Subj : /Capture DOS Screen Text Programmatically
To   : Alejandro Pelaez
From : BotSearch
Date : Sun May 13 2001 06:39 pm

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Messages from the thread "Capture DOS Screen Text Programmatically" Messages 1
- 9 of 9.
Message 1 in thread
From: {Dayang Dai} ({[email protected]})
Subject: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}, micro
Date: 2000/10/14

I am running on NT.  I need to write a program to capture the Screen Display
of a DOS application.  Using the "Print Screen" key will not work for me
because it is a manual process.  (Can I do Print Screen to Clipboard
programmatically?).  Redirect the DOS App's standard output will not work
for me neither because the result is on the screen (like using cprintf() in
that DOS app).

Do I need to deal with the Virtual DOS Machine?

Also, Can I use SendMessage( hWnd, xx, xx ) to send key strokes to the DOS
application?

Basically I want to programmatically control a DOS application.  Which
direction should I go?

Please help and many thanks

Dayang Dai

[email protected]




Message 2 in thread
From: {Dimitris Tripakis} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}, micro
Date: 2000/10/15

>(Can I do Print Screen to Clipboard programmatically?).

If you do
GetDC(NULL);
you will get the HDC of the entire screen.

From there, you can do a BitBlt( ) from the screen to
a compatible DC you have created (probably an HBITMAP,
created by CreateCompatibleBitmap() )

You can read the bytes of this HBITMAP using :
GetObject()

..or you could read directly from the screen using
GetPixel()

I would personally choose the first way, blit an instance
of the screen to a bitmap and work on this one. Otherwise,
if you work on the screen, it might change in time, and
this could cause problems....

Note that you need OCR code to extract the text from this,
since what you will end up with is a "bitmap"...

Dimitris



Message 3 in thread
From: {gu} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}, micro
Date: 2000/10/15


Win32 offers special functions for controlling the console. You can use
ReadConsoleOutput() to get the characters on the console if you just need a
hardcopy of the text.

For really controlling a DOS application, you have to write a shell
programm, which creates three pipes. Then you are able to start your
programm with CreateProcess() and redirecting stdin, stdout and stderr to
your pipes. And in your shell programm you are able to handle stdout and
even put it to the console (using GetStdHandle() and WriteConsole()).

gu



Message 4 in thread
From: {Axel K�ster} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}
Date: 2000/10/16


"Dayang Dai" <[email protected]> wrote

> I am running on NT.  I need to write a program to capture the Screen
> Display
> of a DOS application.  Using the "Print Screen" key will not work for me
> because it is a manual process.  (Can I do Print Screen to Clipboard
> programmatically?).

Hello Dayang Dai,

I suggest to use "Print Screen". You can use keybd_event() with VK_PRINT
as parameter to copy the DOS screen into the clipboard.. The DOS application
must be in foreground (receiving the keyboard input). After that you can usethe
OpenClipboard(), GetClipboardData(), ... to get the content of the
clipboard.
You get only the text (neither graphic nor the text attributes).

Regards,
Axel




Message 5 in thread
From: {Jim Barry} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}
Date: 2000/10/16


Axel K�ster wrote:

> I suggest to use "Print Screen". You can use keybd_event() with
> VK_PRINT as parameter to copy the DOS screen into the clipboard..
> You get only the text (neither graphic nor the text attributes).

Really? I get only a full-screen bitmap (or a window-sized bitmap if the Alt
key is held down).

Cheers,

- Jim


Message 6 in thread
From: {Dayang Dai} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}, micro
Date: 2000/10/16

Thank you everybody for the input.  I end up use GU's suggestion.  I opened
a console screen and then use CreateProcess() to load my real DOS app.
Then I use WriteConsoleInput() to feed the keystrokes (even funtion keys).
For reading screen text, I use the ReadConsoleOutput() the read back the
screen output.  It is great.  Many thanks

Dayang Dai.

gu <[email protected]> wrote in message
{news:#[email protected]}...
> Win32 offers special functions for controlling the console. You can use
> ReadConsoleOutput() to get the characters on the console if you just
> need a
> hardcopy of the text.
>
> For really controlling a DOS application, you have to write a shell
> programm, which creates three pipes. Then you are able to start your
> programm with CreateProcess() and redirecting stdin, stdout and stderr
> to
> your pipes. And in your shell programm you are able to handle stdout and
> even put it to the console (using GetStdHandle() and WriteConsole()).
>
> gu
>
>



Message 7 in thread
From: {Axel K�ster} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}
Date: 2000/10/17

"Jim Barry" <[email protected]> wrote:

> Axel K�ster wrote:
>
> > I suggest to use "Print Screen". You can use keybd_event() with
> > VK_PRINT as parameter to copy the DOS screen into the clipboard..
> > You get only the text (neither graphic nor the text attributes).
>
> Really? I get only a full-screen bitmap (or a window-sized bitmap if the
> Alt
> key is held down).
>
> Cheers,
>
> - Jim

This only work in fullscreen text mode :-(
Sorry, this was my fault.

Thanks,
Axel



Message 8 in thread
From: {Jim Barry} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}
Date: 2000/10/17


Axel K�ster wrote:

> This only work in fullscreen text mode

Ah, right you are.

Cheers,

- Jim



Message 9 in thread
From: {Jonathan de Boyne Pollard} ({[email protected]})
Subject: Re: Capture DOS Screen Text Programmatically
Newsgroups: {microsoft.public.platformsdk.gdi},
{microsoft.public.platformsdk.ui}, {microsoft.public.sbk.windows9x},
{microsoft.public.sbk.windowsnt}, {microsoft.public.win32.programmer.gdi},
{microsoft.public.win32.programmer.kernel},
{microsoft.public.win32.programmer.ui}, {comp.os.ms-windows.programmer.nt.kernel-mode}
Date: 2000/10/17


DD> I am running on NT.  I need to write a program to capture the
DD> Screen Display of a DOS application.

Because of a programming tradition on Microsoft operating systems that
goes all of the way back to the earliest versions of MS-DOS, there is no
one single way to capture the output or control the input of a textual
application.

On Windows NT, the case of DOS applications is actually a subset of the
more general case of "console mode" applications, because DOS
applications run as coroutines within a Win32 process (NTVDM) that
translates their I/O to Win32 equivalents.

There are two classes of console mode applications.  The important
difference between the two is whether they read from and write to their
standard input and standard output in "glass TTY" fashion using
ReadFile() and WriteFile() (what Win32 terms "high-level console I/O"),
or whether they use "random access" APIs such as WriteConsoleOutput()
(what Win32 terms "low-level console I/O").  Translating this to DOS
terms: DOS programs that use INT 21h to read from and write to their
standard input and standard output are in the former class; and DOS
programs that use INT 10h or that write directly to video memory are in
the latter class.

To capture the output and control the input of programs that use
"low-level console I/O", one sits in a loop whilst the child process is
executing, continuously monitoring the contents of the console screen
buffer using ReadConsoleOutput() and sending any keystrokes using
WriteConsoleInput().

There are several problems with this design.  One minor problem is that
it doesn't cope at all well with Win32 programs that take full advantage
of the features of the Win32 low-level console paradigm and use
alternate console screen buffers for their output.  A more major problem
is that because it uses polling (Win32 not providing any handy event
mechanism to latch on to so that the monitor could know when the buffer
has been modified) it is always going to be both unreliable and
expensive.  It is unreliable in that depending from the relative
scheduling priorities of the various processes, something which is going
to vary dynamically with system load, it may well be the case that the
child program may be able to generate reams of output that the
monitoring process will simply miss because its console monitoring
thread won't be scheduled to run often enough.  It is expensive in that
if the child process happens not to generate any output for a while, the
monitoring process is going to consume CPU time needlessly.

To capture the output and control the input of programs that use
"high-level console I/O", one redirects their standard input and
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