Design and Development of a Diagnostics Client for a Beam Loss ...

Design and Development of a Diagnostics Client for a Beam Loss Measurement System at CERN
Figure 27: Offline pick with minimum-maximum enabled and measurement period 2 μs.
4.4.4.1 Design implementation of the offline interface
The offline user interface and the logic behind it, is created and handled by 3 different
sub-classes which extend a JPanel class. The first one named OfflineDataViewerGUI is
responsible for the creation of the interface. Similar to the online interface, this class uses
different layout managers to create small inner panels with all the required components.
An object of this class is created inside the constructor of the OnlineDataViewerGUI. The
second class of the offline concept is named UpperOfflinePanel. Likewise, an object of
that class is created inside the constructor of the OfflineDataViewerGUI and is added to
the north of the interface as a JPanel. Basically, it implements the logic behind the Open
button and all the different components that lie in the upper panel of the interface. It creates
an action listener for the button which handles requests for displaying past online sessions
by the user. Given the selected online session path, all the data are collected by the .stats
files of the acquisition and stored into buffers. These buffers, along with other variables
such as file descriptors and lengths, constitute the arguments of the constructor of the third
class; the DataPicker. This class creates the data-picker graph with the stats plots from
the requested acquisition session. A DataPicker instance is constructed inside the action
listener after a selection of an acquisition session path by the user. This is the reason why
the graph appears in the interface after a valid path selection. This class handles most of
the picking and processing logic of the displayed data in both graphs. It also contains an
action and an item listener for the scaling settings and the measurement period spinner
respectively. Finally, it provides a method to dereference every inner object field. This is
vital to avoid memory leaks in the heap space after a sequence of opening different past
Emmanouil I. Angelogiannopoulos 42