how to end a loop using keystroke/keypress in applescript?

Problem: How to end the loop using keystroke or keycode?

Short answer: Other than the standard Command-period, you can't.

Standard AppleScript doesn't have the ability to detect arbitrary keyboard events midstream. You can do something tacky like post a dialog and capture the response (which will slow down your script, but maybe you could replace the delay 3 with a display dialog... with timeout 3).

Anything more involved means going outside of AppleScript, maybe to ASObjC

Hi mycheal. One option is to create a small utility to detect a modifier key press for use in an AppleScript. Be aware when pasting code to maintain straight quotes. Copy and paste the following Swift code into a plain text editor and save it to your Desktop with a .swift file extension using a name such as modkeys.swift:

import Foundation

import AppKit

func TranslateModifierFlags(modifierFlags: NSEventModifierFlags) -> String {

let rawModifierFlags = modifierFlags.rawValue

var pressedButtons = [String]()

if ((rawModifierFlags & NSEventModifierFlags.ControlKeyMask.rawValue) != 0) { pressedButtons.append("Control") }

if ((rawModifierFlags & NSEventModifierFlags.AlternateKeyMask.rawValue) != 0) { pressedButtons.append("Option") }

if ((rawModifierFlags & NSEventModifierFlags.ShiftKeyMask.rawValue) != 0) { pressedButtons.append("Shift") }

if ((rawModifierFlags & NSEventModifierFlags.CommandKeyMask.rawValue) != 0) { pressedButtons.append("Command") }

if (pressedButtons.count > 0) {

return pressedButtons.joinWithSeparator(" ")

}

return "none"

}

var modifierFlags = NSEvent.modifierFlags()

print(TranslateModifierFlags(modifierFlags))

With Xcode installed, compile the above code with the Swift compiler in Terminal. The following command compiles the source file and outputs the binary to /usr/local/bin:

xcrun -sdk macosx swiftc ~/Desktop/modkeys.swift -o /usr/local/bin/modkeys

You can test the utility in Terminal by preceding the command with a delay and depressing any of the four modifier keys, Control, Option, Shift, and Command, either individually or in combination:

sleep 1; modkeys

Output returned is one or more of “Control”, “Option”, “Shift”, and “Command”. An example of the utility usage in your Applescript:

set dFolder to "~/Desktop/screencapture/"

do shell script ("mkdir -p " & dFolder)

set i to 0

set x to do shell script "date +%Y%m%d-%H%M%S" as string

repeat 10 times

set key_down to (do shell script "/usr/local/bin/modkeys")

if key_down = "Shift" then

beep

display notification "User cancelled"

return

else

set a to do shell script ("screencapture -x -t gif " & dFolder & i & x & ".gif") as string

try

tell application "Image Events"

set this_image to open a

scale this_image to size 10

save this_image

end tell

end try

delay 3

set i to i + 1

end if

end repeat

The beep and display notification in the script provide aural and visual feedback so you know when to release the held Shift key.