subsurface/desktop-widgets/tab-widgets/TabDiveSite.cpp
Berthold Stoeger 396598430b desktop: fix saving of column-widths of device and site tables
Qt's memory management scheme is completely broken and messes
with common expectations.

QObjects are organized as a tree. The children are destroyed
in the destructor of QObject. This means that they are destructed
after the destructor of the parent object has run and its
sub-object were destructed. Obviously, this makes no sense as
the child objects should be able to access their parent at
any time.

To restore the commonly expected deterministic order of
construction and destruction, one might simply do away with
Qt's silly object tree and organise things using classical
subobjects. However, that breaks with the Qt-generated UI
classes: The objects generated by these classes are *not*
destructed with the UI class. Instead, they are attached
to the widget's QObject tree. Thus these are again destructed
*after* the widget! Who comes up with such a scheme?

In our case this means that we cannot have models used for
TableViews as subobjects, because the TableView needs the
model to save the column widths in the destructor. Which,
as detailed above is called *after* the desctructor of the
widget! Thus, turn these models into heap-allocated objects
and add them to the QObject tree.

Funilly, this exposes another insanity of Qt's QObject tree:
Children are destructed in order of construction! One would
expect that if objects are constructed in the sequence
A, B, C one can expect that C can, at any time, access B and A.
Not so in Qt: The destruction order is likewise A, B, C!

Thus, take care to init the widgets before the model. Jeez.

Finally, print a warning in the column-saving code of
TableWidget, so that these kind of subtleties are caught
in the future.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
2020-11-07 11:37:51 -08:00

138 lines
4.7 KiB
C++

// SPDX-License-Identifier: GPL-2.0
#include "TabDiveSite.h"
#include "core/subsurface-qt/divelistnotifier.h"
#include "core/divesite.h"
#include "core/divefilter.h"
#include "qt-models/divelocationmodel.h"
#include "desktop-widgets/mainwindow.h" // to place message box
#include "commands/command.h"
#include <QMessageBox>
TabDiveSite::TabDiveSite(QWidget *parent) : TabBase(parent)
{
ui.setupUi(this);
model = new DiveSiteSortedModel(this);
ui.diveSites->setTitle(tr("Dive sites"));
ui.diveSites->setModel(model);
// Default: sort by name
ui.diveSites->view()->sortByColumn(LocationInformationModel::NAME, Qt::AscendingOrder);
ui.diveSites->view()->setSortingEnabled(true);
ui.diveSites->view()->horizontalHeader()->setSectionResizeMode(LocationInformationModel::NAME, QHeaderView::Stretch);
ui.diveSites->view()->horizontalHeader()->setSectionResizeMode(LocationInformationModel::DESCRIPTION, QHeaderView::Stretch);
ui.diveSites->view()->setSelectionBehavior(QAbstractItemView::SelectRows);
// Show only the first few columns
for (int i = LocationInformationModel::LOCATION; i < LocationInformationModel::COLUMNS; ++i)
ui.diveSites->view()->setColumnHidden(i, true);
connect(ui.diveSites, &TableView::addButtonClicked, this, &TabDiveSite::add);
connect(ui.diveSites, &TableView::itemClicked, this, &TabDiveSite::diveSiteClicked);
connect(ui.diveSites->view()->selectionModel(), &QItemSelectionModel::selectionChanged, this, &TabDiveSite::selectionChanged);
// Subtle: We depend on this slot being executed after the slot in the model.
// This is realized because the model was constructed as a member object and connects in the constructor.
connect(&diveListNotifier, &DiveListNotifier::diveSiteChanged, this, &TabDiveSite::diveSiteChanged);
}
void TabDiveSite::updateData()
{
}
void TabDiveSite::clear()
{
}
void TabDiveSite::diveSiteClicked(const QModelIndex &index)
{
struct dive_site *ds = model->getDiveSite(index);
if (!ds)
return;
switch (index.column()) {
case LocationInformationModel::EDIT:
MainWindow::instance()->editDiveSite(ds);
break;
case LocationInformationModel::REMOVE:
if (ds->dives.nr > 0 &&
QMessageBox::warning(MainWindow::instance(), tr("Delete dive site?"),
tr("This dive site has %n dive(s). Do you really want to delete it?\n", "", ds->dives.nr),
QMessageBox::Yes|QMessageBox::No) == QMessageBox::No)
return;
Command::deleteDiveSites(QVector<dive_site *>{ds});
break;
}
}
void TabDiveSite::add()
{
// This is mighty dirty: We hook into the "dive site added" signal and
// select the name field of the added dive site when the command sends
// the signal. This works only because we know that the model added the
// connection first. Very subtle!
// After the command has finished, the signal is disconnected so that dive
// site names are not selected on regular redo / undo.
connect(&diveListNotifier, &DiveListNotifier::diveSiteAdded, this, &TabDiveSite::diveSiteAdded);
Command::addDiveSite(tr("New dive site"));
disconnect(&diveListNotifier, &DiveListNotifier::diveSiteAdded, this, &TabDiveSite::diveSiteAdded);
}
void TabDiveSite::diveSiteAdded(struct dive_site *, int idx)
{
if (idx < 0)
return;
QModelIndex globalIdx = LocationInformationModel::instance()->index(idx, LocationInformationModel::NAME);
QModelIndex localIdx = model->mapFromSource(globalIdx);
ui.diveSites->view()->setCurrentIndex(localIdx);
ui.diveSites->view()->edit(localIdx);
}
void TabDiveSite::diveSiteChanged(struct dive_site *ds, int field)
{
int idx = get_divesite_idx(ds, &dive_site_table);
if (idx < 0)
return;
QModelIndex globalIdx = LocationInformationModel::instance()->index(idx, field);
QModelIndex localIdx = model->mapFromSource(globalIdx);
ui.diveSites->view()->scrollTo(localIdx);
}
void TabDiveSite::on_purgeUnused_clicked()
{
Command::purgeUnusedDiveSites();
}
void TabDiveSite::on_filterText_textChanged(const QString &text)
{
model->setFilter(text);
}
QVector<dive_site *> TabDiveSite::selectedDiveSites()
{
const QModelIndexList indices = ui.diveSites->view()->selectionModel()->selectedRows();
QVector<dive_site *> sites;
sites.reserve(indices.size());
for (const QModelIndex &idx: indices) {
struct dive_site *ds = model->getDiveSite(idx);
sites.append(ds);
}
return sites;
}
void TabDiveSite::selectionChanged(const QItemSelection &, const QItemSelection &)
{
DiveFilter::instance()->setFilterDiveSite(selectedDiveSites());
}
void TabDiveSite::showEvent(QShowEvent *)
{
// If the user switches to the dive site tab and there was already a selection,
// filter on that selection.
DiveFilter::instance()->startFilterDiveSites(selectedDiveSites());
}
void TabDiveSite::hideEvent(QHideEvent *)
{
// If the user switches to a different tab, stop the dive site filtering
DiveFilter::instance()->stopFilterDiveSites();
}