I need to make a screen capture of a specific application. If I grab the Windows desktop (hwnd = None), everything works, but I get a black screen when I try to grab the screen of a specific application, e.g. hwnd = win32gui.FindWindow(None, 'Albion Online Client').
import cv2 as cv
import numpy as np
import os
from time import time
import win32gui
import win32ui
import win32con
os.chdir(os.path.dirname(os.path.abspath(__file__)))
def window_capture():
w = 1920 # set this
h = 1080 # set this
#hwnd = None ### Everything works
hwnd = win32gui.FindWindow(None, 'Albion Online Client') ### Black Screen
wDC = win32gui.GetWindowDC(hwnd)
dcObj = win32ui.CreateDCFromHandle(wDC)
cDC = dcObj.CreateCompatibleDC()
dataBitMap = win32ui.CreateBitmap()
dataBitMap.CreateCompatibleBitmap(dcObj, w, h)
cDC.SelectObject(dataBitMap)
cDC.BitBlt((0, 0), (w, h), dcObj, (0, 0), win32con.SRCCOPY)
#Save screenshoot
#dataBitMap.SaveBitmapFile(cDC, 'debug.bmp' )
signedIntsArray = dataBitMap.GetBitmapBits(True)
img = np.fromstring(signedIntsArray, dtype='uint8')
img.shape = (h, w, 4)
# Free Resources
dcObj.DeleteDC()
cDC.DeleteDC()
win32gui.ReleaseDC(hwnd, wDC)
win32gui.DeleteObject(dataBitMap.GetHandle())
img = img[..., :3]
img = np.ascontiguousarray(img)
return img
# initialize the WindowCapture clas
loop_time = time()
while(True):
screenshot = window_capture()
cv.imshow('Computer Vision', screenshot)
# debug the loop rate
print('FPS {}'.format(1 / (time() - loop_time)))
loop_time = time()
# press 'q' with the output window focused to exit.
# waits 1 ms every loop to process key presses
if cv.waitKey(1) == ord('q'):
cv.destroyAllWindows()
break
print('Done.')
