Using strings with parameters in dropdown?

[Yexo]

Is there any way to use a string that needs parameters, such as

Code: Select all

STR_GROUP_NAME                                                  :{GROUP}

in a dropdown list? If so, how to I give the parameter?

I've tried the following, but the games just crashes when I try this.

Code: Select all

Group *g; //Some valid pointer to a group
_data_dropdown[0] = STR_GROUP_NAME;
SetDParam(0,g->index);
_data_dropdown[1] = INVALID_STRING_ID;
ShowDropDownMenu(w, _data_dropdown, 0, REW_DATA, 0, 0);

[Rubidium]

No, it is impossible at the moment. (Or you have to rewrite the string handling subsystem)

[peter1138]

Better to rewrite the drop down code...

[DaleStan]

The comments for Patch's dropdown code say[0] that it's possible to pass it a collection of char* instead of a collection of (our version of) StringID.

This might be the best solution; pass the string through the string handler, and then pass that string pointer to the dropdown. The other solution depends on whether or not you still have the control character 82 XX XX, which, in TTD, inserts the string with id XX XX. If that exists, and if {GROUP} has a StringID, just modify the string on the fly.

[0] I don't think this has ever been tested.

[Bilbo]

I asked somewhat similar question - http://tt-forums.net/viewtopic.php?f=33&t=35266

and basically, in OpenTTD you can't just stick bunch of char* into a drop down box.

I'll quote Rubidium from that thread:

[/quote]Partially... you can bind char *strings to stringIDs, but that is kinda tricky. What happens is that you get a StringID from some cyclic buffer, which means the StringID will eventually 'point' to a different string. With the 'wrong' windows open this is after the first redraw. Changing this behaviour means lots of changes and probably much memory leaks.
[/quote]

So you have some chance with using the temporary String ID's, but there are very few of them (I think about 8 or 16 or so) so for longer drop-downs you are out of luck.

[DaleStan]

Hence:

Better to rewrite the drop down code...

StringIDs don't enter into the equation at all.

You allocate one big buffer, tell the string handler to write into that buffer, pass pointers into that buffer, and deallocate the buffer when the dropdown is dismissed. The dropdown handler never receives a StringID, and, in fact, never knows if the string in question ever had a StringID.

Unlike temporary StringIDs, pointers don't magically go invalid just because you opened a different window.

[Yexo]

Well, I still wanted to do this so I created a little patch that makes it possible to give SetDParam arguments to the dropdownhandler. Usage example:

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static StringID _data_dropdown = {
STR_GROUP_NAME,
STR_01D3_SOUND_MUSIC,
STR_GROUP_NAME,
INVALID_STRING_ID
}; 
static uint64 _data_dropdown_arguments = {
SomeGroupID,
SomeOtherGroupID
};
static int _data_dropdown_num_arguments = {
1,
0,
1
};

The strings above are just random examples, but you can pass any number of arguments to any combination of strings.

Edit: FS #1649

[Bilbo]

Well, it seems in 11848 we have the new dropdown handler - so the solution "better to rewrite the dropdown code" was the best one :)

[Yexo]

Well, it seems in 11848 we have the new dropdown handler - so the solution "better to rewrite the dropdown code" was the best one

Yep, I noticed. The only drawback is now that I have to write my code using my custom handler again .