问在Windows中调整图像大小

EN

public static Image ResizePicture( Image image, Size maxSize )
{
  if( image == null )
    throw new ArgumentNullException( "image", "Null passed to ResizePictureToMaximum" );

  if( ( image.Width > maxSize.Width ) || ( image.Height > maxSize.Height ) )
  {
    Image resizedImage = new Bitmap( maxSize.Width, maxSize.Height );

    using( Graphics graphics = Graphics.FromImage( resizedImage ) )
    {
      graphics.Clear( Color.White );

      float widthRatio = maxSize.Width / image.Width;
      float heightRatio = maxSize.Height / image.Height;

      int width = maxSize.Width;
      int height = maxSize.Height;

      if( widthRatio > heightRatio )
      {
        width = ( int )Math.Ceiling( maxSize.Width * heightRatio );
      }
      else if( heightRatio > widthRatio )
      {
        height = ( int )Math.Ceiling( maxSize.Height * widthRatio );
      }

      graphics.DrawImage(
        image,
        new Rectangle( 0, 0, width, height ),
        new Rectangle( 0, 0, image.Width, image.Height ),
        GraphicsUnit.Pixel );
    }

    return resizedImage;
  }

  return image;
}

float widthRatio = (float) maxSize.Width / image.Width;

  float heightRatio = (float) maxSize.Height / image.Height;

graphics.DrawImage(image, new Rectangle((maxSize.Width - width) / 2, (maxSize.Height -height ) / 2, width, height), new Rectangle(0, 0, image.Width, image.Height), GraphicsUnit.Pixel);