#36 Error handling of map downloading and atlas tree features

[CrazyQ]

I have made some feature enhancement for map downloading and atlas tree. These modifications are based on v1.9.16 revsion 2157.

Change details:

Atlas tree features:
Add check box to atlas tree nodes. Only selected layers/maps will be downloaded.

Add "Change map source" to the right clicking popup menu at atlas tree nodes. Map sources of atals, layers and maps can be changed.

Enhance layers and maps names displaying in atlas tree. Map source name and zoom level are appended at the end of the node name of layers and maps.

Atlas tree node name and profile name can input Chinese now. Special charaters that are not allowed in filename are still be filtered out.
I think this fix also works for other non-english languages.

Map downloading features:
Add special dealing with HTTP 404 error when downloading.
Some map servers (e.g This Chinese map provider: http://www.tianditu.com/guide/index.html) will just return a HTTP 404 response code but not an empty tile if there is no map info at the specified locations and/or zoom levels.
The program will use an empty transparent tile automatically if server returns HTTP 404 response code.
The empty tile is a file named "empty_tile.png" at the program directory and must be 256256 size.
If there is no sucn file found at program directory, the program will throw downloading error as before.
Note: This feature only works for 256256 tile size now.

Add global HTTP User-Agent setting in network settings page and aslo add a "userAgent" parameter in custom map source XML file.
The userAgent setting in custom map source XML has higher priority.

Add retrying count and retrying delay parameters for downloading. They can be set at network settings page.

Increase max downloading thread count to 20 in network settings page.

Other:
Fix some translation problems in chinese.

[r_x]

Thanks for the patch CrazyQ,

however I have problems integrating the patch for several reasons:

1. The current trunk version has changed a lot regarding the GUI, especially the map selection, this conflicts with the "Change map source dialog"

2. The checkboxes in atlas content tree increase the complexity of creating an altas IMHO a lot. I prefer having a simple easy to use GUI.

3. "Atlas tree node name and profile name can input Chinese now."
   Sounds reasonable. Can you give me a hint what are the changes you made. Your patch is a bit large.

4. "Map downloading features - 404"
   I am sorry but I dislike this feature. Special features for certain map sources should be handled by the map source implementation, not by MOBAC. You should think about using a BSH map source or create your own custom map pack.

5. "global HTTP User-Agent setting in network settings page"
   The user agent string is not present in the GUI by design. This prevents simple users from faking the user agent for bypassing server side filters, e.g. for OpenStreetMap. I can and will not support that in MOBAC.

6. "Increase max downloading thread"
   The max download thread count was also limited intentionally for preventing/limiting mass server-load.

7. "Fix some translation problems in chinese."
   You are the expert on that topic. I f you say that there are errors/problems...

Conclusion: It would be good if you could provide not one large patch but separate patches for the changes I I planning to integrate.