Providing for ccr/pscr bailout - logging and interactions with libdivecomputer.

[Willem Ferguson]

I am slowly working towards providing for bailout in the dive profile 
display. There are a few decisions that need to be made and I would 
appreciate any comment.

1) The recording of bailout events by dive computers. On Shearwater, 
each dive sample has a boolean that indicates whether the sample was 
during Loop or during Bailout. At the moment this boolean is not exposed 
by libdivecomputer, but Jef and myself are having discussions about 
making this information available in the API. I only have access to 
Shearwater equipment. How do other dive computers, e.g. H-W, record 
bailout events? Obviously, if one implements bailout, one would like to 
do it in a way that is as compatible with what most dive computers do. 
Anyone using other hardware for ccr/pscr, please comment on how your 
computer handles bailout events while logging?

2) Showing bailout events in the Subsurface dive profile. This would 
have two aspects.

     a) Indicating bailout with an icon on the dive profile. The 
inclusion of appropriate events is by far the easiest way to implement 
this. Currently the dive events are very closely tied to the 
libdivecomputer events, so this is somewhat limiting.

     b) Adapting the gas partial pressure graphs to reflect what the 
diver breathes during bailout. When rendering the dive by creating a 
plot_info structure for each sample, the easiest mechanism of 
incorporating bailout would be to use the Shearwater approach: have a 
byte indicating Loop or Bailout and perform the appropriate calculation 
for gas partial pressures.

What worries me about the above is that it uses a dual system of events 
as well as sample-wise boolean values. In the case of Shearwater, the 
events would be created from the sample-wise boolean values. If the 
events are entered by hand, then the sample-wise bolean values would be 
created using the events.

Is this approach too complex?

Kind regards,

willem



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