#  Example 2.xx:
#  ----------------------------------------
#  From "Win32 Perl Programming: Administrators Handbook" by Dave Roth
#  Published by Macmillan Technical Publishing.
#  ISBN # 1-57870-215-1

#  This dumps the class and title (if available) of each window.

use Win32::API;

$GW_CHILD = 5;
$GW_HWNDNEXT = 2;

$GetWindow = new Win32::API( 'User32.dll', 'GetWindow', [N,N], N ) || die;
$GetTopWindow = new Win32::API( 'User32.dll', 'GetTopWindow', [N], N ) || die;
$GetWindowText = new Win32::API( 'User32.dll', 'GetWindowText', [N,P,N], N ) || die;
$GetClassName = new Win32::API( 'User32.dll', 'GetClassName', [N,P,N], N ) || die;
sub GetClassName
{
    my( $hWnd, $String, $Size ) = @_;
    if( ! $GetClassName )
    {
        $GetClassName = new Win32::API( 'User32.dll', 'GetClassName', [N,P,N], N )
            || die "Can not load GetClassName\n";
    }
    return( $GetClassName->Call( $hWnd, $$String, $Size ) );
}

if( $hWnd = $GetTopWindow->Call( 0 ) )
{
#    DumpWindow( $hWnd );
    ProcessWindow( $hWnd );
}

sub ProcessWindow
{
    my( $hWnd ) =  @_;

    if( $hWnd )
    {
        do
        {
            DumpWindow( $hWnd );
            ProcessWindow( $GetWindow->Call( $hWnd, $GW_CHILD ) );
        }
        while( $hWnd = $GetWindow->Call( $hWnd, $GW_HWNDNEXT ) );
    }
    print "\n";
}

sub DumpWindow
{
    my( $hWnd ) = @_;
    my $Size = 256;
    my $Class = String( $Size );
    my $Title = String( $Size );
    my $Length;

    $Length = $GetClassName->Call( $hWnd, $Class, $Size );
    $Class = FixString( $Class );
#    $Length = GetClassName( $hWnd, \$Class, $Size );
    $Length = $GetWindowText->Call( $hWnd, $Title, $Size );
    $Title = FixString( $Title );

    printf( "Wnd: 0x%08x '%s' (%s)\n", $hWnd, $Class, $Title );
}

sub String
{
    my( $Size ) = @_;
    return( "\x00" x ( ++$Size  * ( 1 + Win32::API::IsUnicode() ) ) );
}

sub FixString
{
    my( $String ) = @_;
    $String =~ s/\x00//gs;
    return( $String );
}