Allow to draw produced-item icons in recipe dialog and game world

src/ui/RecipeSelectionDialog.cpp

@@ -3,7 +3,10 @@
 #include <cstddef>
 
 #include <QGridLayout>
+#include <QIcon>
+#include <QPixmap>
 #include <QPushButton>
+#include <QSize>
 #include <QStringList>
 #include <QVBoxLayout>
 
@@ -11,6 +14,7 @@
 #include "BuildingType.h"
 #include "DisplayName.h"
 #include "GameConfig.h"
+#include "ItemIconCache.h"
 #include "RecipesConfig.h"
 #include "RecipeTooltip.h"
 #include "ShipsConfig.h"
@@ -83,23 +87,38 @@ std::vector<RecipeSelectionOption> buildRecipeSelectionOptions(
             {
                 continue;
             }
+            // Icon shown on the option button (REQ-UI-RECIPE-ICON): the recipe's
+            // configured icon item, else its first output item.
+            const std::string iconItemId = recipe.icon
+                ? *recipe.icon
+                : (recipe.outputs.empty() ? std::string()
+                                          : recipe.outputs.front().item);
             options.push_back({recipe.id,
                                QString::fromStdString(toDisplayName(recipe.id)),
-                               buildRecipeTooltip(recipe)});
+                               buildRecipeTooltip(recipe),
+                               iconItemId});
         }
     }
 
     return options;
 }
 
+namespace
+{
+    // On-screen size of a recipe option button's item icon (REQ-UI-RECIPE-ICON).
+    const QSize kOptionIconSize(32, 32);
+}
+
 RecipeSelectionDialog::RecipeSelectionDialog(
     const std::vector<RecipeSelectionOption>& options,
-    const QString& title, QWidget* parent)
+    const QString& title, const QString& itemIconDir, QWidget* parent)
     : QDialog(parent)
 {
     setWindowTitle(title);
     setModal(true);
 
+    ItemIconCache iconCache(itemIconDir);
+
     QVBoxLayout* mainLayout = new QVBoxLayout(this);
     QGridLayout* grid = new QGridLayout();
     mainLayout->addLayout(grid);
@@ -109,7 +128,19 @@ RecipeSelectionDialog::RecipeSelectionDialog(
     {
         const RecipeSelectionOption& option = options[static_cast<std::size_t>(i)];
 
-        QPushButton* button = new QPushButton(option.caption, this);
+        QPushButton* button = new QPushButton(this);
+        // Icon-only when the produced item has an icon (REQ-UI-RECIPE-ICON); otherwise
+        // fall back to the caption. The name stays reachable via the tooltip.
+        if (!option.iconItemId.empty() && iconCache.hasIcon(option.iconItemId))
+        {
+            button->setIcon(QIcon(iconCache.getPixmap(
+                option.iconItemId, kOptionIconSize.width())));
+            button->setIconSize(kOptionIconSize);
+        }
+        else
+        {
+            button->setText(option.caption);
+        }
         if (!option.tooltip.isEmpty())
         {
             button->setToolTip(option.tooltip);