[Freeciv-Dev] switching tilesets at runtime (PR#1930)

[jdorje@xxxxxxxxxxxxxxxxxxxxx]

The time has finally come...the client is, IMO, ready for a patch that 
will switch tilesets at runtime.
The question is, how exactly should this work?

First, here's a little background.  The tileset switching patch will 
switch from one tileset to another, but it is not perfect.  There is a 
strong possibility for memory leaks.  Also, some graphics don't get 
updated propely - for instance in GTK the city dialog window doesn't get 
correctly resized (in other GUIs there are probably other issues).  Both 
of these are acceptable, IMO, so long as the client pops up a dialog 
saying "This feature is experimental.  You may have to restart the 
FreeCiv client for things to work properly."  In time they will no doubt 
be fixed and the dialog will become unnecessary.
All of this can be handled cleanly by the addition of a new gui 
function, which is called at the end of a tileset switch.  For now this 
function will pop up the dialog window; later it will do more 
complicated things like resize all open city dialog windows (or perhaps 
such resizing can be made automatic; I don't know).
Up to here things are straightforward.  But my question is, how should 
the user interface work?  I see several possibilities.
1.  Change the "default tileset" client option to just a "tileset" 
option.  When the options dialog is closed, switch the tileset to the 
specified one (if it has been changed).
2.  Same as above, but make the change immediately.

3.  Leave the options dialog as it is, and add a separate interface for 
changing the tileset.  I would implement this as a "tileset" submenu 
under the "view" menu, with a list of available tilesets in the submenu.
Implementing #1 and #2 would require adding a callback function to the 
option structure: to be called in case the option is changed.  This 
callback function would be called by the GUI when the option was changed 
in the option dialog, and would itself call the tileset update function. 
 #1 is significantly easier than #2, since few changes would be needed 
to the current GUI implementations.
Implementing #3 makes for a cleaner interface for changing the tileset, 
but requires more work on the GUI end and means that changing the 
tileset does not change the *default* tileset.  This last seems like a 
major design flaw to me; on the other hand linking them is also tricky 
since the tileset can be changed with the -t option which currently 
doesn't affect the *default* tileset.
As you can probably tell, I prefer #1.  In any case, I'll put together a 
new patch with a demo interface that will switch tilesets when I get a 
chance.
jason