How do I draw an alpha bmp file on a big bitmap

Hi,

I want to draw a symbol in a control and the control has a bitmap background.

The symbol picture that I want to draw is alpha transparent mode.

But I have no choice to deal with.

I attempted to use BitBltMasked but failed.

The BitBltMasked function is good at the mask has the same size as the bitmap.

Do you know how to do this.

Thank you!

What have you attempted, what have you expected, and what happened?
It is not clear from the description what the problem is with the size.