Fading An Icon Image

[VB6Coder]

I'm using the SHGetFileInfo API get a handle to the 16 x 16 file icon, which all works fine.

How can I fade the icon image, like the Windows Explorer fades hidden files in Windows 2000.

I'm not using the ListView control so I can't use the Ghosted property, and I've already asked the API people and got no joy.

There must be a way of fading an icon image.


Help


Thanks in advance

[plenderj]

Well you could blend it 50/50 with a blank icon, or do a loop over the pixels of the icon to change the pixel colour to halfway between what it is and white...

[VB6Coder]

Have you got any examples please?

[plenderj]

This code doesnt work yet, but I'd do something long these lines :

Option Explicit
 
Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long
Private Declare Function SetPixel Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal crColor As Long) As Long
 
Private Sub Form_Load()
    Picture1.Picture = LoadPicture("c:\a.bmp")
    Me.Show
    HalfFadeToWhite Picture1
End Sub
 
Private Sub HalfFadeToWhite(destPic As PictureBox)
    Dim i As Long, j As Long, col As Long
    Dim colwhite As Long, colRed As Long, colGreen As Long, colBlue As Long
    colwhite = RGB(255, 255, 255)
    destPic.Visible = False
    For i = 0 To destPic.ScaleWidth
        For j = 0 To destPic.ScaleHeight
            col = GetPixel(destPic.hdc, i, j)
            colRed = ((col Mod 256) + 255) / 2
            colGreen = ((((col And &HFF00) / 256&) Mod 256&) + 255) / 2
            colBlue = (((col And &HFF0000) / 65536) + 255) / 2
            SetPixel destPic.hdc, i, j, RGB(colRed, colGreen, colBlue)
        Next
    Next
    destPic.Visible = True
    destPic.Refresh
End Sub

[VB6Coder]

I like the idea.

I'm doing all this in a VB Active X DLL, and I don't want to add any forms to the project.

What is the easiest way to get a DC handle?

Create one using the CreateDC or CreateCompatibleDC API's, or use an existing one using the GetDC API.

If I was going to use an existing DC, which one would I use?
Can I use the Desktop DC?

[plenderj]

Quote from MSDN :

<start quote>
CreateCompatibleDC
The CreateCompatibleDC function creates a memory device context (DC) compatible with the specified device.

HDC CreateCompatibleDC(
HDC hdc // handle to the device context
);

Parameters
hdc
Handle to an existing device context. If this handle is NULL, the function creates a memory device context compatible with the application's current screen.
<end quote>


So it would appear that if you pass a null as the parameter to the createcompatibledc function it'll create a new dc for you anyway.
So try that.

[VB6Coder]

I've just tried:

lngDC = CreateCompatibleDC(0)

and it works . It returns the new compatible DC handle.


Nice one