[Vb6] AlphaBlend API function(strange result)

[LaVolpe]

You can speed it up by removing these lines from inside the loop to outside the loop, before the loop starts:
dblAlpha = Opacy / 100
And: cache value of (1 - dblAlpha) and use it in the R, G, B calculations. Maybe: dblAlphaSrc = Opacy/100: dblAlphaDst = 1-dblAlphaSrc

By making that small change you are doing 4 less math calculations per pixel