Codechange: Use `GetVisibleRangeIterators()` in more places. (#12190)

This replaces more first/last index calculation, along with indexed array/vector access, with iterator access instead.

src/bridge_gui.cpp

@@ -231,11 +231,11 @@ public:
 			case WID_BBS_BRIDGE_LIST: {
 				Rect tr = r.WithHeight(this->resize.step_height).Shrink(WidgetDimensions::scaled.matrix);
 				bool rtl = _current_text_dir == TD_RTL;
-				for (int i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && i < (int)this->bridges.size(); i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->bridges);
-					const BuildBridgeData &bridge_data = this->bridges.at(i);
+				for (auto it = first; it != last; ++it) {
-					const BridgeSpec *b = bridge_data.spec;
+					const BridgeSpec *b = it->spec;
 					DrawSpriteIgnorePadding(b->sprite, b->pal, tr.WithWidth(this->icon_width, rtl), SA_HOR_CENTER | SA_BOTTOM);
-					DrawStringMultiLine(tr.Indent(this->icon_width + WidgetDimensions::scaled.hsep_normal, rtl), GetBridgeSelectString(bridge_data));
+					DrawStringMultiLine(tr.Indent(this->icon_width + WidgetDimensions::scaled.hsep_normal, rtl), GetBridgeSelectString(*it));
 					tr = tr.Translate(0, this->resize.step_height);
 				}
 				break;

src/fios_gui.cpp

@@ -441,8 +441,8 @@ public:
 				GfxFillRect(br, PC_BLACK);
 
 				Rect tr = r.Shrink(WidgetDimensions::scaled.inset).WithHeight(this->resize.step_height);
-				uint scroll_pos = this->vscroll->GetPosition();
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->display_list);
-				for (auto it = this->display_list.begin() + scroll_pos; it != this->display_list.end() && tr.top < br.bottom; ++it) {
+				for (auto it = first; it != last; ++it) {
 					const FiosItem *item = *it;
 
 					if (item == this->selected) {

src/graph_gui.cpp

@@ -1023,13 +1023,11 @@ struct PaymentRatesGraphWindow : BaseGraphWindow {
 
 		bool rtl = _current_text_dir == TD_RTL;
 
-		int pos = this->vscroll->GetPosition();
+		auto [first, last] = this->vscroll->GetVisibleRangeIterators(_sorted_standard_cargo_specs);
-		int max = pos + this->vscroll->GetCapacity();
 
 		Rect line = r.WithHeight(this->line_height);
-		for (const CargoSpec *cs : _sorted_standard_cargo_specs) {
+		for (auto it = first; it != last; ++it) {
-			if (pos-- > 0) continue;
+			const CargoSpec *cs = *it;
-			if (--max < 0) break;
 
 			bool lowered = !HasBit(_legend_excluded_cargo, cs->Index());
 

src/group_gui.cpp

@@ -626,9 +626,9 @@ public:
 				if (this->vli.index != ALL_GROUP && this->grouping == GB_NONE) {
 					/* Mark vehicles which are in sub-groups (only if we are not using shared order coalescing) */
 					Rect mr = r.WithHeight(this->resize.step_height);
-					size_t max = std::min<size_t>(this->vscroll->GetPosition() + this->vscroll->GetCapacity(), this->vehgroups.size());
+					auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->vehgroups);
-					for (size_t i = this->vscroll->GetPosition(); i < max; ++i) {
+					for (auto it = first; it != last; ++it) {
-						const Vehicle *v = this->vehgroups[i].GetSingleVehicle();
+						const Vehicle *v = it->GetSingleVehicle();
 						if (v->group_id != this->vli.index) {
 							GfxFillRect(mr.Shrink(WidgetDimensions::scaled.bevel), GetColourGradient(COLOUR_GREY, SHADE_DARK), FILLRECT_CHECKER);
 						}

src/industry_gui.cpp

@@ -528,8 +528,9 @@ public:
 				icon.top    = r.top + (this->resize.step_height - this->legend.height + 1) / 2;
 				icon.bottom = icon.top + this->legend.height - 1;
 
-				for (uint16_t i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && i < this->vscroll->GetCount(); i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->list);
-					IndustryType type = this->list[i];
+				for (auto it = first; it != last; ++it) {
+					IndustryType type = *it;
 					bool selected = this->selected_type == type;
 					const IndustrySpec *indsp = GetIndustrySpec(type);
 
@@ -1699,20 +1700,19 @@ public:
 					DrawString(ir, STR_INDUSTRY_DIRECTORY_NONE);
 					break;
 				}
-				int n = 0;
 				const CargoID acf_cid = this->accepted_cargo_filter_criteria;
-				for (uint i = this->vscroll->GetPosition(); i < this->industries.size(); i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->industries);
+				for (auto it = first; it != last; ++it) {
 					TextColour tc = TC_FROMSTRING;
 					if (acf_cid != CargoFilterCriteria::CF_ANY && acf_cid != CargoFilterCriteria::CF_NONE) {
-						Industry *ind = const_cast<Industry *>(this->industries[i]);
+						Industry *ind = const_cast<Industry *>(*it);
 						if (IndustryTemporarilyRefusesCargo(ind, acf_cid)) {
 							tc = TC_GREY | TC_FORCED;
 						}
 					}
-					DrawString(ir, this->GetIndustryString(this->industries[i]), tc);
+					DrawString(ir, this->GetIndustryString(*it), tc);
 
 					ir.top += this->resize.step_height;
-					if (++n == this->vscroll->GetCapacity()) break; // max number of industries in 1 window
 				}
 				break;
 			}

src/network/network_content_gui.cpp

@@ -652,11 +652,8 @@ public:
 		int text_y_offset   = (this->resize.step_height - GetCharacterHeight(FS_NORMAL)) / 2;
 
 		Rect mr = r.WithHeight(this->resize.step_height);
-		auto iter = this->content.begin() + this->vscroll->GetPosition();
+		auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->content);
-		size_t last = this->vscroll->GetPosition() + this->vscroll->GetCapacity();
+		for (auto iter = first; iter != last; iter++) {
-		auto end = (last < this->content.size()) ? this->content.begin() + last : this->content.end();
-
-		for (/**/; iter != end; iter++) {
 			const ContentInfo *ci = *iter;
 
 			if (ci == this->selected) GfxFillRect(mr.Shrink(WidgetDimensions::scaled.bevel), PC_GREY);

src/network/network_gui.cpp

@@ -527,10 +527,9 @@ public:
 			case WID_NG_MATRIX: {
 				uint16_t y = r.top;
 
-				const int max = std::min(this->vscroll->GetPosition() + this->vscroll->GetCapacity(), (int)this->servers.size());
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->servers);
-
+				for (auto it = first; it != last; ++it) {
-				for (int i = this->vscroll->GetPosition(); i < max; ++i) {
+					const NetworkGameList *ngl = *it;
-					const NetworkGameList *ngl = this->servers[i];
 					this->DrawServerLine(ngl, y, ngl == this->server);
 					y += this->resize.step_height;
 				}

src/newgrf_debug_gui.cpp

@@ -933,13 +933,13 @@ struct SpriteAlignerWindow : Window {
 				const NWidgetBase *nwid = this->GetWidget<NWidgetBase>(widget);
 				int step_size = nwid->resize_y;
 
-				std::vector<SpriteID> &list = _newgrf_debug_sprite_picker.sprites;
+				const std::vector<SpriteID> &list = _newgrf_debug_sprite_picker.sprites;
-				int max = std::min<int>(this->vscroll->GetPosition() + this->vscroll->GetCapacity(), (uint)list.size());
 
 				Rect ir = r.Shrink(WidgetDimensions::scaled.matrix);
-				for (int i = this->vscroll->GetPosition(); i < max; i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(list);
-					SetDParam(0, list[i]);
+				for (auto it = first; it != last; ++it) {
-					DrawString(ir, STR_JUST_COMMA, list[i] == this->current_sprite ? TC_WHITE : TC_BLACK, SA_RIGHT | SA_FORCE);
+					SetDParam(0, *it);
+					DrawString(ir, STR_JUST_COMMA, *it == this->current_sprite ? TC_WHITE : TC_BLACK, SA_RIGHT | SA_FORCE);
 					ir.top += step_size;
 				}
 				break;

src/newgrf_gui.cpp

@@ -909,11 +909,10 @@ struct NewGRFWindow : public Window, NewGRFScanCallback {
 				Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
 				uint step_height = this->GetWidget<NWidgetBase>(WID_NS_AVAIL_LIST)->resize_y;
 				int offset_y = (step_height - GetCharacterHeight(FS_NORMAL)) / 2;
-				uint min_index = this->vscroll2->GetPosition();
-				uint max_index = std::min(min_index + this->vscroll2->GetCapacity(), (uint)this->avails.size());
 
-				for (uint i = min_index; i < max_index; i++) {
+				auto [first, last] = this->vscroll2->GetVisibleRangeIterators(this->avails);
-					const GRFConfig *c = this->avails[i];
+				for (auto it = first; it != last; ++it) {
+					const GRFConfig *c = *it;
 					bool h = (c == this->avail_sel);
 					const char *text = c->GetName();
 
@@ -2127,13 +2126,13 @@ struct SavePresetWindow : public Window {
 				uint step_height = this->GetWidget<NWidgetBase>(WID_SVP_PRESET_LIST)->resize_y;
 				int offset_y = (step_height - GetCharacterHeight(FS_NORMAL)) / 2;
 				Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
-				uint min_index = this->vscroll->GetPosition();
-				uint max_index = std::min(min_index + this->vscroll->GetCapacity(), (uint)this->presets.size());
 
-				for (uint i = min_index; i < max_index; i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->presets);
-					if ((int)i == this->selected) GfxFillRect(br.left, tr.top, br.right, tr.top + step_height - 1, PC_DARK_BLUE);
+				for (auto it = first; it != last; ++it) {
+					int row = static_cast<int>(std::distance(std::begin(this->presets), it));
+					if (row == this->selected) GfxFillRect(br.left, tr.top, br.right, tr.top + step_height - 1, PC_DARK_BLUE);
 
-					DrawString(tr.left, tr.right, tr.top + offset_y, this->presets[i], ((int)i == this->selected) ? TC_WHITE : TC_SILVER);
+					DrawString(tr.left, tr.right, tr.top + offset_y, *it, (row == this->selected) ? TC_WHITE : TC_SILVER);
 					tr.top += step_height;
 				}
 				break;

src/script/script_gui.cpp

@@ -927,7 +927,7 @@ struct ScriptDebugWindow : public Window {
 	{
 		if (this->filter.script_debug_company == INVALID_COMPANY) return;
 
-		ScriptLogTypes::LogData &log = this->GetLogData();
+		const ScriptLogTypes::LogData &log = this->GetLogData();
 		if (log.empty()) return;
 
 		Rect fr = r.Shrink(WidgetDimensions::scaled.framerect);
@@ -943,8 +943,9 @@ struct ScriptDebugWindow : public Window {
 
 		fr.left -= this->hscroll->GetPosition();
 
-		for (int i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && (size_t)i < log.size(); i++) {
+		auto [first, last] = this->vscroll->GetVisibleRangeIterators(log);
-			const ScriptLogTypes::LogLine &line = log[i];
+		for (auto it = first; it != last; ++it) {
+			const ScriptLogTypes::LogLine &line = *it;
 
 			TextColour colour;
 			switch (line.type) {
@@ -957,7 +958,7 @@ struct ScriptDebugWindow : public Window {
 			}
 
 			/* Check if the current line should be highlighted */
-			if (i == this->highlight_row) {
+			if (std::distance(std::begin(log), it) == this->highlight_row) {
 				fr.bottom = fr.top + this->resize.step_height - 1;
 				GfxFillRect(fr, PC_BLACK);
 				if (colour == TC_BLACK) colour = TC_WHITE; // Make black text readable by inverting it to white.

src/signs_gui.cpp

@@ -211,9 +211,9 @@ struct SignListWindow : Window, SignList {
 				tr = tr.Indent(this->text_offset, rtl);
 
 				/* At least one sign available. */
-				for (uint16_t i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && i < this->vscroll->GetCount(); i++)
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->signs);
-				{
+				for (auto it = first; it != last; ++it) {
-					const Sign *si = this->signs[i];
+					const Sign *si = *it;
 
 					if (si->owner != OWNER_NONE) DrawCompanyIcon(si->owner, icon_left, tr.top + sprite_offset_y);
 

src/station_gui.cpp

@@ -455,7 +455,6 @@ public:
 
 			case WID_STL_LIST: {
 				bool rtl = _current_text_dir == TD_RTL;
-				size_t max = std::min<size_t>(this->vscroll->GetPosition() + this->vscroll->GetCapacity(), this->stations.size());
 				Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
 				uint line_height = this->GetWidget<NWidgetBase>(widget)->resize_y;
 				/* Spacing between station name and first rating graph. */
@@ -463,8 +462,9 @@ public:
 				/* Spacing between additional rating graphs. */
 				int rating_spacing = WidgetDimensions::scaled.hsep_normal;
 
-				for (size_t i = this->vscroll->GetPosition(); i < max; ++i) { // do until max number of stations of owner
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->stations);
-					const Station *st = this->stations[i];
+				for (auto it = first; it != last; ++it) {
+					const Station *st = *it;
 					assert(st->xy != INVALID_TILE);
 
 					/* Do not do the complex check HasStationInUse here, it may be even false
@@ -2320,11 +2320,12 @@ struct SelectStationWindow : Window {
 		if (widget != WID_JS_PANEL) return;
 
 		Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
-		for (uint i = this->vscroll->GetPosition(); i < _stations_nearby_list.size(); ++i, tr.top += this->resize.step_height) {
+		auto [first, last] = this->vscroll->GetVisibleRangeIterators(_stations_nearby_list);
-			if (_stations_nearby_list[i] == NEW_STATION) {
+		for (auto it = first; it != last; ++it, tr.top += this->resize.step_height) {
+			if (*it == NEW_STATION) {
 				DrawString(tr, T::EXPECTED_FACIL == FACIL_WAYPOINT ? STR_JOIN_WAYPOINT_CREATE_SPLITTED_WAYPOINT : STR_JOIN_STATION_CREATE_SPLITTED_STATION);
 			} else {
-				const T *st = T::Get(_stations_nearby_list[i]);
+				const T *st = T::Get(*it);
 				SetDParam(0, st->index);
 				SetDParam(1, st->facilities);
 				DrawString(tr, T::EXPECTED_FACIL == FACIL_WAYPOINT ? STR_STATION_LIST_WAYPOINT : STR_STATION_LIST_STATION);

src/town_gui.cpp

@@ -840,7 +840,6 @@ public:
 				break;
 
 			case WID_TD_LIST: {
-				int n = 0;
 				Rect tr = r.Shrink(WidgetDimensions::scaled.framerect);
 				if (this->towns.empty()) { // No towns available.
 					DrawString(tr, STR_TOWN_DIRECTORY_NONE);
@@ -853,8 +852,9 @@ public:
 				int icon_x = tr.WithWidth(icon_size.width, rtl).left;
 				tr = tr.Indent(icon_size.width + WidgetDimensions::scaled.hsep_normal, rtl);
 
-				for (uint i = this->vscroll->GetPosition(); i < this->towns.size(); i++) {
+				auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->towns);
-					const Town *t = this->towns[i];
+				for (auto it = first; it != last; ++it) {
+					const Town *t = *it;
 					assert(t->xy != INVALID_TILE);
 
 					/* Draw rating icon. */
@@ -872,7 +872,6 @@ public:
 					DrawString(tr.left, tr.right, tr.top + (this->resize.step_height - GetCharacterHeight(FS_NORMAL)) / 2, GetTownString(t));
 
 					tr.top += this->resize.step_height;
-					if (++n == this->vscroll->GetCapacity()) break; // max number of towns in 1 window
 				}
 				break;
 			}

src/vehicle_gui.cpp

@@ -1704,10 +1704,9 @@ void BaseVehicleListWindow::DrawVehicleListItems(VehicleID selected_vehicle, int
 
 	int vehicle_button_x = rtl ? ir.right - profit.width : ir.left;
 
-	uint max = static_cast<uint>(std::min<size_t>(this->vscroll->GetPosition() + this->vscroll->GetCapacity(), this->vehgroups.size()));
+	auto [first, last] = this->vscroll->GetVisibleRangeIterators(this->vehgroups);
-	for (uint i = this->vscroll->GetPosition(); i < max; ++i) {
+	for (auto it = first; it != last; ++it) {
-
+		const GUIVehicleGroup &vehgroup = *it;
-		const GUIVehicleGroup &vehgroup = this->vehgroups[i];
 
 		SetDParam(0, vehgroup.GetDisplayProfitThisYear());
 		SetDParam(1, vehgroup.GetDisplayProfitLastYear());