TransParent Form Q.

[psycopatchet69]

Ive searched on the forums, and havent found what i needed. Ive been working on an mp3 player, and am basically done with it, but forgot about the whole transparent form part of it. I have everything but the controls as one picture, the forms picture, is there a way to just take one color of it and make it transparent? Or will i have to go back to bitblt, or setwindowlong or something?

[dglienna]

If you are using XP/2000, you can use Alpha Blending to make transparencies.
Here is a demo project that uses it.

http://www.vbforums.com/attachment.p...chmentid=36096

[|2eM!x]

Option Explicit
Const WM_NCLBUTTONDOWN = &HA1
Const HTCAPTION = 2
Const LWA_ALPHA = &H2
Const GWL_EXSTYLE = (-20)
Const WS_EX_LAYERED = &H80000
 
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function SetLayeredWindowAttributes Lib "user32" (ByVal hWnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
 
Private Sub Form_Load()
 Dim Ret As Long
    'Set the window style to 'Layered'
    Ret = GetWindowLong(Me.hWnd, GWL_EXSTYLE)
    Ret = Ret Or WS_EX_LAYERED
    SetWindowLong Me.hWnd, GWL_EXSTYLE, Ret
    'Set the opacity of the layered window to 128
SetLayeredWindowAttributes Me.hWnd, 0, 100, LWA_ALPHA
End Sub

makes a form transparent..hope thats what you needed

[psycopatchet69]

oops, sorry, i used the wrong terms, I want to mask a color on the forms picture to be transparent. Thanks for the alpha blending tips though, that will also come in handy.

[|2eM!x]

the only way i can think of is using getpixel and finding if the color is you color then changing it...but that is really slow

[psycopatchet69]

Should i use bitblt then?

[dglienna]

Here is a mask program.

[penagate]

Also if you would like to apply that sort of thing to a form you can pass an RGB colour key value to the SetLayeredWindowAttributes API call and then only pixels of that colour on your form will be drawn alpha-blended.

e.g.

' LWA_COLORKEY = &H1
SetLayeredWindowAttributes Me.hWnd, RGB(0, 0, 0), 100, LWA_ALPHA Or LWA_COLORKEY

... makes all black pixels alpha-blended.