ui: Use update loop in graph panning and zooming for smooth interaction

src/lib_gui/qt/graphics/QtGraphicsView.h

@@ -3,11 +3,12 @@
 
 #include <QGraphicsView>
 
+class QTimer;
+
 class QtGraphicsView
 	: public QGraphicsView
 {
 	Q_OBJECT
-	Q_PROPERTY(qreal zoom READ zoom WRITE setZoom)
 
 public:
 	QtGraphicsView(QWidget* parent);
@@ -15,26 +16,39 @@ public:
 	float getZoomFactor() const;
 	void setAppZoomFactor(float appZoomFactor);
 
-	qreal zoom() const;
-	void setZoom(qreal zoom);
-
 protected:
 	void mousePressEvent(QMouseEvent *event);
 	void mouseReleaseEvent(QMouseEvent *event);
+
 	void keyPressEvent(QKeyEvent* event);
+	void keyReleaseEvent(QKeyEvent* event);
+
 	void wheelEvent(QWheelEvent* event);
 
 signals:
 	void emptySpaceClicked();
 
+private slots:
+	void update();
+
 private:
+	bool moves() const;
+
 	void updateTransform();
-	void updateZoom(float delta, bool animate);
+	void updateZoom(float delta);
 
 	QPoint m_last;
 
 	float m_zoomFactor;
 	float m_appZoomFactor;
+
+	bool m_up;
+	bool m_down;
+	bool m_left;
+	bool m_right;
+	bool m_shift;
+
+	std::shared_ptr<QTimer> m_timer;
 };
 
 #endif // QT_GRAPHICS_VIEW_H