Change: always allow to click on the toolbar icons for road/rail/dock/airport

This change allows a user to see what is available and what will become
available before it is available, instead of only disabling the button
with no further explanation. It also always allows building roads and
canals, even if no vehicles are available for road / water.

For rail/road/tram, a dropdown with available types is shown. If
none are available, it reads "None". If the type is not yet available,
it is greyed out.

For dock/airport, this always open the toolbar, but building airports,
docks, and depots buttons are disabled till vehicles are available
for those.

Road is the only exception, with the primary road always being
available. Here too, stations and depots are disabled till vehicles
become available. It does mean you can now always build roads to
for example help towns grow.

5 files changed, 22 insertions, 31 deletions

diff --git a/src/airport_gui.cpp b/src/airport_gui.cpp
index 8760e1f2a..62eca78f9 100644
--- a/src/airport_gui.cpp
+++ b/src/airport_gui.cpp
@@ -71,6 +71,7 @@ struct BuildAirToolbarWindow : Window {
 	BuildAirToolbarWindow(WindowDesc *desc, WindowNumber window_number) : Window(desc)
 	{
 		this->InitNested(window_number);
+		this->OnInvalidateData();
 		if (_settings_client.gui.link_terraform_toolbar) ShowTerraformToolbar(this);
 		this->last_user_action = WIDGET_LIST_END;
 	}
@@ -90,7 +91,13 @@ struct BuildAirToolbarWindow : Window {
 	{
 		if (!gui_scope) return;
 
-		if (!CanBuildVehicleInfrastructure(VEH_AIRCRAFT)) delete this;
+		bool can_build = CanBuildVehicleInfrastructure(VEH_AIRCRAFT);
+		this->SetWidgetsDisabledState(!can_build,
+			WID_AT_AIRPORT,
+			WIDGET_LIST_END);
+		if (!can_build) {
+			DeleteWindowById(WC_BUILD_STATION, TRANSPORT_AIR);
+		}
 	}
 
 	void OnClick(Point pt, int widget, int click_count) override
@@ -160,7 +167,6 @@ struct BuildAirToolbarWindow : Window {
  */
 static EventState AirportToolbarGlobalHotkeys(int hotkey)
 {
-	if (_game_mode != GM_NORMAL || !CanBuildVehicleInfrastructure(VEH_AIRCRAFT)) return ES_NOT_HANDLED;
 	Window *w = ShowBuildAirToolbar();
 	if (w == nullptr) return ES_NOT_HANDLED;
 	return w->OnHotkey(hotkey);
diff --git a/src/dock_gui.cpp b/src/dock_gui.cpp
index 30a60e74f..7e2d61857 100644
--- a/src/dock_gui.cpp
+++ b/src/dock_gui.cpp
@@ -144,17 +144,14 @@ struct BuildDocksToolbarWindow : Window {
 				break;
 
 			case WID_DT_DEPOT: // Build depot button
-				if (!CanBuildVehicleInfrastructure(VEH_SHIP)) return;
 				if (HandlePlacePushButton(this, WID_DT_DEPOT, SPR_CURSOR_SHIP_DEPOT, HT_RECT)) ShowBuildDocksDepotPicker(this);
 				break;
 
 			case WID_DT_STATION: // Build station button
-				if (!CanBuildVehicleInfrastructure(VEH_SHIP)) return;
 				if (HandlePlacePushButton(this, WID_DT_STATION, SPR_CURSOR_DOCK, HT_SPECIAL)) ShowBuildDockStationPicker(this);
 				break;
 
 			case WID_DT_BUOY: // Build buoy button
-				if (!CanBuildVehicleInfrastructure(VEH_SHIP)) return;
 				HandlePlacePushButton(this, WID_DT_BUOY, SPR_CURSOR_BUOY, HT_RECT);
 				break;
 
diff --git a/src/rail_gui.cpp b/src/rail_gui.cpp
index 177f72acc..37c365881 100644
--- a/src/rail_gui.cpp
+++ b/src/rail_gui.cpp
@@ -437,18 +437,6 @@ struct BuildRailToolbarWindow : Window {
 	}
 
 	/**
-	 * Some data on this window has become invalid.
-	 * @param data Information about the changed data.
-	 * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
-	 */
-	void OnInvalidateData(int data = 0, bool gui_scope = true) override
-	{
-		if (!gui_scope) return;
-
-		if (!CanBuildVehicleInfrastructure(VEH_TRAIN)) delete this;
-	}
-
-	/**
 	 * Configures the rail toolbar for railtype given
 	 * @param railtype the railtype to display
 	 */
@@ -781,7 +769,6 @@ struct BuildRailToolbarWindow : Window {
  */
 static EventState RailToolbarGlobalHotkeys(int hotkey)
 {
-	if (_game_mode != GM_NORMAL || !CanBuildVehicleInfrastructure(VEH_TRAIN)) return ES_NOT_HANDLED;
 	extern RailType _last_built_railtype;
 	Window *w = ShowBuildRailToolbar(_last_built_railtype);
 	if (w == nullptr) return ES_NOT_HANDLED;
diff --git a/src/road_gui.cpp b/src/road_gui.cpp
index 1e1f3e807..dff4d2bc1 100644
--- a/src/road_gui.cpp
+++ b/src/road_gui.cpp
@@ -304,7 +304,17 @@ struct BuildRoadToolbarWindow : Window {
 	{
 		if (!gui_scope) return;
 
-		if (_game_mode != GM_EDITOR && !CanBuildVehicleInfrastructure(VEH_ROAD, GetRoadTramType(this->roadtype))) delete this;
+		bool can_build = CanBuildVehicleInfrastructure(VEH_ROAD, GetRoadTramType(this->roadtype));
+		this->SetWidgetsDisabledState(!can_build,
+			WID_ROT_DEPOT,
+			WID_ROT_BUS_STATION,
+			WID_ROT_TRUCK_STATION,
+			WIDGET_LIST_END);
+		if (!can_build) {
+			DeleteWindowById(WC_BUS_STATION, TRANSPORT_ROAD);
+			DeleteWindowById(WC_TRUCK_STATION, TRANSPORT_ROAD);
+			DeleteWindowById(WC_BUILD_DEPOT, TRANSPORT_ROAD);
+		}
 	}
 
 	void Initialize(RoadType roadtype)
@@ -434,7 +444,6 @@ struct BuildRoadToolbarWindow : Window {
 				break;
 
 			case WID_ROT_DEPOT:
-				if (_game_mode == GM_EDITOR || !CanBuildVehicleInfrastructure(VEH_ROAD, GetRoadTramType(this->roadtype))) return;
 				if (HandlePlacePushButton(this, WID_ROT_DEPOT, this->rti->cursor.depot, HT_RECT)) {
 					ShowRoadDepotPicker(this);
 					this->last_started_action = widget;
@@ -442,7 +451,6 @@ struct BuildRoadToolbarWindow : Window {
 				break;
 
 			case WID_ROT_BUS_STATION:
-				if (_game_mode == GM_EDITOR || !CanBuildVehicleInfrastructure(VEH_ROAD, GetRoadTramType(this->roadtype))) return;
 				if (HandlePlacePushButton(this, WID_ROT_BUS_STATION, SPR_CURSOR_BUS_STATION, HT_RECT)) {
 					ShowRVStationPicker(this, ROADSTOP_BUS);
 					this->last_started_action = widget;
@@ -450,7 +458,6 @@ struct BuildRoadToolbarWindow : Window {
 				break;
 
 			case WID_ROT_TRUCK_STATION:
-				if (_game_mode == GM_EDITOR || !CanBuildVehicleInfrastructure(VEH_ROAD, GetRoadTramType(this->roadtype))) return;
 				if (HandlePlacePushButton(this, WID_ROT_TRUCK_STATION, SPR_CURSOR_TRUCK_STATION, HT_RECT)) {
 					ShowRVStationPicker(this, ROADSTOP_TRUCK);
 					this->last_started_action = widget;
@@ -711,7 +718,6 @@ static EventState RoadTramToolbarGlobalHotkeys(int hotkey, RoadType last_build,
 	Window* w = nullptr;
 	switch (_game_mode) {
 		case GM_NORMAL:
-			if (!CanBuildVehicleInfrastructure(VEH_ROAD, rtt)) return ES_NOT_HANDLED;
 			w = ShowBuildRoadToolbar(last_build);
 			break;
 
diff --git a/src/toolbar_gui.cpp b/src/toolbar_gui.cpp
index 224c8ccdb..6a851d2b5 100644
--- a/src/toolbar_gui.cpp
+++ b/src/toolbar_gui.cpp
@@ -2033,11 +2033,6 @@ struct MainToolbarWindow : Window {
 		this->SetWidgetDisabledState(WID_TN_GOAL, Goal::GetNumItems() == 0);
 		this->SetWidgetDisabledState(WID_TN_STORY, StoryPage::GetNumItems() == 0);
 
-		this->SetWidgetDisabledState(WID_TN_RAILS, !CanBuildVehicleInfrastructure(VEH_TRAIN));
-		this->SetWidgetDisabledState(WID_TN_ROADS, !CanBuildVehicleInfrastructure(VEH_ROAD, RTT_ROAD));
-		this->SetWidgetDisabledState(WID_TN_TRAMS, !CanBuildVehicleInfrastructure(VEH_ROAD, RTT_TRAM));
-		this->SetWidgetDisabledState(WID_TN_AIR, !CanBuildVehicleInfrastructure(VEH_AIRCRAFT));
-
 		this->DrawWidgets();
 	}
 
@@ -2078,11 +2073,11 @@ struct MainToolbarWindow : Window {
 			case MTHK_AIRCRAFT_LIST: ShowVehicleListWindow(_local_company, VEH_AIRCRAFT); break;
 			case MTHK_ZOOM_IN: ToolbarZoomInClick(this); break;
 			case MTHK_ZOOM_OUT: ToolbarZoomOutClick(this); break;
-			case MTHK_BUILD_RAIL: if (CanBuildVehicleInfrastructure(VEH_TRAIN)) ShowBuildRailToolbar(_last_built_railtype); break;
+			case MTHK_BUILD_RAIL: ShowBuildRailToolbar(_last_built_railtype); break;
 			case MTHK_BUILD_ROAD: ShowBuildRoadToolbar(_last_built_roadtype); break;
-			case MTHK_BUILD_TRAM: if (CanBuildVehicleInfrastructure(VEH_ROAD, RTT_TRAM)) ShowBuildRoadToolbar(_last_built_tramtype); break;
+			case MTHK_BUILD_TRAM: ShowBuildRoadToolbar(_last_built_tramtype); break;
 			case MTHK_BUILD_DOCKS: ShowBuildDocksToolbar(); break;
-			case MTHK_BUILD_AIRPORT: if (CanBuildVehicleInfrastructure(VEH_AIRCRAFT)) ShowBuildAirToolbar(); break;
+			case MTHK_BUILD_AIRPORT: ShowBuildAirToolbar(); break;
 			case MTHK_BUILD_TREES: ShowBuildTreesToolbar(); break;
 			case MTHK_MUSIC: ShowMusicWindow(); break;
 			case MTHK_AI_DEBUG: ShowAIDebugWindow(); break;