Capturing a screenshot of a fullscreen game fails

Question

This works on a normal window but in a fullscreen game this is returning a black screen so I changed the dtype = numpy.uint8 to dtype = numpy.uint16 and now I'm getting the this error. I think it has something to do with the 4 in the tuple.

File "C:\Users\phpjunkie\Python\test_debug\testing\test12.py", line 22, in CaptureWwindow
output.shape = (height, width, 4)
^^^^^^^^^^^^
ValueError: cannot reshape array of size 12288000 into shape (1600,3840,4)

Here is the code:

import phpjunkie.Win32 as Win32
import cv2 as cv
import numpy
import win32gui
import win32ui
import win32con


def CaptureWwindow(hwnd: int):
    left, top, right, bottom = win32gui.GetWindowRect(hwnd)
    width, height = right - left,  bottom - top

    wdc = win32gui.GetWindowDC(hwnd)
    dc = win32ui.CreateDCFromHandle(wdc)
    cdc = dc.CreateCompatibleDC()
    bitmap = win32ui.CreateBitmap()
    bitmap.CreateCompatibleBitmap(dc, width, height)
    cdc.SelectObject(bitmap)
    cdc.BitBlt((0, 0), (width, height), dc, (0, 0), win32con.SRCCOPY)

    output = numpy.frombuffer(bitmap.GetBitmapBits(True), dtype = numpy.uint16)
    output.shape = (height, width, 4)

    dc.DeleteDC()
    cdc.DeleteDC()
    win32gui.ReleaseDC(hwnd, wdc)
    win32gui.DeleteObject(bitmap.GetHandle())

    return output


hwnd = Win32.GetWindowHandle(partial = 'Marvel\'s Spider-Man Remastered')
screenshot = CaptureWwindow(hwnd)
screenshot = (screenshot >> 2).astype(numpy.uint8)

cv.imshow('screenshot', screenshot)
print(screenshot.dtype)
print(screenshot.shape)
cv.waitKey()

Answer 1

I saw someone else's code and saw three lines that needed to be added that gave me what I wanted and that was to get a screenshot of the game itself and not a screenshot of the desktop.

import cv2 as cv
import numpy
from ctypes import windll # first line
import win32gui
import win32ui
import win32con
from pyvda import AppView, get_apps_by_z_order


def CaptureWwindow(hwnd: int) -> numpy.ndarray:
    if not bool(hwnd):
        return numpy.array([])

    windll.user32.SetProcessDPIAware() # second line

    left, top, right, bottom = win32gui.GetWindowRect(hwnd)
    width, height = right - left, bottom - top

    wdc = win32gui.GetWindowDC(hwnd)
    dc = win32ui.CreateDCFromHandle(wdc)
    cdc = dc.CreateCompatibleDC()
    bitmap = win32ui.CreateBitmap()
    bitmap.CreateCompatibleBitmap(dc, width, height)
    cdc.SelectObject(bitmap)
    cdc.BitBlt((0, 0), (width, height), dc, (0, 0), win32con.SRCCOPY)

    windll.user32.PrintWindow(hwnd, cdc.GetSafeHdc(), 3) # third line

    output = numpy.frombuffer(bitmap.GetBitmapBits(True), dtype = numpy.uint8)
    output.shape = (height, width, 4)

    dc.DeleteDC()
    cdc.DeleteDC()
    win32gui.ReleaseDC(hwnd, wdc)
    win32gui.DeleteObject(bitmap.GetHandle())

    return output


window = [window for window in get_apps_by_z_order(current_desktop = False) if 'Marvel\'s Spider-Man Remastered' in win32gui.GetWindowText(window.hwnd)]
if bool(len(window)):
    window = window[0]

if isinstance(window, AppView):
    screenshot = CaptureWwindow(window.hwnd)
    cv.imshow(winname = 'screenshot', mat = screenshot)
    cv.waitKey()

The only problem I found with his code is the win32gui.GetClientRect(hwnd) instead of win32gui.GetWindowRect(hwnd) was generating all zeros.