(svn r15695) -Feature [FS#2672]: Allow the number of towns that will be generated in the generate world window to be customized.

Some warnings: 
-the maximum number of towns to be accepted is set to 5000
-the minimum number of towns to be accepted is set to 1
-the number that is specified is NOT guaranteed to be the exact number of towns generated.  The normal mechanism of town creation has not been modified.  So town placement can still fail.
-setting a custom number of town will change your difficulty settings to custom as well

7 files changed, 21 insertions, 5 deletions

diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index 49b8bc633..fd9346c8f 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -25,6 +25,7 @@
 #include "core/random_func.hpp"
 #include "landscape_type.h"
 #include "querystring_gui.h"
+#include "town.h"
 
 #include "table/strings.h"
 #include "table/sprites.h"
@@ -285,7 +286,7 @@ static const StringID _smoothness[]  = {STR_CONFIG_SETTING_ROUGHNESS_OF_TERRAIN_
 static const StringID _tree_placer[] = {STR_CONFIG_SETTING_TREE_PLACER_NONE, STR_CONFIG_SETTING_TREE_PLACER_ORIGINAL, STR_CONFIG_SETTING_TREE_PLACER_IMPROVED, INVALID_STRING_ID};
 static const StringID _rotation[]    = {STR_CONFIG_SETTING_HEIGHTMAP_ROTATION_COUNTER_CLOCKWISE, STR_CONFIG_SETTING_HEIGHTMAP_ROTATION_CLOCKWISE, INVALID_STRING_ID};
 static const StringID _landscape[]   = {STR_CONFIG_SETTING_LAND_GENERATOR_ORIGINAL, STR_CONFIG_SETTING_LAND_GENERATOR_TERRA_GENESIS, INVALID_STRING_ID};
-static const StringID _num_towns[]   = {STR_NUM_VERY_LOW, STR_6816_LOW, STR_6817_NORMAL, STR_6818_HIGH, INVALID_STRING_ID};
+static const StringID _num_towns[]   = {STR_NUM_VERY_LOW, STR_6816_LOW, STR_6817_NORMAL, STR_6818_HIGH, STR_02BF_CUSTOM, INVALID_STRING_ID};
 static const StringID _num_inds[]    = {STR_NONE, STR_NUM_VERY_LOW, STR_6816_LOW, STR_6817_NORMAL, STR_6818_HIGH, INVALID_STRING_ID};
 
 struct GenerateLandscapeWindow : public QueryStringBaseWindow {
@@ -571,6 +572,11 @@ struct GenerateLandscapeWindow : public QueryStringBaseWindow {
 			case GLAND_SMOOTHNESS_PULLDOWN:    _settings_newgame.game_creation.tgen_smoothness = index;  break;
 
 			case GLAND_TOWN_PULLDOWN:
+				if (index == CUSTOM_TOWN_NUMBER_DIFFICULTY) {
+					this->widget_id = widget;
+					SetDParam(0, _settings_newgame.game_creation.custom_town_number);
+					ShowQueryString(STR_CONFIG_SETTING_INT32, STR_NUMBER_OF_TOWNS, 5, 50, this, CS_NUMERAL, QSF_NONE);
+				};
 				IConsoleSetSetting("difficulty.number_towns", index);
 				break;
 
@@ -621,6 +627,10 @@ struct GenerateLandscapeWindow : public QueryStringBaseWindow {
 					this->InvalidateWidget(GLAND_SNOW_LEVEL_TEXT);
 					_settings_newgame.game_creation.snow_line_height = Clamp(value, 2, MAX_SNOWLINE_HEIGHT);
 					break;
+
+				case GLAND_TOWN_PULLDOWN:
+					_settings_newgame.game_creation.custom_town_number = Clamp(value, 1, CUSTOM_TOWN_MAX_NUMBER);
+					break;
 			}
 
 			this->SetDirty();
diff --git a/src/lang/english.txt b/src/lang/english.txt
index f5075d9a9..0519d74fe 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -666,7 +666,6 @@ STR_FULL                                                        :Full
 STR_02BA                                                        :{SILVER}- -  {COMPANY}  - -
 STR_02BB_TOWN_DIRECTORY                                         :Town directory
 STR_02BD                                                        :{BLACK}{STRING}
-STR_02BF_CUSTOM                                                 :Custom
 
 STR_CHECKMARK                                                   :{CHECKMARK}
 ############ range for menu starts
@@ -2129,6 +2128,7 @@ STR_NUM_VERY_LOW                                                :Very low
 STR_6816_LOW                                                    :Low
 STR_6817_NORMAL                                                 :Normal
 STR_6818_HIGH                                                   :High
+STR_02BF_CUSTOM                                                 :Custom
 STR_6819                                                        :{BLACK}{SMALLLEFTARROW}
 STR_681A                                                        :{BLACK}{SMALLRIGHTARROW}
 STR_681B_VERY_SLOW                                              :Very Slow
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index f30440d5a..f904d45d1 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -40,7 +40,7 @@
 
 #include "saveload_internal.h"
 
-extern const uint16 SAVEGAME_VERSION = 114;
+extern const uint16 SAVEGAME_VERSION = 115;
 
 SavegameType _savegame_type; ///< type of savegame we are loading
 
diff --git a/src/settings.cpp b/src/settings.cpp
index 9760ded42..727f9800a 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -1309,7 +1309,7 @@ const SettingDesc _settings[] = {
 	/* Do not ADD or REMOVE something in this "difficulty.XXX" table or before it. It breaks savegame compatability. */
 	 SDT_CONDVAR(GameSettings, difficulty.max_no_competitors,        SLE_UINT8, 97, SL_MAX_VERSION, 0, 0,     2,0,MAX_COMPANIES-1,1,STR_NULL,                                  DifficultyChange),
 	SDT_CONDNULL(                                                            1, 97, 109),
-	 SDT_CONDVAR(GameSettings, difficulty.number_towns,              SLE_UINT8, 97, SL_MAX_VERSION, 0,NG,     2,     0,      3,  1, STR_NUM_VERY_LOW,                          DifficultyChange),
+	 SDT_CONDVAR(GameSettings, difficulty.number_towns,              SLE_UINT8, 97, SL_MAX_VERSION, 0,NG,     2,     0,      4,  1, STR_NUM_VERY_LOW,                          DifficultyChange),
 	 SDT_CONDVAR(GameSettings, difficulty.number_industries,         SLE_UINT8, 97, SL_MAX_VERSION, 0,NG,     4,     0,      4,  1, STR_NONE,                                  DifficultyChange),
 	 SDT_CONDVAR(GameSettings, difficulty.max_loan,                 SLE_UINT32, 97, SL_MAX_VERSION, 0,NG|CR,300000,100000,500000,50000,STR_NULL,                               DifficultyChange),
 	 SDT_CONDVAR(GameSettings, difficulty.initial_interest,          SLE_UINT8, 97, SL_MAX_VERSION, 0,NG,     2,     2,      4,  1, STR_NULL,                                  DifficultyChange),
@@ -1489,6 +1489,7 @@ const SettingDesc _settings[] = {
 	     SDT_VAR(GameSettings, game_creation.map_y,                           SLE_UINT8,                     S, 0,     8,                     6,      11, 0, STR_CONFIG_SETTING_MAP_Y,                 NULL),
 	SDT_CONDBOOL(GameSettings, construction.freeform_edges,                             111, SL_MAX_VERSION, 0, 0,  true,                                    STR_CONFIG_SETTING_ENABLE_FREEFORM_EDGES, CheckFreeformEdges),
 	 SDT_CONDVAR(GameSettings, game_creation.water_borders,                   SLE_UINT8,111, SL_MAX_VERSION, 0, 0,    15,                     0,      16, 0, STR_NULL,                                 NULL),
+	 SDT_CONDVAR(GameSettings, game_creation.custom_town_number,             SLE_UINT16,115, SL_MAX_VERSION, 0, 0,     1,                     1,    5000, 0, STR_NULL,                                 NULL),
 
  SDT_CONDOMANY(GameSettings, locale.currency,                               SLE_UINT8, 97, SL_MAX_VERSION, N, 0, 0, CUSTOM_CURRENCY_ID, "GBP|USD|EUR|YEN|ATS|BEF|CHF|CZK|DEM|DKK|ESP|FIM|FRF|GRD|HUF|ISK|ITL|NLG|NOK|PLN|ROL|RUR|SIT|SEK|YTL|SKK|BRR|custom", STR_NULL, NULL, NULL),
  SDT_CONDOMANY(GameSettings, locale.units,                                  SLE_UINT8, 97, SL_MAX_VERSION, N, 0, 1, 2, "imperial|metric|si", STR_NULL, NULL, NULL),
diff --git a/src/settings_type.h b/src/settings_type.h
index 6185aae72..e96a25802 100644
--- a/src/settings_type.h
+++ b/src/settings_type.h
@@ -156,6 +156,7 @@ struct GameCreationSettings {
 	byte   landscape;                        ///< the landscape we're currently in
 	byte   snow_line;                        ///< the snowline level in this game
 	byte   water_borders;                    ///< bitset of the borders that are water
+	uint16 custom_town_number;               ///< manually entered number of towns
 };
 
 /** Settings related to construction in-game */
diff --git a/src/town.h b/src/town.h
index ac7464e1f..004234cd8 100644
--- a/src/town.h
+++ b/src/town.h
@@ -95,6 +95,9 @@ struct BuildingCounts {
 	uint8 class_count[HOUSE_CLASS_MAX];
 };
 
+static const int CUSTOM_TOWN_NUMBER_DIFFICULTY  = 4; ///< value for custom town number in difficulty settings
+static const int CUSTOM_TOWN_MAX_NUMBER = 5000;  ///< this is the maximum number of towns a user can specify in customisation
+
 DECLARE_OLD_POOL(Town, Town, 3, 8000)
 
 struct Town : PoolItem<Town, TownID, &_Town_pool> {
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
index f656fe76b..a4a47522c 100644
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -1633,7 +1633,8 @@ static const byte _num_initial_towns[4] = {5, 11, 23, 46};  // very low, low, no
 bool GenerateTowns(TownLayout layout)
 {
 	uint num = 0;
-	uint n = ScaleByMapSize(_num_initial_towns[_settings_game.difficulty.number_towns] + (Random() & 7));
+	uint difficulty = _settings_game.difficulty.number_towns;
+	uint n = difficulty == CUSTOM_TOWN_NUMBER_DIFFICULTY ? _settings_game.game_creation.custom_town_number : ScaleByMapSize(_num_initial_towns[difficulty] + (Random() & 7));
 	uint num_cities = _settings_game.economy.larger_towns == 0 ? 0 : n / _settings_game.economy.larger_towns;
 
 	SetGeneratingWorldProgress(GWP_TOWN, n);