+ for ( int x = 0; x < w; x++ )
+ {
+ // RGB order is reversed, and we need to premultiply
+ // all channels by alpha value for use with ::AlphaBlend.
+ const unsigned char a = *alpha++;
+ *dst++ = (unsigned char)((src[2] * a + 127) / 255);
+ *dst++ = (unsigned char)((src[1] * a + 127) / 255);
+ *dst++ = (unsigned char)((src[0] * a + 127) / 255);
+ *dst++ = a;
+ src += 3;
+ }
+ }
+ else // no alpha channel
+ {
+ for ( int x = 0; x < w; x++ )
+ {
+ // RGB order is reversed.
+ *dst++ = src[2];
+ *dst++ = src[1];
+ *dst++ = src[0];
+ src += 3;
+ }