Code lab preview is corrupted

[MadJik]

I'm working on some code lab effect and I have some strange result with the preview.

This is the image I'm working with for the tests.

This is the code I'm using:

void Render(Surface dst, Surface src, Rectangle rect)
{
 double step = 50 / 100.0f;
 double stepx = 0 / 100.0f;
 PdnRegion selectionRegion = EnvironmentParameters.GetSelection(src.Bounds);

 for (int y = rect.Top; y < rect.Bottom; y++)
 {
   for (int x = rect.Left; x < rect.Right; x++)
   {
     double yreflect = (double)(y + x * step);
     if (yreflect < 0) yreflect += dst.Height;
     if (yreflect >= dst.Height) yreflect -= dst.Height;

     double xreflect = (double)(x + y * stepx);
     if (xreflect < 0) xreflect += dst.Width;
     if (xreflect >= dst.Width) xreflect -= dst.Width;

     if (selectionRegion.IsVisible((int)xreflect, (int)yreflect))
     {
       dst[(int)xreflect, (int)yreflect] = src[x, y];
     }
   }
 }
}

Playing with the values for step and stepx I want to obtain an oblic view of the image.

I obtain this strange preview (printscreen)

And when I press Ok the final image is good!

Am I doing something wrong in the code or is this a bug?

[Illnab1024]

dst[(int)xreflect, (int)yreflect] = src[x, y]; 

Due to the PdN Render method, you need to use the same destination pixel that's in the for loop for it to work properly...

e.g. dst[x, y] = src[...]

[Rick Brewster]

Illnab is right. You can't just render whatever destination pixels you feel like. You must render only and all the pixels that the rectangle passed to you describes.

[MadJik]

Ok, nice to know... I have to change my point of view and my code too!

Thanks for answers.