chilimangoes.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#  chilimangoes.py
# Thanks to novel_yet_trivial from Reddit!
# https://www.reddit.com/r/learnpython/comments/99fer7/pyautogui_with_multiple_monitors/

from ctypes import windll, c_int, c_uint, c_char_p, c_buffer
from struct import calcsize, pack
from PIL import Image

gdi32 = windll.gdi32
screen_size = (10000, 10000) #optimistic until we know better

# Win32 functions
CreateDC = gdi32.CreateDCA
CreateCompatibleDC = gdi32.CreateCompatibleDC
GetDeviceCaps = gdi32.GetDeviceCaps
CreateCompatibleBitmap = gdi32.CreateCompatibleBitmap
BitBlt = gdi32.BitBlt
SelectObject = gdi32.SelectObject
GetDIBits = gdi32.GetDIBits
DeleteDC = gdi32.DeleteDC
DeleteObject = gdi32.DeleteObject

# Win32 constants
NULL = 0
HORZRES = 8
VERTRES = 10
SRCCOPY = 13369376
HGDI_ERROR = 4294967295
ERROR_INVALID_PARAMETER = 87

#from http://www.math.uiuc.edu/~gfrancis/illimath/windows/aszgard_mini/movpy-2.0.0-py2.4.4/movpy/lib/win32/lib/win32con.py
SM_XVIRTUALSCREEN = 76
SM_YVIRTUALSCREEN = 77
SM_CXVIRTUALSCREEN = 78
SM_CYVIRTUALSCREEN = 79
SM_CMONITORS = 80

def grab_screen(region=None):
	"""
	Grabs a screenshot. This is a replacement for PIL's ImageGrag.grab() method
	that supports multiple monitors. (SEE: https://github.com/python-pillow/Pillow/issues/1547)

	Returns a PIL Image, so PIL library must be installed.

	param region
	  is in the format (left, top, width, height), which is the same format returned by pyscreeze

	Usage:
		im = grab_screen() # grabs a screenshot of all monitors
		im = grab_screen([0, 0, -1600, 1200]) # grabs a 1600 x 1200 screenshot to the left of the primary monitor
		im.save('screencap.jpg')
	"""
	bitmap = None
	try:
		screen = CreateDC(c_char_p('DISPLAY'.encode('utf-8')),NULL,NULL,NULL)
		screen_copy = CreateCompatibleDC(screen)

		if region:
			left,top,width,height = region
		else:
			left = windll.user32.GetSystemMetrics(SM_XVIRTUALSCREEN)
			top = windll.user32.GetSystemMetrics(SM_YVIRTUALSCREEN)
			width = windll.user32.GetSystemMetrics(SM_CXVIRTUALSCREEN)
			height = windll.user32.GetSystemMetrics(SM_CYVIRTUALSCREEN)

		bitmap = CreateCompatibleBitmap(screen, width, height)
		if bitmap == NULL:
			print('grab_screen: Error calling CreateCompatibleBitmap. Returned NULL')
			exit()

		hobj = SelectObject(screen_copy, bitmap)
		if hobj == NULL or hobj == HGDI_ERROR:
			print('grab_screen: Error calling SelectObject. Returned {0}.'.format(hobj))
			exit()

		if BitBlt(screen_copy, 0, 0, width, height, screen, left, top, SRCCOPY) == NULL:
			print('grab_screen: Error calling BitBlt. Returned NULL.')
			exit()

		bitmap_header = pack('LHHHH', calcsize('LHHHH'), width, height, 1, 24)
		bitmap_buffer = c_buffer(bitmap_header)
		bitmap_bits = c_buffer(' ' * (height * ((width * 3 + 3) & -4)))
		got_bits = GetDIBits(screen_copy, bitmap, 0, height, bitmap_bits, bitmap_buffer, 0)
		if got_bits == NULL or got_bits == ERROR_INVALID_PARAMETER:
			print('grab_screen: Error calling GetDIBits. Returned {0}.'.format(got_bits))
			exit()

		image = Image.frombuffer('RGB', (width, height), bitmap_bits, 'raw', 'BGR', (width * 3 + 3) & -4, -1)
		if not region:
			#if this was a full screen grab then set the size for future use.
			global screen_size
			screen_size = image.size
		return image
	finally:
		if bitmap is not None:
			if bitmap:
				DeleteObject(bitmap)
			DeleteDC(screen_copy)
			DeleteDC(screen)