Keep a set of preferences in the midend.

This commit introduces a serialisation format for the user preferences
stored in game_ui, using the keyword identifiers that get_prefs is
required to write into its list of config_item. As a result, the
serialisation format looks enough like an ordinary config file that a
user could write one by hand.

The preferences for the game backend are kept in serialised form in
me->be_prefs. The typical use of this is to apply it to a just-created
game_ui by calling midend_apply_prefs(), which deserialises the prefs
buffer into a list of config_item and passes it to the backend's
set_prefs function, overwriting the preference fields (but no others)
of the game_ui.

This is duly done when creating a new game, when loading a game from a
save file, and also when printing a puzzle. To make the latter work,
document_add_puzzle now takes a game_ui (and keeps ownership of it
afterwards), and passes that to the backend's compute_size and print
functions.

The backend's own get_prefs and set_prefs functions are wrapped by
midend_get_prefs and midend_set_prefs. This is partly as a convenience
(it deals with optionally constructing a game_ui specially to call the
backend with), but mostly so that there will be a convenient place in
the midend to add standard preferences applying across all puzzles.
No cross-puzzle preferences are provided yet.

There are two external interfaces to all this, and in this commit,
neither one is yet called by any frontend:

A new pair of midend functions is exposed to the front end, called
midend_load_prefs and midend_save_prefs. These have a similar API to
midend_serialise and midend_deserialise, taking a read/write function
pointer and a context. So front ends that can already load/save a game
to a file on disk should find it easy to add a similar set of
functions loading/saving user preferences.

Secondly, a new value CFG_PREFS is added to the enumeration of
configuration dialog types, alongside the ones for the Custom game
type, entering a game description and entering a random seed. This
should make it easy for frontends to offer a Preferences dialog,
because it will operate almost exactly like three dialogs they already
handle.

1 files changed, 7 insertions, 9 deletions

diff --git a/printing.c b/printing.c
index 7301ba0..0a91194 100644
--- a/printing.c
+++ b/printing.c
@@ -10,6 +10,7 @@
 struct puzzle {
     const game *game;
     game_params *par;
+    game_ui *ui;
     game_state *st;
     game_state *st2;
 };
@@ -56,6 +57,7 @@ void document_free(document *doc)
 
     for (i = 0; i < doc->npuzzles; i++) {
 	doc->puzzles[i].game->free_params(doc->puzzles[i].par);
+	doc->puzzles[i].game->free_ui(doc->puzzles[i].ui);
 	doc->puzzles[i].game->free_game(doc->puzzles[i].st);
 	if (doc->puzzles[i].st2)
 	    doc->puzzles[i].game->free_game(doc->puzzles[i].st2);
@@ -75,7 +77,7 @@ void document_free(document *doc)
  * another sheet (typically the solution to the first game_state).
  */
 void document_add_puzzle(document *doc, const game *game, game_params *par,
-			 game_state *st, game_state *st2)
+			 game_ui *ui, game_state *st, game_state *st2)
 {
     if (doc->npuzzles >= doc->puzzlesize) {
 	doc->puzzlesize += 32;
@@ -83,6 +85,7 @@ void document_add_puzzle(document *doc, const game *game, game_params *par,
     }
     doc->puzzles[doc->npuzzles].game = game;
     doc->puzzles[doc->npuzzles].par = par;
+    doc->puzzles[doc->npuzzles].ui = ui;
     doc->puzzles[doc->npuzzles].st = st;
     doc->puzzles[doc->npuzzles].st2 = st2;
     doc->npuzzles++;
@@ -274,14 +277,9 @@ void document_print_page(const document *doc, drawing *dr, int page_nr)
          * permit each game to choose its own?)
          */
         tilesize = 512;
-        {
-            game_ui *ui = pz->game->new_ui(pz->st);
-            pz->game->compute_size(pz->par, tilesize, ui,
-                                   &pixw, &pixh);
-            print_begin_puzzle(dr, xm, xc, ym, yc, pixw, pixh, w, scale);
-            pz->game->print(dr, pass == 0 ? pz->st : pz->st2, ui, tilesize);
-            pz->game->free_ui(ui);
-        }
+        pz->game->compute_size(pz->par, tilesize, pz->ui, &pixw, &pixh);
+        print_begin_puzzle(dr, xm, xc, ym, yc, pixw, pixh, w, scale);
+        pz->game->print(dr, pass == 0 ? pz->st : pz->st2, pz->ui, tilesize);
         print_end_puzzle(dr);
     }