}

Result:

(The grey area is not part of the image. It's there because I can't make the window smaller.)

Answer 2

I will suggest SDL https://www.libsdl.org/ because it is cross platform and it can easily display pixels on the screen.

Here is how you may draw pixels on the screen: https://stackoverflow.com/questions/20579658/how-to-draw-pixels-in-sdl-2-0 .