Python win32ui.error: CreateCompatibleDC failed

Question

我试图使用opencv的win32捕获sceen，但当我启动时，它会给我一个关于CreateCompatibleDC函数的错误。

这是我第一次接触这个库，所以我真的不知道如何解决这个问题。

import numpy as np
import win32gui,win32ui,win32con

class WindowCapture:
# properties
w = 0
h = 0
hwnd = None
cropped_x = 0
cropped_y = 0
offset_x = 0
offset_y = 0
# constructor
def __init__(self, window_name):
# find the handle for the window we want to capture
self.hwnd = win32gui.FindWindow(None, window_name)
if not self.hwnd:
raise Exception('Window not found: {}'.format(window_name))
# get the window size
window_rect = win32gui.GetWindowRect(self.hwnd)
self.w = window_rect[2] - window_rect[0]
self.h = window_rect[3] - window_rect[1]
# account for the window border and titlebar and cut them off
border_pixels = 8
titlebar_pixels = 30
self.w = self.w - (border_pixels * 2)
self.h = self.h - titlebar_pixels - border_pixels
self.cropped_x = border_pixels
self.cropped_y = titlebar_pixels
# set the cropped coordinates offset so we can translate screenshot
# images into actual screen positions
self.offset_x = window_rect[0] + self.cropped_x
self.offset_y = window_rect[1] + self.cropped_y
def get_screenshot(self):
# get the window image data
wDC = win32gui.GetWindowDC(self.hwnd)
dcObj = win32ui.CreateDCFromHandle(wDC)
cDC = dcObj.CreateCompatibleDC()
dataBitMap = win32ui.CreateBitmap()
dataBitMap.CreateCompatibleBitmap(dcObj, self.w, self.h)
cDC.SelectObject(dataBitMap)
cDC.BitBlt((0, 0), (self.w, self.h), dcObj, (self.cropped_x, self.cropped_y), win32con.SRCCOPY)
# convert the raw data into a format opencv can read
#dataBitMap.SaveBitmapFile(cDC, 'debug.bmp')
signedIntsArray = dataBitMap.GetBitmapBits(True)
img = np.fromstring(signedIntsArray, dtype='uint8')
img.shape = (self.h, self.w, 4)
# free resources
dcObj.DeleteDC()
cDC.DeleteDC()
win32gui.ReleaseDC(self.hwnd, wDC)
win32gui.DeleteObject(dataBitMap.GetHandle())
# drop the alpha channel, or cv.matchTemplate() will throw an error like:
#   error: (-215:Assertion failed) (depth == CV_8U || depth == CV_32F) && type == _templ.type() 
#   && _img.dims() <= 2 in function 'cv::matchTemplate'
img = img[...,:3]
# make image C_CONTIGUOUS to avoid errors that look like:
#   File ... in draw_rectangles
#   TypeError: an integer is required (got type tuple)
# see the discussion here:
# https://github.com/opencv/opencv/issues/14866#issuecomment-580207109
img = np.ascontiguousarray(img)
return img
# find the name of the window you're interested in.
# once you have it, update window_capture()
# https://stackoverflow.com/questions/55547940/how-to-get-a-list-of-the-name-of-every-open-window
def list_window_names(self):
def winEnumHandler(hwnd, ctx):
if win32gui.IsWindowVisible(hwnd):
print(hex(hwnd), win32gui.GetWindowText(hwnd))
win32gui.EnumWindows(winEnumHandler, None)
# translate a pixel position on a screenshot image to a pixel position on the screen.
# pos = (x, y)
# WARNING: if you move the window being captured after execution is started, this will
# return incorrect coordinates, because the window position is only calculated in
# the __init__ constructor.
def get_screen_position(self, pos):
return (pos[0] + self.offset_x, pos[1] + self.offset_y)

这就是我写的，指的是通过游戏学习代码视频

但当启动时，出现错误：

File "C:Xwindowcapture.py", line 49, in get_screenshot
dataBitMap.CreateCompatibleBitmap(dcObj, self.w, self.h)
win32ui.error: CreateCompatibleDC failed

Answer 1

来源：

border_pixels = 8
titlebar_pixels = 30
self.w = self.w - (border_pixels * 2)
self.h = self.h - titlebar_pixels - border_pixels
self.cropped_x = border_pixels
self.cropped_y = titlebar_pixels

收件人：

border_pixels = 1  # <-- Change this
titlebar_pixels = 10  # <-- Change this
self.w = self.w - border_pixels  # <-- Change this
self.h = self.h - titlebar_pixels - border_pixels
self.cropped_x = border_pixels
self.cropped_y = titlebar_pixels

Answer 2

看来win32gui API无法为您的编程创建位图。

因此，一开始，您必须保持想要捕获的窗口处于活动状态(不最小化或不创建(将该窗口留在代码窗口后面，然后重试。

Answer 3

#ya只是确认他说的是正确的，有效的。不知道为什么，但它确实稍微降低了你的fps，除非你在低端机器上不是什么大问题：

border_pixels = 8
titlebar_pixels = 30
self.w = self.w - (border_pixels * 2)
self.h = self.h - titlebar_pixels - border_pixels
self.cropped_x = border_pixels
self.cropped_y = titlebar_pixels
To:
border_pixels = 1  # <-- Change this
titlebar_pixels = 10  # <-- Change this
self.w = self.w - border_pixels  # <-- Change this
self.h = self.h - titlebar_pixels - border_pixels
self.cropped_x = border_pixels
self.cropped_y = titlebar_pixels