Add custom hitTest SDL via ffi calls - for love2d

conf.lua

love.conf = function(t)
  t.window.borderless = true
end

main.lua

local ffi = require("ffi")

ffi.cdef[[
  typedef struct SDL_Window SDL_Window; // https://wiki.libsdl.org/SDL2/SDL_Window

  typedef enum {
    SDL_HITTEST_NORMAL,
    SDL_HITTEST_DRAGGABLE,
    SDL_HITTEST_RESIZE_TOPLEFT,
    SDL_HITTEST_RESIZE_TOP,
    SDL_HITTEST_RESIZE_TOPRIGHT,
    SDL_HITTEST_RESIZE_RIGHT,
    SDL_HITTEST_RESIZE_BOTTOMRIGHT,
    SDL_HITTEST_RESIZE_BOTTOM,
    SDL_HITTEST_RESIZE_BOTTOMLEFT,
    SDL_HITTEST_RESIZE_LEFT
  } SDL_HitTestResult; // https://wiki.libsdl.org/SDL2/SDL_HitTestResult

  typedef struct SDL_Point {
    int x;
    int y;
  } SDL_Point; // https://wiki.libsdl.org/SDL2/SDL_

  typedef SDL_HitTestResult (__cdecl *SDL_HitTest)(
    SDL_Window *win,
    const SDL_Point *area,
    void* data); // https://wiki.libsdl.org/SDL2/SDL_HitTest

  int SDL_SetWindowHitTest(SDL_Window *win, SDL_HitTest callback, void *callback_data); // https://wiki.libsdl.org/SDL2/SDL_SetWindowHitTest

  SDL_Window* SDL_GL_GetCurrentWindow(void); // https://wiki.libsdl.org/SDL2/SDL_GL_GetCurrentWindow
]]

local sdl2 = ffi.load("SDL2")
local win = sdl2.SDL_GL_GetCurrentWindow();

local result = sdl2.SDL_SetWindowHitTest(win, function(win, area, data)
  -- Note, this function will be called for EVERY mouse hit, keep it simple.
  --  You may want to implement DPI scaling, unless it's a personal project that doesn't need it.
  if area.y <= 50 and area.x <= 50 then
    return sdl2.SDL_HITTEST_DRAGGABLE
  end
  return sdl2.SDL_HITTEST_NORMAL
end, nil)

if result ~= 0 then
  -- fall back
  local w, h, mode = love.window.getMode()
  mode.borderless = true
  love.window.setMode(w, h, mode)
end