internal PdfFormXObject(PdfDocument thisDocument, PdfImportedObjectTable importedObjectTable, XPdfForm form)
            : base(thisDocument)
        {
            Debug.Assert(ReferenceEquals(thisDocument, importedObjectTable.Owner));
            Elements.SetName(Keys.Type, "/XObject");
            Elements.SetName(Keys.Subtype, "/Form");

            if (form.IsTemplate)
            {
                Debug.Assert(importedObjectTable == null);
                // TODO more initialization here???
                return;
            }
            Debug.Assert(importedObjectTable != null);

            XPdfForm pdfForm = form;
            // Get import page
            PdfPages importPages = importedObjectTable.ExternalDocument.Pages;

            if (pdfForm.PageNumber < 1 || pdfForm.PageNumber > importPages.Count)
            {
                PSSR.ImportPageNumberOutOfRange(pdfForm.PageNumber, importPages.Count, form._path);
            }
            PdfPage importPage = importPages[pdfForm.PageNumber - 1];

            // Import resources
            PdfItem res = importPage.Elements["/Resources"];

            if (res != null) // unlikely but possible
            {
#if true
                // Get root object
                PdfObject root;
                if (res is PdfReference)
                {
                    root = ((PdfReference)res).Value;
                }
                else
                {
                    root = (PdfDictionary)res;
                }

                root = ImportClosure(importedObjectTable, thisDocument, root);
                // If the root was a direct object, make it indirect.
                if (root.Reference == null)
                {
                    thisDocument._irefTable.Add(root);
                }

                Debug.Assert(root.Reference != null);
                Elements["/Resources"] = root.Reference;
#else
                // Get transitive closure
                PdfObject[] resources = importPage.Owner.Internals.GetClosure(resourcesRoot);
                int         count     = resources.Length;
#if DEBUG_
                for (int idx = 0; idx < count; idx++)
                {
                    Debug.Assert(resources[idx].XRef != null);
                    Debug.Assert(resources[idx].XRef.Document != null);
                    Debug.Assert(resources[idx].Document != null);
                    if (resources[idx].ObjectID.ObjectNumber == 12)
                    {
                        GetType();
                    }
                }
#endif
                // 1st step. Already imported objects are reused and new ones are cloned.
                for (int idx = 0; idx < count; idx++)
                {
                    PdfObject obj = resources[idx];
                    if (importedObjectTable.Contains(obj.ObjectID))
                    {
                        // external object was already imported
                        PdfReference iref = importedObjectTable[obj.ObjectID];
                        Debug.Assert(iref != null);
                        Debug.Assert(iref.Value != null);
                        Debug.Assert(iref.Document == Owner);
                        // replace external object by the already clone counterpart
                        resources[idx] = iref.Value;
                    }
                    else
                    {
                        // External object was not imported ealier and must be cloned
                        PdfObject clone = obj.Clone();
                        Debug.Assert(clone.Reference == null);
                        clone.Document = Owner;
                        if (obj.Reference != null)
                        {
                            // add it to this (the importer) document
                            Owner.irefTable.Add(clone);
                            Debug.Assert(clone.Reference != null);
                            // save old object identifier
                            importedObjectTable.Add(obj.ObjectID, clone.Reference);
                            //Debug.WriteLine("Cloned: " + obj.ObjectID.ToString());
                        }
                        else
                        {
                            // The root object (the /Resources value) is not an indirect object
                            Debug.Assert(idx == 0);
                            // add it to this (the importer) document
                            Owner.irefTable.Add(clone);
                            Debug.Assert(clone.Reference != null);
                        }
                        // replace external object by its clone
                        resources[idx] = clone;
                    }
                }
#if DEBUG_
                for (int idx = 0; idx < count; idx++)
                {
                    Debug.Assert(resources[idx].XRef != null);
                    Debug.Assert(resources[idx].XRef.Document != null);
                    Debug.Assert(resources[idx].Document != null);
                    if (resources[idx].ObjectID.ObjectNumber == 12)
                    {
                        GetType();
                    }
                }
#endif

                // 2nd step. Fix up indirect references that still refers to the import document.
                for (int idx = 0; idx < count; idx++)
                {
                    PdfObject obj = resources[idx];
                    Debug.Assert(obj.Owner != null);
                    FixUpObject(importedObjectTable, importedObjectTable.Owner, obj);
                }

                // Set resources key to the root of the clones
                Elements["/Resources"] = resources[0].Reference;
#endif
            }

            // Take /Rotate into account
            PdfRectangle rect   = importPage.Elements.GetRectangle(PdfPage.Keys.MediaBox);
            int          rotate = importPage.Elements.GetInteger(PdfPage.Keys.Rotate);
            //rotate = 0;
            if (rotate == 0)
            {
                // Set bounding box to media box
                Elements["/BBox"] = rect;
            }
            else
            {
                // TODO: Have to adjust bounding box? (I think not, but I'm not sure -> wait for problem)
                Elements["/BBox"] = rect;

                // Rotate the image such that it is upright
                XMatrix matrix = new XMatrix();
                double  width  = rect.Width;
                double  height = rect.Height;
                matrix.RotateAtPrepend(-rotate, new XPoint(width / 2, height / 2));

                // Translate the image such that its center lies on the center of the rotated bounding box
                double offset = (height - width) / 2;
                if (height > width)
                {
                    matrix.TranslatePrepend(offset, offset);
                }
                else
                {
                    matrix.TranslatePrepend(-offset, -offset);
                }

                //string item = "[" + PdfEncoders.ToString(matrix) + "]";
                //Elements[Keys.Matrix] = new PdfLiteral(item);
                Elements.SetMatrix(Keys.Matrix, matrix);
            }

            // Preserve filter because the content keeps unmodified
            PdfContent content = importPage.Contents.CreateSingleContent();
#if !DEBUG
            content.Compressed = true;
#endif
            PdfItem filter = content.Elements["/Filter"];
            if (filter != null)
            {
                Elements["/Filter"] = filter.Clone();
            }

            // (no cloning needed because the bytes keep untouched)
            Stream = content.Stream; // new PdfStream(bytes, this);
            Elements.SetInteger("/Length", content.Stream.Value.Length);
        }
        /// <summary>
        /// Replace all indirect references to external objects by their cloned counterparts
        /// owned by the importer document.
        /// </summary>
        void FixUpObject_old(PdfImportedObjectTable iot, PdfObject value)
        {
            // TODO: merge with PdfXObject.FixUpObject
            PdfDictionary dict;
            PdfArray      array;

            if ((dict = value as PdfDictionary) != null)
            {
                // Set document for cloned direct objects
                if (dict.Owner == null)
                {
                    dict.Document = Owner;
                }
                else
                {
                    Debug.Assert(dict.Owner == Owner);
                }

                // Search for indirect references in all keys
                PdfName[] names = dict.Elements.KeyNames;
                foreach (PdfName name in names)
                {
                    PdfItem item = dict.Elements[name];
                    // Is item an iref?
                    PdfReference iref = item as PdfReference;
                    if (iref != null)
                    {
                        // Does the iref already belong to this document?
                        if (iref.Document == Owner)
                        {
                            // Yes: fine
                            continue;
                        }
                        else
                        {
                            Debug.Assert(iref.Document == iot.ExternalDocument);
                            // No: replace with iref of cloned object
                            PdfReference newXRef = iot[iref.ObjectID];
                            Debug.Assert(newXRef != null);
                            Debug.Assert(newXRef.Document == Owner);
                            dict.Elements[name] = newXRef;
                        }
                    }
                    else if (item is PdfObject)
                    {
                        // Fix up inner objects
                        FixUpObject_old(iot, (PdfObject)item);
                    }
                }
            }
            else if ((array = value as PdfArray) != null)
            {
                // Set document for cloned direct objects
                if (array.Owner == null)
                {
                    array.Document = Owner;
                }
                else
                {
                    Debug.Assert(array.Owner == Owner);
                }

                // Search for indirect references in all array elements
                int count = array.Elements.Count;
                for (int idx = 0; idx < count; idx++)
                {
                    PdfItem item = array.Elements[idx];
                    // Is item an iref?
                    PdfReference iref = item as PdfReference;
                    if (iref != null)
                    {
                        // Does the iref belongs to this document?
                        if (iref.Document == Owner)
                        {
                            // Yes: fine
                            continue;
                        }
                        else
                        {
                            Debug.Assert(iref.Document == iot.ExternalDocument);
                            // No: replace with iref of cloned object
                            PdfReference newXRef = iot[iref.ObjectID];
                            Debug.Assert(newXRef != null);
                            Debug.Assert(newXRef.Document == Owner);
                            array.Elements[idx] = newXRef;
                        }
                    }
                    else if (item is PdfObject)
                    {
                        // Fix up inner objects
                        FixUpObject_old(iot, (PdfObject)item);
                    }
                }
            }
        }