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 ImageEnView1.IO.CaptureFromScreen		  New Topic  Reply to Topic
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w2m

USA
1990 Posts
Posted - Aug 27 2012 :  13:32:46  Show Profile  Reply
Before calling ImageEnView1.IO.CaptureFromScreen(iecsForegroundWindow) is there any API to determine if there is a foreground window?

A question posted at StackOverflow failed to produce any code that works.

I created a work-around for the problem that seems to work, but some windows API would be better.

If you call ImageEnView1.IO.CaptureFromScreen(iecsForegroundWindow) and there is no foreground window a large completely black bitmap is returned. The work-around uses imageen to determine if the dominantcolor of the capturedimage is 100%. If the dominantcolor is 100 then you can display an error message and blank the image.
iPercentage := ImageEnView1.Proc.GetDominantColor(iColor);
//the image is all one color!
if iPercentage = 100 then
begin
   ImageEnView1.Blank;
   MessageBox(0, 'There is no foreground window.' + #10#13 + 'Make a window the foreground window, then try again.', 'No Active Window', MB_ICONWARNING or MB_OK);
end;

It is also interesting that if there is no foreground window, the ImageEnView1.IO.CaptureFromScreen(iecsForegroundWindowClient) returns a bitmap of the start button on the taskbar.

William Miller
Adirondack Software & Graphics
Email: w2m@frontiernet.net
EBook: http://www.imageen.com/ebook/
Apprehend: http://www.frontiernet.net/~w2m/index.html

w2m

USA
1990 Posts
Posted - Aug 30 2012 :  08:29:25  Show Profile  Reply
No one has any ideas?

William Miller
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ehkhalid

27 Posts
Posted - Aug 31 2012 :  00:23:10  Show Profile  Reply
I use another way to detect if a page is blank, I calculcate "standard deviation" it give you if pixels variation is uniform or not, so if it's uniform, it mean image's pixels has the same color.

Hope this help
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Uwe

284 Posts
Posted - Aug 31 2012 :  10:23:42  Show Profile  Reply
William, does this help?

http://msdn.microsoft.com/en-us/library/windows/desktop/ms633505%28v=vs.85%29.aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/ms632599%28v=vs.85%29.aspx#foreground

Quote:
"To check if your application window is the foreground window, compare the handle returned by GetForegroundWindow to that of your application window."

Uwe
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w2m

USA
1990 Posts
Posted - Aug 31 2012 :  14:13:05  Show Profile  Reply
Uwe,

I am not sure if this will help because I think you have to click on the window to get the correct foreground window.... will investigate this more.

William Miller
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fab

1310 Posts
Posted - Sep 03 2012 :  13:39:52  Show Profile  Reply
Hi Bill,
I don't know if this helps. When there isn't a foreground window then GetForegroundWindow should return the same value of GetShellWindow, so you could try:

if GetForegroundWindow() = GetShellWindow() then
...there is no foreground....
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w2m

USA
1990 Posts
Posted - Sep 04 2012 :  11:24:59  Show Profile  Reply
Hi Fabrizio,

With Windows 7, GetForegroundWindow = 263058 and GetShellWindow = 65866 when there are no visible windows on the deskup... so the test fails. I think you have to click on the desktop for this to work, but when capturing a clientwindow with ImageEnView1.IO.CaptureFromScreen(iecsForegroundWindow) there is no API to force a mouseclick on the desktop is there?


William Miller
Adirondack Software & Graphics
Email: w2m@frontiernet.net
EBook: http://www.imageen.com/ebook/
Apprehend: http://www.frontiernet.net/~w2m/index.html
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fab

1310 Posts
Posted - Sep 05 2012 :  10:12:41  Show Profile  Reply
To what window GetForegroundWindow refers returning 263058? Is that "minimized"? In this case you could check the window status (minimized, hided, etc...).
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