add context menu with select/deselect all options

python/gui/qgscheckablecombobox.sip

@@ -72,6 +72,10 @@ class QgsCheckableComboBox : QComboBox
      */
     virtual void hidePopup();
 
+    /** Filters events to enable context menu
+     */
+    virtual bool eventFilter( QObject *object, QEvent *event );
+
   signals:
 
     /** This signal is emitted whenever the checked items list changed.
@@ -90,4 +94,18 @@ class QgsCheckableComboBox : QComboBox
     /** Handler for widget resizing
      */
     virtual void resizeEvent( QResizeEvent *event );
+
+  protected slots:
+    /** Display context menu which allows to select/deselect
+     * all items at once.
+     */
+    void showContextMenu( const QPoint &pos );
+
+    /** Selects all items.
+     */
+    void selectAllOptions();
+
+    /** Removes selection from all items.
+     */
+    void deselectAllOptions();
 };

src/gui/qgscheckablecombobox.cpp

@@ -17,7 +17,10 @@
 
 #include "qgscheckablecombobox.h"
 
+#include <QEvent>
+#include <QMouseEvent>
 #include <QLineEdit>
+#include <QPoint>
 #include <QAbstractItemView>
 
 
@@ -81,6 +84,16 @@ QgsCheckableComboBox::QgsCheckableComboBox( QWidget *parent )
   lineEdit->setReadOnly( true );
   setLineEdit( lineEdit );
 
+  mContextMenu = new QMenu( this );
+  mSelectAllAction = mContextMenu->addAction( tr( "Select all" ) );
+  mDeselectAllAction = mContextMenu->addAction( tr( "Deselect all" ) );
+  connect( mSelectAllAction, &QAction::triggered, this, &QgsCheckableComboBox::selectAllOptions );
+  connect( mDeselectAllAction, &QAction::triggered, this, &QgsCheckableComboBox::deselectAllOptions );
+
+  view()->viewport()->installEventFilter( this );
+  view()->setContextMenuPolicy( Qt::CustomContextMenu );
+  connect( view(), &QAbstractItemView::customContextMenuRequested, this, &QgsCheckableComboBox::showContextMenu );
+
   QgsCheckableItemModel *myModel = qobject_cast<QgsCheckableItemModel *>( model() );
   connect( myModel, &QgsCheckableItemModel::itemCheckStateChanged, this, &QgsCheckableComboBox::updateCheckedItems );
   connect( model(), &QStandardItemModel::rowsInserted, this, [ = ]( const QModelIndex &, int, int ) { updateCheckedItems(); } );
@@ -162,6 +175,49 @@ void QgsCheckableComboBox::hidePopup()
   }
 }
 
+void QgsCheckableComboBox::showContextMenu( const QPoint &pos )
+{
+  Q_UNUSED( pos );
+
+  mContextMenu->exec( QCursor::pos() );
+}
+
+void QgsCheckableComboBox::selectAllOptions()
+{
+  blockSignals( true );
+  for ( int i;  i < count(); i++ )
+  {
+    setItemData( i, Qt::Checked, Qt::CheckStateRole );
+  }
+  blockSignals( false );
+  updateCheckedItems();
+}
+
+void QgsCheckableComboBox::deselectAllOptions()
+{
+  blockSignals( true );
+  for ( int i;  i < count(); i++ )
+  {
+    setItemData( i, Qt::Unchecked, Qt::CheckStateRole );
+  }
+  blockSignals( false );
+  updateCheckedItems();
+}
+
+bool QgsCheckableComboBox::eventFilter( QObject *object, QEvent *event )
+{
+  Q_UNUSED( object );
+
+  if ( event->type() == QEvent::MouseButtonRelease )
+  {
+    if ( static_cast<QMouseEvent *>( event )->button() == Qt::RightButton )
+    {
+      return true;
+    }
+  }
+  return false;
+}
+
 void QgsCheckableComboBox::setCheckedItems( const QStringList &items )
 {
   Q_FOREACH ( const QString &text, items )
@@ -202,3 +258,4 @@ void QgsCheckableComboBox::updateDisplayText()
   text = fontMetrics.elidedText( text, Qt::ElideRight, rect.width() );
   setEditText( text );
 }
+

src/gui/qgscheckablecombobox.h

@@ -19,11 +19,14 @@
 #define QGSCHECKABLECOMBOBOX_H
 
 #include <QComboBox>
+#include <QMenu>
 #include <QStandardItemModel>
 #include <QStyledItemDelegate>
 
 #include "qgis_gui.h"
 
+class QEvent;
+
 /** \class QgsCheckableItemModel
  * \ingroup gui
  * QStandardItemModel subclass which makes all items checkable
@@ -178,6 +181,10 @@ class GUI_EXPORT QgsCheckableComboBox : public QComboBox
      */
     virtual void hidePopup();
 
+    /** Filters events to enable context menu
+     */
+    virtual bool eventFilter( QObject *object, QEvent *event ) override;
+
   signals:
 
     /** This signal is emitted whenever the checked items list changed.
@@ -198,12 +205,31 @@ class GUI_EXPORT QgsCheckableComboBox : public QComboBox
      */
     virtual void resizeEvent( QResizeEvent *event );
 
+  protected slots:
+
+    /** Display context menu which allows to select/deselect
+     * all items at once.
+     */
+    void showContextMenu( const QPoint &pos );
+
+    /** Selects all items.
+     */
+    void selectAllOptions();
+
+    /** Removes selection from all items.
+     */
+    void deselectAllOptions();
+
   private:
     void updateCheckedItems();
     void updateDisplayText();
 
     QString mSeparator;
     QString mDefaultText;
+
+    QMenu *mContextMenu = nullptr;
+    QAction *mSelectAllAction = nullptr;
+    QAction *mDeselectAllAction = nullptr;
 };
 
 #endif // QGSCHECKABLECOMBOBOX_H