Visual Studio 2010 - C++ MFC application with Ribbon UI - Transparency in bitmaps

Question

I am playing around with a small MFC-wizard-generated application, in Visual C++ 2010, and I just decided to put my own bitmap into the resources to replace the three-cubes MFC bitmap that shows up in the ribbon UI Application Button, aka the "marble".

The original appeared to use black (0,0,0) as a transparency color, but I am unable to determine what the MFC Ribbon (mfc-feature-pack stuff) stuff in Visual Studio 2010 does to determine transparency on a bitmap used as the ribbon's main icon.

The properties of the ribbon (IDR_RIBBON) show Image=IDB_MAIN, and IDB_MAIN is a 32x32 bitmap in BMP format, loaded from a disk file called main.bmp.

Some of the bitmap resources in this project have what looks like what I would expect: A magenta color which becomes transparent, but the MFC main bitmap did not use this color scheme or palette.

Here is an example of the actual results, which are I hope show that the results are not what I wanted:

Incidentally, It does not seem possible to use an ICON resource in the Application Button, so I am a little mystified how they pull off the transparency in it.

Answer 1

Translucent PNG, perhaps? Did you know that BMP files can also have alpha channels?

Answer 2

You need to create a 32-bit bitmap that has an alpha channel for transparency. The method by which I've done this is not very straightforward but it was the only thing I could come up with.

• Use Paint.Net to convert your source image into a PNG that preserves the transparency. Unfortunately Paint.Net does not support creating 32-bit bitmaps directly.
• Then download AlphaConv which can create the 32-bit bitmap from the PNG file.