A faster numpy ImageGrab with no dependencies

grabber.py

# A port of https://github.com/phoboslab/jsmpeg-vnc/blob/master/source/grabber.c to python
# License information (GPLv3) is here https://github.com/phoboslab/jsmpeg-vnc/blob/master/README.md
from ctypes import Structure, c_int, POINTER, WINFUNCTYPE, windll, WinError, sizeof
from ctypes.wintypes import BOOL, HWND, RECT, HDC, HBITMAP, HGDIOBJ, DWORD, LONG, WORD, UINT, LPVOID
import numpy as np

SRCCOPY = 0x00CC0020
DIB_RGB_COLORS = 0
BI_RGB = 0


class BITMAPINFOHEADER(Structure):
    _fields_ = [('biSize', DWORD),
                ('biWidth', LONG),
                ('biHeight', LONG),
                ('biPlanes', WORD),
                ('biBitCount', WORD),
                ('biCompression', DWORD),
                ('biSizeImage', DWORD),
                ('biXPelsPerMeter', LONG),
                ('biYPelsPerMeter', LONG),
                ('biClrUsed', DWORD),
                ('biClrImportant', DWORD)]


def err_on_zero_or_null_check(result, func, args):
    if not result:
        raise WinError()
    return args


def quick_win_define(name, output, *args, **kwargs):
    dllname, fname = name.split('.')
    params = kwargs.get('params', None)
    if params:
        params = tuple([(x, ) for x in params])
    func = (WINFUNCTYPE(output, *args))((fname, getattr(windll, dllname)), params)
    err = kwargs.get('err', err_on_zero_or_null_check)
    if err:
        func.errcheck = err
    return func


GetClientRect = quick_win_define('user32.GetClientRect', BOOL, HWND, POINTER(RECT), params=(1, 2))
GetDC = quick_win_define('user32.GetDC', HDC, HWND)
CreateCompatibleDC = quick_win_define('gdi32.CreateCompatibleDC', HDC, HDC)
CreateCompatibleBitmap = quick_win_define('gdi32.CreateCompatibleBitmap', HBITMAP, HDC, c_int, c_int)
ReleaseDC = quick_win_define('user32.ReleaseDC', c_int, HWND, HDC)
DeleteDC = quick_win_define('gdi32.DeleteDC', BOOL, HDC)
DeleteObject = quick_win_define('gdi32.DeleteObject', BOOL, HGDIOBJ)
SelectObject = quick_win_define('gdi32.SelectObject', HGDIOBJ, HDC, HGDIOBJ)
BitBlt = quick_win_define('gdi32.BitBlt', BOOL, HDC, c_int, c_int, c_int, c_int, HDC, c_int, c_int, DWORD)
GetDIBits = quick_win_define('gdi32.GetDIBits', c_int, HDC, HBITMAP, UINT, UINT, LPVOID, POINTER(BITMAPINFOHEADER), UINT)
GetDesktopWindow = quick_win_define('user32.GetDesktopWindow', HWND)


class Grabber(object):
    def __init__(self, window=None, with_alpha=False, bbox=None):
        window = window or GetDesktopWindow()
        self.window = window
        rect = GetClientRect(window)
        self.width = rect.right - rect.left
        self.height = rect.bottom - rect.top
        if bbox:
            bbox = [bbox[0], bbox[1], bbox[2] - bbox[0], bbox[3] - bbox[1]]
            if not bbox[2] or not bbox[3]:
                bbox[2] = self.width - bbox[0]
                bbox[3] = self.height - bbox[1]
            self.x, self.y, self.width, self.height = bbox
        else:
            self.x = 0
            self.y = 0
        self.windowDC = GetDC(window)
        self.memoryDC = CreateCompatibleDC(self.windowDC)
        self.bitmap = CreateCompatibleBitmap(self.windowDC, self.width, self.height)
        self.bitmapInfo = BITMAPINFOHEADER()
        self.bitmapInfo.biSize = sizeof(BITMAPINFOHEADER)
        self.bitmapInfo.biPlanes = 1
        self.bitmapInfo.biBitCount = 32 if with_alpha else 24
        self.bitmapInfo.biWidth = self.width
        self.bitmapInfo.biHeight = -self.height
        self.bitmapInfo.biCompression = BI_RGB
        self.bitmapInfo.biSizeImage = 0
        self.channels = 4 if with_alpha else 3
        self.closed = False

    def __del__(self):
        try:
            self.close()
        except:
            pass

    def close(self):
        if self.closed:
            return
        ReleaseDC(self.window, self.windowDC)
        DeleteDC(self.memoryDC)
        DeleteObject(self.bitmap)
        self.closed = True

    def grab(self, output=None):
        if self.closed:
            raise ValueError('Grabber already closed')
        if output is None:
            output = np.empty((self.height, self.width, self.channels), dtype='uint8')
        else:
            if output.shape != (self.height, self.width, self.channels):
                raise ValueError('Invalid output dimentions')
        SelectObject(self.memoryDC, self.bitmap)
        BitBlt(self.memoryDC, 0, 0, self.width, self.height, self.windowDC, self.x, self.y, SRCCOPY)
        GetDIBits(self.memoryDC, self.bitmap, 0, self.height, output.ctypes.data, self.bitmapInfo, DIB_RGB_COLORS)
        return output


if __name__ == "__main__":
    import cv2
    from PIL import ImageGrab

    grabber = Grabber(bbox=(0, 40, 800, 640))
    import time
    s = time.clock()
    pic = None
    for i in range(10):
        pic = grabber.grab(pic)
    e = time.clock()
    print (e - s) / 10
    cv2.imwrite('a.tif', pic)
    s = time.clock()
    for i in range(10):
        pic = np.array(ImageGrab.grab(bbox=(0, 40, 800, 640)))
    e = time.clock()
    print (e - s) / 10
    cv2.imwrite('b.tif', pic)