In DiveListView, we have a very fundamental problem: When
On the one hand, we get informed of user-selection in the
DiveListView::selectionChanged() slot. This has to set the
correct flags in the C-backend.
On the other hand, sometimes we have to set the selection
programatically, e.g. when selecting a trip. This is done
by calling QItemSelectionModel::select().
But: this will *also* call into the above slot, in which
we can't tell whether it was a user interaction or an
internal call. This can lead to either infinite loops or
very inefficient behavior, because the current dive
is set numerous times.
The current code is aware of that and disconnects the
corresponding signal. This is scary, as these signals are
set internally by the model and view. Replace this
by a global "command executing" flag in DiveListNotifier.
The flag is set using a "marker" class, which resets the flag
once it goes out of scope (cf. RAII pattern).
In DiveListView, only process a selection if the flag is not
set. Otherwise simply call the QTreeView base class, to reflect
the new selection in the UI.
To have a common point for notifications of selection changes,
add such a signal to DiveListNotifier. This signal will be
used by the DiveListView as well as the Command-objects.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Previously, each dive-list modifying function would lead to a
full model reset. Instead, implement proper Qt-model semantics
using beginInsertRows()/endInsertRows(), beginRemoveRows()/
endRemoveRows(), dataChange().
To do so, a DiveListNotifer singleton is generatated, which
broadcasts all changes to the dive-list. Signals are sent by
the commands and received by the DiveTripModel. Signals are
batched by dive-trip. This seems to be an adequate compromise
for the two kinds of list-views (tree and list). In the common
usecase mostly dives of a single trip are affected.
Thus, batching of dives is performed in two positions:
- At command-level to batch by trip
- In DiveTripModel to feed batches of contiguous elements
to Qt's begin*/end*-functions.
This is conceptually simple, but rather complex code. To avoid
repetition of complex loops, the batching is implemented in
templated-functions, which are passed lambda-functions, which
are called for each batch.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
