Draw a semi transparent rectangle over image box

[Mahmood Khaleel Pira]

Hi dear friends I want to make a semi-transparent rectangle over image box. I googled I found it but it was for VB.Net (http://www.vbforums.com/showthread.p...over-image-box ) how can I do it in VB 6.0 click the above link to see the code (vb.net)

[dilettante]

Well it isn't clear exactly what you want to accomplish. The .Net thread seems chaotic to me so I'm not sure what they were trying to do or whether or not it might be what you want to do.

But there aren't any operations built into VB6 to do this so you have to use GDI calls, GDI+ calls, or a wrapper library for one of those APIs, or some 3rd party thing that does it some other way.

I have a class that wraps a lot of GDI operations and extending it to call AlphaBlend was pretty easy. It compiles down quite small, but you can also chop out the things it has that you don't need in your program.

Taking a stab at the problem I came up with:

Option Explicit

Private Sub mnuDoit_Click()
    Dim AlphaPicture As StdPicture
    Dim TextRECT As RECT

    With New Drawing
        .Clear .ARound(Image1.Picture.Width * .PxPerHmX), _
               .ARound(Image1.Picture.Height * .PxPerHmY), _
               vbBlue 'We'll "gray it" with vbBlue.
        .ForeColor = vbWhite
        With .Font
            .Name = "Comic Sans MS"
            .Size = 28
        End With
        TextRECT.Right = .Width
        TextRECT.Bottom = .Height
        .DrawText "Grayed out!", TextRECT, vbCenter, TRANSPARENT, True, valignMiddle
        Set AlphaPicture = .Picture
        Set .Picture = Image1.Picture
        .PaintPicture AlphaPicture, Alpha:=64 'Mostly transparent.
        Set Image1.Picture = .Picture
    End With
End Sub

Plopping text on it was just an embellishment.

You can also just pull out the API calls and plop them inline within your Form too of course.

[Elroy]

Mahmood,

Maybe this thread will also be of use to you. It contains concepts that I use on certain Modal forms that overlay non-Modal forms.

Enjoy,
Elroy

[dilettante]

Well you could combine that with a new feature introduced in Windows 8 and accomplish it pretty easily.

Here I have a Visible = False blue PictureBox that I set to a layered window with Alpha at 64 positioned on top of the Image control.

The "Do it" operation merely assigns Visible = True:

Option Explicit

Private Declare Function GetWindowLong Lib "user32" _
    Alias "GetWindowLongA" ( _
    ByVal hWnd As Long, _
    ByVal nIndex 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 Declare Function SetWindowLong Lib "user32" _
    Alias "SetWindowLongA" ( _
    ByVal hWnd As Long, _
    ByVal nIndex As Long, _
    ByVal dwNewLong As Long) As Long

Private Const GWL_EXSTYLE = -20
Private Const WS_EX_LAYERED = &H80000
Private Const LWA_COLORKEY = &H1&
Private Const LWA_ALPHA = &H2&

Private Sub Form_Load()
    With Picture1
        .Move Image1.Left, Image1.Top, Image1.Width, Image1.Height
        SetWindowLong .hWnd, _
                      GWL_EXSTYLE, _
                      GetWindowLong(.hWnd, GWL_EXSTYLE) Or WS_EX_LAYERED
        SetLayeredWindowAttributes .hWnd, 0, 64, LWA_ALPHA
    End With
End Sub

Private Sub mnuDoit_Click()
    Picture1.Visible = True
End Sub

Running in the IDE with no "Win8 aware" manifest




Running as a compiled EXE with a "Win8 aware" manifest

Sadly most people aren't paying attention to the wealth of new things we got beginning in Vista, let alone Windows 8 and beyond. More reason to kick the habit of laying back on that dogeared, long in the tooth, creaky, old Windows XP.