gistfile1.cs

private Size shrinkSize(Size origSize)
{
  const int maxWidth = 900;
  const int maxHeight = 700;
  const double flipRatio = (double)maxWidth / maxHeight;

  if (origSize.Width < maxWidth &&
    origSize.Height < maxHeight)
    return origSize;

  // determine wether its better to shrink by height or by width
  var ratio = (double)origSize.Width / origSize.Height;

  if (ratio < flipRatio)
    return new Size(
      (int)(origSize.Width * ((double)maxHeight / origSize.Height)),
      maxHeight);
  else
    return new Size(
      maxWidth,
      (int)(origSize.Height * ((double)maxWidth / origSize.Width)));
}