AlphaBlend . アルファブレンド


AlphaBlend(
  HDC hdcDest,
  int x, y, w, h
  HDC hdcSrc,
  int xs, yx, ws, hs,
  BLENDFUNCTION  fn
);

BLENDFUNCTION fn = {0};

fn.BlendOp = AC_SRC_OVER;
fn.SourceConstantAlpha = 128;
  msimg32.lib