screenshot grabber

grab.py

import PIL
import PIL.ImageGrab
import os.path
import sys
import keyboard
import ctypes.wintypes
from getopt import getopt

def makefilename(base):
    if base.lower().endswith(".png"):
        suffix = ".png"
        base = base[:-4]
    elif base.lower().endswith(".jpg"):
        suffix = ".jpg"
        base = base[:-4]
    else:
        suffix = ".png"
    for i in range(10000):
        name = base + "%04d"%i + suffix
        if not os.path.exists(name):
            return name
    raise Exception("Too many images of that name")
    
def windowSize(window):
    rect = ctypes.wintypes.RECT()
    ctypes.windll.dwmapi.DwmGetWindowAttribute(
        window,
        ctypes.wintypes.DWORD(9),
        ctypes.byref(rect), ctypes.sizeof(rect))
    return (rect.left,rect.top,rect.right,rect.bottom)
    
def processId(window):
    pid = ctypes.wintypes.DWORD(0)
    ctypes.windll.user32.GetWindowThreadProcessId(window, ctypes.byref(pid))
    return pid.value
    
def activeAppArea():
    pid = processId(ctypes.windll.user32.GetForegroundWindow())
    EnumWindows = ctypes.windll.user32.EnumWindows
    EnumWindowsProc = ctypes.WINFUNCTYPE(ctypes.c_bool, ctypes.POINTER(ctypes.c_int), ctypes.POINTER(ctypes.c_int))
    dimensions = [float("inf"),float("inf"),float("-inf"),float("-inf")]
    def updateDimensions(window, param):
        if processId(window)==pid and ctypes.windll.user32.IsWindowVisible(window):
            size = windowSize(window)
            dimensions[0] = min(dimensions[0], size[0])
            dimensions[1] = min(dimensions[1], size[1])
            dimensions[2] = max(dimensions[2], size[2])
            dimensions[3] = max(dimensions[3], size[3])
        return True
    EnumWindows(EnumWindowsProc(updateDimensions), 0)
    return dimensions
    
def grab(name, mode=None):
    fname = makefilename(name)
    print("Capturing to "+fname)

    if mode is None:
        area = activeAppArea()
    elif mode == "full-screen":
        area = None
    else:
        area = windowSize(ctypes.windll.user32.GetForegroundWindow())
    PIL.ImageGrab.grab(bbox=area).save(makefilename(name))
    
if __name__ == '__main__':
    mode = None
    once = False
    instant = False
    
    opts,args = getopt(sys.argv[1:], "fw1i", ["full-screen", "window", "1", "instant"])
    for o,a in opts:
        if o in ("-f", "--full-screen"):
            mode = "full-screen"
        elif o in ("-w", "--window"):
            mode = "window"
        elif o in ("-1", "--1"):
            once = True
        elif o in ("-i", "--instant"):
            instant = True
    print("Capturing screen with 'Print Screen'. Press ctrl-c to exit.")
    while True:
        if not instant:
            keyboard.wait("print screen")
        grab(args[0] if args else "screenshot", mode=mode)
        if once or instant:
            break