Introduce negate-toggle buttons to filter lists

Introduce toggle buttons which mean "filter all dives except
those fulfilling the selected criteria".

The old code used to check for rowCount() == 0. This should never happen,
because there is always a row "empty field". This check was moved into
the preamble of the functions to seperate it from the actual logic.

Fixes #435

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

4 files changed, 55 insertions, 41 deletions

diff --git a/desktop-widgets/listfilter.ui b/desktop-widgets/listfilter.ui
index 48d813d21..b1d717bf0 100644
--- a/desktop-widgets/listfilter.ui
+++ b/desktop-widgets/listfilter.ui
@@ -51,6 +51,16 @@
        </property>
       </widget>
      </item>
+     <item>
+      <widget class="QToolButton" name="notButton">
+       <property name="text">
+        <string>¬</string>
+       </property>
+       <property name="checkable">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
     </layout>
    </item>
    <item>
diff --git a/desktop-widgets/simplewidgets.cpp b/desktop-widgets/simplewidgets.cpp
index b63349819..f8cd96943 100644
--- a/desktop-widgets/simplewidgets.cpp
+++ b/desktop-widgets/simplewidgets.cpp
@@ -516,6 +516,7 @@ FilterBase::FilterBase(FilterModelBase *model_, QWidget *parent) : QWidget(paren
 	filter->setSourceModel(model);
 	filter->setFilterCaseSensitivity(Qt::CaseInsensitive);
 	connect(ui.filterInternalList, SIGNAL(textChanged(QString)), filter, SLOT(setFilterFixedString(QString)));
+	connect(ui.notButton, &QToolButton::toggled, model, &FilterModelBase::setNegate);
 	ui.filterList->setModel(filter);
 
 	addContextMenuEntry(tr("Select All"), &FilterModelBase::selectAll);
diff --git a/qt-models/filtermodels.cpp b/qt-models/filtermodels.cpp
index 004ff8493..48a2fd9b9 100644
--- a/qt-models/filtermodels.cpp
+++ b/qt-models/filtermodels.cpp
@@ -26,7 +26,8 @@ CREATE_INSTANCE_METHOD(SuitsFilterModel)
 CREATE_INSTANCE_METHOD(MultiFilterSortModel)
 
 FilterModelBase::FilterModelBase(QObject *parent) : QStringListModel(parent),
-	anyChecked(false)
+	anyChecked(false),
+	negate(false)
 {
 }
 
@@ -115,6 +116,12 @@ void FilterModelBase::invertSelection()
 	emit dataChanged(createIndex(0, 0), createIndex(rowCount() - 1, 0));
 }
 
+void FilterModelBase::setNegate(bool negateParam)
+{
+	negate = negateParam;
+	emit dataChanged(createIndex(0, 0), createIndex(rowCount() - 1, 0));
+}
+
 SuitsFilterModel::SuitsFilterModel(QObject *parent) : FilterModelBase(parent)
 {
 }
@@ -129,28 +136,25 @@ bool SuitsFilterModel::doFilter(dive *d, QModelIndex &index0, QAbstractItemModel
 	Q_UNUSED(index0);
 	Q_UNUSED(sourceModel);
 
-	if (!anyChecked) {
+	// rowCount() == 0 should never happen, because we have the "no suits" row
+	// let's handle it gracefully anyway.
+	if (!anyChecked || rowCount() == 0)
 		return true;
-	}
 
 	// Checked means 'Show', Unchecked means 'Hide'.
 	QString suit(d->suit);
 	// only show empty suit dives if the user checked that.
-	if (suit.isEmpty()) {
-		if (rowCount() > 0)
-			return checkState[rowCount() - 1];
-		else
-			return true;
-	}
+	if (suit.isEmpty())
+		return checkState[rowCount() - 1] != negate;
 
 	// there is a suit selected
 	QStringList suitList = stringList();
 	// Ignore last item, since this is the "Show Empty Tags" entry
 	for (int i = 0; i < rowCount() - 1; i++) {
 		if (checkState[i] && suit == suitList[i])
-			return true;
+			return !negate;
 	}
-	return false;
+	return negate;
 }
 
 void SuitsFilterModel::repopulate()
@@ -200,18 +204,16 @@ bool TagFilterModel::doFilter(dive *d, QModelIndex &index0, QAbstractItemModel *
 	Q_UNUSED(sourceModel);
 
 	// If there's nothing checked, this should show everything
-	if (!anyChecked) {
+	// rowCount() == 0 should never happen, because we have the "no tags" row
+	// let's handle it gracefully anyway.
+	if (!anyChecked || rowCount() == 0)
 		return true;
-	}
+
 	// Checked means 'Show', Unchecked means 'Hide'.
 	struct tag_entry *head = d->tag_list;
 
-	if (!head) { // last tag means "Show empty tags";
-		if (rowCount() > 0)
-			return checkState[rowCount() - 1];
-		else
-			return true;
-	}
+	if (!head) // last tag means "Show empty tags";
+		return checkState[rowCount() - 1] != negate;
 
 	// have at least one tag.
 	QStringList tagList = stringList();
@@ -221,11 +223,11 @@ bool TagFilterModel::doFilter(dive *d, QModelIndex &index0, QAbstractItemModel *
 			QString tagName(head->tag->name);
 			int index = tagList.indexOf(tagName);
 			if (checkState[index])
-				return true;
+				return !negate;
 			head = head->next;
 		}
 	}
-	return false;
+	return negate;
 }
 
 BuddyFilterModel::BuddyFilterModel(QObject *parent) : FilterModelBase(parent)
@@ -243,30 +245,28 @@ bool BuddyFilterModel::doFilter(dive *d, QModelIndex &index0, QAbstractItemModel
 	Q_UNUSED(sourceModel);
 
 	// If there's nothing checked, this should show everything
-	if (!anyChecked) {
+	// rowCount() == 0 should never happen, because we have the "no tags" row
+	// let's handle it gracefully anyway.
+	if (!anyChecked || rowCount() == 0)
 		return true;
-	}
+
 	// Checked means 'Show', Unchecked means 'Hide'.
 	QString persons = QString(d->buddy) + "," + QString(d->divemaster);
 	QStringList personsList = persons.split(',', QString::SkipEmptyParts);
 	for (QString &s : personsList)
 		s = s.trimmed();
 	// only show empty buddie dives if the user checked that.
-	if (personsList.isEmpty()) {
-		if (rowCount() > 0)
-			return checkState[rowCount() - 1];
-		else
-			return true;
-	}
+	if (personsList.isEmpty())
+		return checkState[rowCount() - 1] != negate;
 
 	// have at least one buddy
 	QStringList buddyList = stringList();
 	// Ignore last item, since this is the "Show Empty Tags" entry
 	for (int i = 0; i < rowCount() - 1; i++) {
 		if (checkState[i] && personsList.contains(buddyList[i], Qt::CaseInsensitive))
-			return true;
+			return !negate;
 	}
-	return false;
+	return negate;
 }
 
 void BuddyFilterModel::repopulate()
@@ -302,27 +302,25 @@ bool LocationFilterModel::doFilter(struct dive *d, QModelIndex &index0, QAbstrac
 	Q_UNUSED(index0);
 	Q_UNUSED(sourceModel);
 
-	if (!anyChecked) {
+	// rowCount() == 0 should never happen, because we have the "no location" row
+	// let's handle it gracefully anyway.
+	if (!anyChecked || rowCount() == 0)
 		return true;
-	}
+
 	// Checked means 'Show', Unchecked means 'Hide'.
 	QString location(get_dive_location(d));
 	// only show empty location dives if the user checked that.
-	if (location.isEmpty()) {
-		if (rowCount() > 0)
-			return checkState[rowCount() - 1];
-		else
-			return true;
-	}
+	if (location.isEmpty())
+		return checkState[rowCount() - 1] != negate;
 
 	// There is a location selected
 	QStringList locationList = stringList();
 	// Ignore last item, since this is the "Show Empty Tags" entry
 	for (int i = 0; i < rowCount() - 1; i++) {
 		if (checkState[i] && location == locationList[i])
-			return true;
+			return !negate;
 	}
-	return false;
+	return negate;
 }
 
 void LocationFilterModel::repopulate()
diff --git a/qt-models/filtermodels.h b/qt-models/filtermodels.h
index 9db5e5a97..b866b68b2 100644
--- a/qt-models/filtermodels.h
+++ b/qt-models/filtermodels.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 class FilterModelBase : public QStringListModel {
+	Q_OBJECT
 public:
 	virtual bool doFilter(struct dive *d, QModelIndex &index0, QAbstractItemModel *sourceModel) const = 0;
 	void clearFilter();
@@ -15,6 +16,10 @@ public:
 	void invertSelection();
 	std::vector<char> checkState;
 	bool anyChecked;
+	bool negate;
+public
+slots:
+	void setNegate(bool negate);
 protected:
 	explicit FilterModelBase(QObject *parent = 0);
 	void updateList(const QStringList &new_list);