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APNG Viewer

By , , 6 May 2009
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Introduction

APNG stands for animated PNG, which is similar to gif89, but gif89 only has 256 colors, so APNG might be a better choice in some scenarios. The APNG Viewer is based on the excellent .NET MNG Viewer written by SprinterDave, all credits go to him. It uses pure C#, without any third-party components, and with a very small footprint (only 30K).

Background

I've been searching for a native .NET APNG parser/viewer, but unfortunately, as what I have encountered before writing DBX Parser, I just could not find it (what the heck with Google, er?), so I had to do it by myself.

File Format

There are quite a few articles you might need to read in order to know what is APNG:

APNG is only a small extension to PNG, and it's compatible with PNG, so browsers like Internet Explorer and other viewers that do not support APNG will still display the first frame. Here we could see a diagram that could give us a brief idea of APNG file format:

Samples Files

Other Languages

Maybe you are looking for other languages. Here goes:

How It Works

It reads chunk by chunk as .NET MNG Viewer does, rebuilds each PNG frame according to the base header. If you look closer at the file format, you will find that the PNG specification is pretty simple.

Using the Code

First create a new instance of APNG, then use the Load function to read the file, then you can loop through NumEmbeddedPNG, using the ToBitmap function to save each frame to a PNG file.

Here goes a sample code:

APNG png = new APNG();
png.Load(@"animated.png");
for (int i = 0; i < png.NumEmbeddedPNG; i++)
{
    Bitmap image = png.ToBitmap(i);
    image.Save("frame" + i + ".png", ImageFormat.Png);
}       

or with indexer:

APNG png = new APNG();
png.Load(@"animated.png");
for (int i = 0; i < png.NumEmbeddedPNG; i++)
{
    png[i].Save("frame" + i + ".png", ImageFormat.Png);
}       

Besides returning a new Bitmap, the APNG provides a SaveFile that you could use to save the actual frame data (complete original PNG file data).

Points of Interest

Because I suffered a lot while finding such code, I contribute it here as others won't have to get crazy looking for it. If you have any comments or suggestions, please feel free to tell me, or just modify the code yourself.

History

  • Version 1.0 - 2009-5-5 First release
  • Version 1.1 - 2009-5-6 Added indexer, more detailed introduction

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Authors

SprinterDave
Software Developer (Senior) Bally Technologies
United States United States
I've been software developer since early 1991. My focuses have ranged from deeply embedded (Intel and ARM architectures,) to firmware (C and C++), to application level software under Linux and Windows (C, C++ and C#.) Applications developed with .NET under Windows have been primarily test and support applications for other development activities.

Huisheng Chen
Architect www.xnlab.com
Australia Australia
I was born in the south of China, started to write GWBASIC code since 1993 when I was 13 years old, with professional .net(c#) and vb, founder of www.xnlab.com
 
Now I am living in Sydney, Australia.
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Comments and Discussions

 
QuestionAn updated code for this article Pinmemberamemiyasss23-Jul-12 20:18 
I have written an apng parser using C#, with the help of this article. The project is hosted at https://github.com/xupefei/APNG.NET[^] . Thanks Dave and Chen for the great work!
AnswerRe: An updated code for this article PinmemberHuisheng Chen24-Jul-12 19:16 
QuestionExtend Bitmap to display one frame at a time? PinmemberdivStar26-Nov-10 8:14 
AnswerRe: Extend Bitmap to display one frame at a time? PinmemberUnruled Boy28-Jan-11 19:55 
Generalblend_op are not supported :( Pinmembereviral16-Oct-10 11:00 
GeneralMy vote of 1 Pinmemberabcd1234f10-Aug-09 8:38 
GeneralRe: My vote of 1 PinmemberSmart K84-Dec-09 10:17 
GeneralJust.... awesome!! PinmemberAPBilbo30-Jun-09 11:44 
GeneralRe: Just.... awesome!! PinmemberUnruled Boy30-Jun-09 17:35 
GeneralGreat Job~~~ Pinmemberpen_lake10-May-09 5:16 
GeneralRe: Great Job~~~ PinmemberUnruled Boy10-May-09 19:03 
GeneralSuggestion Pinmemberharold aptroot5-May-09 7:40 
GeneralRe: Suggestion PinmemberUnruled Boy5-May-09 15:42 
Generalplease comment PinmemberUnruled Boy4-May-09 20:09 
GeneralRe: please comment Pinmembernicholas_pei6-May-09 2:46 
GeneralRe: please comment PinmemberUnruled Boy6-May-09 3:58 
Generalrecompile images? Pinmemberagent_zer024-Oct-09 15:33 

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