Reapply build button grid icons

Revert of "Undo build button grid icons" (614dda8): restore the per-building
SVG icons, the QtSvg-based icon loading in BuildButtonGrid, the icon dir
plumbing in MainWindow, and the Qt5::Svg dependency.

This returns the unlock-groups branch to having the icons. The preceding
undo commit exists only so the Demolish -> Deconstruct rename can be
cherry-picked on its own (rename+icons commit together with the undo).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc

src/CMakeLists.txt

@@ -117,6 +117,7 @@ target_link_libraries(${TARGET_UI_NAME}
     Qt5::Network
     Qt5::Multimedia
     Qt5::Charts
+    Qt5::Svg
 )
 target_compile_definitions(${TARGET_UI_NAME} PRIVATE TOML_FLOAT_CHARCONV=0)
 

src/ui/BuildButtonGrid.cpp

@@ -2,9 +2,18 @@
 
 #include <string>
 
+#include <QByteArray>
+#include <QFile>
 #include <QGridLayout>
+#include <QIcon>
+#include <QPainter>
+#include <QPixmap>
 #include <QPushButton>
+#include <QRegularExpression>
 #include <QSignalMapper>
+#include <QSize>
+#include <QString>
+#include <QSvgRenderer>
 
 #include "BuildingType.h"
 #include "BuildingTypeSelectedEvent.h"
@@ -14,11 +23,60 @@
 #include "ExitBuilderModeRequestedEvent.h"
 #include "Simulation.h"
 
+namespace
+{
+    // Pixel size the SVG chips are rasterized at; downscaled to the button icon size.
+    const int kIconRenderSize = 64;
+    const QSize kIconSize(28, 28);
 
-BuildButtonGrid::BuildButtonGrid(Simulation* sim, const GameConfig* config, QWidget* parent)
+    QPixmap renderChip(const QByteArray& svg)
+    {
+        QSvgRenderer renderer(svg);
+        QPixmap pixmap(kIconRenderSize, kIconRenderSize);
+        pixmap.fill(Qt::transparent);
+        QPainter painter(&pixmap);
+        renderer.render(&painter);
+        return pixmap;
+    }
+
+    // Builds a build-button icon from a "<id>.svg" chip file. The returned QIcon also
+    // carries a Disabled-mode pixmap whose chip background is recolored grey, so an
+    // unaffordable (disabled) button shows the grey variant automatically
+    // (REQ-UI-BUILD-DISABLED) without any extra work in updateAffordability().
+    QIcon loadBuildingIcon(const QString& path)
+    {
+        QFile file(path);
+        if (!file.open(QIODevice::ReadOnly))
+        {
+            return QIcon();
+        }
+        const QByteArray svg = file.readAll();
+
+        QIcon icon;
+        icon.addPixmap(renderChip(svg), QIcon::Normal);
+
+        // Recolor only the chip background: the first "#rrggbb" fill in the file is the
+        // rounded background rect; the white glyph uses fill="none" and is left alone.
+        QString greyed = QString::fromUtf8(svg);
+        static const QRegularExpression fillPattern(QStringLiteral("fill=\"#[0-9a-fA-F]{6}\""));
+        const QRegularExpressionMatch match = fillPattern.match(greyed);
+        if (match.hasMatch())
+        {
+            greyed.replace(match.capturedStart(), match.capturedLength(),
+                           QStringLiteral("fill=\"#5f636e\""));
+        }
+        icon.addPixmap(renderChip(greyed.toUtf8()), QIcon::Disabled);
+        return icon;
+    }
+}
+
+
+BuildButtonGrid::BuildButtonGrid(Simulation* sim, const GameConfig* config,
+                                 const std::string& iconDir, QWidget* parent)
     : QWidget(parent)
     , m_sim(sim)
     , m_config(config)
+    , m_iconDir(iconDir)
 {
     QGridLayout* layout = new QGridLayout(this);
     layout->setSpacing(4);
@@ -53,6 +111,12 @@ BuildButtonGrid::BuildButtonGrid(Simulation* sim, const GameConfig* config, QWid
         QPushButton* btn = new QPushButton(label, this);
         btn->setCheckable(true);
         btn->setFixedHeight(48);
+        // Icon file name matches the building id (REQ-UI-BUILD-GRID); Tunnel Entry's
+        // "tunnel_entry.svg" serves the shared Tunnel button.
+        const QString iconPath = QString::fromStdString(m_iconDir) + "/"
+            + QString::fromStdString(def.id) + ".svg";
+        btn->setIcon(loadBuildingIcon(iconPath));
+        btn->setIconSize(kIconSize);
         if (def.tooltip)
         {
             btn->setToolTip(QString::fromStdString(*def.tooltip));
@@ -76,6 +140,9 @@ BuildButtonGrid::BuildButtonGrid(Simulation* sim, const GameConfig* config, QWid
     m_deconstructButton = new QPushButton(tr("Deconstruct"), this);
     m_deconstructButton->setCheckable(true);
     m_deconstructButton->setFixedHeight(48);
+    m_deconstructButton->setIcon(loadBuildingIcon(
+        QString::fromStdString(m_iconDir) + "/deconstruct.svg"));
+    m_deconstructButton->setIconSize(kIconSize);
     layout->addWidget(m_deconstructButton, row, col);
     connect(m_deconstructButton, &QPushButton::clicked, this, [this]() {
         EventManager::getInstance()->sendEventImmediately(

src/ui/BuildButtonGrid.h

@@ -2,6 +2,7 @@
 
 #include <map>
 #include <optional>
+#include <string>
 #include <vector>
 
 #include <QWidget>
@@ -28,7 +29,10 @@ class BuildButtonGrid : public QWidget,
     Q_OBJECT
 
 public:
-    BuildButtonGrid(Simulation* sim, const GameConfig* config, QWidget* parent = nullptr);
+    // iconDir is the directory holding the per-building "<id>.svg" chip icons
+    // (REQ-UI-BUILD-GRID); read from disk at runtime, like the config files.
+    BuildButtonGrid(Simulation* sim, const GameConfig* config,
+                    const std::string& iconDir, QWidget* parent = nullptr);
     ~BuildButtonGrid() override;
 
     void clearActiveButton();
@@ -55,6 +59,7 @@ private slots:
 private:
     Simulation*                      m_sim;
     const GameConfig*                m_config;
+    std::string                      m_iconDir;
     std::vector<BuildingType>        m_types;
     std::vector<QPushButton*>        m_buttons;
     std::map<BuildingType, int>      m_costs;

src/ui/MainWindow.cpp

@@ -6,6 +6,7 @@
 
 #include <QApplication>
 #include <QCloseEvent>
+#include <QDir>
 #include <QFile>
 #include <QMessageBox>
 #include <QPushButton>
@@ -51,8 +52,13 @@ MainWindow::MainWindow(Simulation* sim, const std::string& configDir,
     sideLayout->setContentsMargins(1, 1, 1, 1);
     sideLayout->setSpacing(1);
 
+    // Building icons live alongside the config (a sibling of the config dir), read
+    // from disk at runtime the same way visuals.toml is.
+    const std::string iconDir = QDir::cleanPath(
+        QString::fromStdString(m_configDir) + "/../icons/buildings").toStdString();
+
     m_selectedBuildingPanel = new SelectedBuildingPanel(sim, &sim->getConfig(), m_sidePanel);
-    m_buildButtonGrid       = new BuildButtonGrid(sim, &sim->getConfig(), m_sidePanel);
+    m_buildButtonGrid       = new BuildButtonGrid(sim, &sim->getConfig(), iconDir, m_sidePanel);
     m_blueprintPanel        = new BlueprintPanel(sim, &sim->getConfig(), m_sidePanel);
 
     sideLayout->addWidget(m_selectedBuildingPanel, 1);