#NoEnv
#SingleInstance Force
#Persistent

; Try to retrieve user-set resolutions

RegRead, ResolutionsString, HKEY_CURRENT_USER\Software\JohnAJ\DRM, Resolutions

if (ErrorLevel != 1)
  goto Start

; Fall back on default resolutions

ResolutionsString = 1600x1200|1024x768|800x600|640x480 ; 4:3
if (A_ScreenWidth/A_ScreenHeight = 1.6)
  ResolutionsString = 1920x1200|1680x1050|1440x900|1280x800 ; 16:10
if (Round(A_ScreenWidth/A_ScreenHeight, 2) = 1.77)
  ResolutionsString = 1920x1080|1366x768|1280x720|854x480 ; 16:9

RegWrite, REG_SZ, HKEY_CURRENT_USER\Software\JohnAJ\DRM, Resolutions, %ResolutionsString%

; Set up tray menu

Start:
Resolutions := StrSplit(ResolutionsString, "|")
Menu, Tray, NoStandard
Menu, Tray, Tip, Dynamic Resolution Manager
for k, res in Resolutions
  Menu, Tray, Add, %res%, SelectMenuResolution
Menu, Tray, Add
Menu, Tray, Add, E&xit, ButtonExit
return

ButtonExit:
ExitApp

; Select resolution from tray menu

SelectMenuResolution(ItemName, ItemPos, MenuName)
{
  ResArray := StrSplit(ItemName, "x")
  SwitchToResolutionFrom(ResArray[1], ResArray[2], A_ScreenWidth, A_ScreenHeight) 
}

; Save window positions, switch to given resolution, restore window positions

SwitchToResolutionFrom(WidthNew, HeightNew, WidthOrig, HeightOrig)
{
  Positions := {}
  
  Save(Positions)
  SetResolution(WidthNew, HeightNew)
  Sleep, 500
  Restore(Positions)
  
  TrayTip, Resolution changed, % "Press Escape within 3 seconds to revert."
  KeyWait, Esc, D T3
  TrayTip
  if (ErrorLevel = 1) ; user didn't press escape
    return
  
  SetResolution(%WidthOrig%, %HeightOrig%)
  Sleep, 500
  Restore(Positions)
}

; Set screen resolution

SetResolution(Width, Height, ColorDepth := 32)
{
  VarSetCapacity(DeviceMode, 156, 0)
  NumPut(156, DeviceMode, 36) 
  DllCall("EnumDisplaySettingsA", UInt, 0, UInt, -1, UInt, &DeviceMode)
  NumPut(0x5c0000, DeviceMode, 40) 
  NumPut(ColorDepth, DeviceMode, 104)
  NumPut(Width, DeviceMode, 108)
  NumPut(Height, DeviceMode, 112)
  DllCall("ChangeDisplaySettingsA", UInt, &DeviceMode, UInt, 0)
}

Save(ByRef Positions)
{
  Positions := {}
  WinGet, id, list
  SysGet, WorkArea, MonitorWorkArea
  Width := WorkAreaRight - WorkAreaLeft
  Height := WorkAreaBottom - WorkAreaTop
  Loop, %id%
  {
    i := id%A_Index%
    WinReallyGetPos(i, x, y, w, h)
    Positions[i] := [x / Width, y / Height, w / Width, h / Height]
  }
}

Restore(Positions)
{
  SysGet, WorkArea, MonitorWorkArea
  Width := WorkAreaRight - WorkAreaLeft
  Height := WorkAreaBottom - WorkAreaTop
  for i, props in Positions
  {
    x := props[1]
    y := props[2]
    w := props[3]
    h := props[4]
    WinReallyMove(i, x * Width, y * Height, w * Width, h * Height)
  }
}

; Get position of any window, even a minimized one

WinReallyGetPos(hwnd, ByRef x, ByRef y, ByRef w="", ByRef h="")
{
    VarSetCapacity(wp, 44), NumPut(44, wp)
    DllCall("GetWindowPlacement", "uint", hwnd, "uint", &wp)
    x := NumGet(wp, 28, "int")
    y := NumGet(wp, 32, "int")
    w := NumGet(wp, 36, "int") - x
    h := NumGet(wp, 40, "int") - y
}

; Set position of any window, even a minimized one

WinReallyMove(hwnd, x, y, w, h)
{
    VarSetCapacity(wp, 44, 0), NumPut(44, wp, "uint")
    NumPut(5, wp, 8, "uint")
    NumPut(x, wp, 28, "int")
    NumPut(y, wp, 32, "int")
    NumPut(w + x, wp, 36, "int")
    NumPut(h + y, wp, 40, "int")
    DllCall("SetWindowPlacement", "ptr", hwnd, "ptr", &wp)
}