Zoom no gui.ahk

#NoEnv
SetBatchLines -1

CoordMode Mouse, Screen
OnExit GuiClose
zoom = 2                ; initial magnification, 1..32
antialize = 0
Rx = 128                ; half vertical/horizontal side of magnifier window
Ry = 128
Zx := Rx/zoom           ; frame x/y size
Zy := Ry/zoom
                        ; GUI to show the magnified image
Gui +AlwaysOnTop +Resize +ToolWindow
Gui Show, % "w" 2*Rx " h" 2*Ry " x0 y0", Magnifier
WinGet MagnifierID, id,  Magnifier
WinSet Transparent, 255, Magnifier ; makes the window invisible to magnification
WinGet PrintSourceID, ID

hdd_frame := DllCall("GetDC", UInt, PrintSourceID)
hdc_frame := DllCall("GetDC", UInt, MagnifierID)

SetTimer Repaint, 50    ; flow through

Repaint:
   MouseGetPos x, y
   xz := In(x-Zx-6,0,A_ScreenWidth-2*Zx) ; keep the frame on screen
   yz := In(y-Zy-6,0,A_ScreenHeight-2*Zy)
  ; WinMove Frame,,%xz%, %yz%, % 2*Zx, % 2*Zy
   DllCall("gdi32.dll\StretchBlt", UInt,hdc_frame, Int,0, Int,0, Int,2*Rx, Int,2*Ry
   , UInt,hdd_frame, UInt,xz, UInt,yz, Int,2*Zx, Int,2*Zy, UInt,0xCC0020) ; SRCCOPY
Return


GuiSize:
   Rx := A_GuiWidth/2
   Ry := A_GuiHeight/2
   Zx := Rx/zoom
   Zy := Ry/zoom
   TrayTip,,% "Frame  =  " Round(2*Zx) " × " Round(2*Zy) "`nMagnified to = " A_GuiWidth "×" A_GuiHeight
Return

#a::
  antialize := !antialize
  DllCall( "gdi32.dll\SetStretchBltMode", "uint", hdc_frame, "int", 4*antialize )  ; Antializing ?
Return

#x::
GuiClose:
   DllCall("gdi32.dll\DeleteDC", UInt,hdc_frame )
   DllCall("gdi32.dll\DeleteDC", UInt,hdd_frame )
ExitApp

#p::
MButton::
   if paused =
   {
        Gui, 2:Hide
        Gui, Hide
        SetTimer, Repaint, Off
        paused = 1
   }
   else
   {
        Gui, 2:Show
        Gui, Show
        SetTimer, Repaint, 50
        paused =
   }
Return

^+Up::
^+Down::
^+WheelUp::                      ; Ctrl+Shift+WheelUp to zoom in
^+WheelDown::                    ; Ctrl+Shift+WheelUp to zoom out
   If (zoom < 31 and ( A_ThisHotKey = "^+WheelUp" or A_ThisHotKey = "^+Up" ))
      zoom *= 1.189207115         ; sqrt(sqrt(2))
   If (zoom >  1 and ( A_ThisHotKey = "^+WheelDown" or A_ThisHotKey = "^+Down" ))
      zoom /= 1.189207115
   Zx := Rx/zoom
   Zy := Ry/zoom
   TrayTip,,% "Zoom = " Round(100*zoom) "%"
Return

In(x,a,b) {                      ; closest number to x in [a,b]
   IfLess x,%a%, Return a
   IfLess b,%x%, Return b
   Return x
}