Codechange: Add DropDownIcon constructor to override dimension.

This avoids the need to construct a DropDownIcon and set the dimension after.

src/rail_gui.cpp

@@ -2354,9 +2354,7 @@ DropDownList GetRailTypeDropDownList(bool for_replacement, bool all_option)
 			list.push_back(std::make_unique<DropDownListStringItem>(rti->strings.replace_text, rt, !HasBit(avail_railtypes, rt)));
 		} else {
 			StringID str = rti->max_speed > 0 ? STR_TOOLBAR_RAILTYPE_VELOCITY : STR_JUST_STRING;
-			auto iconitem = std::make_unique<DropDownListIconItem>(rti->gui_sprites.build_x_rail, PAL_NONE, str, rt, !HasBit(avail_railtypes, rt));
-			iconitem->SetDimension(d);
-			list.push_back(std::move(iconitem));
+			list.push_back(std::make_unique<DropDownListIconItem>(d, rti->gui_sprites.build_x_rail, PAL_NONE, str, rt, !HasBit(avail_railtypes, rt)));
 		}
 	}
 

src/road_gui.cpp

@@ -1828,9 +1828,7 @@ DropDownList GetRoadTypeDropDownList(RoadTramTypes rtts, bool for_replacement, b
 			list.push_back(std::make_unique<DropDownListStringItem>(rti->strings.replace_text, rt, !HasBit(avail_roadtypes, rt)));
 		} else {
 			StringID str = rti->max_speed > 0 ? STR_TOOLBAR_RAILTYPE_VELOCITY : STR_JUST_STRING;
-			auto iconitem = std::make_unique<DropDownListIconItem>(rti->gui_sprites.build_x_road, PAL_NONE, str, rt, !HasBit(avail_roadtypes, rt));
-			iconitem->SetDimension(d);
-			list.push_back(std::move(iconitem));
+			list.push_back(std::make_unique<DropDownListIconItem>(d, rti->gui_sprites.build_x_road, PAL_NONE, str, rt, !HasBit(avail_roadtypes, rt)));
 		}
 	}
 
@@ -1869,9 +1867,7 @@ DropDownList GetScenRoadTypeDropDownList(RoadTramTypes rtts)
 		SetDParam(0, rti->strings.menu_text);
 		SetDParam(1, rti->max_speed / 2);
 		StringID str = rti->max_speed > 0 ? STR_TOOLBAR_RAILTYPE_VELOCITY : STR_JUST_STRING;
-		auto item = std::make_unique<DropDownListIconItem>(rti->gui_sprites.build_x_road, PAL_NONE, str, rt, !HasBit(avail_roadtypes, rt));
-		item->SetDimension(d);
-		list.push_back(std::move(item));
+		list.push_back(std::make_unique<DropDownListIconItem>(d, rti->gui_sprites.build_x_road, PAL_NONE, str, rt, !HasBit(avail_roadtypes, rt)));
 	}
 
 	if (list.empty()) {

src/widgets/dropdown_type.h

@@ -149,6 +149,12 @@ public:
 		this->dbounds = this->dsprite;
 	}
 
+	template <typename... Args>
+	explicit DropDownIcon(const Dimension &dim, SpriteID sprite, PaletteID palette, Args&&... args) : TBase(std::forward<Args>(args)...), sprite(sprite), palette(palette), dbounds(dim)
+	{
+		this->dsprite = GetSpriteSize(this->sprite);
+	}
+
 	uint Height() const override { return std::max(this->dbounds.height, this->TBase::Height()); }
 	uint Width() const override { return this->dbounds.width + WidgetDimensions::scaled.hsep_normal + this->TBase::Width(); }
 
@@ -159,15 +165,6 @@ public:
 		DrawSprite(this->sprite, this->palette, CenterBounds(ir.left, ir.right, this->dsprite.width), CenterBounds(r.top, r.bottom, this->dsprite.height));
 		this->TBase::Draw(full, r.Indent(this->dbounds.width + WidgetDimensions::scaled.hsep_normal, rtl), sel, bg_colour);
 	}
-
-	/**
-	 * Override bounding box dimensions of sprite, to allow multiple options to have consistent spacing.
-	 * @param dim New bounding box to assign.
-	 */
-	void SetDimension(const Dimension &dim)
-	{
-		this->dbounds = dim;
-	}
 };
 
 /**