show recipes visually instead of describing them in text

src/ui/RecipeLineRow.h

@@ -0,0 +1,98 @@
+#pragma once
+
+#include <optional>
+#include <string>
+#include <vector>
+
+#include <QString>
+#include <QWidget>
+
+#include "BuildingType.h"
+
+class BuildingIconCache;
+class ItemIconCache;
+class QHBoxLayout;
+
+// One recipe drawn on a line: what it consumes, an arrow, what it produces, and how
+// long a cycle takes (REQ-UI-RECIPE-SUMMARY). Every place the UI states what something
+// makes draws this same line, so a recipe reads alike wherever it is shown:
+//
+//  * beneath the selection button, for the recipe a building is running
+//    (REQ-UI-RECIPE-SUMMARY);
+//  * on a selection dialog's option buttons, under the option's name
+//    (REQ-UI-SELECT-OPTIONS);
+//  * in an item's production tooltip and in the unlock-choice dialog, there led by the
+//    icon of the building that runs the recipe and its name
+//    (REQ-UI-ITEM-TOOLTIP, REQ-DEF-SCHEMATIC-DROP);
+//  * on a module button and in the layout dialog's build cost, where there is a price
+//    and a time but nothing produced (REQ-MOD-UI-DIALOG, REQ-MOD-UI-STATS-PANEL).
+class RecipeLineRow : public QWidget
+{
+    Q_OBJECT
+
+public:
+    // One item and how many of it the line states.
+    struct Amount
+    {
+        std::string itemId;
+        int         amount = 0;
+
+        bool operator==(const Amount& other) const
+        {
+            return itemId == other.itemId && amount == other.amount;
+        }
+    };
+
+    // What the line says. Everything but the inputs is optional, which is what lets the
+    // one widget serve the summary, the option buttons, the tooltip lines and the cost
+    // lines.
+    struct Spec
+    {
+        // Drawn as a leading chip when the line has to say which building runs the
+        // recipe -- an item may have several producers (REQ-UI-ITEM-TOOLTIP). Unset
+        // wherever the surrounding widget already establishes the building.
+        std::optional<BuildingType> building;
+        // Leading recipe name, for the same reason. Empty where the name is the
+        // caption above the line instead.
+        QString                     name;
+        std::vector<Amount>         inputs;
+        // Empty for a line that produces no item of its own: a ship schematic, or a
+        // module's price. No arrow is drawn then.
+        std::vector<Amount>         outputs;
+        std::optional<double>       durationSeconds;
+        // True where the time is added to something else rather than being a cycle of
+        // its own, and so reads "+3.0 s" (REQ-MOD-UI-DIALOG).
+        bool                        durationIsAddition = false;
+
+        bool operator==(const Spec& other) const
+        {
+            return building == other.building && name == other.name
+                && inputs == other.inputs && outputs == other.outputs
+                && durationSeconds == other.durationSeconds
+                && durationIsAddition == other.durationIsAddition;
+        }
+
+        bool isEmpty() const { return inputs.empty() && outputs.empty(); }
+    };
+
+    // Both caches may be null, which leaves the icons off: an item with no square and
+    // no icon falls back to its id, and a building with no chip to its name alone.
+    // Neither is owned.
+    RecipeLineRow(ItemIconCache* itemIcons, BuildingIconCache* buildingIcons,
+                  QWidget* parent = nullptr);
+
+    // Hides the row when the spec has nothing to state, which is how a building with no
+    // recipe shows no summary at all (REQ-UI-RECIPE-SUMMARY).
+    void setLine(const Spec& spec);
+
+private:
+    void rebuild(const Spec& spec);
+    void addAmounts(const std::vector<Amount>& amounts);
+
+    ItemIconCache*     m_itemIcons;
+    BuildingIconCache* m_buildingIcons;
+    QHBoxLayout*       m_layout;
+    // What the row currently shows, so a refresh at tick rate rebuilds it only when the
+    // recipe actually changed.
+    Spec               m_spec;
+};