OK, I discovered the mirrored property and am now trying the following code:
if (bmpData.Stride < 0)
{
voloret = Volo.Set(volo, Volo.PROP_IMAGE_LINE_DELTA, -bmpData.Stride);
voloret = Volo.Set(volo, Volo.PROP_IMAGE_MIRRORED, Volo.CONST_ENABLED);
}
else
voloret = Volo.Set(volo, Volo.PROP_IMAGE_LINE_DELTA, ...