;; Plan 9-like scrollbar for Windows XP ---------------------------------------

;; The following rules apply:

;; * Press/hold left mouse button to scroll down.
;; * Press/hold right mouse button to scroll up.
;; * The closer to the top of the scrollbar, the slower the speed.
;; * The closer to the bottom of the scrollbar, the faster the speed.

;; The scrolling is achieved by simulating the mouse wheel.
;; Windows without mousewheel support do not work.

;; To use the scrollbar normally, hold any modifier key while clicking the
;; mouse. Ctrl works well, as Ctrl-clicking a scrollbar does nothing special.

;; -> init

GroupAdd, ScrollbarExceptions, ahk_class Shell_TrayWnd
GroupAdd, ScrollbarExceptions, ahk_class #32768

;; -> body

#If (ScrollbarClip or WinActive("ahk_class MozillaWindowClass")) and (ScrollbarCurrent := CurrentScrollbar())

LButton::
MouseGetPos,, my
s := ScrollbarCurrent
r := ceil((my - s.a) / (s.b - s.a) * 10)
ScrollbarAmount := r
if (WinActive("ahk_class PuTTY"))
  ScrollbarDown = ^{PgDn}
else
  ScrollbarDown = {WheelDown}
ScrollbarNew := true
if (not ScrollbarScrolling)
  SetTimer, ScrollbarScroll, 0
return

RButton::
MouseGetPos,, my
s := ScrollbarCurrent
r := ceil((my - s.a) / (s.b - s.a) * 10)
ScrollbarAmount := -r
if (WinActive("ahk_class PuTTY"))
  ScrollbarUp = ^{PgUp}
else
  ScrollbarUp = {WheelUp}
ScrollbarNew := true
if (not ScrollbarScrolling)
  SetTimer, ScrollbarScroll, 0
return

#If

<^>!§::SendInput, {Text}§

§::
global ScrollbarClip
DllCall("ClipCursor", "Ptr", &0)
WinGetPos, x,, w,, A
MouseGetPos, mx, my
s := CurrentScrollbar(w - 12, my)
ScrollbarClip := !ScrollbarClip
if (not ScrollbarClip or not s)
  return
WinGetPos, x, y
VarSetCapacity(r, 12, 0)
NumPut(x + s.aa + 6, &r + 0)
NumPut(y + s.a + 1, &r + 4)
NumPut(x + s.bb + 6, &r + 8)
NumPut(y + s.b, &r + 12)
DllCall("ClipCursor", "UInt", &R)
r = ""
return

;; -> library

ScrollbarScroll:
SetTimer, ScrollbarScroll, Off
ScrollbarScrolling := true
ScrollbarNew := false
i := 0
j := abs(ScrollbarAmount)
while (i < j or GetKeyState(ScrollbarAmount > 0 ? "LButton" : "RButton", "P"))
{
  i += 1
  if (ScrollbarNew)
  {
    i := 0
    j := abs(ScrollbarAmount)
    ScrollbarNew := false
  }
  MouseGetPos,, my
  s := ScrollbarCurrent
  if (my < s.a)
    r := 1
  else
    r := ceil((my - s.a) / (s.b - s.a) * 10)
  ScrollbarAmount := ScrollbarAmount > 0 ? r : -r
  if (ScrollbarAmount > 0)
    SendInput, %ScrollbarDown%
  else
    SendInput, %ScrollbarUp%
  Sleep, % 100 / abs(ScrollbarAmount)
  if (not (i < j or GetKeyState(ScrollbarAmount > 0 ? "LButton" : "RButton", "P")))
    break
  if (i = j)
    Sleep, 150
}
ScrollbarScrolling := false
return

CurrentScrollbar(mx = "", my = "")
{
  static size := 17
  static GA_ROOT := 2
  
  old := A_BatchLines
  SetBatchLines, -1
  goto begin
end:
  SetBatchLines, % A_BatchLines
  return false
begin:
  
  ;; Because this function is run whenever the left mouse button is pressed, it
  ;; is important to return false as early as possible.
  
  CoordMode, Mouse, Window
  if (mx = "" and my = "")
    MouseGetPos, mx, my, hwnd
  if (mx = "" and my != "")
    MouseGetPos,, my, hwnd
  if (mx != "" and my = "")
    MouseGetPos, mx,, hwnd
  if (mx != "" and my != "")
    MouseGetPos,,, hwnd
  WinGet, id, id, ahk_id %hwnd% ahk_group ScrollbarExceptions
  if (hwnd = id)
    goto end
  if (not ScrollbarScrolling and hwnd != WinActive("A"))
    goto end
  
  tmp := A_CoordModePixel
  CoordMode, Pixel, Window
  
  ImageSearch,, wy, % mx - size, % my - size, % mx + size, % my + size, whitesection.bmp
  ImageSearch,, by, % mx - size, % my - size, % mx + size, % my + size, *50 bluesection.bmp
  if (wy = "" and by = "")
    goto end
  
  WinGetPos,,,, h, A
  quit := false
  
  if (my > h / 2)
  {
    gosub ScrollbarFindDownBelow
    if (quit)
      goto end
    gosub ScrollbarFindUpAbove
    if (quit)
      goto end
  } else {
    gosub ScrollbarFindUpAbove
    if (quit)
      goto end
    gosub ScrollbarFindDownBelow
    if (quit)
      goto end
  }
  goto ScrollbarFindRest
  
ScrollbarFindUpAbove:
  y := 20
  Loop
  {
    ImageSearch, uax, uay, % mx - size, % my - y, % mx + size, % my, arrowup.bmp
    y += 20
  } until (uay != "" or my - y <= 0)
  
  if (uay = "")
  {
    CoordMode, Pixel, % tmp
    quit := true
  }
  return
  
ScrollbarFindDownBelow:
  ImageSearch, dbx, dby, % mx - size, % my, % mx + size, % h, arrowdown.bmp
  
  if (dby = "")
  {
    CoordMode, Pixel, % tmp
    quit := true
  }
  return
  
ScrollbarFindRest:
  y := 20
  ; Find down arrow above
  Loop
  {
    ImageSearch, dax, day, % mx - size, 0, % mx + size, % h, arrowdown.bmp ; above
    y += 20
  } until (day != "" or my - y <= 0)
  
  ; Find up arrow below
  ImageSearch, ubx, uby, % mx - size, % my, % mx + size, % h, arrowup.bmp
  
  ; In the middle of two scrollbars
  if (day != "" and uby != "" and day > uay and uby < dby)
  {
    CoordMode, Pixel, % tmp
    goto end
  }
  
  CoordMode, Pixel, % tmp
  SetBatchLines, % A_BatchLines
  return { a: uay + size + 1, b: dby - 1, aa: uax, bb: dbx }
}