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win32ui screen capture

P: n/a
i,
I have trying to code a small console app that will
allow a user to select a window and then create a
screen capture of the window. I haven't been able to
figure out how to do the screen capture part. The
code is as follows, the commented out lines at the end
are things I have tried, but don't work. Whenever I
try to create a compatibe Bitmap or DC it comes back
with an error as
win32ui: CreateCompatibleDC failed
or
AttributeError: CreateCompatibleDC
Any help would be greatly appreciated.

import win32gui
import win32ui

numWindows = 0
windows = []
winDict = {}
windowsText=[]
inc = 0

def _MyCallback( hwnd, extra ):
extra.append(hwnd)
win32gui.EnumWindows(_MyCallback, windows)
for i in windows:
if win32gui.IsWindowVisible(i):
if win32gui.IsWindowVisible:
windowsText.append(i)
winDict[numWindows] = i
numWindows +=1


print "Please select a window to capture"
for window in windowsText:
windowText = win32gui.GetWindowText(window)
print inc, windowText
inc += 1

selection = input()

print win32gui.GetWindowText(winDict[selection])
myDC = win32ui.CreateDCFromHandle(winDict[selection])
win32gui.SetForegroundWindow(winDict[selection])
win_sz = win32gui.GetClientRect(winDict[selection])
myBitMap = win32ui.CreateBitmap()
#myMemDC = win32ui.CreateCompatibleDC(myDC)
#myBitMap.BitBlt((0,0),(win_sz[2],win_sz[3],myDC,(0,0),0))
#myBitMap.CreateCompatibleBitMap(myDC,win_sz[2], win_sz[3])
#myBitMap.CreateCompatibleDC(myDC)
Thanks,
Rob
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Jul 18 '05 #1
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3 Replies


P: n/a
On Fri, 27 Jun 2003 05:11:04 GMT, "Mark S Pryor"
<ma**************@CHENEYverizon.net> wrote:
Hi,
<Me Mine> wrote in message
news:o4********************************@4ax.com.. .
i,
I have trying to code a small console app that will
allow a user to select a window and then create a
screen capture of the window. I haven't been able to
figure out how to do the screen capture part. The
code is as follows, the commented out lines at the end
are things I have tried, but don't work. Whenever I
try to create a compatibe Bitmap or DC it comes back
with an error as
win32ui: CreateCompatibleDC failed
or
AttributeError: CreateCompatibleDC
Any help would be greatly appreciated.

import win32gui
import win32ui

numWindows = 0
windows = []
winDict = {}
windowsText=[]
inc = 0

def _MyCallback( hwnd, extra ):
extra.append(hwnd)
win32gui.EnumWindows(_MyCallback, windows)
for i in windows:
if win32gui.IsWindowVisible(i):
if win32gui.IsWindowVisible:
windowsText.append(i)
winDict[numWindows] = i
numWindows +=1


print "Please select a window to capture"
for window in windowsText:
windowText = win32gui.GetWindowText(window)
print inc, windowText
inc += 1

selection = input()

print win32gui.GetWindowText(winDict[selection])
myDC = win32ui.CreateDCFromHandle(winDict[selection])
win32gui.SetForegroundWindow(winDict[selection])
win_sz = win32gui.GetClientRect(winDict[selection])
myBitMap = win32ui.CreateBitmap()
#myMemDC = win32ui.CreateCompatibleDC(myDC)
#myBitMap.BitBlt((0,0),(win_sz[2],win_sz[3],myDC,(0,0),0))
#myBitMap.CreateCompatibleBitMap(myDC,win_sz[2], win_sz[3])
#myBitMap.CreateCompatibleDC(myDC)
Thanks,
Rob


You may be able to make this work ... eventually. However,
circulating in the Python community you will find the C file
_grabscreen.c with all the same API calls you are trying to use
in standard C.

see this post
http://groups.google.com/groups?selm...ython-list%40p
ython.org

It explains how to compile the module _grabscreen.pyd with MS Visual C.
I was able to get a screen shot script in 10 minutes after I read this
post. If you don't have a grabscreen module already, see this ZIP file
for the relevant files. Use the file ImageGrab1.py to make a screen
capture of the desktop and save the results as PNG.

(for ActivePython 2.2 only)
http://mysite.verizon.net/res1ur2j/GrabScreen.zip

you will need PIL from
http://www.pythonware.com/products/pil/

hth,
Mark Pryor

Thanks for reponding Mark. I have looked at the grab function in
ImagrGrab from PIL. And it does do exactly what I want it to do,
which is great, but I was hoping to do the program using win32ui and
win32gui so that I could get a better understanding over how Windows
(the OS) operates. The part that bothers me (and the reason why I'm
pursueing this) is because in MS C++ the BitBlt function can take the
Window DC directly as opposed to the BitBlt function in python, which
cannot. Python's BitBlt function (for PyCDC objects in win32ui), can
only take other PyCDC objects for the source of the copy.
Unfortunatley, once I have the window handle I can call the
GetWindowDC method, but it returns HDC Yet, I unable to use this
object to call BitBlt on. When I uncomment the the BitBlt line of
code I get a n error of

TypeError: The 'O' param must be a PyCDC object

So, it appears that I need to do something with the HDC, so I can do a
bitblt transer to the memory DC, but I don't know how to get a PyCDC
object from a HDC.

Thanks,

Rob
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Jul 18 '05 #2

P: n/a

<Me Mine> wrote in message
news:bn********************************@4ax.com...
Hi again,

ok, so now I'm closer. I can create a compatible memory dc and a new
bitmap, which is always black is created. But I can't figure out how
to BitBlt to the memory DC from the window DC. The line is commented


I tried for 30 minutes, but no joy. I too get a black BMP result.

One suggestion. Add this
import win32con as con

In bltbit( , , , 204) use
con.SRCCOPY) instead

hth,
Mark Pryor
Jul 18 '05 #3

P: n/a
Mark S Pryor wrote:
You may be able to make this work ... eventually. However,
circulating in the Python community you will find the C file
_grabscreen.c with all the same API calls you are trying to use
in standard C.

see this post
http://groups.google.com/groups?selm...ython-list%40p
ython.org

It explains how to compile the module _grabscreen.pyd with MS Visual C.
I was able to get a screen shot script in 10 minutes after I read this
post. If you don't have a grabscreen module already, see this ZIP file
for the relevant files. Use the file ImageGrab1.py to make a screen
capture of the desktop and save the results as PNG.

(for ActivePython 2.2 only)
http://mysite.verizon.net/res1ur2j/GrabScreen.zip

you will need PIL from
http://www.pythonware.com/products/pil/


note that PIL 1.1.3 and later includes screen grabbing facilities;
for details, see:

http://www.effbot.org/zone/pil-imagegrab.htm

</F>


Jul 18 '05 #4

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