Feature: Add a window for joining depots.

src/depot.cpp

@@ -100,6 +100,7 @@ void Depot::AfterAddRemove(TileArea ta, bool adding)
 		this->ta.Add(tile);
 	}
 
+	VehicleType veh_type = this->veh_type;
 	if (this->ta.tile != INVALID_TILE) {
 		this->RescanDepotTiles();
 		assert(!this->depot_tiles.empty());
@@ -107,6 +108,8 @@ void Depot::AfterAddRemove(TileArea ta, bool adding)
 	} else {
 		delete this;
 	}
+
+	InvalidateWindowData(WC_SELECT_DEPOT, veh_type);
 }
 
 /**

src/depot_cmd.cpp

@@ -75,3 +75,69 @@ CommandCost CmdRenameDepot(DoCommandFlag flags, DepotID depot_id, const std::str
 	}
 	return CommandCost();
 }
+
+/**
+ * Look for or check depot to join to, building a new one if necessary.
+ * @param ta The area of the new depot.
+ * @param veh_type The vehicle type of the new depot.
+ * @param join_to DepotID of the depot to join to.
+ *                     If INVALID_DEPOT, look whether it is possible to join to an existing depot.
+ *                     If NEW_DEPOT, directly create a new depot.
+ * @param depot The pointer to the depot.
+ * @param adjacent Whether adjacent depots are allowed
+ * @return command cost with the error or 'okay'
+ */
+CommandCost FindJoiningDepot(TileArea ta, VehicleType veh_type, DepotID &join_to, Depot *&depot, bool adjacent, DoCommandFlag flags)
+{
+	/* Look for a joining depot if needed. */
+	if (join_to == INVALID_DEPOT) {
+		assert(depot == nullptr);
+		DepotID closest_depot = INVALID_DEPOT;
+
+		TileArea check_area(ta);
+		check_area.Expand(1);
+
+		/* Check around to see if there's any depot there. */
+		for (TileIndex tile_cur : check_area) {
+			if (IsValidTile(tile_cur) && IsDepotTile(tile_cur)) {
+				Depot *d = Depot::GetByTile(tile_cur);
+				assert(d != nullptr);
+				if (d->veh_type != veh_type) continue;
+				if (d->owner != _current_company) continue;
+
+				if (closest_depot == INVALID_DEPOT) {
+					closest_depot = d->index;
+				} else if (closest_depot != d->index) {
+					if (!adjacent) return_cmd_error(STR_ERROR_ADJOINS_MORE_THAN_ONE_EXISTING_DEPOT);
+				}
+			}
+		}
+
+		if (closest_depot != INVALID_DEPOT) {
+			assert(Depot::IsValidID(closest_depot));
+			depot = Depot::Get(closest_depot);
+		}
+
+		join_to = depot == nullptr ? NEW_DEPOT : depot->index;
+	}
+
+	/* At this point, join_to is NEW_DEPOT or a valid DepotID. */
+
+	if (join_to == NEW_DEPOT) {
+		/* New depot needed. */
+		if (!Depot::CanAllocateItem()) return CMD_ERROR;
+		if (flags & DC_EXEC) {
+			depot = new Depot(ta.tile, veh_type, _current_company);
+			depot->build_date = TimerGameCalendar::date;
+		}
+	} else {
+		/* Joining depots. */
+		assert(Depot::IsValidID(join_to));
+		depot = Depot::Get(join_to);
+		assert(depot->owner == _current_company);
+		assert(depot->veh_type == veh_type);
+		return depot->BeforeAddTiles(ta);
+	}
+
+	return CommandCost();
+}

src/depot_func.h

@@ -10,8 +10,10 @@
 #ifndef DEPOT_FUNC_H
 #define DEPOT_FUNC_H
 
+#include "depot_type.h"
 #include "vehicle_type.h"
 #include "slope_func.h"
+#include "command_type.h"
 
 void ShowDepotWindow(DepotID depot_id);
 void InitDepotWindowBlockSizes();
@@ -33,4 +35,10 @@ inline bool CanBuildDepotByTileh(DiagDirection direction, Slope tileh)
 	return IsSteepSlope(tileh) ? (tileh & entrance_corners) == entrance_corners : (tileh & entrance_corners) != 0;
 }
 
+struct Depot;
+CommandCost FindJoiningDepot(TileArea ta, VehicleType veh_type, DepotID &join_to, Depot *&depot, bool adjacent, DoCommandFlag flags);
+
+using DepotPickerCmdProc = std::function<bool(DepotID join_to)>;
+void ShowSelectDepotIfNeeded(TileArea ta, DepotPickerCmdProc proc, VehicleType veh_type);
+
 #endif /* DEPOT_FUNC_H */

src/depot_gui.cpp

@@ -33,6 +33,7 @@
 #include "train_cmd.h"
 #include "vehicle_cmd.h"
 #include "core/geometry_func.hpp"
+#include "depot_func.h"
 
 #include "widgets/depot_widget.h"
 
@@ -1167,3 +1168,244 @@ void DeleteDepotHighlightOfVehicle(const Vehicle *v)
 		if (w->sel == v->index) ResetObjectToPlace();
 	}
 }
+
+static std::vector<DepotID> _depots_nearby_list;
+
+/** Structure with user-data for AddNearbyDepot. */
+struct AddNearbyDepotData {
+	TileArea search_area;  ///< Search area.
+	VehicleType type;      ///< Vehicle type of the searched depots.
+};
+
+/**
+ * Add depot on this tile to _depots_nearby_list if it's fully within the
+ * depot spread.
+ * @param tile Tile just being checked
+ * @param user_data Pointer to TileArea context
+ */
+static bool AddNearbyDepot(TileIndex tile, void *user_data)
+{
+	AddNearbyDepotData *andd = (AddNearbyDepotData *)user_data;
+
+	/* Check if own depot and if we stay within station spread */
+	if (!IsDepotTile(tile)) return false;
+	Depot *dep = Depot::GetByTile(tile);
+	if (dep->owner != _local_company || dep->veh_type != andd->type ||
+			(find(_depots_nearby_list.begin(), _depots_nearby_list.end(), dep->index) != _depots_nearby_list.end())) {
+		return false;
+	}
+
+	CommandCost cost = dep->BeforeAddTiles(andd->search_area);
+	if (cost.Succeeded()) {
+		_depots_nearby_list.push_back(dep->index);
+	}
+
+	return false;
+}
+
+/**
+ * Circulate around the to-be-built depot to find depots we could join.
+ * Make sure that only depots are returned where joining wouldn't exceed
+ * depot spread and are our own depot.
+ * @param ta Base tile area of the to-be-built depot
+ * @param veh_type Vehicle type depots to look for
+ * @param distant_join Search for adjacent depots (false) or depots fully
+ *                     within depot spread
+ */
+static const Depot *FindDepotsNearby(TileArea ta, VehicleType veh_type, bool distant_join)
+{
+	_depots_nearby_list.clear();
+	_depots_nearby_list.push_back(NEW_DEPOT);
+
+	/* Check the inside, to return, if we sit on another big depot */
+	Depot *depot;
+	for (TileIndex t : ta) {
+		if (!IsDepotTile(t)) continue;
+		depot = Depot::GetByTile(t);
+		if (depot->veh_type == veh_type && depot->owner == _current_company) return depot;
+	}
+
+	/* Only search tiles where we have a chance to stay within the depot spread.
+	 * The complete check needs to be done in the callback as we don't know the
+	 * extent of the found depot, yet. */
+	if (distant_join && std::min(ta.w, ta.h) >= _settings_game.depot.depot_spread) return nullptr;
+	uint max_dist = distant_join ? _settings_game.depot.depot_spread - std::min(ta.w, ta.h) : 1;
+
+	AddNearbyDepotData andd;
+	andd.search_area = ta;
+	andd.type = veh_type;
+
+	TileIndex tile = TileAddByDir(andd.search_area.tile, DIR_N);
+	CircularTileSearch(&tile, max_dist, ta.w, ta.h, AddNearbyDepot, &andd);
+
+	return nullptr;
+}
+
+/**
+ * Check whether we need to show the depot selection window.
+ * @param ta Tile area of the to-be-built depot.
+ * @param proc The procedure for the depot picker.
+ * @param veh_type the vehicle type of the depot.
+ * @return whether we need to show the depot selection window.
+ */
+static bool DepotJoinerNeeded(TileArea ta, VehicleType veh_type)
+{
+	/* If a window is already opened and we didn't ctrl-click,
+	 * return true (i.e. just flash the old window) */
+	Window *selection_window = FindWindowById(WC_SELECT_DEPOT, veh_type);
+	if (selection_window != nullptr) {
+		/* Abort current distant-join and start new one */
+		selection_window->Close();
+		UpdateTileSelection();
+	}
+
+	/* Only show the popup if we press ctrl. */
+	if (!_ctrl_pressed) return false;
+
+	/* Test for adjacent depot or depot below selection.
+	 * If adjacent-stations is disabled and we are building next to a depot, do not show the selection window.
+	 * but join the other depot immediately. */
+	const Depot *depot = FindDepotsNearby(ta, veh_type, false);
+	return depot == nullptr && (_settings_game.depot.adjacent_depots || std::any_of(std::begin(_depots_nearby_list), std::end(_depots_nearby_list), [](DepotID s) { return s != NEW_DEPOT; }));
+}
+
+/**
+ * Window for selecting depots to (distant) join to.
+ */
+struct SelectDepotWindow : Window {
+	DepotPickerCmdProc select_depot_proc; ///< The procedure params
+	TileArea area;                        ///< Location of new depot
+	Scrollbar *vscroll;                   ///< Vertical scrollbar for the window
+
+	SelectDepotWindow(WindowDesc &desc, TileArea ta, DepotPickerCmdProc& proc, VehicleType veh_type) :
+		Window(desc),
+		select_depot_proc(std::move(proc)),
+		area(ta)
+	{
+		this->CreateNestedTree();
+		this->vscroll = this->GetScrollbar(WID_JD_SCROLLBAR);
+		this->FinishInitNested(veh_type);
+		this->OnInvalidateData(0);
+	}
+
+	void UpdateWidgetSize(int widget, Dimension &size, const Dimension &padding, [[maybe_unused]] Dimension &fill, Dimension &resize) override
+	{
+		if (widget != WID_JD_PANEL) return;
+
+		resize.height = GetCharacterHeight(FS_NORMAL);
+		size.height = 5 * resize.height + padding.height;
+
+		/* Determine the widest string. */
+		Dimension d = GetStringBoundingBox(STR_JOIN_DEPOT_CREATE_SPLITTED_DEPOT);
+		for (const auto &depot : _depots_nearby_list) {
+			if (depot == NEW_DEPOT) continue;
+			const Depot *dep = Depot::Get(depot);
+			SetDParam(0, this->window_number);
+			SetDParam(1, dep->index);
+			d = maxdim(d, GetStringBoundingBox(STR_DEPOT_LIST_DEPOT));
+		}
+
+		d.height = 5 * resize.height;
+		d.width += padding.width;
+		d.height += padding.height;
+		size = d;
+	}
+
+	void DrawWidget(const Rect &r, int widget) const override
+	{
+		if (widget != WID_JD_PANEL) return;
+
+		Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
+
+		auto [first, last] = this->vscroll->GetVisibleRangeIterators(_depots_nearby_list);
+		for (auto it = first; it != last; ++it, tr.top += this->resize.step_height) {
+			if (*it == NEW_DEPOT) {
+				DrawString(tr, STR_JOIN_DEPOT_CREATE_SPLITTED_DEPOT);
+			} else {
+				SetDParam(0, this->window_number);
+				SetDParam(1, *it);
+				[[maybe_unused]] Depot *depot = Depot::GetIfValid(*it);
+				assert(depot != nullptr);
+				DrawString(tr, STR_DEPOT_LIST_DEPOT);
+			}
+		}
+	}
+
+	void OnClick(Point pt, int widget, [[maybe_unused]] int click_count) override
+	{
+		if (widget != WID_JD_PANEL) return;
+
+		auto it = this->vscroll->GetScrolledItemFromWidget(_depots_nearby_list, pt.y, this, WID_JD_PANEL, WidgetDimensions::scaled.framerect.top);
+		if (it == _depots_nearby_list.end()) return;
+
+		/* Execute stored Command */
+		this->select_depot_proc(*it);
+
+		InvalidateWindowData(WC_SELECT_DEPOT, window_number);
+		this->Close();
+	}
+
+	void OnRealtimeTick([[maybe_unused]] uint delta_ms) override
+	{
+		if (_thd.dirty & 2) {
+			_thd.dirty &= ~2;
+			this->SetDirty();
+		}
+	}
+
+	void OnResize() override
+	{
+		this->vscroll->SetCapacityFromWidget(this, WID_JD_PANEL, WidgetDimensions::scaled.framerect.Vertical());
+	}
+
+	/**
+	 * 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([[maybe_unused]] int data = 0, bool gui_scope = true) override
+	{
+		if (!gui_scope) return;
+		FindDepotsNearby(this->area, (VehicleType)this->window_number, true);
+		this->vscroll->SetCount((uint)_depots_nearby_list.size());
+		this->SetDirty();
+	}
+};
+
+static const NWidgetPart _nested_select_depot_widgets[] = {
+	NWidget(NWID_HORIZONTAL),
+		NWidget(WWT_CLOSEBOX, COLOUR_DARK_GREEN),
+		NWidget(WWT_CAPTION, COLOUR_DARK_GREEN, WID_JD_CAPTION), SetDataTip(STR_JOIN_DEPOT_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
+		NWidget(WWT_DEFSIZEBOX, COLOUR_DARK_GREEN),
+	EndContainer(),
+	NWidget(NWID_HORIZONTAL),
+		NWidget(WWT_PANEL, COLOUR_DARK_GREEN, WID_JD_PANEL), SetResize(1, 0), SetScrollbar(WID_JD_SCROLLBAR), EndContainer(),
+		NWidget(NWID_VERTICAL),
+			NWidget(NWID_VSCROLLBAR, COLOUR_DARK_GREEN, WID_JD_SCROLLBAR),
+			NWidget(WWT_RESIZEBOX, COLOUR_DARK_GREEN),
+		EndContainer(),
+	EndContainer(),
+};
+
+static WindowDesc _select_depot_desc(
+	WDP_AUTO, "build_depot_join", 200, 180,
+	WC_SELECT_DEPOT, WC_NONE,
+	WDF_CONSTRUCTION,
+	_nested_select_depot_widgets
+);
+
+/**
+ * Show the depot selection window when needed. If not, build the depot.
+ * @param ta Area to build the depot in.
+ * @param proc Details of the procedure for the depot picker.
+ * @param veh_type Vehicle type of the depot to be built.
+ */
+void ShowSelectDepotIfNeeded(TileArea ta, DepotPickerCmdProc proc, VehicleType veh_type)
+{
+	if (DepotJoinerNeeded(ta, veh_type)) {
+		if (!_settings_client.gui.persistent_buildingtools) ResetObjectToPlace();
+		new SelectDepotWindow(_select_depot_desc, ta, proc, veh_type);
+	} else {
+		proc(INVALID_DEPOT);
+	}
+}

src/depot_type.h

@@ -14,6 +14,7 @@ typedef uint16_t DepotID; ///< Type for the unique identifier of depots.
 struct Depot;
 
 static const DepotID INVALID_DEPOT = UINT16_MAX;
+static const DepotID NEW_DEPOT     = INVALID_DEPOT - 1;
 
 static const uint MAX_LENGTH_DEPOT_NAME_CHARS = 32; ///< The maximum length of a depot name in characters including '\0'
 

src/dock_gui.cpp

@@ -275,6 +275,7 @@ struct BuildDocksToolbarWindow : Window {
 		CloseWindowById(WC_BUILD_STATION, TRANSPORT_WATER);
 		CloseWindowById(WC_BUILD_DEPOT, TRANSPORT_WATER);
 		CloseWindowById(WC_SELECT_STATION, 0);
+		CloseWindowById(WC_SELECT_DEPOT, VEH_SHIP);
 		CloseWindowByClass(WC_BUILD_BRIDGE);
 	}
 
@@ -529,6 +530,12 @@ public:
 		UpdateDocksDirection();
 	}
 
+	void Close([[maybe_unused]] int data = 0) override
+	{
+		CloseWindowById(WC_SELECT_DEPOT, VEH_SHIP);
+		this->PickerWindowBase::Close();
+	}
+
 	void UpdateWidgetSize(WidgetID widget, Dimension &size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension &fill, [[maybe_unused]] Dimension &resize) override
 	{
 		switch (widget) {
@@ -569,6 +576,7 @@ public:
 		switch (widget) {
 			case WID_BDD_X:
 			case WID_BDD_Y:
+				CloseWindowById(WC_SELECT_DEPOT, VEH_SHIP);
 				this->RaiseWidget(WID_BDD_X + _ship_depot_direction);
 				_ship_depot_direction = (widget == WID_BDD_X ? AXIS_X : AXIS_Y);
 				this->LowerWidget(WID_BDD_X + _ship_depot_direction);

src/lang/english.txt

@@ -2769,6 +2769,11 @@ STR_JOIN_STATION_CREATE_SPLITTED_STATION                        :{YELLOW}Build a
 STR_JOIN_WAYPOINT_CAPTION                                       :{WHITE}Join waypoint
 STR_JOIN_WAYPOINT_CREATE_SPLITTED_WAYPOINT                      :{YELLOW}Build a separate waypoint
 
+# Join depot window
+STR_JOIN_DEPOT_CAPTION                                          :{WHITE}Join depot
+STR_JOIN_DEPOT_CREATE_SPLITTED_DEPOT                            :{YELLOW}Build a separate depot
+STR_DEPOT_LIST_DEPOT                                            :{YELLOW}{DEPOT}
+
 # Generic toolbar
 STR_TOOLBAR_DISABLED_NO_VEHICLE_AVAILABLE                       :{BLACK}Disabled as currently no vehicles are available for this infrastructure
 
@@ -5120,6 +5125,7 @@ STR_ERROR_CAN_T_BUILD_ROAD_DEPOT                                :{WHITE}Can't bu
 STR_ERROR_CAN_T_BUILD_TRAM_DEPOT                                :{WHITE}Can't build tram vehicle depot here...
 STR_ERROR_CAN_T_BUILD_SHIP_DEPOT                                :{WHITE}Can't build ship depot here...
 
+STR_ERROR_ADJOINS_MORE_THAN_ONE_EXISTING_DEPOT                  :{WHITE}... adjoins more than one existing depot
 STR_ERROR_CAN_T_RENAME_DEPOT                                    :{WHITE}Can't rename depot...
 
 STR_ERROR_TRAIN_MUST_BE_STOPPED_INSIDE_DEPOT                    :{WHITE}... must be stopped inside a depot

src/rail_gui.cpp

@@ -804,6 +804,7 @@ struct BuildRailToolbarWindow : Window {
 		CloseWindowById(WC_BUILD_DEPOT, TRANSPORT_RAIL);
 		CloseWindowById(WC_BUILD_WAYPOINT, TRANSPORT_RAIL);
 		CloseWindowById(WC_SELECT_STATION, 0);
+		CloseWindowById(WC_SELECT_DEPOT, VEH_TRAIN);
 		CloseWindowByClass(WC_BUILD_BRIDGE);
 	}
 
@@ -1705,6 +1706,12 @@ struct BuildRailDepotWindow : public PickerWindowBase {
 		this->LowerWidget(WID_BRAD_DEPOT_NE + _build_depot_direction);
 	}
 
+	void Close([[maybe_unused]] int data = 0) override
+	{
+		CloseWindowById(WC_SELECT_DEPOT, VEH_TRAIN);
+		this->PickerWindowBase::Close();
+	}
+
 	void UpdateWidgetSize(WidgetID widget, Dimension &size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension &fill, [[maybe_unused]] Dimension &resize) override
 	{
 		if (!IsInsideMM(widget, WID_BRAD_DEPOT_NE, WID_BRAD_DEPOT_NW + 1)) return;
@@ -1734,6 +1741,7 @@ struct BuildRailDepotWindow : public PickerWindowBase {
 			case WID_BRAD_DEPOT_SE:
 			case WID_BRAD_DEPOT_SW:
 			case WID_BRAD_DEPOT_NW:
+				CloseWindowById(WC_SELECT_DEPOT, VEH_TRAIN);
 				this->RaiseWidget(WID_BRAD_DEPOT_NE + _build_depot_direction);
 				_build_depot_direction = (DiagDirection)(widget - WID_BRAD_DEPOT_NE);
 				this->LowerWidget(WID_BRAD_DEPOT_NE + _build_depot_direction);

src/road_gui.cpp

@@ -687,6 +687,7 @@ struct BuildRoadToolbarWindow : Window {
 		CloseWindowById(WC_BUILD_DEPOT, TRANSPORT_ROAD);
 		CloseWindowById(WC_BUILD_WAYPOINT, TRANSPORT_ROAD);
 		CloseWindowById(WC_SELECT_STATION, 0);
+		CloseWindowById(WC_SELECT_DEPOT, VEH_ROAD);
 		CloseWindowByClass(WC_BUILD_BRIDGE);
 	}
 
@@ -1106,6 +1107,12 @@ struct BuildRoadDepotWindow : public PickerWindowBase {
 		this->FinishInitNested(TRANSPORT_ROAD);
 	}
 
+	void Close([[maybe_unused]] int data = 0) override
+	{
+		CloseWindowById(WC_SELECT_DEPOT, VEH_ROAD);
+		this->PickerWindowBase::Close();
+	}
+
 	void UpdateWidgetSize(WidgetID widget, Dimension &size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension &fill, [[maybe_unused]] Dimension &resize) override
 	{
 		if (!IsInsideMM(widget, WID_BROD_DEPOT_NE, WID_BROD_DEPOT_NW + 1)) return;
@@ -1135,6 +1142,7 @@ struct BuildRoadDepotWindow : public PickerWindowBase {
 			case WID_BROD_DEPOT_NE:
 			case WID_BROD_DEPOT_SW:
 			case WID_BROD_DEPOT_SE:
+				CloseWindowById(WC_SELECT_DEPOT, VEH_ROAD);
 				this->RaiseWidget(WID_BROD_DEPOT_NE + _road_depot_orientation);
 				_road_depot_orientation = (DiagDirection)(widget - WID_BROD_DEPOT_NE);
 				this->LowerWidget(WID_BROD_DEPOT_NE + _road_depot_orientation);

src/table/settings/game_settings.ini

@@ -157,6 +157,7 @@ from     = SLV_DEPOT_SPREAD
 def      = true
 str      = STR_CONFIG_SETTING_DISTANT_JOIN_DEPOTS
 strhelp  = STR_CONFIG_SETTING_DISTANT_JOIN_DEPOTS_HELPTEXT
+post_cb  = [](auto) { CloseWindowByClass(WC_SELECT_DEPOT); }
 
 [SDT_VAR]
 var      = depot.depot_spread
@@ -168,6 +169,7 @@ max      = 64
 str      = STR_CONFIG_SETTING_DEPOT_SPREAD
 strhelp  = STR_CONFIG_SETTING_DEPOT_SPREAD_HELPTEXT
 strval   = STR_CONFIG_SETTING_TILE_LENGTH
+post_cb  = [](auto) { CloseWindowByClass(WC_SELECT_DEPOT); }
 cat      = SC_BASIC
 
 [SDT_OMANY]

src/widgets/depot_widget.h

@@ -32,4 +32,11 @@ enum DepotWidgets : WidgetID {
 	WID_D_START_ALL,       ///< Start all button.
 };
 
+/** Widgets of the #SelectDepotWindow class. */
+enum JoinDepotWidgets {
+	WID_JD_CAPTION,   // Caption of the window.
+	WID_JD_PANEL,     // Main panel.
+	WID_JD_SCROLLBAR, // Scrollbar of the panel.
+};
+
 #endif /* WIDGETS_DEPOT_WIDGET_H */

src/window_type.h

@@ -241,6 +241,12 @@ enum WindowClass {
 	 */
 	WC_SELECT_STATION,
 
+	/**
+	 * Select depot (when joining depots); %Window numbers:
+	 *   - #Vehicle type = #JoinDepotWidgets
+	 */
+	WC_SELECT_DEPOT,
+
 	/**
 	 * News window; %Window numbers:
 	 *   - 0 = #NewsWidgets