dictionary - Making a draggable map with inertia in XNA C# (Custom framework) -

i trying make draggable map inertia,friction, i'm kindda lost right example: http://www.emanueleferonato.com/2016/01/18/how-to-create-a-html-draggable-and-scrollable-map-with-inertia-using-phaser-framework/

this have far:

 override public void update()     {         base.update();          if (getstate() == state_dragging)         {             if (input.mouse.pressed())             {                 setvelocityx(drag_x - input.mouse.getx());             }         }         if (getstate() == state_stale)         {              if (cmouse.pressed())             {                 drag_x = input.mouse.getx();                 drag_y = input.mouse.gety();                 setstate(state_dragging);              }          }}