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

src/ui/ItemIconCache.cpp

@@ -0,0 +1,64 @@
+#include "ItemIconCache.h"
+
+#include <QFile>
+#include <QPainter>
+#include <QSvgRenderer>
+
+ItemIconCache::ItemIconCache(const QString& iconDir)
+    : m_iconDir(iconDir)
+{
+}
+
+const QByteArray& ItemIconCache::getSvg(const std::string& itemId)
+{
+    const std::map<std::string, QByteArray>::const_iterator cached =
+        m_svgById.find(itemId);
+    if (cached != m_svgById.end())
+    {
+        return cached->second;
+    }
+
+    // An absent or unreadable file caches an empty byte array so it is not retried;
+    // a missing icon is not an error (REQ-UI-ITEM-ICON).
+    QByteArray svg;
+    QFile file(m_iconDir + "/" + QString::fromStdString(itemId) + ".svg");
+    if (file.open(QIODevice::ReadOnly))
+    {
+        svg = file.readAll();
+    }
+    return m_svgById.emplace(itemId, std::move(svg)).first->second;
+}
+
+bool ItemIconCache::hasIcon(const std::string& itemId)
+{
+    return !getSvg(itemId).isEmpty();
+}
+
+QPixmap ItemIconCache::getPixmap(const std::string& itemId, int sizePx)
+{
+    if (sizePx <= 0)
+    {
+        return QPixmap();
+    }
+
+    const std::pair<std::string, int> key(itemId, sizePx);
+    const std::map<std::pair<std::string, int>, QPixmap>::const_iterator cached =
+        m_pixmapCache.find(key);
+    if (cached != m_pixmapCache.end())
+    {
+        return cached->second;
+    }
+
+    const QByteArray& svg = getSvg(itemId);
+    QPixmap pixmap;
+    if (!svg.isEmpty())
+    {
+        QSvgRenderer renderer(svg);
+        pixmap = QPixmap(sizePx, sizePx);
+        pixmap.fill(Qt::transparent);
+        QPainter painter(&pixmap);
+        painter.setRenderHint(QPainter::Antialiasing, true);
+        renderer.render(&painter);
+    }
+    return m_pixmapCache.emplace(key, std::move(pixmap)).first->second;
+}