[Icons] Render lock and dropdown glyphs through the icon engine

Both generators rendered the sentinel SVG to a fixed height x height pixmap
at DPR 1. The pre-migration path rendered larger and let QIcon scale it, so
on a 2x display the games-list lock (13px) and the banner dropdown arrow
(24px) came back crisp; the new path hands the widget a DPR-1 bitmap that
gets upscaled and blurred.

- The games list asks the themed engine for `icons/lock` directly, so the
  item view paints it at the device pixel ratio and the lock also follows
  HighlightedText on a selected row.
- The dropdown goes through `loadThemedIcon(...).pixmap(size, dpr)`, which
  keeps the glyph's aspect ratio and renders at the requested ratio.
- LockPixmapGenerator has no consumer left, so it and its cache are gone.

cockatrice/src/interface/pixel_map_generator.cpp

@@ -4,6 +4,7 @@
 #include "theme_icon.h"
 #include "theme_manager.h"
 
+#include <QApplication>
 #include <QBrush>
 #include <QByteArray>
 #include <QChar>
@@ -435,39 +436,19 @@ QIcon UserLevelPixmapGenerator::generateIconWithColorOverride(int height,
 
 QMap<QString, QIcon> UserLevelPixmapGenerator::iconCache;
 
-QPixmap LockPixmapGenerator::generatePixmap(int height)
-{
-
-    int key = height;
-    if (pmCache.contains(key)) {
-        return pmCache.value(key);
-    }
-
-    const QString resolved = themeManager->assetPath(QStringLiteral("icons/lock"));
-    QPixmap pixmap = loadSentinelSvgPixmap(resolved, QPalette::WindowText, QSize(height, height));
-    if (pixmap.isNull()) {
-        pixmap = tryLoadImage(QStringLiteral("theme:") + resolved, QSize(height, height), true);
-    }
-    pmCache.insert(key, pixmap);
-    return pixmap;
-}
-
-QMap<int, QPixmap> LockPixmapGenerator::pmCache;
-
 QPixmap DropdownIconPixmapGenerator::generatePixmap(int height, bool expanded)
 {
-    QString key = QString::number(expanded) + ":" + QString::number(height);
+    const QString key = QString::number(expanded) + ":" + QString::number(height);
     if (pmCache.contains(key)) {
         return pmCache.value(key);
     }
 
+    // Render through the themed icon engine: it keeps the glyph's aspect ratio,
+    // follows the palette, and renders at the device pixel ratio instead of
+    // handing a DPR-1 bitmap to a label that would upscale and blur it on a 2x
+    // display.
     const QString prefix = QStringLiteral("icons/") + (expanded ? "dropdown_expanded" : "dropdown_collapsed");
-    const QString resolved = themeManager->assetPath(prefix);
-    QPixmap pixmap = loadSentinelSvgPixmap(resolved, QPalette::WindowText, QSize(height, height));
-    if (pixmap.isNull()) {
-        pixmap = tryLoadImage(QStringLiteral("theme:") + resolved, QSize(height, height), true);
-    }
-
+    const QPixmap pixmap = loadThemedIcon(prefix).pixmap(QSize(height, height), qApp->devicePixelRatio());
     pmCache.insert(key, pixmap);
     return pixmap;
 }
@@ -539,7 +520,6 @@ void clearPixmapGeneratorCaches()
     PingPixmapGenerator::clear();
     CountryPixmapGenerator::clear();
     UserLevelPixmapGenerator::clear();
-    LockPixmapGenerator::clear();
     DropdownIconPixmapGenerator::clear();
     ManaSymbolPixmapGenerator::clear();
 }

cockatrice/src/interface/pixel_map_generator.h

@@ -106,19 +106,6 @@ public:
     }
 };
 
-class LockPixmapGenerator
-{
-private:
-    static QMap<int, QPixmap> pmCache;
-
-public:
-    static QPixmap generatePixmap(int height);
-    static void clear()
-    {
-        pmCache.clear();
-    }
-};
-
 class DropdownIconPixmapGenerator
 {
 private:

cockatrice/src/interface/widgets/server/games_model.cpp

@@ -1,6 +1,7 @@
 #include "games_model.h"
 
 #include "../../../client/settings/cache_settings.h"
+#include "../../theme_icon.h"
 #include "../interface/pixel_map_generator.h"
 #include "libcockatrice/protocol/pb/serverinfo_user.pb.h"
 #include "user/user_list_proxy.h"
@@ -85,7 +86,8 @@ const QString GamesModel::getGameCreatedString(const int secs)
 }
 
 GamesModel::GamesModel(const QMap<int, QString> &_rooms, const QMap<int, GameTypeMap> &_gameTypes, QObject *parent)
-    : QAbstractTableModel(parent), rooms(_rooms), gameTypes(_gameTypes)
+    : QAbstractTableModel(parent), rooms(_rooms), gameTypes(_gameTypes),
+      lockIcon(loadThemedIcon(QStringLiteral("icons/lock")))
 {
 }
 
@@ -188,7 +190,9 @@ QVariant GamesModel::data(const QModelIndex &index, int role) const
                     return result.join(", ");
                 }
                 case Qt::DecorationRole: {
-                    return gameentry.with_password() ? QIcon(LockPixmapGenerator::generatePixmap(13)) : QVariant();
+                    // One engine per model: it is palette- and theme-aware and
+                    // invalidates itself, so a repaint must not build a new one.
+                    return gameentry.with_password() ? lockIcon : QVariant();
                     case Qt::TextAlignmentRole:
                         return Qt::AlignLeft;
                     default:

cockatrice/src/interface/widgets/server/games_model.h

@@ -5,6 +5,7 @@
 #include "game_type_map.h"
 
 #include <QAbstractTableModel>
+#include <QIcon>
 #include <QList>
 #include <QMap>
 #include <QModelIndex>
@@ -32,6 +33,7 @@ private:
     QList<ServerInfo_Game> gameList;  /**< List of games currently displayed. */
     QMap<int, QString> rooms;         /**< Map of room IDs to room names. */
     QMap<int, GameTypeMap> gameTypes; /**< Map of room IDs to available game types. */
+    QIcon lockIcon;                   /**< Themed lock for password-protected games. */
 
     static const int NUM_COLS = 8; /**< Number of columns in the table. */