give the selection cards their own parts instead of label blobs

src/ui/selection/BufferSection.h

@@ -5,20 +5,25 @@
 
 #include <QWidget>
 
-struct Building;
-class QLabel;
+#include "SelectionContext.h"
 
-// The input and output buffer contents of one building (REQ-UI-SINGLE-SELECTION).
+struct Building;
+class ItemChipRow;
+class SectionBox;
+
+// The input and output buffer contents of one building, each a captioned section of item
+// chips (REQ-UI-SINGLE-SELECTION).
 //
 // Counting what is in the buffers is the same for every building type, so it happens
 // here; what a cycle consumes and produces is not, so the owning content supplies those
-// per-cycle amounts. An item with no entry in the maps is shown without a denominator.
+// per-cycle amounts. An item with no entry in the maps is shown without a denominator,
+// and a section holding nothing is not shown at all.
 class BufferSection : public QWidget
 {
     Q_OBJECT
 
 public:
-    explicit BufferSection(QWidget* parent = nullptr);
+    explicit BufferSection(const SelectionContext& context, QWidget* parent = nullptr);
 
     // perCycleInputs and perCycleOutputs map an item id to the amount one production
     // cycle consumes or produces. Both may be empty, for a building that runs no cycle.
@@ -27,5 +32,8 @@ public:
                     const std::map<std::string, int>& perCycleOutputs);
 
 private:
-    QLabel* m_label;
+    SectionBox*  m_inputSection;
+    ItemChipRow* m_inputChips;
+    SectionBox*  m_outputSection;
+    ItemChipRow* m_outputChips;
 };