proper pixmap caching for hand counter

cockatrice/src/handcounter.cpp

 #include <QPainter>
 #include <QSvgRenderer>
+#include <QPixmapCache>
 #include "handcounter.h"
 #include "cardzone.h"
 
@@ -7,17 +8,10 @@ HandCounter::HandCounter(QGraphicsItem *parent)
 	: AbstractGraphicsItem(parent), number(0)
 {
 	setCacheMode(DeviceCoordinateCache);
-	
-	QSvgRenderer svg(QString(":/resources/hand.svg"));
-	handImage = new QPixmap(72, 72);
-	handImage->fill(Qt::transparent);
-	QPainter painter(handImage);
-	svg.render(&painter, QRectF(0, 0, 72, 72));
 }
 
 HandCounter::~HandCounter()
 {
-	delete handImage;
 }
 
 void HandCounter::updateNumber()
@@ -33,6 +27,20 @@ QRectF HandCounter::boundingRect() const
 
 void HandCounter::paint(QPainter *painter, const QStyleOptionGraphicsItem * /*option*/, QWidget * /*widget*/)
 {
-	painter->drawPixmap(handImage->rect(), *handImage, handImage->rect());
+	painter->save();
+	QSize translatedSize = painter->combinedTransform().mapRect(boundingRect()).size().toSize();
+	QPixmap cachedPixmap;
+	if (!QPixmapCache::find("handCounter" + QString::number(translatedSize.width()), &cachedPixmap)) {
+		QSvgRenderer svg(QString(":/resources/hand.svg"));
+		cachedPixmap = QPixmap(translatedSize);
+		cachedPixmap.fill(Qt::transparent);
+		QPainter painter(&cachedPixmap);
+		svg.render(&painter, QRectF(0, 0, translatedSize.width(), translatedSize.height()));
+		QPixmapCache::insert("handCounter" + QString::number(translatedSize.width()), cachedPixmap);
+	}
+	painter->resetTransform();
+	painter->drawPixmap(cachedPixmap.rect(), cachedPixmap, cachedPixmap.rect());
+	painter->restore();
+	
 	paintNumberEllipse(number, 24, Qt::white, -1, painter);
 }

cockatrice/src/handcounter.h

@@ -11,7 +11,6 @@ class HandCounter : public QObject, public AbstractGraphicsItem {
 	Q_OBJECT
 private:
 	int number;
-	QPixmap *handImage;
 public slots:
 	void updateNumber();
 public: