Control

When running a visualisation-annotated ECLiPSe program with a Java VC attached, control of the ECLiPSe process may pass between ECLiPSe and the VC throughout the program run. That is to say at certain key events in the program, ECLiPSe will pause in its running of the program and wait for user interaction with the VC before continuing. In such circumstances, the VC is said to hold the control.

Table 3.1 details the default behaviour for each of the visualisation events which may occur, and indicates whether or not this default behaviour can be altered.

Table 3.1: VC default behaviour for visualisation event.

Event	Triggered by	Default hold	Alterable
viewable creation	viewable_create/2 viewable_create/3 viewable_create/4	yes	no
viewable expansion	viewable_expand/3 viewable_expand/4	no	yes
viewable contraction	Backtracked over a viewable expansion	no	yes
viewable destruction	Backtracked over a viewable creation	yes	yes
forward update	One or more elements in a viewable have been updated, ie. had their domain reduced or have been instantiated	no	yes
backward update	A forward update has been backtracked over	no	yes

Should the VC hold, control can be passed back to ECLiPSe by pressing the Resume button at the bottom of the VC window, or by setting the auto resume timer. The Resume button and the auto resume timer are disabled when ECLiPSe has control, see Figure 3.2.

Figure 3.2: The VC showing the auto resume menu option and timer slider.