[perl-win32-gui-users] Drawing transparently.

[Giuseppe J. C. <msj...@ho...>]

Hi all,
While getting ready for the upcoming Xmas holidays ....

I am writing an application that collects video from network cameras and displays the content via a "Graphic" control, I would also like to display additional information over the images (i.e. Date and Time etc. etc.).
To achieve my goal I am using a second overlayed "Graphic" control with transparent background on which I write the needed information via:

<snippet>
    if(defined $$refGUIObj){
        my $DC = $$refGUIObj->GetDC();
        # Write text trasparently
        $DC->BkMode($Transparent);
        $DC->SelectObject(new Win32::GUI::Font(
                            -name => $Font,
                            -size => $FontSize,
                            -bold => 0,
                          )
        );
        $DC->BackColor(0);
        $DC->TextColor($FgColor);
        $DC->TextOut($X, $Y, $Text);
        $DC->Validate();
    }
</snippet>

Unfortunately every new instance overwrites the previous "TextOut". I have attempted to handle it inside the Paint event via:

<snippet>
	my $clip_rgn = Win32::GUI::Region->CreateRectRgn( $l, $t, $r, $b );
	$dc->SelectClipRgn($clip_rgn); 
</snippet>

But only to obtain a yes redrawn window but with the "default" gray background.

Thank you in advance for any assistance you can offer,

Giuseppe

PS For multiple reasons I cannot write directly on the image, hence the need for a transparent "overlay" on which to handle all extra information.