Mailing List Archive: Cool API Function

[REBOL] Cool API Function

From: tbrownell::l3technology::com at: 31-Jan-2003 4:34


Hello all, long time no post.

I've been toying with a alpha transparency for an actual view window in
Win2000, XP.
This would allow funky shaped GUIs with the alpha color being an hole to the
window beneath.

It utilizes the SetLayeredWindowAttributes call in the user32.dll

But I can't get it to work.

Here's a link regarding the API call
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/WinUI
/WindowsUserInterface/Windowing/Windows/WindowReference/WindowFunctions/SetL
ayeredWindowAttributes.asp

Theoretically, the following code should launch a copy of Notepad, and make
it 50% transparent?

rebol []
call "notepad"
wait 1 ;Give Notepad a chance to load

win-user: load/library %user32.dll

   find-window-by-class: make routine! [
        ClassName   [string!]
        WindowName  [integer!]
        return:     [integer!]
    ] win-user "FindWindowA"

wahwnd: find-window-by-class "Notepad" 0

a: %/c/windows/system32/user32.dll
b: load/library a
c: "SetLayeredWindowAttributes"
r: make routine! [
    hwnd [integer!]
    crKey [integer!]
    bAlpha [integer!]
    dwFlags [integer!]
] b c
  note-hwnd: find-window-by-class "Notepad" 0

view layout [btn "test" [r note-hwnd 0 128 0]
btn "quit" [quit]
]

halt
;----End---

But alas, it doesn't work.

Anyone have any ideas?

Terry Brownell