As is, this captures a bitmap of the whole screen. Use "%{PrtScn}" for just the current window. Interpreting and manipulating the bitmap captured is over to you. You may find this document useful. The site's pretty damn useful too. Qudos to PodMaster for a reference to that some time back.

#! perl -slw
#use Win32::Bitmap;
use strict;
use Win32::GuiTest qw[SendKeys];
use Win32::Clipboard;

my $cb = Win32::Clipboard->new();

$cb->Empty();
SendKeys( "+{PRTSCR}" );
$cb->WaitForChange();

my $image = $cb->GetBitmap() or die 'No bitmap there';

print 'Total size:', length $image;
my %BMPinfo;
@BMPinfo{
    (
        '01UINT  type',                    #! 2
        '02DWORD size',                    #! 4
        '03UINT  Reserved1',            #! 2
        '04UINT  Reserved2',            #! 2
        '05DWORD Offset',                #! 4
        '06DWORD biSize',                #! 4
        '07LONG  biWidth',                #! 4
        '08LONG  biHeight',                #! 4
        '09WORD  biPlanes',                #! 2
        '10WORD  biBitCount',            #! 2
        '11DWORD biCompression',        #! 4
        '12DWORD biSizeImage',            #! 4
        '13LONG  biXPelsPerMeter',        #! 4
        '14LONG  biYPelsPerMeter',        #! 4
        '15DWORD biClrUsed',            #! 4
        '16DWORD biClrImportant',        #! 4
    )                                    #!54
} = unpack 'A2 L S S L L V V s s L L V V L L', substr $image, 0, 54;

printf '%23s : %s'.$/, $_, $BMPinfo{$_} 
    for sort keys %BMPinfo;
__END__
C:\test>231894
Total size:1572918
           01UINT  type : BM
           02DWORD size : 1572918
      03UINT  Reserved1 : 0
      04UINT  Reserved2 : 0
         05DWORD Offset : 54
         06DWORD biSize : 40
        07LONG  biWidth : 1024
       08LONG  biHeight : 768
       09WORD  biPlanes : 1
     10WORD  biBitCount : 16
  11DWORD biCompression : 3
    12DWORD biSizeImage : 1572864
13LONG  biXPelsPerMeter : 0
14LONG  biYPelsPerMeter : 0
      15DWORD biClrUsed : 0
 16DWORD biClrImportant : 0
[download]

Of course, that's capturing the whole screen (printscreen) or the active window (alt-printscreen). Once you had that, though, you could use ImageMagick to crop to the section you need. (That's one way, anyway. TIMTOWTDI, I'm sure.)

- Matt Riffle

This is not quite what I am looking for. I want the capturing fully controled by my program, without any human interaction, so printscreen does not work (I don't press buttons ;-)

However to capture the whole screen instead of an area is okay with me, I can process it after.



Update

Cool, I will take a look, thanks.

My reading of that code (and I've never used any of the Win32 modules ever, so YMMV) was that you didn't press anything -- it simulated the keystroke for you.

The part I'm talking about is:

# press the key!!
$key->Call(0x2C, 0x45, 0x01, 0); #simulate a "printscrn" key press
$key->Call(0x2C, 0x45, 0x03, 0); # & release
[download]

- Matt Riffle

In my exploration of wxPerl, I came up with the following , it has extra "fluff", but you can clean it to suit you

package ScreenShot;
use Wx qw[ :everything ];
use Wx::Colour qw[ :everything ];
use Wx::Event qw[ :everything ];
use Wx::App;
use base qw[Wx::App];

sub OnInit {
    my( $self )=@_;
    if(1){
    #    my $w = new Wx::Frame(undef,-1,"crap",[-1,-1,],[-1,-1],wxTRAN
+SPARENT_WINDOW );
        my $w = new Wx::Frame(undef,-1,"crap",[-1,-1,],[-1,-1],wxTRANS
+PARENT_WINDOW );

    #    my $w = new Wx::Frame(undef,-1,"crap",[-1,-1,],[-1,-1],wxSTAY
+_ON_TOP); 
    #    my $w = new Wx::Frame(undef,-1,"crap",[-1,-1,],[-1,-1],wxNO_B
+ORDER | wxMINIMIZE_BOX | wxMAXIMIZE_BOX | wxSYSTEM_MENU | wxCAPTION )
+;
    #    my $w = new Wx::Frame(undef,-1,"crap",[-1,-1,],[-1,-1],wxSTAY
+_ON_TOP|wxDEFAULT_FRAME_STYLE|wxNO_BORDER); 
        EVT_PAINT( $w, sub {
            my($s,$e)=@_;
            my $dc = Wx::PaintDC->new($s); # must create, to stop crap
            $self->PaintThisBitch;
            return 0;
        });
    
        $w->Show(1);
        $w->CaptureMouse();
        $w->Clear();
        $w->Refresh;
    }
    EVT_MOTION( $self, sub {warn"@_"});

    return 1;
}

sub TakeScreenshot {
    my($self, $file ) = @_;
    $file ||= 'test.bmp';
    my $screen = Wx::ScreenDC->new();
    my( $x, $y) = $screen->GetSizeWH();
    my $bitmap = Wx::Bitmap->new($x,$y,-1);
    my $memory = Wx::MemoryDC->new();
       $memory->SelectObject( $bitmap );
       $memory->Blit(0,0,$x,$y, $screen, 0, 0);
       $bitmap->SaveFile( $file , wxBITMAP_TYPE_BMP ) ;
}

sub PaintThisBitch {
    my $screen = Wx::ScreenDC->new();
    $screen->SetBackgroundMode( wxTRANSPARENT );
    
    
    $screen->SetFont(Wx::Font->new( 40, wxDECORATIVE, wxNORMAL, wxBOLD
+, 0 ));

        for(1..255){
            my $c = $_;

                $screen->SetTextForeground( Wx::Colour->newRGB(0,0,$c)
+);
                $screen->DrawRotatedText("wxPerl",410 ,400 ,$_);
                $screen->DrawRotatedText("wxPerl and PodMaster",410 ,5
+00 ,0);
                $screen->DrawRotatedText("are messing up your screen",
+410 ,550 ,0);
                select undef, undef, undef, 0.0001;
        }
        for(1..255){
            my $c = $_;

                $screen->SetTextForeground( Wx::Colour->newRGB(0,$c,0)
+);
                $screen->DrawRotatedText("wxPerl",410 ,400 ,$_);
                $screen->DrawRotatedText("wxPerl and PodMaster",410 ,5
+00 ,0);
                $screen->DrawRotatedText("are messing up your screen",
+410 ,550 ,0);
                select undef, undef, undef, 0.0001;

        }
        for(1..255){
            my $c = $_;

                $screen->SetTextForeground( Wx::Colour->newRGB($c,0,0)
+);
                $screen->DrawRotatedText("wxPerl",410 ,400 ,$_);
                $screen->DrawRotatedText("wxPerl and PodMaster",410 ,5
+00 ,0);
                $screen->DrawRotatedText("are messing up your screen",
+410 ,550 ,0);
                select undef, undef, undef, 0.0001;
        }
    
    return 0;
}

package main;
my $i = ScreenShot->new;
$i->TakeScreenshot('testor.bmp');
$i->PaintThisBitch;
$i->MainLoop;

__END__
wxScreenDC
context = wxClientDC( self ) 
memory = wxMemoryDC( ) 
x,y = self.GetClientSizeTuple() 
bitmap = wxEmptyBitmap( x,y, -1 ) 
memory.SelectObject( bitmap ) 
memory.Blit( 0,0,x,y, context, 0,0) 
memory.SelectObject( wxNullBitmap) 
bitmap.SaveFile( "test.bmp", wxBITMAP_TYPE_BMP )
[download]

MJD says you can't just make shit up and expect the computer to know what you mean, retardo! ** The Third rule of perl club is a statement of fact: pod is sexy.