PM> Install-Package Spire.PDF

using Spire.Pdf;
using Spire.Pdf.Graphics;
using Spire.Pdf.Graphics.Layer;
using System.Drawing;

namespace AddLayersToPdf
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument instance and load a sample PDF file
            PdfDocument pdf = new PdfDocument();
            pdf.LoadFromFile(@"C:\Users\Administrator\Desktop\Sample.pdf");

            //Invoke AddLayerWatermark method to add a watermark layer
            AddLayerWatermark(pdf);

            //Invoke AddLayerHeader method to add a header layer
            AddLayerHeader(pdf);

            //Save to file
            pdf.SaveToFile("AddLayers.pdf");
            pdf.Close();
        }

        private static void AddLayerWatermark(PdfDocument doc)
        {
            //Create a layer named "Watermark"
            PdfLayer layer = doc.Layers.AddLayer("Watermark");

            //Create a font
            PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial", 48), true);

            //Specify the watermark text
            string watermarkText = "CONFIDENTIAL";

            //Get text size
            SizeF fontSize = font.MeasureString(watermarkText);

            //Calculate two offsets
            float offset1 = (float)(fontSize.Width * System.Math.Sqrt(2) / 4);
            float offset2 = (float)(fontSize.Height * System.Math.Sqrt(2) / 4);

            //Get page count
            int pageCount = doc.Pages.Count;

            //Declare two variables
            PdfPageBase page;
            PdfCanvas canvas;

            //Loop through the pages
            for (int i = 0; (i < pageCount); i++)
            {
                page = doc.Pages[i];

                //Create a canvas from layer
                canvas = layer.CreateGraphics(page.Canvas);
                canvas.TranslateTransform(page.Canvas.Size.Width / 2 - offset1 - offset2, page.Canvas.Size.Height / 2 + offset1 - offset2);
                canvas.SetTransparency(0.4f);
                canvas.RotateTransform(-45);

                //Draw sting on the canvas of layer
                canvas.DrawString(watermarkText, font, PdfBrushes.DarkBlue, 0, 0);
            }
        }
        private static void AddLayerHeader(PdfDocument doc)
        {
            // Create a layer named "Header"
            PdfLayer layer = doc.Layers.AddLayer("Header");

            //Get page size
            SizeF size = doc.Pages[0].Size;

            //Specify the initial values of X and y
            float x = 90;
            float y = 40;

            //Get page count
            int pageCount = doc.Pages.Count;

            //Declare two variables
            PdfPageBase page;
            PdfCanvas canvas;

            //Loop through the pages
            for (int i = 0; (i < pageCount); i++)
            {
                //Draw an image on the layer
                PdfImage pdfImage = PdfImage.FromFile(@"C:\Users\Administrator\Desktop\img.jpg");
                float width = pdfImage.Width;
                float height = pdfImage.Height;
                page = doc.Pages[i];
                canvas = layer.CreateGraphics(page.Canvas);
                canvas.DrawImage(pdfImage, x, y, width, height);

                //Draw a line on the layer
                PdfPen pen = new PdfPen(PdfBrushes.DarkGray, 2);
                canvas.DrawLine(pen, x, (y + (height + 5)), (size.Width - x), (y + (height + 2)));
            }
        }
    }
} 

Imports Spire.Pdf
Imports Spire.Pdf.Graphics
Imports Spire.Pdf.Graphics.Layer
Imports System.Drawing

Namespace AddLayersToPdf
    Class Program
        Private Shared Sub Main(ByVal args() As String)

            'Create a PdfDocument instance and load a sample PDF file
            Dim pdf As PdfDocument = New PdfDocument
            pdf.LoadFromFile("C:\Users\Administrator\Desktop\Sample.pdf")

            'Invoke AddLayerWatermark method to add a watermark layer
            Program.AddLayerWatermark(pdf)

            'Invoke AddLayerHeader method to add a header layer
            Program.AddLayerHeader(pdf)

            'Save to file
            pdf.SaveToFile("AddLayers.pdf")
            pdf.Close()
        End Sub

        Private Shared Sub AddLayerWatermark(ByVal doc As PdfDocument)

            'Create a layer named "Watermark"
            Dim layer As PdfLayer = doc.Layers.AddLayer("Watermark")

            'Create a font
            Dim font As PdfTrueTypeFont = New PdfTrueTypeFont(New Font("Arial", 48), True)

            'Specify the watermark text
            Dim watermarkText As String = "CONFIDENTIAL"

            'Get text size
            Dim fontSize As SizeF = font.MeasureString(watermarkText)

            'Calculate two offsets
            Dim offset1 As Single = CSng((fontSize.Width * System.Math.Sqrt(2) / 4))
            Dim offset2 As Single = CSng((fontSize.Height * System.Math.Sqrt(2) / 4))

            'Get page count
            Dim pageCount As Integer = doc.Pages.Count

            'Declare two variables
            Dim page As PdfPageBase
            Dim canvas As PdfCanvas

            'Loop through the pages
            Dim i As Integer = 0
            While (i < pageCount)
                page = doc.Pages(i)

                'Create a canvas from layer
                canvas = layer.CreateGraphics(page.Canvas)
                canvas.TranslateTransform(page.Canvas.Size.Width / 2 - offset1 - offset2, page.Canvas.Size.Height / 2 + offset1 - offset2)
                canvas.SetTransparency(0.4F)
                canvas.RotateTransform(-45)

                'Draw sting on the canvas of layer
                canvas.DrawString(watermarkText, font, PdfBrushes.DarkBlue, 0, 0)
                i = (i + 1)
                i += 1
            End While
        End Sub

        Private Shared Sub AddLayerHeader(ByVal doc As PdfDocument)

            ' Create a layer named "Header"
            Dim layer As PdfLayer = doc.Layers.AddLayer("Header")

            'Get page size
            Dim size As SizeF = doc.Pages(0).Size

            'Specify the initial values of X and y
            Dim x As Single = 90
            Dim y As Single = 40

            'Get page count
            Dim pageCount As Integer = doc.Pages.Count

            'Declare two variables
            Dim page As PdfPageBase
            Dim canvas As PdfCanvas

            'Loop through the pages
            Dim i As Integer = 0
            While (i < pageCount)

                'Draw an image on the layer
                Dim pdfImage As PdfImage = PdfImage.FromFile("C:\Users\Administrator\Desktop\img.jpg")
                Dim width As Single = pdfImage.Width
                Dim height As Single = pdfImage.Height
                page = doc.Pages(i)
                canvas = layer.CreateGraphics(page.Canvas)
                canvas.DrawImage(pdfImage, x, y, width, height)

                'Draw a line on the layer
                Dim pen As PdfPen = New PdfPen(PdfBrushes.DarkGray, 2)
                canvas.DrawLine(pen, x, (y + (height + 5)), (size.Width - x), (y + (height + 2)))
                i += 1
            End While
        End Sub
    End Class
End Namespace

using Spire.Pdf;
using Spire.Pdf.Graphics.Layer;

namespace HideLayer
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument instance
            PdfDocument pdf = new PdfDocument();

            //Load a sample PDF document
            pdf.LoadFromFile("AddLayers.pdf");

            //Hide a specified layer by index
            pdf.Layers[0].Visibility = PdfVisibility.Off;

            //Hide a specified layer by name
            //pdf.Layers["Watermark"].Visibility = PdfVisibility.Off;

            //Save the result document
            pdf.SaveToFile("HideLayer.pdf");
        }
    }
}

Imports Spire.Pdf
Imports Spire.Pdf.Graphics.Layer

Namespace HideLayer
    Class Program
        Private Shared Sub Main(ByVal args() As String)

            'Create a PdfDocument instance
            Dim pdf As PdfDocument = New PdfDocument

            'Load a sample PDF document
            pdf.LoadFromFile("AddLayers.pdf")

            'Hide a specified layer by index
            pdf.Layers(0).Visibility = PdfVisibility.Off

            'Hide a specified layer by name
            'pdf.Layers["Watermark"].Visibility = PdfVisibility.Off;

            'Save the result document
            pdf.SaveToFile("HideLayer.pdf")
        End Sub
    End Class
End Namespace

using Spire.Pdf;

namespace DeleteLayer
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument instance
            PdfDocument pdf = new PdfDocument();

            //Load a sample PDF document
            pdf.LoadFromFile("AddLayers.pdf");

            //Remove a layer by name
            pdf.Layers.RemoveLayer(("Watermark"));

            //Save the result document
            pdf.SaveToFile("DeleteLayer.pdf", FileFormat.PDF);
        }
    }
}

Imports Spire.Pdf

Namespace DeleteLayer
    Class Program
        Private Shared Sub Main(ByVal args() As String)
            'Create a PdfDocument instance
            Dim pdf As PdfDocument = New PdfDocument

            'Load a sample PDF document
            pdf.LoadFromFile("AddLayers.pdf")

            'Remove a layer by name
            pdf.Layers.RemoveLayer("Watermark")

            'Save the result document
            pdf.SaveToFile("DeleteLayer.pdf", FileFormat.PDF)
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.Presentation

using Spire.Presentation;

namespace ConvertPowerPointToHtml
{
    class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Presentation class
            Presentation ppt = new Presentation();
            //Load a PowerPoint presentation
            ppt.LoadFromFile(@"E:\Program Files\Sample.pptx");

            //Specify the file path of the output HTML file 
            String result = @"E:\Program Files\PowerPointToHtml.html";

            //Save the PowerPoint presentation to HTML format
            ppt.SaveToFile(result, FileFormat.Html);
        }
    }
}

Imports Spire.Presentation

Namespace ConvertPowerPointToHtml
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Presentation class
            Dim ppt As Presentation = New Presentation()
            'Load the PowerPoint presentation
            ppt.LoadFromFile("E:\Program Files\Sample.pptx")

            'Specify the file path of the output HTML file 
            Dim result = "E:\Program Files\PowerPointToHtml.html"

            'Save the PowerPoint presentation to HTML format
            ppt.SaveToFile(result, FileFormat.Html)
        End Sub
    End Class
End Namespace

using Spire.Presentation;
using System;

namespace ConvertPowerPointSlideToHtml
{
    class Program
    {
        static void Main(string[] args)
        {
            //Initialize an instance of the Presentation class
            Presentation presentation = new Presentation();
            //Load the PowerPoint presentation
            presentation.LoadFromFile(@"E:\Program Files\Sample.pptx");

            //Get the first slide
            ISlide slide = presentation.Slides[0];

            //Specify the file path of the output HTML file 
            String result = @"E:\Program Files\SlideToHtml.html";

            //Save the first slide to HTML format
            slide.SaveToFile(result, FileFormat.Html);
        }
    }
}

Imports Spire.Presentation

Namespace ConvertPowerPointSlideToHtml
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Initialize an instance of the Presentation class
            Dim presentation As Presentation = New Presentation()
            'Load the PowerPoint presentation
            presentation.LoadFromFile("E:\Program Files\Sample.pptx")

            'Get the first slide
            Dim slide As ISlide = presentation.Slides(0)

            'Specify the file path of the output HTML file 
            Dim result = "E:\Program Files\SlideToHtml.html"

            'Save the first slide to HTML format
            slide.SaveToFile(result, FileFormat.Html)
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.XLS

using Spire.Xls;

namespace ConvertCsvToPdf
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Workbook instance
            Workbook wb = new Workbook();
            //Load a CSV file
            wb.LoadFromFile("Sample.csv", ",");

            //Set SheetFitToPage property as true to ensure the worksheet is converted to 1 PDF page
            wb.ConverterSetting.SheetFitToPage = true;

            //Get the first worksheet
            Worksheet sheet = wb.Worksheets[0];

            //Loop through the columns in the worksheet
            for (int i = 1; i < sheet.Columns.Length; i++)
            {
                //AutoFit columns
                sheet.AutoFitColumn(i);
            }

            //Save the worksheet to PDF
            sheet.SaveToPdf("toPDF.pdf");
        }
    }
}

Imports Spire.Xls

Namespace ConvertCsvToPdf
    Friend Class Program
        Private Shared Sub Main(ByVal args As String())
            'Create a Workbook instance
            Dim wb As Workbook = New Workbook()
            'Load a CSV file
            wb.LoadFromFile("Sample.csv", ",")

            'Set SheetFitToPage property as true to ensure the worksheet is converted to 1 PDF page
            wb.ConverterSetting.SheetFitToPage = True

            'Get the first worksheet
            Dim sheet As Worksheet = wb.Worksheets(0)

            'Loop through the columns in the worksheet
            For i As Integer = 1 To sheet.Columns.Length - 1
                'AutoFit columns
                sheet.AutoFitColumn(i)
            Next

            'Save the worksheet to PDF
            sheet.SaveToPdf("toPDF.pdf")
        End Sub
    End Class
End Namespace

PM> Install-Package Spire.XLS

using Spire.Xls;
using Spire.Xls.Core;

namespace AddShapesInExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create a Workbook object
            Workbook workbook = new Workbook();

            // Get the first worksheet
            Worksheet sheet = workbook.Worksheets[0];

            // Add a rectangle
            IPrstGeomShape rectangle = sheet.PrstGeomShapes.AddPrstGeomShape(3, 2, 270, 40, PrstGeomShapeType.Rect);

            // Set text for the shape
            rectangle.Text = "Add various types of shapes to Excel";
            rectangle.TextVerticalAlignment = ExcelVerticalAlignment.MiddleCentered;

            // Add a triangle, a pie, a curved right arrow, a heart, a smile face, and an octagon to the worksheet
            sheet.PrstGeomShapes.AddPrstGeomShape(8, 2, 100, 100, PrstGeomShapeType.Triangle);
            sheet.PrstGeomShapes.AddPrstGeomShape(8, 6, 100, 100, PrstGeomShapeType.Pie);
            sheet.PrstGeomShapes.AddPrstGeomShape(8, 10, 100, 100, PrstGeomShapeType.CurvedRightArrow);

            sheet.PrstGeomShapes.AddPrstGeomShape(18, 2, 100, 100, PrstGeomShapeType.Heart);
            sheet.PrstGeomShapes.AddPrstGeomShape(18, 6, 100, 100, PrstGeomShapeType.SmileyFace);
            sheet.PrstGeomShapes.AddPrstGeomShape(18, 10, 100, 100, PrstGeomShapeType.Octagon);

            // Save the workbook to an Excel file
            workbook.SaveToFile("AddShapes.xlsx", ExcelVersion.Version2016);

            // Dispose resources
            workbook.Dispose();
        }
    }
}

using Spire.Xls;
using Spire.Xls.Core;
using System.Drawing;

namespace FormatShapesInExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create a Workbook object
            Workbook workbook = new Workbook();

            // Get the first worksheet
            Worksheet sheet = workbook.Worksheets[0];

            // Add the first rectangle to the worksheet
            IPrstGeomShape rectangle_one = sheet.PrstGeomShapes.AddPrstGeomShape(4, 2, 220, 120, PrstGeomShapeType.Rect);

            // Set the line style, width, and color
            rectangle_one.Line.DashStyle = ShapeDashLineStyleType.Dashed;
            rectangle_one.Line.Weight = 1.0;
            rectangle_one.Line.ForeColor = Color.Red;

            // Set the fill type and fore color
            rectangle_one.Fill.FillType = ShapeFillType.SolidColor;
            rectangle_one.Fill.ForeColor = Color.LightGray;

            // Add the second rectangle and format the shape
            IPrstGeomShape rectangle_two = sheet.PrstGeomShapes.AddPrstGeomShape(4, 6, 220, 120, PrstGeomShapeType.Rect);
            rectangle_two.Line.Visible = false;
            rectangle_two.Fill.FillType = ShapeFillType.Gradient;
            rectangle_two.Fill.ForeColor = Color.LightGray;
            rectangle_two.Fill.GradientStyle = GradientStyleType.Vertical;

            // Add the third rectangle and format the shape
            IPrstGeomShape rectangle_three = sheet.PrstGeomShapes.AddPrstGeomShape(4, 10, 220, 120, PrstGeomShapeType.Rect);
            rectangle_three.Line.Weight = 1.0;
            rectangle_three.Fill.FillType = ShapeFillType.Pattern;
            rectangle_three.Fill.Pattern = GradientPatternType.Pat80Percent;
            rectangle_three.Fill.ForeColor = Color.White;
            rectangle_three.Fill.BackColor = Color.Pink;

            // Add the fourth rectangle and format the shape
            IPrstGeomShape rectangle_four = sheet.PrstGeomShapes.AddPrstGeomShape(15, 2, 220, 120, PrstGeomShapeType.Rect);
            rectangle_four.Line.Weight = 1.0;
            rectangle_four.Fill.CustomPicture("C:\\Users\\Administrator\\Desktop\\cartoon.jpeg");

            // Add the fifth rectangle and format the shape
            IPrstGeomShape rectangle_five = sheet.PrstGeomShapes.AddPrstGeomShape(15, 6, 220, 120, PrstGeomShapeType.Rect);
            rectangle_five.Line.Weight = 1.0;
            rectangle_five.Fill.FillType  = ShapeFillType.NoFill;

            // Add the sixth rectangle and format the shape
            IPrstGeomShape rectangle_six = sheet.PrstGeomShapes.AddPrstGeomShape(15, 10, 220, 120, PrstGeomShapeType.Rect);
            rectangle_six.Line.Weight = 1.0;
            rectangle_six.Fill.FillType = ShapeFillType.Texture;
            rectangle_six.Fill.Texture = GradientTextureType.Canvas;

            // Save the workbook to an Excel file
            workbook.SaveToFile("FormatShapes.xlsx", ExcelVersion.Version2016);

            // Dispose resources
            workbook.Dispose();
        }
    }
}

using Spire.Xls;
using Spire.Xls.Core.Spreadsheet.Collections;

namespace RemoveShapesFromExcel
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create a Workbook object
            Workbook workbook = new Workbook();

            // Load an Excel file
            workbook.LoadFromFile("C:\\Users\\Administrator\\Desktop\\Shapes.xlsx");

            // Get a specific worksheet
            Worksheet sheet = workbook.Worksheets[0];

            // Get the shape collection from the worksheet
            PrstGeomShapeCollection shapes = sheet.PrstGeomShapes;

            // Remove a specific shape
            shapes[1].Remove();

            /*
            // Remove all shapes
            for (int i = shapes.Count - 1; i >= 0; i--)
            {
                shapes[i].Remove();
            }
            */
            
            // Save the workbook to an Excel file
            workbook.SaveToFile("RemoveShape.xlsx", ExcelVersion.Version2013);

            // Dispose resources
            workbook.Dispose();
        }
    }
}