Show Win32 popup menu with PNG icons from resources - c++

Question

It's been a long time since I've had to deal with Win32 menus. I need to add some PNG icons to a Win32 context popup menu. Naturally, I want to preserve PNG transparency and all the per-pixel-alpha in the process. Is this possible?
I was thinking on using SetMenuItemBitmaps. Is that the way to go?
I imported my PNGs as "PNG" resources but I can't seem to load them neither with LoadBitmap nor with LoadImage. I found some suggestions about using Gdi+ but obviously I won't be drawing the menu - the system will.
There seems to be a way to get a HBITMAP from a Gdi+ Bitmap but it looks as if all the alpha is getting lost in the process. AFAIK, a HBITMAP can happily host alpha information.

Answer 1

You need GDI+ to load a PNG. Then you need to create a 32-bit alpha bitmap of the correct size, create a Graphics on the bitmap, and use DrawImage to copy the PNG to the bitmap. That gives you a bitmap with an alpha channel.
Something like this:
Image* pimgSrc = Image::FromFile("MyIcon.png"L, FALSE);
Bitmap* pbmpImage = new Bitmap(
iWidth, iHeight,
PixelFormat32bppARGB
);
Graphics* pgraphics = Graphics::FromImage(bmpImage))
{
// This draws the PNG onto the bitmap, scaling it if necessary.
// You may want to set the scaling quality
graphics->DrawImage(
imageSrc,
Rectangle(0,0, bmpImage.Width, bmpImage.Height),
Rectangle(0,0, imgSrc.Width, imgSrc.Height),
GraphicsUnitPixel
);
}
// You can now get the HBITMAP from the Bitmap object and use it.
// Don't forget to delete the graphics, image and bitmap when done.

Answer 2

Perhaps you could use icon instead?
Here are my reasons for using icons instead of PNGs:
The Win32 API has good support icons, and it relatively much easier to draw icons, since GDI+ is not required.
Icons also support 8-bit transparency (just like PNGs).
Icons can be any size in pixels (just like PNGs).
Icons can easily be embedded in the executable as a resource.
Icons can be edited via Visual Studio.
To load an icon from a resource or a file use:
LoadImage()
To draw the icon, use:
DrawIcon() or DrawIconEx()