Create independent states only on demand

Use a shared state pre feature but have a action to crete/delete
independent states for each feature. This is less confusing to use.

co-authored by ronso0@mixxx.org

src/library/baseexternalplaylistmodel.h

@@ -29,7 +29,11 @@ class BaseExternalPlaylistModel : public BaseSqlTableModel {
     bool isColumnInternal(int column) override;
     Qt::ItemFlags flags(const QModelIndex &index) const override;
     Capabilities getCapabilities() const override;
-    QString modelKey() const override {
+    QString modelKey(bool noSearch = false) const override {
+        if (noSearch) {
+            return QStringLiteral("external/") +
+                    QString::number(m_currentPlaylistId);
+        }
         return QStringLiteral("external/") +
                 QString::number(m_currentPlaylistId) +
                 QStringLiteral("#") +

src/library/basesqltablemodel.h

@@ -71,9 +71,12 @@ class BaseSqlTableModel : public BaseTrackTableModel {
     int fieldIndex(
             ColumnCache::Column column) const final;
 
-    virtual QString modelKey() const override {
-        return QLatin1String("table:") + m_tableName +
-                QLatin1String("#") +
+    virtual QString modelKey(bool noSearch = false) const override {
+        if (noSearch) {
+            return QStringLiteral("table:") + m_tableName;
+        }
+        return QStringLiteral("table:") + m_tableName +
+                QStringLiteral("#") +
                 currentSearch();
     }
 

src/library/browse/browsetablemodel.h

@@ -77,15 +77,20 @@ class BrowseTableModel final : public QStandardItemModel, public virtual TrackMo
     bool isColumnSortable(int column) const override;
     TrackModel::SortColumnId sortColumnIdFromColumnIndex(int index) const override;
     int columnIndexFromSortColumnId(TrackModel::SortColumnId sortColumn) const override;
-    QString modelKey() const override {
+    QString modelKey(bool noSearch = false) const override {
         // TODO re-introduce m_current_directory / m_currentPath
         // see https://github.com/mixxxdj/mixxx/commit/dcc6f9e71aac3ee56627bb93c4e37e93cf675bfd#diff-12546d29721e9b62bfba012a790de93c1e5c045a9ac4cc47f48d9c7d93b99d70L166
         // or make m_pBrowseThread->m_path public
         //m_current_directory.dir().path() +
-        return QStringLiteral("browse/") +
-                QString("directory Unknown") +
-                QStringLiteral("#") +
-                currentSearch();
+        if (noSearch) {
+            return QStringLiteral("browse/");
+            // + m_current_directory.dir().path();
+        } else {
+            return QStringLiteral("browse/") +
+                    //m_current_directory.dir().path() +
+                    QStringLiteral("#") +
+                    currentSearch();
+        }
     }
 
   signals:

src/library/hiddentablemodel.h

@@ -16,7 +16,10 @@ class HiddenTableModel final : public BaseSqlTableModel {
     Qt::ItemFlags flags(const QModelIndex &index) const final;
     Capabilities getCapabilities() const final;
 
-    virtual QString modelKey() const override {
+    virtual QString modelKey(bool noSearch = false) const override {
+        if (noSearch) {
+            return QStringLiteral("hidden:") + m_tableName;
+        }
         return QStringLiteral("hidden:") + m_tableName +
                 QStringLiteral("#") +
                 currentSearch();

src/library/missingtablemodel.h

@@ -21,7 +21,10 @@ class MissingTableModel final : public BaseSqlTableModel {
     Qt::ItemFlags flags(const QModelIndex &index) const final;
     Capabilities getCapabilities() const final;
 
-    virtual QString modelKey() const override {
+    virtual QString modelKey(bool noSearch = false) const override {
+        if (noSearch) {
+            return QStringLiteral("missing:") + m_tableName;
+        }
         return QStringLiteral("missing:") + m_tableName +
                 QStringLiteral("#") +
                 currentSearch();

src/library/proxytrackmodel.cpp

@@ -69,8 +69,8 @@ void ProxyTrackModel::search(const QString& searchText, const QString& extraFilt
     }
 }
 
-QString ProxyTrackModel::modelKey() const {
-    return m_pTrackModel ? m_pTrackModel->modelKey() : QString();
+QString ProxyTrackModel::modelKey(bool noSearch) const {
+    return m_pTrackModel ? m_pTrackModel->modelKey(noSearch) : QString();
 }
 
 const QString ProxyTrackModel::currentSearch() const {

src/library/proxytrackmodel.h

@@ -46,7 +46,7 @@ class ProxyTrackModel : public QSortFilterProxyModel, public TrackModel {
 
     // Inherited from QAbstractItemModel
     void sort(int column, Qt::SortOrder order = Qt::AscendingOrder) final;
-    QString modelKey() const override;
+    QString modelKey(bool noSearch = false) const override;
 
   private:
     TrackModel* m_pTrackModel;

src/library/trackmodel.h

@@ -204,11 +204,10 @@ class TrackModel {
     virtual void select() {
     }
 
-    virtual QString modelKey() const {
-        return pointerToQString(this) +
-                QLatin1String("#") +
-                currentSearch();
-    }
+    /// @brief modelKey returns a unique identifier for the model
+    /// @param noSearch don't include the current search in the key
+    /// @param baseOnly return only a identifier for the whole subsystem
+    virtual QString modelKey(bool noSearch = false) const = 0;
 
   private:
     QSqlDatabase m_db;

src/library/trackset/crate/cratetablemodel.cpp

@@ -182,13 +182,20 @@ void CrateTableModel::removeTracks(const QModelIndexList& indices) {
     select();
 }
 
-QString CrateTableModel::modelKey() const {
+QString CrateTableModel::modelKey(bool noSearch) const {
     if (this->m_selectedCrate.isValid()) {
+        if (noSearch) {
+            return QStringLiteral("crate/") +
+                    QString::number(m_selectedCrate.value());
+        }
         return QStringLiteral("crate/") +
                 QString::number(m_selectedCrate.value()) +
                 QStringLiteral("#") +
                 currentSearch();
     } else {
+        if (noSearch) {
+            return QStringLiteral("crate");
+        }
         return QStringLiteral("crate#") +
                 currentSearch();
     }

src/library/trackset/crate/cratetablemodel.h

@@ -23,7 +23,7 @@ class CrateTableModel final : public TrackSetTableModel {
     int addTracks(const QModelIndex& index, const QList<QString>& locations) final;
 
     Capabilities getCapabilities() const final;
-    QString modelKey() const override;
+    QString modelKey(bool noSearch = false) const override;
 
   private:
     CrateId m_selectedCrate;

src/widget/wlibrarytableview.h

@@ -30,16 +30,16 @@ class WLibraryTableView : public QTableView, public virtual LibraryView {
 
     void moveSelection(int delta) override;
 
-    /// @brief saveTrackModelState function saves current position of scrollbar
-    /// using string key - can be any value but should invariant for model
+    /// @brief saveTrackModelState function saves current positions of scrollbars,
+    /// current item selection and current index in a QCache using a unique
+    /// string key - can be any value but should invariant for model
     /// @param key unique for trackmodel
     void saveTrackModelState(const QAbstractItemModel* model, const QString& key);
-
-    /// @brief restoreTrackModelState function finds scrollbar value associated with model
-    /// by given key and restores it
+    /// @brief restoreTrackModelState function finds scrollbar positions,
+    /// item selection and current index values associated with model by given
+    /// key and restores it
     /// @param key unique for trackmodel
     void restoreTrackModelState(const QAbstractItemModel* model, const QString& key);
-    /// @brief clears the state cache until it's size is = kClearModelStatesLowWatermark
     void saveCurrentViewState() override;
     void restoreCurrentViewState() override;