Thumbnails

[AlexBern44]

Hello,

My question is about mobile development. Perhaps this is not the right forum, although my question has to do with programming. I have a great need to get expert advice and I have not found among the forums, a section more relevant than this. Would you be so kind if someone knows, please reply.

I am developing a mobile app (Android). This app includes a file manager.
Users can view their files through this app. It's like regular file lists.
And I would like them to be able to see small thumbnails of DWG files, just like they see small thumbnails of JPG files and other images.
I would like to consult this forum about possible ways to implement this task in an Android environment.

Thanks for reply.

[norman.yuan · Accepted solution]

*.dwg file's thumbnail preview image can be retrieved when the drawing file is loaded into AutoCAD, or can be retrieved directly as binary data from the DWG file (unofficially documented). 

When you say "...developing a mobile app (Android)...", I assume it is the "front-end" app running in Android phone/tab device, not an app running inside a web browser showing in the Android device. So, this mobile app will not store DWG file locally in the device, because there is no AutoCAD running in Android device. So, either ways of getting Thumbnail image of DWG file mentioned above does not matter to your mobile app. It should be done in the backend/remote end of your mobile app eco-system, where the drawing files are stored, and your mobile app only download the file name list and their thumbnail along with them.

Therefore, you only need to know how to get DWH file's thumbnail if you also develop the back end system. 

[AlexBern44]

Thank you for your detailed reply.
I would like to clarify some points from your answer.

You are right, I am talking about a "front-end" application running on a smartphone. Just in case, I have attached a screenshot of what I would like it to look like. 
And you made a correct conclusion, I would like to know how to get a thumbnail of the DWG file, using a backend system that can be part of this project.

And now that we are clear, could you please advise the easiest way to implement this system? The only function of which is the ability to get file thumbnails.

[norman.yuan]

DWG file's thumbnail can be extracted from DWG file without opening the DWG file in AutoCAD. See this discussion thread:

http://www.theswamp.org/index.php?topic=30985.0