Library to do 2D image manipulation

Question

I'm looking for a 2D image manipulation library for C++, ideally something modern which uses C++20.

Requirements:

• works on Windows 10 (support for Windows filenames, mainly)
• works with Visual Studio 2022 (no makefiles please)
• simple to include (maybe header only; ideally just a few files), like GLFW if you know that
• produces no or few warnings only, when being comiled
• I only need basic operations like
  • get pixel / set pixel
  • draw line, ellipse and rectangle
• support for PNG files (JPG and BMP welcome), reading and writing
• gratis

Non-requirements:

• displaying images on screen

I have tried:

• Magick++
  • the site says it's up to Windows 7
  • the download location is unclear

    'win2k' subdirectory of the ImageMagick ftp site (and mirrors)

  • Visual Studio version is outdated

    ready-made Visual C++ 8.0 build environment

• Leptonica
  • looks very C-ish, not C++-ish

Answer 1

I found SFML to suit my needs.

I really like the method names. They are straight forward, IMHO. Not cryptic or abbreviated.

For the requirements:

• works on Windows 10

• works with Visual Studio 2022.

  The download site mentions Visual Studio 2017 as the latest versions, but when I opened an issue on Github, the answer was that the VS2017 version is compatible with VS2019 and VS2022.

• simple to include.

  The Tutorial for Visual Studio tells you what you need to do. Basically add some paths so that SFML can be found - stuff you know how to do when doing C++ development in Visual Studio.

• get pixel / set pixel

  The code I used is as simple as

    sf::Image buffer;
    buffer.create(size, size, sf::Color(0, 0, 0));
    // some loop here
         buffer.setPixel(x, y, sf::Color::Green);

    buffer.saveToFile("test.png");

• support for PNG files (JPG and BMP welcome), reading and writing

  Writing is definitely possible, see code before.

• gratis

  zlib/png licensed

Displaying an image as a window was not so straight forward. It can't draw images on the window. It needs a sprite for that. And the Sprite needs a texture. I see that this may have benefit in game development and might speed up stuff if textures are reused. So the code is a little more complicated, but still ok:

    sf::RenderWindow window(sf::VideoMode(1000, 1000), "Visualization");

    sf::Image buffer;
    buffer.create(size, size, sf::Color(0, 0, 0));
    // Some loop here
        buffer.setPixel(x, y, sf::Color::Green);

    sf::Texture texture;
    texture.create(size,size);
    texture.update(buffer);

    sf::Sprite sprite;
    sprite.setTexture(texture);
    sprite.setPosition(sf::Vector2f(0.f, 0.f));
    sprite.scale(1000.f / size, 1000.f / size);

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }

        window.clear();
        window.draw(sprite);
        window.display();
    }