Move code to update units table into a dedicated method

This commit moves the logic to update the units table into a dedicated
method and adapts the code in a way, that the content of the units
table is not regenerated on update, but the already existing table
contents are updated as needed. This allows the table to keep its
selection on update.

client/views/view_units.cpp

@@ -131,15 +131,25 @@ void units_view::init() { queen()->game_tab_widget->setCurrentIndex(index); }
  * Refresh all widgets for units view
  */
 void units_view::update_view()
+{
+  QTimer *timer = new QTimer(this);
+  connect(timer, &QTimer::timeout, this, &units_view::update_waiting);
+  timer->start(1000);
+
+  update_units();
+  update_waiting();
+}
+
+/**
+   Updates the units table
+*/
+void units_view::update_units()
 {
   // used to set the height of the unit sprite
   QFont f = QApplication::font();
   QFontMetrics fm(f);
   int h = fm.height() + 24;
 
-  ui.units_table->setRowCount(0);
-  ui.units_table->clearContents();
-
   int entries_used = 0; // Position in the units array
   struct unit_view_entry unit_entries[U_LAST];
 
@@ -152,14 +162,43 @@ void units_view::update_view()
   int total_gold = 0;   // Sum of gold upkeep
   int total_shield = 0; // Sum of shield upkeep
   int total_food = 0;   // Sum of food upkeep
-  int max_row = 0;      // Max rows in the table widget
+  int max_row = ui.units_table->rowCount(); // Max rows in the table widget
+
+  // Remove "footer" rows from units table
+  if (max_row >= 1) {
+    max_row--;
+    ui.units_table->removeRow(max_row);
+  }
+
+  // Keep tab of all unit types currently in the table. This is used to
+  // update already existing rows in the table. After updating a unit type
+  // the corresponding entry is removed from the map. Once all unit types,
+  // used by the player, have been processed the remaining unit types can be
+  // removed from the units table.
+  std::map<cid, QTableWidgetItem *> unittypes_in_table;
+  for (int r = 0; r < ui.units_table->rowCount(); r++) {
+    QTableWidgetItem *item = ui.units_table->item(r, 0);
+
+    bool ok = false;
+    cid key = (cid) item->data(Qt::UserRole).toInt(&ok);
+    fc_assert_action(ok == true, continue);
+    unittypes_in_table[key] = ui.units_table->item(r, 0);
+  }
 
   for (int i = 0; i < entries_used; i++) {
     struct unit_view_entry *pentry = unit_entries + i;
     const struct unit_type *putype = pentry->type;
     cid id = cid_encode_unit(putype);
 
-    ui.units_table->insertRow(max_row);
+    auto existing_row_for_unittype = unittypes_in_table.find(id);
+    bool new_row = existing_row_for_unittype == unittypes_in_table.end();
+    int current_row = max_row;
+    if (new_row) {
+      ui.units_table->insertRow(max_row);
+    } else {
+      current_row = existing_row_for_unittype->second->row();
+    }
+
     for (int j = 0; j < 8; j++) {
       QTableWidgetItem *item = new QTableWidgetItem;
       switch (j) {
@@ -172,7 +211,7 @@ void units_view::update_view()
           QLabel *lbl = new QLabel;
           lbl->setPixmap(QPixmap(sprite));
           lbl->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
-          ui.units_table->setCellWidget(i, j, lbl);
+          ui.units_table->setCellWidget(current_row, j, lbl);
         }
         item->setData(Qt::UserRole, id);
         break;
@@ -234,9 +273,20 @@ void units_view::update_view()
         total_gold += pentry->gold_cost;
         break;
       }
-      ui.units_table->setItem(max_row, j, item);
+      ui.units_table->setItem(current_row, j, item);
+    }
+
+    if (new_row) {
+      max_row++;
+    } else {
+      unittypes_in_table.erase(id);
     }
-    max_row++;
+  }
+
+  // Remove rows no longer needed in the table.
+  for (const auto &[_, value] : unittypes_in_table) {
+    ui.units_table->removeRow(value->row());
+    max_row--;
   }
 
   // Add a "footer" to the table showing the totals.
@@ -291,12 +341,6 @@ void units_view::update_view()
     ui.units_table->verticalHeader()->setSectionResizeMode(
         QHeaderView::ResizeToContents);
   }
-
-  QTimer *timer = new QTimer(this);
-  connect(timer, &QTimer::timeout, this, &units_view::update_waiting);
-  timer->start(1000);
-
-  update_waiting();
 }
 
 /**

client/views/view_units.h

@@ -62,6 +62,7 @@ class units_view : public QWidget {
   units_view();
   ~units_view();
   void update_view();
+  void update_units();
   void update_waiting();
   void init();