Use a dedicated graphics item for drawing the text instead a pixmap

src/textitem.h

@@ -0,0 +1,28 @@
+#ifndef TEXTITEM_H
+#define TEXTITEM_H
+
+#include <QGraphicsItem>
+#include <QPen>
+#include <QFont>
+#include <QString>
+
+class TextItem : public QGraphicsItem
+{
+public:
+	TextItem(const QString &text, const QPointF &pos, const QFont &font,
+	  int maxTextWidth, QGraphicsItem *parent = 0);
+
+	QRectF boundingRect() const {return _boundingRect;}
+	void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
+	  QWidget *widget);
+
+	void setPen(const QPen &pen) {_pen = pen;}
+
+private:
+	QString _text;
+	QRectF _boundingRect;
+	QFont _font;
+	QPen _pen;
+};
+
+#endif // TEXTITEM_H