// Creates some content (a path in the shape of a heart) and associate it with the vector layer
        static Obj CreateGroup2(PDFDoc doc, Obj layer)
        {
            using (ElementWriter writer = new ElementWriter())
                using (ElementBuilder builder = new ElementBuilder())
                {
                    writer.Begin(doc);

                    // Create a path object in the shape of a heart.
                    builder.PathBegin();                        // start constructing the path
                    builder.MoveTo(306, 396);
                    builder.CurveTo(681, 771, 399.75, 864.75, 306, 771);
                    builder.CurveTo(212.25, 864.75, -69, 771, 306, 396);
                    builder.ClosePath();
                    Element element = builder.PathEnd();             // the path geometry is now specified.

                    // Set the path FILL color space and color.
                    element.SetPathFill(true);
                    GState gstate = element.GetGState();
                    gstate.SetFillColorSpace(ColorSpace.CreateDeviceCMYK());
                    gstate.SetFillColor(new ColorPt(1, 0, 0, 0));              // cyan

                    // Set the path STROKE color space and color.
                    element.SetPathStroke(true);
                    gstate.SetStrokeColorSpace(ColorSpace.CreateDeviceRGB());
                    gstate.SetStrokeColor(new ColorPt(1, 0, 0));              // red
                    gstate.SetLineWidth(20);

                    gstate.SetTransform(0.5, 0, 0, 0.5, 280, 300);

                    writer.WriteElement(element);

                    Obj grp_obj = writer.End();


                    // Indicate that this form (content group) belongs to the given layer (OCG).
                    grp_obj.PutName("Subtype", "Form");
                    grp_obj.Put("OC", layer);
                    grp_obj.PutRect("BBox", 0, 0, 1000, 1000);                  // Set the clip box for the content.

                    return(grp_obj);
                }
        }
        static void Main(string[] args)
        {
            PDFNet.Initialize();

            // Relative path to the folder containing test files.
            string input_path  = "../../TestFiles/";
            string output_path = "../../TestFiles/Output/";


            try
            {
                using (PDFDoc doc = new PDFDoc())
                    using (ElementBuilder eb = new ElementBuilder())                    // ElementBuilder is used to build new Element objects
                        using (ElementWriter writer = new ElementWriter())              // ElementWriter is used to write Elements to the page
                        {
                            // Start a new page ------------------------------------
                            // Position an image stream on several places on the page
                            Page page = doc.PageCreate(new Rect(0, 0, 612, 794));

                            writer.Begin(page);                 // begin writing to this page

                            // Create an Image that can be reused multiple times in the document or
                            // multiple on the same page.
                            MappedFile   img_file = new MappedFile(input_path + "peppers.jpg");
                            FilterReader img_data = new FilterReader(img_file);
                            Image        img      = Image.Create(doc, img_data, 400, 600, 8, ColorSpace.CreateDeviceRGB(), Image.InputFilter.e_jpeg);

                            Element element = eb.CreateImage(img, new Matrix2D(200, -145, 20, 300, 200, 150));
                            writer.WritePlacedElement(element);

                            GState gstate = element.GetGState();                // use the same image (just change its matrix)
                            gstate.SetTransform(200, 0, 0, 300, 50, 450);
                            writer.WritePlacedElement(element);

                            // use the same image again (just change its matrix).
                            writer.WritePlacedElement(eb.CreateImage(img, 300, 600, 200, -150));

                            writer.End();              // save changes to the current page
                            doc.PagePushBack(page);

                            // Start a new page ------------------------------------
                            // Construct and draw a path object using different styles
                            page = doc.PageCreate(new Rect(0, 0, 612, 794));

                            writer.Begin(page);                 // begin writing to this page
                            eb.Reset();                         // Reset GState to default


                            eb.PathBegin();                     // start constructing the path
                            eb.MoveTo(306, 396);
                            eb.CurveTo(681, 771, 399.75, 864.75, 306, 771);
                            eb.CurveTo(212.25, 864.75, -69, 771, 306, 396);
                            eb.ClosePath();
                            element = eb.PathEnd();                             // the path is now finished
                            element.SetPathFill(true);                          // the path should be filled

                            // Set the path color space and color
                            gstate = element.GetGState();
                            gstate.SetFillColorSpace(ColorSpace.CreateDeviceCMYK());
                            gstate.SetFillColor(new ColorPt(1, 0, 0, 0));              // cyan
                            gstate.SetTransform(0.5, 0, 0, 0.5, -20, 300);
                            writer.WritePlacedElement(element);

                            // Draw the same path using a different stroke color
                            element.SetPathStroke(true);                        // this path is should be filled and stroked
                            gstate.SetFillColor(new ColorPt(0, 0, 1, 0));       // yellow
                            gstate.SetStrokeColorSpace(ColorSpace.CreateDeviceRGB());
                            gstate.SetStrokeColor(new ColorPt(1, 0, 0));        // red
                            gstate.SetTransform(0.5, 0, 0, 0.5, 280, 300);
                            gstate.SetLineWidth(20);
                            writer.WritePlacedElement(element);

                            // Draw the same path with with a given dash pattern
                            element.SetPathFill(false);                  // this path is should be only stroked
                            gstate.SetStrokeColor(new ColorPt(0, 0, 1)); // blue
                            gstate.SetTransform(0.5, 0, 0, 0.5, 280, 0);
                            double[] dash_pattern = { 30 };
                            gstate.SetDashPattern(dash_pattern, 0);
                            writer.WritePlacedElement(element);

                            // Use the path as a clipping path
                            writer.WriteElement(eb.CreateGroupBegin());                 // Save the graphics state
                            // Start constructing a new path (the old path was lost when we created
                            // a new Element using CreateGroupBegin()).
                            eb.PathBegin();
                            eb.MoveTo(306, 396);
                            eb.CurveTo(681, 771, 399.75, 864.75, 306, 771);
                            eb.CurveTo(212.25, 864.75, -69, 771, 306, 396);
                            eb.ClosePath();
                            element = eb.PathEnd();             // path is now built
                            element.SetPathClip(true);          // this path is a clipping path
                            element.SetPathStroke(true);        // this path is should be filled and stroked
                            gstate = element.GetGState();
                            gstate.SetTransform(0.5, 0, 0, 0.5, -20, 0);
                            writer.WriteElement(element);
                            writer.WriteElement(eb.CreateImage(img, 100, 300, 400, 600));
                            writer.WriteElement(eb.CreateGroupEnd()); // Restore the graphics state

                            writer.End();                             // save changes to the current page
                            doc.PagePushBack(page);


                            // Start a new page ------------------------------------
                            page = doc.PageCreate(new Rect(0, 0, 612, 794));

                            writer.Begin(page);                 // begin writing to this page
                            eb.Reset();                         // Reset GState to default

                            // Begin writing a block of text
                            element = eb.CreateTextBegin(Font.Create(doc, Font.StandardType1Font.e_times_roman), 12);
                            writer.WriteElement(element);

                            string data = "Hello World!";
                            element = eb.CreateTextRun(data);
                            element.SetTextMatrix(10, 0, 0, 10, 0, 600);
                            element.GetGState().SetLeading(15);                          // Set the spacing between lines
                            writer.WriteElement(element);

                            writer.WriteElement(eb.CreateTextNewLine());              // New line

                            element = eb.CreateTextRun(data);
                            gstate  = element.GetGState();
                            gstate.SetTextRenderMode(GState.TextRenderingMode.e_stroke_text);
                            gstate.SetCharSpacing(-1.25);
                            gstate.SetWordSpacing(-1.25);
                            writer.WriteElement(element);

                            writer.WriteElement(eb.CreateTextNewLine());              // New line

                            element = eb.CreateTextRun(data);
                            gstate  = element.GetGState();
                            gstate.SetCharSpacing(0);
                            gstate.SetWordSpacing(0);
                            gstate.SetLineWidth(3);
                            gstate.SetTextRenderMode(GState.TextRenderingMode.e_fill_stroke_text);
                            gstate.SetStrokeColorSpace(ColorSpace.CreateDeviceRGB());
                            gstate.SetStrokeColor(new ColorPt(1, 0, 0));                // red
                            gstate.SetFillColorSpace(ColorSpace.CreateDeviceCMYK());
                            gstate.SetFillColor(new ColorPt(1, 0, 0, 0));               // cyan
                            writer.WriteElement(element);

                            writer.WriteElement(eb.CreateTextNewLine());              // New line

                            // Set text as a clipping path to the image.
                            element = eb.CreateTextRun(data);
                            gstate  = element.GetGState();
                            gstate.SetTextRenderMode(GState.TextRenderingMode.e_clip_text);
                            writer.WriteElement(element);

                            // Finish the block of text
                            writer.WriteElement(eb.CreateTextEnd());

                            // Draw an image that will be clipped by the above text
                            writer.WriteElement(eb.CreateImage(img, 10, 100, 1300, 720));

                            writer.End();              // save changes to the current page
                            doc.PagePushBack(page);

                            // Start a new page ------------------------------------
                            //
                            // The example illustrates how to embed the external font in a PDF document.
                            // The example also shows how ElementReader can be used to copy and modify
                            // Elements between pages.

                            using (ElementReader reader = new ElementReader())
                            {
                                // Start reading Elements from the last page. We will copy all Elements to
                                // a new page but will modify the font associated with text.
                                reader.Begin(doc.GetPage(doc.GetPageCount()));

                                page = doc.PageCreate(new Rect(0, 0, 1300, 794));

                                writer.Begin(page);                     // begin writing to this page
                                eb.Reset();                             // Reset GState to default

                                // Embed an external font in the document.
                                Font font = Font.CreateTrueTypeFont(doc, input_path + "font.ttf");

                                while ((element = reader.Next()) != null)                       // Read page contents
                                {
                                    if (element.GetType() == Element.Type.e_text)
                                    {
                                        element.GetGState().SetFont(font, 12);
                                    }

                                    writer.WriteElement(element);
                                }

                                reader.End();
                                writer.End();                  // save changes to the current page

                                doc.PagePushBack(page);


                                // Start a new page ------------------------------------
                                //
                                // The example illustrates how to embed the external font in a PDF document.
                                // The example also shows how ElementReader can be used to copy and modify
                                // Elements between pages.

                                // Start reading Elements from the last page. We will copy all Elements to
                                // a new page but will modify the font associated with text.
                                reader.Begin(doc.GetPage(doc.GetPageCount()));

                                page = doc.PageCreate(new Rect(0, 0, 1300, 794));

                                writer.Begin(page);                     // begin writing to this page
                                eb.Reset();                             // Reset GState to default

                                // Embed an external font in the document.
                                Font font2 = Font.CreateType1Font(doc, input_path + "Misc-Fixed.pfa");

                                while ((element = reader.Next()) != null)                       // Read page contents
                                {
                                    if (element.GetType() == Element.Type.e_text)
                                    {
                                        element.GetGState().SetFont(font2, 12);
                                    }

                                    writer.WriteElement(element);
                                }

                                reader.End();
                                writer.End();                  // save changes to the current page
                                doc.PagePushBack(page);


                                // Start a new page ------------------------------------
                                page = doc.PageCreate();
                                writer.Begin(page);                     // begin writing to this page
                                eb.Reset();                             // Reset GState to default

                                // Begin writing a block of text
                                element = eb.CreateTextBegin(Font.Create(doc, Font.StandardType1Font.e_times_roman), 12);
                                element.SetTextMatrix(1.5, 0, 0, 1.5, 50, 600);
                                element.GetGState().SetLeading(15);                     // Set the spacing between lines
                                writer.WriteElement(element);

                                string para = "A PDF text object consists of operators that can show " +
                                              "text strings, move the text position, and set text state and certain " +
                                              "other parameters. In addition, there are three parameters that are " +
                                              "defined only within a text object and do not persist from one text " +
                                              "object to the next: Tm, the text matrix, Tlm, the text line matrix, " +
                                              "Trm, the text rendering matrix, actually just an intermediate result " +
                                              "that combines the effects of text state parameters, the text matrix " +
                                              "(Tm), and the current transformation matrix";

                                int para_end = para.Length;
                                int text_run = 0;
                                int text_run_end;

                                double para_width = 300;                 // paragraph width is 300 units
                                double cur_width  = 0;

                                while (text_run < para_end)
                                {
                                    text_run_end = para.IndexOf(' ', text_run);
                                    if (text_run_end < 0)
                                    {
                                        text_run_end = para_end - 1;
                                    }

                                    string text = para.Substring(text_run, text_run_end - text_run + 1);
                                    element = eb.CreateTextRun(text);
                                    if (cur_width + element.GetTextLength() < para_width)
                                    {
                                        writer.WriteElement(element);
                                        cur_width += element.GetTextLength();
                                    }
                                    else
                                    {
                                        writer.WriteElement(eb.CreateTextNewLine());                          // New line
                                        text      = para.Substring(text_run, text_run_end - text_run + 1);
                                        element   = eb.CreateTextRun(text);
                                        cur_width = element.GetTextLength();
                                        writer.WriteElement(element);
                                    }

                                    text_run = text_run_end + 1;
                                }

                                // -----------------------------------------------------------------------
                                // The following code snippet illustrates how to adjust spacing between
                                // characters (text runs).
                                element = eb.CreateTextNewLine();
                                writer.WriteElement(element); // Skip 2 lines
                                writer.WriteElement(element);

                                writer.WriteElement(eb.CreateTextRun("An example of space adjustments between inter-characters:"));
                                writer.WriteElement(eb.CreateTextNewLine());

                                // Write string "AWAY" without space adjustments between characters.
                                element = eb.CreateTextRun("AWAY");
                                writer.WriteElement(element);

                                writer.WriteElement(eb.CreateTextNewLine());

                                // Write string "AWAY" with space adjustments between characters.
                                element = eb.CreateTextRun("A");
                                writer.WriteElement(element);

                                element = eb.CreateTextRun("W");
                                element.SetPosAdjustment(140);
                                writer.WriteElement(element);

                                element = eb.CreateTextRun("A");
                                element.SetPosAdjustment(140);
                                writer.WriteElement(element);

                                element = eb.CreateTextRun("Y again");
                                element.SetPosAdjustment(115);
                                writer.WriteElement(element);

                                // Draw the same strings using direct content output...
                                writer.Flush(); // flush pending Element writing operations.

                                // You can also write page content directly to the content stream using
                                // ElementWriter.WriteString(...) and ElementWriter.WriteBuffer(...) methods.
                                // Note that if you are planning to use these functions you need to be familiar
                                // with PDF page content operators (see Appendix A in PDF Reference Manual).
                                // Because it is easy to make mistakes during direct output we recommend that
                                // you use ElementBuilder and Element interface instead.
                                writer.WriteString("T* T* ");                 // New Lines
                                // writer.WriteElement(eb.CreateTextNewLine());
                                writer.WriteString("(Direct output to PDF page content stream:) Tj  T* ");
                                writer.WriteString("(AWAY) Tj T* ");
                                writer.WriteString("[(A)140(W)140(A)115(Y again)] TJ ");

                                // Finish the block of text
                                writer.WriteElement(eb.CreateTextEnd());

                                writer.End();                  // save changes to the current page
                                doc.PagePushBack(page);

                                // Start a new page ------------------------------------

                                // Image Masks
                                //
                                // In the opaque imaging model, images mark all areas they occupy on the page as
                                // if with opaque paint. All portions of the image, whether black, white, gray,
                                // or color, completely obscure any marks that may previously have existed in the
                                // same place on the page.
                                // In the graphic arts industry and page layout applications, however, it is common
                                // to crop or 'mask out' the background of an image and then place the masked image
                                // on a different background, allowing the existing background to show through the
                                // masked areas. This sample illustrates how to use image masks.

                                page = doc.PageCreate();
                                writer.Begin(page); // begin writing to the page

                                // Create the Image Mask
                                MappedFile   imgf      = new MappedFile(input_path + "imagemask.dat");
                                FilterReader mask_read = new FilterReader(imgf);

                                ColorSpace device_gray = ColorSpace.CreateDeviceGray();
                                Image      mask        = Image.Create(doc, mask_read, 64, 64, 1, device_gray, Image.InputFilter.e_ascii_hex);

                                mask.GetSDFObj().PutBool("ImageMask", true);

                                element = eb.CreateRect(0, 0, 612, 794);
                                element.SetPathStroke(false);
                                element.SetPathFill(true);
                                element.GetGState().SetFillColorSpace(device_gray);
                                element.GetGState().SetFillColor(new ColorPt(0.8));
                                writer.WritePlacedElement(element);

                                element = eb.CreateImage(mask, new Matrix2D(200, 0, 0, -200, 40, 680));
                                element.GetGState().SetFillColor(new ColorPt(0.1));
                                writer.WritePlacedElement(element);

                                element.GetGState().SetFillColorSpace(ColorSpace.CreateDeviceRGB());
                                element.GetGState().SetFillColor(new ColorPt(1, 0, 0));
                                element = eb.CreateImage(mask, new Matrix2D(200, 0, 0, -200, 320, 680));
                                writer.WritePlacedElement(element);

                                element.GetGState().SetFillColor(new ColorPt(0, 1, 0));
                                element = eb.CreateImage(mask, new Matrix2D(200, 0, 0, -200, 40, 380));
                                writer.WritePlacedElement(element);

                                {
                                    // This sample illustrates Explicit Masking.
                                    img = Image.Create(doc, input_path + "peppers.jpg");

                                    // mask is the explicit mask for the primary (base) image
                                    img.SetMask(mask);

                                    element = eb.CreateImage(img, new Matrix2D(200, 0, 0, -200, 320, 380));
                                    writer.WritePlacedElement(element);
                                }

                                writer.End(); // save changes to the current page
                                doc.PagePushBack(page);

                                // Transparency sample ----------------------------------

                                // Start a new page -------------------------------------
                                page = doc.PageCreate();
                                writer.Begin(page);                     // begin writing to this page
                                eb.Reset();                             // Reset the GState to default

                                // Write some transparent text at the bottom of the page.
                                element = eb.CreateTextBegin(Font.Create(doc, Font.StandardType1Font.e_times_roman), 100);

                                // Set the text knockout attribute. Text knockout must be set outside of
                                // the text group.
                                gstate = element.GetGState();
                                gstate.SetTextKnockout(false);
                                gstate.SetBlendMode(GState.BlendMode.e_bl_difference);
                                writer.WriteElement(element);

                                element = eb.CreateTextRun("Transparency");
                                element.SetTextMatrix(1, 0, 0, 1, 30, 30);
                                gstate = element.GetGState();
                                gstate.SetFillColorSpace(ColorSpace.CreateDeviceCMYK());
                                gstate.SetFillColor(new ColorPt(1, 0, 0, 0));

                                gstate.SetFillOpacity(0.5);
                                writer.WriteElement(element);

                                // Write the same text on top the old; shifted by 3 points
                                element.SetTextMatrix(1, 0, 0, 1, 33, 33);
                                gstate.SetFillColor(new ColorPt(0, 1, 0, 0));
                                gstate.SetFillOpacity(0.5);

                                writer.WriteElement(element);
                                writer.WriteElement(eb.CreateTextEnd());

                                // Draw three overlapping transparent circles.
                                eb.PathBegin();                         // start constructing the path
                                eb.MoveTo(459.223, 505.646);
                                eb.CurveTo(459.223, 415.841, 389.85, 343.04, 304.273, 343.04);
                                eb.CurveTo(218.697, 343.04, 149.324, 415.841, 149.324, 505.646);
                                eb.CurveTo(149.324, 595.45, 218.697, 668.25, 304.273, 668.25);
                                eb.CurveTo(389.85, 668.25, 459.223, 595.45, 459.223, 505.646);
                                element = eb.PathEnd();
                                element.SetPathFill(true);

                                gstate = element.GetGState();
                                gstate.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
                                gstate.SetFillColor(new ColorPt(0, 0, 1));                                     // Blue Circle

                                gstate.SetBlendMode(GState.BlendMode.e_bl_normal);
                                gstate.SetFillOpacity(0.5);
                                writer.WriteElement(element);

                                // Translate relative to the Blue Circle
                                gstate.SetTransform(1, 0, 0, 1, 113, -185);
                                gstate.SetFillColor(new ColorPt(0, 1, 0));                                     // Green Circle
                                gstate.SetFillOpacity(0.5);
                                writer.WriteElement(element);

                                // Translate relative to the Green Circle
                                gstate.SetTransform(1, 0, 0, 1, -220, 0);
                                gstate.SetFillColor(new ColorPt(1, 0, 0));                                     // Red Circle
                                gstate.SetFillOpacity(0.5);
                                writer.WriteElement(element);

                                writer.End();                  // save changes to the current page
                                doc.PagePushBack(page);

                                // End page ------------------------------------
                            }

                            doc.Save(output_path + "element_builder.pdf", SDFDoc.SaveOptions.e_remove_unused);
                            Console.WriteLine("Done. Result saved in element_builder.pdf...");
                        }
            }
            catch (PDFNetException e)
            {
                Console.WriteLine(e.Message);
            }
        }