Add setting to control if and how land purchasing is permitted

src/lang/english.txt

@@ -1893,6 +1893,16 @@ STR_CONFIG_SETTING_ALLOW_GRF_OBJECTS_UNDER_BRIDGES_HELPTEXT     :Allow all NewGR
 STR_CONFIG_SETTING_ALLOW_STATIONS_UNDER_BRIDGES                 :Allow stations under bridges: {STRING2}
 STR_CONFIG_SETTING_ALLOW_STATIONS_UNDER_BRIDGES_HELPTEXT        :Allow stations to be built under bridges (excluding airports, and rail stations/waypoints where the required bridge clearance is set by the GRF).{}This may result in graphical issues.
 
+STR_CONFIG_SETTING_PURCHASE_LAND_PERMITTED                      :Permit purchasing land: {STRING2}
+STR_CONFIG_SETTING_PURCHASE_LAND_PERMITTED_HELPTEXT             :Set whether companies are permitted to purchase tiles of land, and in what quantity
+
+STR_PURCHASE_LAND_PERMITTED_NO                                  :No
+STR_PURCHASE_LAND_PERMITTED_SINGLE                              :Yes, 1 tile at a time
+STR_PURCHASE_LAND_PERMITTED_AREA                                :Yes, large areas at a time
+
+STR_PURCHASE_LAND_NOT_PERMITTED                                 :Purchasing of land is not permitted
+STR_PURCHASE_LAND_NOT_PERMITTED_BULK                            :Purchasing of large areas of land is not permitted
+
 STR_CONFIG_SETTING_QUERY_CAPTION                                :{WHITE}Change setting value
 
 STR_CONFIG_SETTING_ADJACENT_CROSSINGS                           :Close adjacent level crossings: {STRING2}

src/object_cmd.cpp

@@ -226,6 +226,7 @@ CommandCost CmdBuildObject(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 	TileArea ta(tile, size_x, size_y);
 
 	if (type == OBJECT_OWNED_LAND) {
+		if (_settings_game.construction.purchase_land_permitted == 0) return_cmd_error(STR_PURCHASE_LAND_NOT_PERMITTED);
 		/* Owned land is special as it can be placed on any slope. */
 		cost.AddCost(DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR));
 	} else {
@@ -375,6 +376,8 @@ CommandCost CmdBuildObject(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 CommandCost CmdPurchaseLandArea(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
 {
 	if (p1 >= MapSize()) return CMD_ERROR;
+	if (_settings_game.construction.purchase_land_permitted == 0) return_cmd_error(STR_PURCHASE_LAND_NOT_PERMITTED);
+	if (_settings_game.construction.purchase_land_permitted != 2) return_cmd_error(STR_PURCHASE_LAND_NOT_PERMITTED_BULK);
 
 	Money money = GetAvailableMoneyForCommand();
 	CommandCost cost(EXPENSES_CONSTRUCTION);

src/settings_gui.cpp

@@ -1746,6 +1746,7 @@ static SettingsContainer &GetSettingsTree()
 			limitations->Add(new SettingEntry("construction.rail_custom_bridge_heads"));
 			limitations->Add(new SettingEntry("construction.allow_grf_objects_under_bridges"));
 			limitations->Add(new SettingEntry("construction.allow_stations_under_bridges"));
+			limitations->Add(new SettingEntry("construction.purchase_land_permitted"));
 		}
 
 		SettingsPage *disasters = main->Add(new SettingsPage(STR_CONFIG_SETTING_ACCIDENTS));

src/settings_type.h

@@ -378,6 +378,7 @@ struct ConstructionSettings {
 	uint8  rail_custom_bridge_heads;         ///< allow construction of rail custom bridge heads
 	bool   allow_grf_objects_under_bridges;  ///< allow all NewGRF objects under bridges
 	bool   allow_stations_under_bridges;     ///< allow all station tiles under bridges
+	byte   purchase_land_permitted;          ///< whether and how purchasing land is permitted
 
 	uint32 terraform_per_64k_frames;         ///< how many tile heights may, over a long period, be terraformed per 65536 frames?
 	uint16 terraform_frame_burst;            ///< how many tile heights may, over a short period, be terraformed?

src/table/settings.ini

@@ -1524,6 +1524,20 @@ str      = STR_CONFIG_SETTING_ALLOW_STATIONS_UNDER_BRIDGES
 strhelp  = STR_CONFIG_SETTING_ALLOW_STATIONS_UNDER_BRIDGES_HELPTEXT
 patxname = ""allow_stations_under_bridges.construction.allow_stations_under_bridges""
 
+[SDT_VAR]
+base     = GameSettings
+var      = construction.purchase_land_permitted
+type     = SLE_UINT8
+guiflags = SGF_MULTISTRING
+def      = 1
+min      = 0
+max      = 2
+interval = 1
+str      = STR_CONFIG_SETTING_PURCHASE_LAND_PERMITTED
+strhelp  = STR_CONFIG_SETTING_PURCHASE_LAND_PERMITTED_HELPTEXT
+strval   = STR_PURCHASE_LAND_PERMITTED_NO
+patxname = ""purchase_land_permitted.construction.purchase_land_permitted""
+
 [SDT_BOOL]
 base     = GameSettings
 var      = station.adjacent_stations

src/terraform_gui.cpp

@@ -179,6 +179,7 @@ struct TerraformToolbarWindow : Window {
 		/* Don't show the place object button when there are no objects to place. */
 		NWidgetStacked *show_object = this->GetWidget<NWidgetStacked>(WID_TT_SHOW_PLACE_OBJECT);
 		show_object->SetDisplayedPlane(ObjectClass::GetUIClassCount() != 0 ? 0 : SZSP_NONE);
+		SetWidgetDisabledState(WID_TT_BUY_LAND, _settings_game.construction.purchase_land_permitted == 0);
 	}
 
 	virtual void OnClick(Point pt, int widget, int click_count)
@@ -253,7 +254,19 @@ struct TerraformToolbarWindow : Window {
 				break;
 
 			case WID_TT_BUY_LAND: // Buy land button
-				VpStartPlaceSizing(tile, VPM_X_AND_Y, DDSP_BUY_LAND);
+				switch (_settings_game.construction.purchase_land_permitted) {
+					case 0:
+					case 1:
+						DoCommandP(tile, OBJECT_OWNED_LAND, 0, CMD_BUILD_OBJECT | CMD_MSG(STR_ERROR_CAN_T_PURCHASE_THIS_LAND), CcPlaySound_SPLAT_RAIL);
+						break;
+
+					case 2:
+						VpStartPlaceSizing(tile, VPM_X_AND_Y, DDSP_BUY_LAND);
+						break;
+
+					default:
+						NOT_REACHED();
+				}
 				break;
 
 			case WID_TT_MEASUREMENT_TOOL: