ENH: Allow selection of data series/lines to plot.

[bradyzp]

Issue: Currently we plot only a default set of data series in our three plot areas: Gravity, Long/Cross, and Eotvos correction.

To improve functionality we need to provide users with a means to select other channels to plot versus each other in a selected sub-plot.
Previously this had been accomplished using a list of channels with check-boxes, allowing the user to select the check box to plot it on the chart.

I feel this solution is rather inelegant however, as we have multiple plots, there needs to be an easy way to select which plot the data will be plotted in.

Idea 1
Use the check-box method described above, with a drop down box to allow the user to select which chart to plot on.
It is unfeasible at this time to allow plot selection by clicking on the plot, as we use this to trigger a flight-line selection (though we may add a toggle-able mode to turn this functionality on/off).

Idea 2

• Investigate the ability to drag-and-drop channels from a list into the plot area, allowing a user to intuitively choose which plot to add data to.
• Qt potentially provides this functionality, though there could be some difficulty interfacing with the MPL canvas in terms of determining which plot to drop the widget into.
• Additionally need to determine how a user would remove a line from the plot after it has been dropped in.
• Assuming we allow the user to only plot each individual channel once (i.e. you can't plot gravity on plot 1 and 3 at the same time), this could be accomplished by adding a button 'remove' next to the channel in the list after it has been added to the plot.

[cbertinato]

I think that something along the lines of idea 2 would be most feasible. Even if drag-and-drop turns out to be tricky to implement, we could probably start with a list of channels and perhaps use a double-click or context menu to add and/or delete plots.

[bradyzp]

Agreed, I'll start working on modularizing the plotting code to make it easier to add/remove lines on demand in order to implement this feature.

Drag-and-drop will hopefully be feasible, I'm working on a prototype to see if it will be able to work with the matplotlib canvas directly, or if we need to think of some other method for graphically selecting plot-lines. Can possibly use mpl's 'button_release_event' in the axes which will then query Qt to see what was being dragged.

[bradyzp]

Next commit will have almost working implementation - using a tree view to allow drag-n-drop of channels to different plots.
Need to update the TreeView stylesheet, both for the plot selection and project view - as it was never really finished, just a rough implementation.

Issue: Gravity and GPS have a field with the same name (long) i.e. long acceleration and long(itude) which leads to some confusion on the plot.
Possible resolution is to prefix the labels with the data source e.g. '<gps>long' or '<grav>long'

[cbertinato]

I would not be opposed to using the full word for longitude in this case (and latitude as well for consistency).

[bradyzp]

Closing this issue as functionally complete for initial release. Further improvements/features will be added to later branches/issues.

[bradyzp]

Re-opening to continue development on model/view class to better support drag-n-drop, and to limit plots to 2 channels so that we can implement a dual Y scale.