Color-/Lineshifts under Windows?

[Hauke Heibel]

I comitted a fix. You can find it here:

http://github.com/hauke76/OpenSlide/commits/

There is an issue left with the alpha channel. I am not sure where it
is coming from. Using this code in test.c

    if ((val >> 24) == 0xFF)
    {
      putc((val >> 16) & 0xFF, f); // R
      putc((val >> 8) & 0xFF, f);  // G
      putc((val >> 0) & 0xFF, f);  // B
    }
    else
    {
      putc(0xFF, f);
      putc(0xFF, f);
      putc(0xFF, f);
    }

I am still seeing a regular pattern of white points. Maybe that is a
cairo bug?? I am not sure.

After some more testing I also understand now, that cairo seems to
really blend the image data when sub-pixel transformations are
applied. The only consequence is that the level 9 image looks a bit
more blurry than SlideAC's version. On the other hand side,
downscaling can be seen as blurring and then dropping every second
pixel, right? So this might be expected and acceptable.

Regards,
- Hauke