How to draw a transparent image using WinAPI ImageList_DrawIndirect?

Question

I need to draw a 32-bit image from a native API imagelist with the specified level of transparency, but I can't do that. I'm using the ImageList_DrawIndirect call and the ILS_ALPHA image state in the IMAGELISTDRAWPARAMS structure passed to ImageList_DrawIndirect, but it seems it doesn't work as expected. ComCtl of v6 is "attached" to my app so it's not the reason of the problem.

How to do that?

My code looks like this:

Dim idp As IMAGELISTDRAWPARAMS

idp.cbSize = Len(idp)
idp.himl = m_hIml
idp.hdcDst = hdc
idp.rgbBk = -1
idp.x = xPixels
idp.y = yPixels
idp.i = 0
idp.fState = ILS_ALPHA
idp.Frame = 128

ImageList_DrawIndirect(idp)

It's VB6, but it doesn't matter - in fact, we are working only with pure WinAPI at this point.

Answer 1

That code works perfectly for me in my app. By that I mean that I have the same code in my app, with the sole exception that I am not setting rgbBk.

My guess is that somehow the images in your image list have lost their alpha channel.

I'm surprised to see that you set rgbBk because I believe it has no effect for images with alpha.