Android Question Somebody has experienced extended usage of Google map

[jcredk]

Hi all,
I need to design a kind of "document viewer" that could be used to browse detailed documents.
During my analysis, I found an excellent article on a blog (here) dealing with the usage of google map api while browsing other things thatn just maps ...

This seems an interresting approach for my project but leads to several questions:
- Do you think it's a possible approach with B4A with the google map api library?
- Did you already experienced this?
- Do you think that there is a way to "calibrate" the google map api local cache size on the device? For instance: I would like to be able to set it in a smart way so that one document fully fit in the cache size (on SD card), but also be able to clean the cache if the document is upgraded on the server ... also ensuring to keep a "high level zoom" view of each doc would be nice!

So many questions! But if it could avoid me to reimplement such mechanism it make sense
Any advice is welcome!

Thx
Jo

PS: My documents (electronic version of printed high quality brochures) goes from 20MB PDFs up to 100MB when looking at sources (eps file types), and I may have up to 50~100 such docs on a device. Devices are from a pool of controled devices where 100MB * 100docs = 10GB can be ensured as available on SD cards ...

 

[warwound]

You have i think two options:

• Use a GroundOverlay and set the map type to 'none' so no map tiles are loaded.
  There's an example here: http://www.b4x.com/android/forum/threads/google-maps-android-v2-tutorial.24415/page-3#post-152012
  BUT i'm sure you'll find you'll get out of memory problems with such large images.
• For each image you want to display in a map you could create a custom tile set and display it using a TileOverlay.
  You'd have no memory problems with a TileOverlay but you would have the extra work required to take each of your images and create a set of tiles.
  Then you'd have to decide whether you want to:
  • Serve these tiles from the internet (example code here: http://www.b4x.com/android/forum/threads/google-maps-android-v2-tutorial.24415/page-3#post-152010)
  • Load them from the device's external memory (See http://www.b4x.com/android/forum/threads/googlemapsextras.26277/page-3#post-191301 for info on the CustomTileProvider).
    Storing large numbers of tiles on the device can be very inefficient.
    The FAT32 file system cluster size dictates the minimum amount of memory space a file will use.
    A 4KB cluster size means each tile will use at least 4KBs of memory space, and always a multiple of 4KBs memory space (4KBs, 8KBs, 12Kbs) etc.
    Also the FAT32 file system has a limit on the number of files that can be stored in a single directory.
    Note that CustomTileProvider has been updated but not yet uploaded to the forum - let me know if you want a copy)

A custom tile set for each image, UrlTileProvider and an internet based server serving the custom tiles is probably the easiest way to go.

Martin.

 

[jcredk]

Thanks warwound for the answer.
I have the solution to make the tiles ==> then I have 256*256 png tiles with x, y, z coordinates system.
And like you, I believe only tiles are manageable in term of memory use I will not put one huge image to work with
I will carefully read your other topic (http://www.b4x.com/android/forum/threads/googlemapsextras.26277/page-3#post-191301) and will continue the discussion there (if not self explanatory) ...
Thx