Use fuzzy text bounding rect computation to improve performance

Do not use QGraphicsScene as it is not thread-safe

src/text.h

@@ -1,18 +1,27 @@
 #ifndef TEXT_H
 #define TEXT_H
 
-#include <QGraphicsScene>
+#include "textitem.h"
 
-class Text : public QGraphicsScene
+class Text
 {
 public:
-	Text(int size, QObject *parent = 0) : QGraphicsScene(parent)
-	  {setSceneRect(0, 0, size, size);}
+	Text(int size) : _sceneRect(QRectF(0, 0, size, size)) {}
+	~Text();
+
+	void render(QPainter *painter);
 
 	void addLabel(const QString &text, const QPointF &pos, const QFont &font,
 	  const QPen &pen, qreal maxTextWidth);
 	void addLabel(const QString &text, const QPainterPath &path,
 	  const QFont &font, const QPen &pen, qreal maxAngle);
+
+private:
+	void addItem(TextItem *item) {_items.append(item);}
+	QList<TextItem *> collidingItems(const TextItem *item) const;
+
+	QRectF _sceneRect;
+	QList<TextItem *> _items;
 };
 
 #endif // TEXT_H