Autohotkey: end a loop by pressing a certain shortcut

Question

I searched a lot on the site but did not find how to do it. This is my current script:

MButton::
  MouseGetPos, xpos, ypos
  Sleep, 50
  Click
  Loop
  {
    Sleep 50
    Send, {\ down}
    Sleep 50
    Send, {\ up}
  }
  Click %xpos%, %ypos%, 0
Return

I would like to end the loop by pressing the middle button of the mouse (MButton). I think is not a difficult task but cannot find it out, can you help thanks very much

EDIT so the code posted by @Jim U, and @user3419297 works very well! Code by GroggyOtter gives error when I run it. Code by Forivin seems to work in another way (explained below). Thank you so much to all of you!

EDIT 2 an even more easy code

MButton::
MouseGetPos, xpos, ypos
Sleep, 50
Click
Loop
{
    Sleep 50
    Send, {\ down}
    Sleep 50
    Send, {\ up}
    If GetKeyState("MButton", "P") AND (A_TimeSinceThisHotkey > 300)    ; When the MButton is pressed and after 300ms have elapsed(to prevent it from stopping direcly after triggering it.
        Break
}
Click %xpos%, %ypos%, 0
Return

Answer 1

This starts and interrupts a loop when MButton is pressed

#MaxThreadsPerHotkey 2

MButton::mbutton_pressed()

mbutton_pressed()
{
  global running := !running

  if running
    run()
}


run()
{
  global running

  MouseGetPos, xpos, ypos
  Sleep, 50
  Click

  while running
  {
    Sleep 50
    Send, {\ down}
    Sleep 50
    Send, {\ up}
  }
  Click %xpos%, %ypos%, 0
}

#MaxThreadsPerHotkey 2 allows us to invoke MButton even if the previous invocation of MButton hasn't completed. This allows us to use MButton to both start and interrupt the loop.

Answer 2

A simple solution would be this:

#If !mbuttonIsRunning ;Only enable this hotkey when it is not running
    MButton Up:: ;When the MButton is pressed
        mbuttonIsRunning := True 
        MouseGetPos, xpos, ypos
        Sleep, 50
        Click
        Loop
        {
            Sleep 50
            Send, {\ down}
            Sleep 50
            Send, {\ up}
            If GetKeyState("MButton", "P") ;If MButton is pressed
                Break ;Break out of the loop
        }
        Click %xpos%, %ypos%, 0
        mbuttonIsRunning := False
    Return
#If

Answer 3

Another approach (based on Forivin's code):

; autoexecute-section (top of the script):
loop_enabled := false ; the loop is disabled by default

; Press MButton down to enable the loop
MButton:: loop_enabled := true

#If (loop_enabled) ; If you enable the loop by pressing MButton down

    MButton Up::  ; release MButton to start the loop
        MouseGetPos, xpos, ypos
        Sleep, 50
        Click
        Loop
        {
            Sleep 50
            Send, {\ down}
            Sleep 50
            Send, {\ up}
            If GetKeyState("MButton", "P") ; by pressing MButton while the loop is enabled
            {
                loop_enabled := false      ; disable and
                    break                  ; terminate the loop
            }
        }
        Click %xpos%, %ypos%, 0 
    Return

#If

Answer 4

All it should take is adding a toggle. Use a variable to track on and off status and use the command SetTimer to control your loop.

; Set to 0 by default so when we press the button the first time
; it executes the if statement first.
toggle  := 0
return

MButton::
    toggle  := !toggle  ; This is the variable that tracks on/off for your loop.
                        ; 1 becomes 0. 0 Becomes 1. It's updated as soon as the hotkey fires.

    if (toggle = 1){    ; If toggle is 1, do this stuff.
        MouseGetPos, xpos, ypos
        Sleep, 50
        Click
        SetTimer, BackslashLoop, 50 ; Runs the BackslashLoop label over and over until it's turned off
                                    ; To turn it off, press MButton again.
    }else{ ; Only do this stuff after MButton has been clicked again and toggle has been changed.
        SetTimer, BackslashLoop, Off
        Click %xpos%, %ypos%, 0
    }
return

BackslashLoop:
        Send, {\ down}
        Sleep 50
        Send, {\ up}    
return

If this fixed your problem, please mark this answered. If not, let us know what isn't working so we can figure out what's up.