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Convert PDF to Image (.NET)
Convert PDF to image on Android (Xamarin)
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Convert PDF to image in Windows Store apps (.NET)
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PDF to image in Universal Windows Store apps (.NET)
Free PDF Viewer control for Windows Forms (.NET)
How to integrate PDF Viewer control in WPF app (.NET)
Creating WPF PDF Viewer supporting bookmarks (.NET)
Cross-platform PDF Viewer using GTK# (MONO)
Silverlight PDF viewer control (Silverlight 5)
Multithreaded PDF rendering (.NET)
Convert pdf to image in Silverlight app (C# sample)
How to set fallback fonts for PDF rendering (C#)
Avoiding the out-of-memory exception on rendering (C#)
PDF viewer single page application (WebAPI, AngularJS)
PDF viewer control for Windows 10 universal applications
Use custom ICC profile for CMYK to RGB conversion
PDF layers - separate images, text, annotations, graphics

PDF Forms Creation PDF Security
Conversion to PDF/A
Other topics
PDF Document Manipulation PDF Content Generation
Fixed and Flow layout document API (.NET)
Creation of grids and tables in PDF (C# sample)
How to create interactive documents using Actions (C# sample)
Text flow effects in PDF (C# sample)
How to generate ordered and bulleted lists in PDF (C# sample)
Convert HTML to PDF using flow layout API (C# sample)
How to use custom fonts for PDF generation (.NET)
Create document with differently sized pages (C#)
Create PDF documents using MONO (C#/MONO/Windows/OSX)
How to use background images for content elements (C#/PDF Kit/FlowLayout)
Add transparent images to PDF document (C#)
Draw round rect borders in PDF documents(C#)
ICC color profiles and and ICC based colors in PDF (C#)
How to use bidirectional and right to left text in PDF (C#)
Create PDF documents from XML templates (C# sample)
How to resize PDF pages and use custom stamps (C#)
Add header and footer to PDF page (.NET sample)
How to use clipping mask for drawing on PDF page
Fill graphics path with gradient brushes in PDF (Shadings)
Apitron PDF Kit and Rasterizer engine settings
Add layers to PDF page (optional content, C# sample)
How to create free text annotation with custom appearance
PDF Content Extraction PDF Navigation
PDF to TIFF conversion
Contact us if you have a PDF related question and we'll cover it in our blog.


Fixed and Flow document layout in Apitron PDF Kit .NET component


Apitron PDF Kit is a .NET component that makes you able to create, edit, combine, split, sign and do whatever you want with PDF documents. It offers full support for PDF forms and advanced PDF graphics along with the easy to use and clean API. It’s a cross platform pdf library that can be used to create applications for all modern mobile, desktop, web or cloud platforms. Read more about it here or download free book available by the following link.

This article is intended to give you brief overview of the API and explain the difference between two approaches which the library offers for PDF generation and manipulation. The topic was deeply covered in our book “Apitron PDF Kit in Action” linked above, and this article is a quick and packed summary of the concepts from this book.

PDF and Fixed Layout

“Classical” approach for PDF generation and creation, everyone is used to, is based on structures and entities defined by PDF specification. So most libraries offer APIs which are based on these low-level definitions, with an attempt to provide more high level abstraction depending on own architectural decision made by the developer.

E.g. a sequence of drawing operations can be called a GraphicsPath to make it look like the one from Windows GDI,  and one would be required to instantiate this path object and add commands to it. Others call such objects Shapes or Paths. Same approach is used to name various routines, e.g. you could find DrawString, DrawText or SaveState in almost all such APIs.

While it’s all different it’s stays the same – it makes you able to create PDF documents based on absolute coordinates for all objects and that’s why we call it a fixed layout. We offer this classic model as well, with a few exceptions described below:

  • We tried to avoid the introduction of objects which are not part of PDF specification, therefore we didn’t map the API to any known graphics system except defined by PDF. And we did it only if it was absolutely necessary. As a result, PDF specification can be used to look up things and our library to generate them. API follows it very strictly, overcoming all possible limitations, which might have been introduced by producing a PDF version of some well-known drawing API. PDF is an extremely complex format with rich graphical component and it’s hard to find a universal way to work with it.
  • We isolated the binary specifics of the PDF and, as a consequence, developers are not required to manage the binary part of format. The specification remains a good source of information about PDF features, objects appearance and their logical structure without the need to know how-tos related to binary form. You create PDF objects, move them around, copy etc. and library manages these, sometimes tricky, tasks and keeps everything consistent and readable.

This subset of Apitron PDF Kit API is located in Apitron.PDF.Kit.FixedLayout namespace and PDF document object is represented by FixedDocument class. Using this class and related fixed layout objects one may do whatever he or she needs with PDF document. PDF specification is fully covered by this subset.

Let’s check out how to create “Hello world” sample using fixed layout API:

// create output PDF file
using (FileStream outputStream = new FileStream("outfile.pdf", FileMode.Create, FileAccess.Write))
    // create new document
    FixedDocument document = new FixedDocument();

    // add blank first page
    document.Pages.Add(new Page(Boundaries.A4));

    // create text object and append text to it
    TextObject textObject = new TextObject(StandardFonts.Helvetica,12);               

    // apply identity matrix, that doesn't change default appearance
    textObject.AppendText("Hello world using Apitron PDF Kit!");

    // set current transformation matrix so text will be added to the top of the page,
    // PDF coordinate system has Y-axis directed from bottom to top.
    document.Pages[0].Content.Translate(10, 820);

    // add text object to content, it'll automatically add text showing operators                               

    // save to output stream

The result will look like this:

Pic.1 FixedDocument, “Hello world” sample.

PDF and Flow Layout

In addition to “classic” approach described in section PDF and Fixed Layout, Apitron PDF Kit offers API subset called Flow Layout. It’s different from the fixed alternative being completely styles driven and using non-absolute element positioning approach. The closest alternative which can be seen is HTML + CSS.

In flow layout API subset PDF document is represented by the class FlowDocument and all flow layout-related classes can be found in Apitron.PDF.Kit.FlowLayout namespace. Styles and corresponding objects are defined in Apitron.PDF.Kit.Styles namespace.

The general approach for creating a flow layout document is to construct it from various pre-defined content elements, e.g. text blocks, sections, grids, form controls, line breaks. Each of these elements can be styled either individually or by a matching style. Styles are assigned using specific selectors, so one may assign, for example, the border color to all text blocks in document using a single style with type selector.

 See the styling code sample provided below:

using (Stream outputStream = File.Create("selectors.pdf"))
    // create new flow document
    FlowDocument document = new FlowDocument();
    // register style that matches all textblocks and sets their text color
    document.StyleManager.RegisterStyle("textblock", new Style(){Color = RgbColors.Red});
    // add textual content element
    document.Add(new TextBlock("A textblock with red text"));
    // add textual content element and directly set its property overriding the matched style
    document.Add(new TextBlock("A textblock with black text"){Color = RgbColors.Black});
    // save to output stream with page size A4
    document.Write(outputStream, new ResourceManager(), new PageBoundary(Boundaries.A4));

Resulting file looks as follows:

Pic.2  FlowDocument, TextBlock styling sample

Supported features

Using Apitron PDF Kit you can do the following (the component is being regularly updated so the list may be incomplete):
  • Create new PDF file from scratch or by copying content from other files
  • Merge two or more documents into single PDF file
  • Split PDF documents to separate pages
  • Add, modify or extract content from PDF documents including text, images or attachments
  • Work with transparency and complex graphics in PDF documents
  • Create new or fill existing PDF forms , create or remove custom fields
  • Check resources stored inside the PDF file, e.g. fonts, embedded files
  • Digitally sign or check existing signatures present in PDF documents
  • Protect document with a password or set permissions
  • Work with navigation objects, e.g. create bookmarks or links
  • Annotate document using all supported annotation objects
  • Add various actions e.g. JavaScript or GoTo actions
  • Search text in PDF files
  • Use any font which is declared as supported in PDF specification
  • Use and embed custom fonts
  • Create custom Type3 fonts
  • Use colors defined in all available colorspaces, e.g. Lab, XYZ, CMYK
  • Control PDF viewer behavior using custom preview settings
  • Save resulting files using PDF sub-standards e.g. PDF/A.
  • Create cross-platform code which works on Windows, Windows Phone, Android and iOS (using Xamarin), Mac OS (using Mono) and any system Mono exists for.
  • Create cloud PDF processing applications

The component is available for download by the following link. We’ll be happy to answer your questions and welcome any feedback.

Downloadable version of this article can be found by the following link [PDF].

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