protected void LoadDocument(IntPtr document) { _document = document; NativePdfiumMethods.FPDF_GetDocPermissions(_document); _formCallbacks = new NativePdfiumMethods.FPDF_FORMFILLINFO(); _formCallbacksHandle = GCHandle.Alloc(_formCallbacks); _formCallbacks.version = 1; _form = NativePdfiumMethods.FPDFDOC_InitFormFillEnvironment(_document, ref _formCallbacks); NativePdfiumMethods.FPDF_SetFormFieldHighlightColor(_form, 0, 0xFFE4DD); NativePdfiumMethods.FPDF_SetFormFieldHighlightAlpha(_form, 100); NativePdfiumMethods.FORM_DoDocumentJSAction(_form); NativePdfiumMethods.FORM_DoDocumentOpenAction(_form); Bookmarks = new PdfBookmarkCollection(); LoadBookmarks(Bookmarks, NativePdfiumMethods.FPDF_BookmarkGetFirstChild(document, IntPtr.Zero)); }