Event handling and basic window operations

Table VI presents the additional energy for GUI event handling and basic window operations in terms of EUs. ``Event loop" shows the additional energy for an event to go through the event loop. It is very energy-efficient compared to ``System event," which includes additional energy for hardware interrupt, OS and platform event processing. Windows outperforms Qt and X/GTK significantly, which may be attributed to tighter integration of its GUI platform and OS. ``Create window" shows the additional energy for a GUI platform to claim and relinquish resources for a window according to the request from the applicaion. ``Show window" shows the additional energy for the GUI platform to show and hide a full screen window according to the request from the application. The window shown is identical to the background window. Therefore, there is no additional energy incurred due to framebuffer updating, LCDC or LCD. The additional energy can only be attributed to changes in the internal data of the GUI platform as in the cases of ``Event loop" and ``Create window". While Qt and Windows are relatively close, X/GTK performs significantly worse in ``Show window". This hints at the overhead of using an X server.

Table VI: Energy characterization in EUs for different GUI platforms

	Qt	Windows	X/GTK
Event handling
Event loop	27	11	40
System event	1,100	300	900
Basic window operations
Create window	1,900	2,600	1,000
Show window	9,900	7,900	18,000
Using windows of different types
Menu	12,800	15,400	6,100
Message box	14,400	6,000	13,300
Scroll bar	33,400$\sim$	20,000$\sim$	38,800$\sim$
	78,000	59,000	84,000
Tabbed panel	10,300	12,000	-
Draw text	-	1,600	-