Scroll for Logitech Trackman Marble trackball

marble_scroll.lua

--------------------------------------
-- Scroll for Logitech Trackman Marble
--------------------------------------
-- This script is based on the project "MarbleScroll for Logitech Trackman Marble" by Primož.
-- https://www.fewprojects.com/marblescroll-for-logitech-trackman-marble/
-- The original code was rewritten to LuaJIT FFI and slightly modified by Egor Skriptunoff.

-- Logitech Trackman Marble trackball has only 4 buttons: LMB, RMB, Back, Forward.
-- It lacks scroll wheel and middle button.
-- This script adds the following possibilities:
--
--   buttons combination     function
--   -------------------     -------------
--   Back alone            = Back
--   Forward alone         = Forward
--   Back + Forward        = Middle Mouse Button
--   Back + Marble turn    = Scroll (horizontal, vertical, diagonal)
--   Forward + Marble turn = Fast Scroll (speed x10)
--
-- How to run the script:
--    wluajit.exe marble_scroll.lua
--
-- The script runs in the background, it creates neither console nor GUI window.
--
-- How to install:
--    1) If you use SetPoint, you need to set "Generic Button" as a task for the buttons 3 and 4:
--          https://www.fewprojects.com/files/marblescroll/setpoint.jpg
--    2) Get windowless LuaJIT:
--          either download binary files (wluajit.exe + lua51.dll) from this repo:
--             https://github.com/Egor-Skriptunoff/LGS_extension
--          or build LuaJIT from sources using instructions at:
--             https://gist.github.com/Egor-Skriptunoff/22bf55c1abe44d7825605e132e48c084
--    3) Place the 3 files
--          * wluajit.exe
--          * lua51.dll
--          * marble_scroll.lua
--       in any folder on your hard drive and create a shortcut for
--          wluajit.exe marble_scroll.lua
--    4) Put the shortcut in Startup folder for auto start at reboot.

---------------------------- SETTINGS -----------------------------
local sens_x = 20  -- mouse move required for one horizontal scroll
local sens_y = 30  -- mouse move required for one vertical scroll
local fast_scroll_factor = 10
-------------------------------------------------------------------

-- Script version: November 1st 2021

local ffi = require'ffi'
local C, AND, HEX, tonumber = ffi.C, bit.band, bit.tohex, tonumber
ffi.cdef[[

// common WinAPI definitions
typedef int       BOOL;
typedef uint32_t  DWORD;
typedef intptr_t  LRESULT;
typedef intptr_t  LPARAM;
typedef uintptr_t WPARAM;
typedef intptr_t  HANDLE;
typedef HANDLE    HINSTANCE;
typedef HANDLE    HWND;
typedef HANDLE    HHOOK;

// Low Level Mouse Hook
typedef struct {
  int       x;
  int       y;
  int16_t   reserved;
  int16_t   mouseData_high;
  DWORD     flags;
  DWORD     time;
  uintptr_t dwExtraInfo;
} MSLLHOOKSTRUCT;
typedef LRESULT (__stdcall * MSHOOKPROC)(
  int              nCode,
  WPARAM           wParam,
  MSLLHOOKSTRUCT * lParam
);

// Hook Functions
HHOOK SetWindowsHookExA(
  int        idHook,
  MSHOOKPROC lpfn,
  HINSTANCE  hmod,
  DWORD      dwThreadId
);
BOOL UnhookWindowsHookEx(HHOOK hhk);
LRESULT CallNextHookEx(
  HHOOK  hhk,
  int    nCode,
  WPARAM wParam,
  void * lParam
);

// Misc Functions
void mouse_event(
   DWORD     dwFlags,
   int       dx,
   int       dy,
   DWORD     dwData,
   uintptr_t dwExtraInfo
);
typedef struct { int x, y; } POINT;
HWND WindowFromPoint(POINT Point);
HWND GetForegroundWindow();
BOOL SetForegroundWindow(HWND hWnd);
HWND GetAncestor(HWND hwnd, DWORD gaFlags);
BOOL GetMessageA(
  void * lpMsg,
  HWND   hWnd,
  DWORD  wMsgFilterMin,
  DWORD  wMsgFilterMax
);
]]

local POINT = ffi.typeof"POINT"
local back_is_down, forward_is_down, pure_x_btn, middle_is_down, last_x, last_y, dx, dy

local function LowLevelMouseProc(nCode, wParam, lParam)
   if nCode == 0 then  -- HC_ACTION
      local msg_id = tonumber(wParam)
      if msg_id == 0x020B then  -- WM_XBUTTONDOWN
         if not (back_is_down or forward_is_down) then
            pure_x_btn = true
            last_x, last_y, dx, dy = lParam.x, lParam.y, 0, 0
            -- for scrolling in window under mouse pointer
            local pt = POINT(last_x, last_y)
            local focus_window = C.WindowFromPoint(pt)
            local foreground_window = C.GetForegroundWindow()
            -- only focus if window is not already focused
            if C.GetAncestor(focus_window, 3) ~= C.GetAncestor(foreground_window, 3) then  -- GA_ROOTOWNER
               C.SetForegroundWindow(focus_window)
            end
         end
         local x_btn_mask = lParam.mouseData_high
         back_is_down    = back_is_down    or AND(x_btn_mask, 1) ~= 0
         forward_is_down = forward_is_down or AND(x_btn_mask, 2) ~= 0
         if back_is_down and forward_is_down then
            C.mouse_event(0x0020, lParam.x, lParam.y, 0, 0)  -- MOUSEEVENTF_MIDDLEDOWN
            middle_is_down = true
            pure_x_btn = false
         end
         return 1
      elseif msg_id == 0x020C then  -- WM_XBUTTONUP
         if middle_is_down then
            C.mouse_event(0x0040, lParam.x, lParam.y, 0, 0)  -- MOUSEEVENTF_MIDDLEUP
            middle_is_down = false
         end
         local x_btn_mask = lParam.mouseData_high
         back_is_down    = back_is_down    and AND(x_btn_mask, 1) == 0
         forward_is_down = forward_is_down and AND(x_btn_mask, 2) == 0
         if back_is_down or forward_is_down or not pure_x_btn then
            return 1
         end
      elseif msg_id == 0x0200 and (back_is_down or forward_is_down) then  -- WM_MOUSEMOVE
         local speed_factor = forward_is_down and fast_scroll_factor or 1
         dx = dx + (lParam.x - last_x) * speed_factor
         dy = dy + (lParam.y - last_y) * speed_factor
         last_x, last_y = lParam.x, lParam.y
         repeat
            local wheel_dist
            if dx >= sens_x then
               dx = dx - sens_x
               wheel_dist = 120
            elseif dx <= -sens_x then
               dx = dx + sens_x
               wheel_dist = -120
            end
            if wheel_dist then
               C.mouse_event(0x1000, 0, 0, wheel_dist, 0)  -- MOUSEEVENTF_HWHEEL
               pure_x_btn = false
               wheel_dist = false
            end
            if dy >= sens_y then
               dy = dy - sens_y
               wheel_dist = -120
            elseif dy <= -sens_y then
               dy = dy + sens_y
               wheel_dist = 120
            end
            if wheel_dist then
               C.mouse_event(0x0800, 0, 0, wheel_dist, 0)  -- MOUSEEVENTF_WHEEL
               pure_x_btn = false
            end
         until wheel_dist == nil
      end
   end
   return C.CallNextHookEx(0, nCode, wParam, lParam)
end

local ms_hook = C.SetWindowsHookExA(14, LowLevelMouseProc, 0, 0)  -- WH_MOUSE_LL
if ms_hook ~= 0 then
   local msg = ffi.new("intptr_t[?]", 8)  -- this memory block must be large enough to hold the MSG struct
   repeat
      local res = C.GetMessageA(msg, 0, 0, 0)
   until res == 0 or res == -1
   C.UnhookWindowsHookEx(ms_hook)
end