Codechange: Simplify cargo filter lists, building only when required.

Some cargo filter lists were built in advance, and used as lookups to test which cargo type to filter.

Instead, use the Cargo ID directly as the filter parameter, and build the lists only when the drop down list is used.

src/build_vehicle_gui.cpp

@@ -1135,9 +1135,7 @@ struct BuildVehicleWindow : Window {
 	EngineID sel_engine;                        ///< Currently selected engine, or #INVALID_ENGINE
 	EngineID rename_engine;                     ///< Engine being renamed.
 	GUIEngineList eng_list;
-	CargoID cargo_filter[NUM_CARGO + 3];        ///< Available cargo filters; CargoID or CF_ANY or CF_NONE or CF_ENGINES
+	CargoID cargo_filter_criteria;              ///< Selected cargo filter
-	StringID cargo_filter_texts[NUM_CARGO + 4]; ///< Texts for filter_cargo, terminated by INVALID_STRING_ID
-	byte cargo_filter_criteria;                 ///< Selected cargo filter
 	int details_height;                         ///< Minimal needed height of the details panels, in text lines (found so far).
 	Scrollbar *vscroll;
 	TestedEngineDetails te;                     ///< Tested cost and capacity after refit.
@@ -1149,8 +1147,8 @@ struct BuildVehicleWindow : Window {
 	{
 		NWidgetCore *widget = this->GetWidget<NWidgetCore>(WID_BV_BUILD);
 
-		bool refit = this->sel_engine != INVALID_ENGINE && this->cargo_filter[this->cargo_filter_criteria] != CF_ANY && this->cargo_filter[this->cargo_filter_criteria] != CF_NONE;
+		bool refit = this->sel_engine != INVALID_ENGINE && this->cargo_filter_criteria != CF_ANY && this->cargo_filter_criteria != CF_NONE;
-		if (refit) refit = Engine::Get(this->sel_engine)->GetDefaultCargoType() != this->cargo_filter[this->cargo_filter_criteria];
+		if (refit) refit = Engine::Get(this->sel_engine)->GetDefaultCargoType() != this->cargo_filter_criteria;
 
 		if (refit) {
 			widget->widget_data = STR_BUY_VEHICLE_TRAIN_BUY_REFIT_VEHICLE_BUTTON + this->vehicle_type;
@@ -1272,58 +1270,29 @@ struct BuildVehicleWindow : Window {
 		}
 	}
 
+	StringID GetCargoFilterLabel(CargoID cid) const
+	{
+		switch (cid) {
+			case CF_ANY: return STR_PURCHASE_INFO_ALL_TYPES;
+			case CF_ENGINES: return STR_PURCHASE_INFO_ENGINES_ONLY;
+			case CF_NONE: return STR_PURCHASE_INFO_NONE;
+			default: return CargoSpec::Get(cid)->name;
+		}
+	}
+
 	/** Populate the filter list and set the cargo filter criteria. */
 	void SetCargoFilterArray()
 	{
-		uint filter_items = 0;
+		/* Set the last cargo filter criteria. */
-
+		this->cargo_filter_criteria = _engine_sort_last_cargo_criteria[this->vehicle_type];
-		/* Add item for disabling filtering. */
-		this->cargo_filter[filter_items] = CF_ANY;
-		this->cargo_filter_texts[filter_items] = STR_PURCHASE_INFO_ALL_TYPES;
-		filter_items++;
-
-		/* Specific filters for trains. */
-		if (this->vehicle_type == VEH_TRAIN) {
-			/* Add item for locomotives only in case of trains. */
-			this->cargo_filter[filter_items] = CF_ENGINES;
-			this->cargo_filter_texts[filter_items] = STR_PURCHASE_INFO_ENGINES_ONLY;
-			filter_items++;
-
-			/* Add item for vehicles not carrying anything, e.g. train engines.
-			 * This could also be useful for eyecandy vehicles of other types, but is likely too confusing for joe, */
-			this->cargo_filter[filter_items] = CF_NONE;
-			this->cargo_filter_texts[filter_items] = STR_PURCHASE_INFO_NONE;
-			filter_items++;
-		}
-
-		/* Collect available cargo types for filtering. */
-		for (const CargoSpec *cs : _sorted_standard_cargo_specs) {
-			this->cargo_filter[filter_items] = cs->Index();
-			this->cargo_filter_texts[filter_items] = cs->name;
-			filter_items++;
-		}
-
-		/* Terminate the filter list. */
-		this->cargo_filter_texts[filter_items] = INVALID_STRING_ID;
-
-		/* If not found, the cargo criteria will be set to all cargoes. */
-		this->cargo_filter_criteria = 0;
-
-		/* Find the last cargo filter criteria. */
-		for (uint i = 0; i < filter_items; i++) {
-			if (this->cargo_filter[i] == _engine_sort_last_cargo_criteria[this->vehicle_type]) {
-				this->cargo_filter_criteria = i;
-				break;
-			}
-		}
 
 		this->eng_list.SetFilterFuncs(_filter_funcs);
-		this->eng_list.SetFilterState(this->cargo_filter[this->cargo_filter_criteria] != CF_ANY);
+		this->eng_list.SetFilterState(this->cargo_filter_criteria != CF_ANY);
 	}
 
 	void SelectEngine(EngineID engine)
 	{
-		CargoID cargo = this->cargo_filter[this->cargo_filter_criteria];
+		CargoID cargo = this->cargo_filter_criteria;
 		if (cargo == CF_ANY || cargo == CF_ENGINES || cargo == CF_NONE) cargo = CT_INVALID;
 
 		this->sel_engine = engine;
@@ -1359,7 +1328,7 @@ struct BuildVehicleWindow : Window {
 	/** Filter the engine list against the currently selected cargo filter */
 	void FilterEngineList()
 	{
-		this->eng_list.Filter(this->cargo_filter[this->cargo_filter_criteria]);
+		this->eng_list.Filter(this->cargo_filter_criteria);
 		if (0 == this->eng_list.size()) { // no engine passed through the filter, invalidate the previously selected engine
 			this->SelectEngine(INVALID_ENGINE);
 		} else if (std::find(this->eng_list.begin(), this->eng_list.end(), this->sel_engine) == this->eng_list.end()) { // previously selected engine didn't pass the filter, select the first engine of the list
@@ -1370,9 +1339,8 @@ struct BuildVehicleWindow : Window {
 	/** Filter a single engine */
 	bool FilterSingleEngine(EngineID eid)
 	{
-		CargoID filter_type = this->cargo_filter[this->cargo_filter_criteria];
 		GUIEngineListItem item = {eid, eid, EngineDisplayFlags::None, 0};
-		return CargoAndEngineFilter(&item, filter_type);
+		return CargoAndEngineFilter(&item, this->cargo_filter_criteria);
 	}
 
 	/** Filter by name and NewGRF extra text */
@@ -1594,6 +1562,29 @@ struct BuildVehicleWindow : Window {
 		this->eng_list.RebuildDone();
 	}
 
+	DropDownList BuildCargoDropDownList() const
+	{
+		DropDownList list;
+
+		/* Add item for disabling filtering. */
+		list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_ANY), CF_ANY, false));
+		/* Specific filters for trains. */
+		if (this->vehicle_type == VEH_TRAIN) {
+			/* Add item for locomotives only in case of trains. */
+			list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_ENGINES), CF_ENGINES, false));
+			/* Add item for vehicles not carrying anything, e.g. train engines.
+			 * This could also be useful for eyecandy vehicles of other types, but is likely too confusing for joe, */
+			list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_NONE), CF_NONE, false));
+		}
+
+		/* Add cargos */
+		for (const CargoSpec *cs : _sorted_standard_cargo_specs) {
+			list.push_back(std::make_unique<DropDownListStringItem>(cs->name, cs->Index(), false));
+		}
+
+		return list;
+	}
+
 	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
 	{
 		switch (widget) {
@@ -1645,7 +1636,7 @@ struct BuildVehicleWindow : Window {
 				break;
 
 			case WID_BV_CARGO_FILTER_DROPDOWN: // Select cargo filtering criteria dropdown menu
-				ShowDropDownMenu(this, this->cargo_filter_texts, this->cargo_filter_criteria, WID_BV_CARGO_FILTER_DROPDOWN, 0, 0);
+				ShowDropDownList(this, this->BuildCargoDropDownList(), this->cargo_filter_criteria, widget);
 				break;
 
 			case WID_BV_SHOW_HIDE: {
@@ -1659,7 +1650,7 @@ struct BuildVehicleWindow : Window {
 			case WID_BV_BUILD: {
 				EngineID sel_eng = this->sel_engine;
 				if (sel_eng != INVALID_ENGINE) {
-					CargoID cargo = this->cargo_filter[this->cargo_filter_criteria];
+					CargoID cargo = this->cargo_filter_criteria;
 					if (cargo == CF_ANY || cargo == CF_ENGINES || cargo == CF_NONE) cargo = CT_INVALID;
 					if (this->vehicle_type == VEH_TRAIN && RailVehInfo(sel_eng)->railveh_type == RAILVEH_WAGON) {
 						Command<CMD_BUILD_VEHICLE>::Post(GetCmdBuildVehMsg(this->vehicle_type), CcBuildWagon, this->window_number, sel_eng, true, cargo, INVALID_CLIENT_ID);
@@ -1735,7 +1726,7 @@ struct BuildVehicleWindow : Window {
 				break;
 
 			case WID_BV_CARGO_FILTER_DROPDOWN:
-				SetDParam(0, this->cargo_filter_texts[this->cargo_filter_criteria]);
+				SetDParam(0, this->GetCargoFilterLabel(this->cargo_filter_criteria));
 				break;
 
 			case WID_BV_SHOW_HIDE: {
@@ -1771,6 +1762,10 @@ struct BuildVehicleWindow : Window {
 				break;
 			}
 
+			case WID_BV_CARGO_FILTER_DROPDOWN:
+				size->width = std::max(size->width, GetDropDownListDimension(this->BuildCargoDropDownList()).width + padding.width);
+				break;
+
 			case WID_BV_BUILD:
 				*size = GetStringBoundingBox(STR_BUY_VEHICLE_TRAIN_BUY_VEHICLE_BUTTON + this->vehicle_type);
 				*size = maxdim(*size, GetStringBoundingBox(STR_BUY_VEHICLE_TRAIN_BUY_REFIT_VEHICLE_BUTTON + this->vehicle_type));
@@ -1859,9 +1854,9 @@ struct BuildVehicleWindow : Window {
 			case WID_BV_CARGO_FILTER_DROPDOWN: // Select a cargo filter criteria
 				if (this->cargo_filter_criteria != index) {
 					this->cargo_filter_criteria = index;
-					_engine_sort_last_cargo_criteria[this->vehicle_type] = this->cargo_filter[this->cargo_filter_criteria];
+					_engine_sort_last_cargo_criteria[this->vehicle_type] = this->cargo_filter_criteria;
 					/* deactivate filter if criteria is 'Show All', activate it otherwise */
-					this->eng_list.SetFilterState(this->cargo_filter[this->cargo_filter_criteria] != CF_ANY);
+					this->eng_list.SetFilterState(this->cargo_filter_criteria != CF_ANY);
 					this->eng_list.ForceRebuild();
 					this->SelectEngine(this->sel_engine);
 				}

src/group_gui.cpp

@@ -424,7 +424,7 @@ public:
 				break;
 
 			case WID_GL_FILTER_BY_CARGO:
-				size->width = GetStringListWidth(this->cargo_filter_texts) + padding.width;
+				size->width = std::max(size->width, GetDropDownListDimension(this->BuildCargoDropDownList()).width + padding.width);
 				break;
 
 			case WID_GL_MANAGE_VEHICLES_DROPDOWN: {
@@ -470,7 +470,7 @@ public:
 	{
 		switch (widget) {
 			case WID_GL_FILTER_BY_CARGO:
-				SetDParam(0, this->cargo_filter_texts[this->cargo_filter_criteria]);
+				SetDParam(0, this->GetCargoFilterLabel(this->cargo_filter_criteria));
 				break;
 
 			case WID_GL_AVAILABLE_VEHICLES:
@@ -549,9 +549,6 @@ public:
 		/* Set text of "sort by" dropdown widget. */
 		this->GetWidget<NWidgetCore>(WID_GL_SORT_BY_DROPDOWN)->widget_data = this->GetVehicleSorterNames()[this->vehgroups.SortType()];
 
-		/* Set text of filter by cargo dropdown */
-		this->GetWidget<NWidgetCore>(WID_GL_FILTER_BY_CARGO)->widget_data = this->cargo_filter_texts[this->cargo_filter_criteria];
-
 		this->DrawWidgets();
 	}
 
@@ -668,7 +665,7 @@ public:
 				return;
 
 			case WID_GL_FILTER_BY_CARGO: // Select filtering criteria dropdown menu
-				ShowDropDownMenu(this, this->cargo_filter_texts, this->cargo_filter_criteria, WID_GL_FILTER_BY_CARGO, 0, 0);
+				ShowDropDownList(this, this->BuildCargoDropDownList(), this->cargo_filter_criteria, widget);
 				break;
 
 			case WID_GL_ALL_VEHICLES: // All vehicles button

src/industry_gui.cpp

@@ -1319,10 +1319,8 @@ protected:
 	Scrollbar *vscroll;
 	Scrollbar *hscroll;
 
-	CargoID cargo_filter[NUM_CARGO + 2];        ///< Available cargo filters; CargoID or CF_ANY or CF_NONE
+	CargoID produced_cargo_filter_criteria;     ///< Selected produced cargo filter index
-	StringID cargo_filter_texts[NUM_CARGO + 3]; ///< Texts for filter_cargo, terminated by INVALID_STRING_ID
+	CargoID accepted_cargo_filter_criteria;     ///< Selected accepted cargo filter index
-	byte produced_cargo_filter_criteria;        ///< Selected produced cargo filter index
-	byte accepted_cargo_filter_criteria;        ///< Selected accepted cargo filter index
 	static CargoID produced_cargo_filter;
 
 	const int MAX_FILTER_LENGTH = 16;           ///< The max length of the filter, in chars
@@ -1345,7 +1343,7 @@ protected:
 		if (this->produced_cargo_filter_criteria != index) {
 			this->produced_cargo_filter_criteria = index;
 			/* deactivate filter if criteria is 'Show All', activate it otherwise */
-			bool is_filtering_necessary = this->cargo_filter[this->produced_cargo_filter_criteria] != CF_ANY || this->cargo_filter[this->accepted_cargo_filter_criteria] != CF_ANY;
+			bool is_filtering_necessary = this->produced_cargo_filter_criteria != CF_ANY || this->accepted_cargo_filter_criteria != CF_ANY;
 
 			this->industries.SetFilterState(is_filtering_necessary);
 			this->industries.SetFilterType(0);
@@ -1362,7 +1360,7 @@ protected:
 		if (this->accepted_cargo_filter_criteria != index) {
 			this->accepted_cargo_filter_criteria = index;
 			/* deactivate filter if criteria is 'Show All', activate it otherwise */
-			bool is_filtering_necessary = this->cargo_filter[this->produced_cargo_filter_criteria] != CF_ANY || this->cargo_filter[this->accepted_cargo_filter_criteria] != CF_ANY;
+			bool is_filtering_necessary = this->produced_cargo_filter_criteria != CF_ANY || this->accepted_cargo_filter_criteria != CF_ANY;
 
 			this->industries.SetFilterState(is_filtering_necessary);
 			this->industries.SetFilterType(0);
@@ -1370,38 +1368,26 @@ protected:
 		}
 	}
 
+	StringID GetCargoFilterLabel(CargoID cid) const
+	{
+		switch (cid) {
+			case CF_ANY: return STR_INDUSTRY_DIRECTORY_FILTER_ALL_TYPES;
+			case CF_NONE: return STR_INDUSTRY_DIRECTORY_FILTER_NONE;
+			default: return CargoSpec::Get(cid)->name;
+		}
+	}
+
 	/**
 	 * Populate the filter list and set the cargo filter criteria.
 	 */
 	void SetCargoFilterArray()
 	{
-		byte filter_items = 0;
+		this->produced_cargo_filter_criteria = CF_ANY;
-
+		this->accepted_cargo_filter_criteria = CF_ANY;
-		/* Add item for disabling filtering. */
-		this->cargo_filter[filter_items] = CF_ANY;
-		this->cargo_filter_texts[filter_items] = STR_INDUSTRY_DIRECTORY_FILTER_ALL_TYPES;
-		this->produced_cargo_filter_criteria = filter_items;
-		this->accepted_cargo_filter_criteria = filter_items;
-		filter_items++;
-
-		/* Add item for industries not producing anything, e.g. power plants */
-		this->cargo_filter[filter_items] = CF_NONE;
-		this->cargo_filter_texts[filter_items] = STR_INDUSTRY_DIRECTORY_FILTER_NONE;
-		filter_items++;
-
-		/* Collect available cargo types for filtering. */
-		for (const CargoSpec *cs : _sorted_standard_cargo_specs) {
-			this->cargo_filter[filter_items] = cs->Index();
-			this->cargo_filter_texts[filter_items] = cs->name;
-			filter_items++;
-		}
-
-		/* Terminate the filter list. */
-		this->cargo_filter_texts[filter_items] = INVALID_STRING_ID;
 
 		this->industries.SetFilterFuncs(_filter_funcs);
 
-		bool is_filtering_necessary = this->cargo_filter[this->produced_cargo_filter_criteria] != CF_ANY || this->cargo_filter[this->accepted_cargo_filter_criteria] != CF_ANY;
+		bool is_filtering_necessary = this->produced_cargo_filter_criteria != CF_ANY || this->accepted_cargo_filter_criteria != CF_ANY;
 
 		this->industries.SetFilterState(is_filtering_necessary);
 	}
@@ -1438,8 +1424,7 @@ protected:
 			this->industries.shrink_to_fit();
 			this->industries.RebuildDone();
 
-			auto filter = std::make_pair(this->cargo_filter[this->accepted_cargo_filter_criteria],
+			auto filter = std::make_pair(this->accepted_cargo_filter_criteria, this->produced_cargo_filter_criteria);
-										this->cargo_filter[this->produced_cargo_filter_criteria]);
 
 			this->industries.Filter(filter);
 
@@ -1447,7 +1432,7 @@ protected:
 			this->vscroll->SetCount(this->industries.size()); // Update scrollbar as well.
 		}
 
-		IndustryDirectoryWindow::produced_cargo_filter = this->cargo_filter[this->produced_cargo_filter_criteria];
+		IndustryDirectoryWindow::produced_cargo_filter = this->produced_cargo_filter_criteria;
 		this->industries.Sort();
 
 		this->SetDirty();
@@ -1599,7 +1584,7 @@ protected:
 
 		/* If the produced cargo filter is active then move the filtered cargo to the beginning of the list,
 		 * because this is the one the player interested in, and that way it is not hidden in the 'n' more cargos */
-		const CargoID cid = this->cargo_filter[this->produced_cargo_filter_criteria];
+		const CargoID cid = this->produced_cargo_filter_criteria;
 		if (cid != CF_ANY && cid != CF_NONE) {
 			auto filtered_ci = std::find_if(cargos.begin(), cargos.end(), [cid](const CargoInfo &ci) -> bool {
 				return ci.cargo_id == cid;
@@ -1669,11 +1654,11 @@ public:
 				break;
 
 			case WID_ID_FILTER_BY_ACC_CARGO:
-				SetDParam(0, this->cargo_filter_texts[this->accepted_cargo_filter_criteria]);
+				SetDParam(0, this->GetCargoFilterLabel(this->accepted_cargo_filter_criteria));
 				break;
 
 			case WID_ID_FILTER_BY_PROD_CARGO:
-				SetDParam(0, this->cargo_filter_texts[this->produced_cargo_filter_criteria]);
+				SetDParam(0, this->GetCargoFilterLabel(this->produced_cargo_filter_criteria));
 				break;
 		}
 	}
@@ -1705,7 +1690,7 @@ public:
 					break;
 				}
 				int n = 0;
-				const CargoID acf_cid = this->cargo_filter[this->accepted_cargo_filter_criteria];
+				const CargoID acf_cid = this->accepted_cargo_filter_criteria;
 				for (uint i = this->vscroll->GetPosition(); i < this->industries.size(); i++) {
 					TextColour tc = TC_FROMSTRING;
 					if (acf_cid != CF_ANY && acf_cid != CF_NONE) {
@@ -1758,6 +1743,22 @@ public:
 		}
 	}
 
+	DropDownList BuildCargoDropDownList() const
+	{
+		DropDownList list;
+
+		/* Add item for disabling filtering. */
+		list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_ANY), CF_ANY, false));
+		/* Add item for industries not producing anything, e.g. power plants */
+		list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_NONE), CF_NONE, false));
+
+		/* Add cargos */
+		for (const CargoSpec *cs : _sorted_standard_cargo_specs) {
+			list.push_back(std::make_unique<DropDownListStringItem>(cs->name, cs->Index(), false));
+		}
+
+		return list;
+	}
 
 	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
 	{
@@ -1772,11 +1773,11 @@ public:
 				break;
 
 			case WID_ID_FILTER_BY_ACC_CARGO: // Cargo filter dropdown
-				ShowDropDownMenu(this, this->cargo_filter_texts, this->accepted_cargo_filter_criteria, WID_ID_FILTER_BY_ACC_CARGO, 0, 0);
+				ShowDropDownList(this, this->BuildCargoDropDownList(), this->accepted_cargo_filter_criteria, widget);
 				break;
 
 			case WID_ID_FILTER_BY_PROD_CARGO: // Cargo filter dropdown
-				ShowDropDownMenu(this, this->cargo_filter_texts, this->produced_cargo_filter_criteria, WID_ID_FILTER_BY_PROD_CARGO, 0, 0);
+				ShowDropDownList(this, this->BuildCargoDropDownList(), this->produced_cargo_filter_criteria, widget);
 				break;
 
 			case WID_ID_INDUSTRY_LIST: {

src/vehicle_gui.cpp

@@ -300,7 +300,7 @@ void BaseVehicleListWindow::SetCargoFilterIndex(byte index)
 	if (this->cargo_filter_criteria != index) {
 		this->cargo_filter_criteria = index;
 		/* Deactivate filter if criteria is 'Show All', activate it otherwise. */
-		this->vehgroups.SetFilterState(this->cargo_filter[this->cargo_filter_criteria] != CF_ANY);
+		this->vehgroups.SetFilterState(this->cargo_filter_criteria != CF_ANY);
 		this->vehgroups.SetFilterType(0);
 		this->vehgroups.ForceRebuild();
 	}
@@ -311,36 +311,9 @@ void BaseVehicleListWindow::SetCargoFilterIndex(byte index)
  */
 void BaseVehicleListWindow::SetCargoFilterArray()
 {
-	byte filter_items = 0;
+	this->cargo_filter_criteria = CF_ANY;
-
-	/* Add item for disabling filtering. */
-	this->cargo_filter[filter_items] = CF_ANY;
-	this->cargo_filter_texts[filter_items] = STR_CARGO_TYPE_FILTER_ALL;
-	this->cargo_filter_criteria = filter_items;
-	filter_items++;
-
-	/* Add item for freight (i.e. vehicles with cargo capacity and with no passenger capacity). */
-	this->cargo_filter[filter_items] = CF_FREIGHT;
-	this->cargo_filter_texts[filter_items] = STR_CARGO_TYPE_FILTER_FREIGHT;
-	filter_items++;
-
-	/* Add item for vehicles not carrying anything, e.g. train engines. */
-	this->cargo_filter[filter_items] = CF_NONE;
-	this->cargo_filter_texts[filter_items] = STR_CARGO_TYPE_FILTER_NONE;
-	filter_items++;
-
-	/* Collect available cargo types for filtering. */
-	for (const auto &cs : _sorted_cargo_specs) {
-		this->cargo_filter[filter_items] = cs->Index();
-		this->cargo_filter_texts[filter_items] = cs->name;
-		filter_items++;
-	}
-
-	/* Terminate the filter list. */
-	this->cargo_filter_texts[filter_items] = INVALID_STRING_ID;
-
 	this->vehgroups.SetFilterFuncs(_filter_funcs);
-	this->vehgroups.SetFilterState(this->cargo_filter[this->cargo_filter_criteria] != CF_ANY);
+	this->vehgroups.SetFilterState(this->cargo_filter_criteria != CF_ANY);
 }
 
 /**
@@ -348,7 +321,7 @@ void BaseVehicleListWindow::SetCargoFilterArray()
  */
 void BaseVehicleListWindow::FilterVehicleList()
 {
-	this->vehgroups.Filter(this->cargo_filter[this->cargo_filter_criteria]);
+	this->vehgroups.Filter(this->cargo_filter_criteria);
 	if (this->vehicles.empty()) {
 		/* No vehicle passed through the filter, invalidate the previously selected vehicle */
 		this->vehicle_sel = INVALID_VEHICLE;
@@ -388,6 +361,35 @@ void BaseVehicleListWindow::OnInit()
 	this->SetCargoFilterArray();
 }
 
+StringID BaseVehicleListWindow::GetCargoFilterLabel(CargoID cid) const
+{
+	switch (cid) {
+		case CF_ANY: return STR_CARGO_TYPE_FILTER_ALL;
+		case CF_FREIGHT: return STR_CARGO_TYPE_FILTER_FREIGHT;
+		case CF_NONE: return STR_CARGO_TYPE_FILTER_NONE;
+		default: return CargoSpec::Get(cid)->name;
+	}
+}
+
+DropDownList BaseVehicleListWindow::BuildCargoDropDownList() const
+{
+	DropDownList list;
+
+	/* Add item for disabling filtering. */
+	list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_ANY), CF_ANY, false));
+	/* Add item for freight (i.e. vehicles with cargo capacity and with no passenger capacity). */
+	list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_FREIGHT), CF_FREIGHT, false));
+	/* Add item for vehicles not carrying anything, e.g. train engines. */
+	list.push_back(std::make_unique<DropDownListStringItem>(this->GetCargoFilterLabel(CF_NONE), CF_NONE, false));
+
+	/* Add cargos */
+	for (const CargoSpec *cs : _sorted_cargo_specs) {
+		list.push_back(std::make_unique<DropDownListStringItem>(cs->name, cs->Index(), false));
+	}
+
+	return list;
+}
+
 /**
  * Display the Action dropdown window.
  * @param show_autoreplace If true include the autoreplace item.
@@ -1874,7 +1876,7 @@ public:
 				break;
 
 			case WID_VL_FILTER_BY_CARGO:
-				size->width = GetStringListWidth(this->cargo_filter_texts) + padding.width;
+				size->width = std::max(size->width, GetDropDownListDimension(this->BuildCargoDropDownList()).width + padding.width);
 				break;
 
 			case WID_VL_MANAGE_VEHICLES_DROPDOWN: {
@@ -1895,7 +1897,7 @@ public:
 				break;
 
 			case WID_VL_FILTER_BY_CARGO:
-				SetDParam(0, this->cargo_filter_texts[this->cargo_filter_criteria]);
+				SetDParam(0, this->GetCargoFilterLabel(this->cargo_filter_criteria));
 				break;
 
 			case WID_VL_CAPTION:
@@ -1975,7 +1977,7 @@ public:
 		/* Set text of sort by dropdown widget. */
 		this->GetWidget<NWidgetCore>(WID_VL_SORT_BY_PULLDOWN)->widget_data = this->GetVehicleSorterNames()[this->vehgroups.SortType()];
 
-		this->GetWidget<NWidgetCore>(WID_VL_FILTER_BY_CARGO)->widget_data = this->cargo_filter_texts[this->cargo_filter_criteria];
+		this->GetWidget<NWidgetCore>(WID_VL_FILTER_BY_CARGO)->widget_data = this->GetCargoFilterLabel(this->cargo_filter_criteria);
 
 		this->DrawWidgets();
 	}
@@ -2004,7 +2006,7 @@ public:
 				return;
 
 			case WID_VL_FILTER_BY_CARGO: // Cargo filter dropdown
-				ShowDropDownMenu(this, this->cargo_filter_texts, this->cargo_filter_criteria, WID_VL_FILTER_BY_CARGO, 0, 0);
+				ShowDropDownList(this, this->BuildCargoDropDownList(), this->cargo_filter_criteria, widget);
 				break;
 
 			case WID_VL_LIST: { // Matrix to show vehicles

src/vehicle_gui_base.h

@@ -88,8 +88,6 @@ struct BaseVehicleListWindow : public Window {
 	Scrollbar *vscroll;
 	VehicleListIdentifier vli;                  ///< Identifier of the vehicle list we want to currently show.
 	VehicleID vehicle_sel;                      ///< Selected vehicle
-	CargoID cargo_filter[NUM_CARGO + 3];        ///< Available cargo filters; CargoID or CF_ANY or CF_FREIGHT or CF_NONE
-	StringID cargo_filter_texts[NUM_CARGO + 4]; ///< Texts for filter_cargo, terminated by INVALID_STRING_ID
 	byte cargo_filter_criteria;                 ///< Selected cargo filter index
 	uint order_arrow_width;                     ///< Width of the arrow in the small order list.
 
@@ -125,6 +123,8 @@ struct BaseVehicleListWindow : public Window {
 	void SetCargoFilterIndex(byte index);
 	void SetCargoFilterArray();
 	void FilterVehicleList();
+	StringID GetCargoFilterLabel(CargoID cid) const;
+	DropDownList BuildCargoDropDownList() const;
 	Dimension GetActionDropdownSize(bool show_autoreplace, bool show_group, bool show_create);
 	DropDownList BuildActionDropdownList(bool show_autoreplace, bool show_group, bool show_create);
 

src/widgets/dropdown.cpp

@@ -335,6 +335,21 @@ struct DropdownWindow : Window {
 	}
 };
 
+/**
+ * Determine width and height required to fully display a DropDownList
+ * @param list The list.
+ * @return Dimension required to display the list.
+ */
+Dimension GetDropDownListDimension(const DropDownList &list)
+{
+	Dimension dim{};
+	for (const auto &item : list) {
+		dim.height += item->Height();
+		dim.width = std::max(dim.width, item->Width());
+	}
+	return dim;
+}
+
 /**
  * Show a drop down list.
  * @param w        Parent window for the list.
@@ -356,18 +371,9 @@ void ShowDropDownListAt(Window *w, DropDownList &&list, int selected, int button
 	/* The preferred width equals the calling widget */
 	uint width = wi_rect.Width();
 
-	/* Longest item in the list */
+	/* Get the height and width required for the list. */
-	uint max_item_width = 0;
+	Dimension dim = GetDropDownListDimension(list);
-
+	dim.width += WidgetDimensions::scaled.fullbevel.Horizontal();
-	/* Total height of list */
-	uint height = 0;
-
-	for (const auto &item : list) {
-		height += item->Height();
-		max_item_width = std::max(max_item_width, item->Width());
-	}
-
-	max_item_width += WidgetDimensions::scaled.fullbevel.Horizontal();
 
 	/* Scrollbar needed? */
 	bool scroll = false;
@@ -379,7 +385,7 @@ void ShowDropDownListAt(Window *w, DropDownList &&list, int selected, int button
 	uint available_height = std::max(GetMainViewBottom() - top - (int)WidgetDimensions::scaled.fullbevel.Vertical() * 2, 0);
 
 	/* If the dropdown doesn't fully fit below the widget... */
-	if (height > available_height) {
+	if (dim.height > available_height) {
 
 		uint available_height_above = std::max(w->top + wi_rect.top - GetMainViewTop() - (int)WidgetDimensions::scaled.fullbevel.Vertical() * 2, 0);
 
@@ -390,29 +396,28 @@ void ShowDropDownListAt(Window *w, DropDownList &&list, int selected, int button
 		}
 
 		/* If the dropdown doesn't fully fit, we need a dropdown. */
-		if (height > available_height) {
+		if (dim.height > available_height) {
 			scroll = true;
-			uint avg_height = height / (uint)list.size();
+			uint avg_height = dim.height / (uint)list.size();
 
 			/* Fit the list; create at least one row, even if there is no height available. */
 			uint rows = std::max<uint>(available_height / avg_height, 1);
-			height = rows * avg_height;
+			dim.height = rows * avg_height;
 
 			/* Add space for the scrollbar. */
-			max_item_width += NWidgetScrollbar::GetVerticalDimension().width;
+			dim.width += NWidgetScrollbar::GetVerticalDimension().width;
 		}
 
 		/* Set the top position if needed. */
 		if (above) {
-			top = w->top + wi_rect.top - height - WidgetDimensions::scaled.fullbevel.Vertical() * 2;
+			top = w->top + wi_rect.top - dim.height - WidgetDimensions::scaled.fullbevel.Vertical() * 2;
 		}
 	}
 
-	width = std::max(width, max_item_width);
+	dim.width = std::max(width, dim.width);
 
 	Point dw_pos = { w->left + (_current_text_dir == TD_RTL ? wi_rect.right + 1 - (int)width : wi_rect.left), top};
-	Dimension dw_size = {width, height};
+	DropdownWindow *dropdown = new DropdownWindow(w, std::move(list), selected, button, instant_close, dw_pos, dim, wi_colour, scroll);
-	DropdownWindow *dropdown = new DropdownWindow(w, std::move(list), selected, button, instant_close, dw_pos, dw_size, wi_colour, scroll);
 
 	/* The dropdown starts scrolling downwards when opening it towards
 	 * the top and holding down the mouse button. It can be fooled by

src/widgets/dropdown_type.h

@@ -76,4 +76,6 @@ void ShowDropDownListAt(Window *w, DropDownList &&list, int selected, int button
 
 void ShowDropDownList(Window *w, DropDownList &&list, int selected, int button, uint width = 0, bool instant_close = false);
 
+Dimension GetDropDownListDimension(const DropDownList &list);
+
 #endif /* WIDGETS_DROPDOWN_TYPE_H */