Re: [perl-win32-gui-users] [win32-gui] SetLayeredWindowAttributes ?

[Steve L. <ste...@sc...>]

OK, that will teach me to post code before I run into head-scratching 
problems :)

You can set the color-key area to be totally transparent, or you can set 
the window to be a variable level of translucent, or both... but it 
appears you cannot set a color-key area to be partially transparent, its 
all or nothing.... unless someone can show me how

Steve


Steve Loughran wrote:
> here we go, a very rough idea of how I managed to get it to work. (Am 
> doing a reinstall at the moment on the other machine, so things are a 
> bit of a mess here right now)
> 
> You will need to cut-n-paste the relevant pieces into your code, but I 
> hope its clear enough. I haven't managed to get translucency and 
> transparency to work on the same window at the same time, but I haven't 
> actually tried all that hard :)
> 
> Original Visual Basic info found here:
> 
> http://www.codeguru.com/vb/gen/vb_graphics/transparency/article.php/c6979__1
> 
> and
> 
> http://www.codeguru.com/vb/gen/vb_graphics/transparency/article.php/c6981/
> 
> #==============================
> 
> #for the "SetLayeredWindowAttributes" call import
> use Win32::API;
> 
> use constant WS_EX_LAYERED    => 0x00080000;
> use constant LWA_COLORKEY     => 0x00000001;
> use constant LWA_ALPHA	      => 0x00000002;
> use constant GWL_EXSTYLE      => -20;
> 
> my $SetLayeredWindowAttributes = 
> Win32::API->new("user32","SetLayeredWindowAttributes", "LLIN", "I")
> 	or die "Failed to load SetLayeredWindowAttributes: $!";
> 
> #============
> # For Translucency
> #
> # This affects the entire window and contents
> #
> # where $value is between 255 (solid) and 0 (invisible)
> #============
> 
> my $winstyle = $window->GetWindowLong(GWL_EXSTYLE);
> 
> $winstyle = $winstyle | WS_EX_LAYERED;
> 
> $window->SetWindowLong(GWL_EXSTYLE, $winstyle || WS_EX_LAYERED);
> 
> $SetLayeredWindowAttributes->Call($window->{-handle}, 0, $value,
> 					LWA_ALPHA);
> 
> #============
> # For Transparency
> #
> # This makes color-keyed areas transparent, so any area of the window
> # or any item within it that has the exact RGB color match will be
> # affected by any applied transparency. The rest of the window and items
> # within it will be unaffected by this.
> #
> # where $value is a 0x00bbggrr color value
> # where $alpha is from 255 (solid) to 0 (completely transparent)
> #
> # NOTE: where the $alpha is 0, you can click-through the window into
> # windows behind it through those transparent areas!! Seriously!
> #============
> 
> my $winstyle = $window->GetWindowLong(GWL_EXSTYLE);
> $winstyle = $winstyle | WS_EX_LAYERED;
> 
> $window->SetWindowLong(GWL_EXSTYLE, $winstyle || WS_EX_LAYERED);
> 
> $SetLayeredWindowAttributes->Call($window->{-handle}, $value, $alpha,
> 				LWA_COLORKEY);
> 
> #==============================
> 
> 
> I hope that is helpful to someone.
> 
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