win32ui vs wxPy screen capture multi monitor

[nobugus]

Just posting a solution to the problem of capturing the whole virtual screen area, including all monitors with python and pywin32.
Because this doesn't work even with PIL's imagegrab module.

import win32gui,  win32ui,  win32con, win32api
 
hwnd = win32gui.GetDesktopWindow()
print hwnd
 
# you can use this to capture only a specific window
#l, t, r, b = win32gui.GetWindowRect(hwnd)
#w = r - l
#h = b - t
 
# get complete virtual screen including all monitors
SM_XVIRTUALSCREEN = 76
SM_YVIRTUALSCREEN = 77
SM_CXVIRTUALSCREEN = 78
SM_CYVIRTUALSCREEN = 79
w = vscreenwidth = win32api.GetSystemMetrics(SM_CXVIRTUALSCREEN)
h = vscreenheigth = win32api.GetSystemMetrics(SM_CYVIRTUALSCREEN)
l = vscreenx = win32api.GetSystemMetrics(SM_XVIRTUALSCREEN)
t = vscreeny = win32api.GetSystemMetrics(SM_YVIRTUALSCREEN)
r = l + w
b = t + h
 
print l, t, r, b, ' -> ', w, h
 
hwndDC = win32gui.GetWindowDC(hwnd)
mfcDC  = win32ui.CreateDCFromHandle(hwndDC)
saveDC = mfcDC.CreateCompatibleDC()
 
saveBitMap = win32ui.CreateBitmap()
saveBitMap.CreateCompatibleBitmap(mfcDC, w, h)
saveDC.SelectObject(saveBitMap)
saveDC.BitBlt((0, 0), (w, h),  mfcDC,  (l, t),  win32con.SRCCOPY)
saveBitMap.SaveBitmapFile(saveDC,  'screencapture.bmp')
 

[nobugus]

and to save that file as jpg, png... you can use PIL:

bmpinfo = saveBitMap.GetInfo()
print bmpinfo
bmpstr = saveBitMap.GetBitmapBits(True)
 
import Image
im = Image.frombuffer('RGB', (bmpinfo['bmWidth'], bmpinfo['bmHeight']), bmpstr, 'raw', 'BGRX', 0, 1)
#im.save('screencapture.jpg', format = 'jpeg', quality = 85)
im.save('screencapture.png', format = 'png')
 

[nobugus]

to do the whole thing even easier use wx:

import wx
 
app = wx.PySimpleApp()
 
context = wx.ScreenDC()
r, b = context.GetSize()
 
# i have a second monitor left of my primary, so these value are negativ
l, t = (-1280, -256) # coulfn't find a wx function to get these
 
w, h = (r - l, b - t)
bitmap = wx.EmptyBitmap(w, h, -1)
 
memory = wx.MemoryDC()
memory.SelectObject(bitmap)
memory.Blit(0, 0, w, h, context, l, t)
memory.SelectObject(wx.NullBitmap)
 
#bitmap.SaveFile("screencapture.bmp", wx.BITMAP_TYPE_BMP)
#bitmap.SaveFile("screencapture.jpg", wx.BITMAP_TYPE_JPEG)
bitmap.SaveFile("screencapture.png", wx.BITMAP_TYPE_PNG)
 

[bartonc]

Wow. Thanks nobugus. This is very useful.

[bartonc]

Wow. Thanks nobugus. This is very useful.

This one is really worth a bump to the top.

[CuriousLemur]

First, many thanks to nobugus for this post, I had been hunting around for a way to do this for a while now, and this post was a huge boon!

It's worth noting though, that the code as is in the first post has a memory leak, and that if you wrap his code in a function take enough screenshots it will eventually crash with a windows error code 8. (On my system, this happens somewhere between 100 and 200 screenshots).

Adding the following after saving the screenshot (or doing whatever you like with it) seems to close the leak:

saveDC.DeleteDC()
win32gui.DeleteObject(saveBitMap.GetHandle())

I don't understand the details of why python/pywin32 garbage collection isn't handling this when the variables leave scope, but I thought I'd post this in case anyone else had the same problem. I experimented with leaving out just one line or the other, but both seem necessary. If anyone wants to explain to me why this works, I'm all ears!