How to reduce PDF file size

static void reduceFileSize(ShapeCollection shapes, int dpi)
{
  for (int i = 0; i < shapes.Count; i++)
  {
    Shape shape = shapes[i];

    if (shape is ShapeCollection)
    {
      // recurse
      reduceFileSize(shape as ShapeCollection, dpi);
    }
    else if (shape is ImageShape)
    {
      shapes.RemoveAt(i);
      ImageShape downScaled = downScale(shape as ImageShape, dpi);
      shapes.Insert(i, downScaled);
    }
    else if (shape is TextShape)
    {
      TextShape textShape = shape as TextShape;
      
      var fontName = !string.IsNullOrEmpty(textShape.Font.FamilyName)
                     ? textShape.Font.FamilyName.ToLower()
                     : !string.IsNullOrEmpty(textShape.Font.Name)
                     ? textShape.Font.Name.ToLower()
                     : string.Empty;

      if (fontName == "arial")
      {
        shapes.RemoveAt(i);

        TallComponents.PDF.Fonts.Font subsetted =
          TallComponents.PDF.Fonts.Font.Create("Arial", false, false);
        subsetted.EmbedMode = TallComponents.PDF.Fonts.EmbedMode.Subset;
        textShape.Font = subsetted;
        shapes.Insert(i, textShape);
      }
    }
  }
}


``` vb
Private Sub reduceFileSize(shapes As ShapeCollection, dpi As Integer)
        For i As Integer = 0 To shapes.Count - 1
            Dim shape As Shape = shapes(i)

            If TypeOf shape Is ShapeCollection Then
                ' recurse
                reduceFileSize(TryCast(shape, ShapeCollection), dpi)
            ElseIf TypeOf shape Is ImageShape Then
                shapes.RemoveAt(i)
                Dim downScaled As ImageShape = downScale(TryCast(shape, ImageShape), dpi)
                shapes.Insert(i, downScaled)
            ElseIf TypeOf shape Is TextShape Then
                Dim textShape As TextShape = TryCast(shape, TextShape)

                Dim fontName = If(Not String.IsNullOrEmpty(textShape.Font.FamilyName), textShape.Font.FamilyName.ToLower(), If(Not String.IsNullOrEmpty(textShape.Font.Name), textShape.Font.Name.ToLower(), String.Empty))

                If fontName = "arial" Then
                    shapes.RemoveAt(i)

                    Dim subsetted As TallComponents.PDF.Fonts.Font = TallComponents.PDF.Fonts.Font.Create("Arial", False, False)
                    subsetted.EmbedMode = TallComponents.PDF.Fonts.EmbedMode.Subset
                    textShape.Font = subsetted
                    shapes.Insert(i, textShape)
                End If
            End If
        Next
    End Sub

static ImageShape downScale(ImageShape image, int dpi)
{
  Matrix matrix = image.Transform.CreateGdiMatrix();
  PointF[] points = new PointF[] {
                new PointF(0, 0), 
                new PointF((float)image.Width, 0),
                new PointF(0, (float)image.Height) 
            };
  matrix.TransformPoints(points);

  // real dimensions of the image in points as it appears on the page
  float realWidth = distance(points[0], points[1]);
  float realHeight = distance(points[0], points[2]);

  // given the desired resolution, these are the desired number of cols/rows of the optimized image
  int desiredColumns = (int)(realWidth * ((float)dpi / 72f));
  int desiredRows = (int)(realHeight * ((float)dpi / 72f));

  if (desiredColumns < 5) return image;
  if (desiredRows < 5) return image;

  // create the new image and copy the source image to it (resampling happens here)
  using (Bitmap bitmap = image.CreateBitmap())
  {
    if (desiredColumns > bitmap.Width) return image; // prevent upscale
    if (desiredRows > bitmap.Width) return image; // prevent upscale

    Bitmap optimizedBitmap = new Bitmap(desiredColumns, desiredRows, PixelFormat.Format32bppArgb);
            using (Graphics graphics = Graphics.FromImage(optimizedBitmap))
    {
      graphics.DrawImage(bitmap, 0, 0, desiredColumns, desiredRows);
    }

    ImageShape optimized = new ImageShape(optimizedBitmap, true);
    optimized.Compression = Compression.Jpeg;
    optimized.Width = image.Width;
    optimized.Height = image.Height;
    optimized.Transform = image.Transform;

    optimized.Opacity = image.Opacity;
    optimized.BlendMode = image.BlendMode;
    optimized.Transform = image.Transform;

    return optimized;
  }
}

static float distance(PointF a, PointF b)
{
  return (float)Math.Sqrt((a.X - b.X) * (a.X - b.X) + (a.Y - b.Y) * (a.Y - b.Y));
}

Private Function downScale(image As ImageShape, dpi As Integer) As ImageShape
        Dim matrix As Matrix = image.Transform.CreateGdiMatrix()
        Dim points As PointF() = New PointF() {New PointF(0, 0), New PointF(CSng(image.Width), 0), New PointF(0, CSng(image.Height))}
        matrix.TransformPoints(points)

        ' real dimensions of the image in points as it appears on the page
        Dim realWidth As Single = distance(points(0), points(1))
        Dim realHeight As Single = distance(points(0), points(2))

        ' given the desired resolution, these are the desired number of cols/rows of the optimized image
        Dim desiredColumns As Integer = CInt(realWidth * (CSng(dpi) / 72.0F))
        Dim desiredRows As Integer = CInt(realHeight * (CSng(dpi) / 72.0F))

        If desiredColumns < 5 Then
            Return image
        End If
        If desiredRows < 5 Then
            Return image
        End If

        ' create the new image and copy the source image to it (resampling happens here)
        Using bitmap As Bitmap = image.CreateBitmap()
            If desiredColumns > bitmap.Width Then
                Return image
            End If
            ' prevent upscale
            If desiredRows > bitmap.Width Then
                Return image
            End If
            ' prevent upscale
            Dim optimizedBitmap As New Bitmap(desiredColumns, desiredRows, PixelFormat.Format32bppArgb)
            Using graphics__1 As Graphics = Graphics.FromImage(optimizedBitmap)
                graphics__1.DrawImage(bitmap, 0, 0, desiredColumns, desiredRows)
            End Using

            Dim optimized As New ImageShape(optimizedBitmap, True)
            optimized.Compression = Compression.Jpeg
            optimized.Width = image.Width
            optimized.Height = image.Height
            optimized.Transform = image.Transform

            optimized.Opacity = image.Opacity
            optimized.BlendMode = image.BlendMode
            optimized.Transform = image.Transform

            Return optimized
        End Using
    End Function

    Private Function distance(a As PointF, b As PointF) As Single
        Return CSng(Math.Sqrt((a.X - b.X) * (a.X - b.X) + (a.Y - b.Y) * (a.Y - b.Y)))
    End Function