Add method to 'trigger' QgsTasks

Triggering occurs when a task is clicked in the task manager
widget, and this can be used to e.g. open a dialog showing
detailed task progress (or reopen a closed dialog which started
the task)

python/core/qgstaskmanager.sip

@@ -419,6 +419,15 @@ Returns the number of active (queued or running) tasks.
 .. seealso:: :py:func:`activeTasks`
 
 .. seealso:: :py:func:`countActiveTasksChanged`
+%End
+
+  public slots:
+
+    void trigger( QgsTask *task );
+%Docstring
+Triggers a task, e.g. as a result of a GUI interaction.
+
+.. seealso:: :py:func:`triggered()`
 %End
 
   signals:
@@ -473,6 +482,15 @@ Emitted when all tasks are complete
 Emitted when the number of active tasks changes
 
 .. seealso:: :py:func:`countActiveTasks`
+%End
+
+    void triggered( QgsTask *task );
+%Docstring
+Emitted when a ``task`` is triggered. This occurs when a user clicks on
+the task from the QGIS GUI, and can be used to show detailed progress
+reports or re-open a related dialog.
+
+.. seealso:: :py:func:`trigger()`
 %End
 
 };

src/core/qgstaskmanager.cpp

@@ -607,6 +607,12 @@ int QgsTaskManager::countActiveTasks() const
   return tasks.intersect( mParentTasks ).count();
 }
 
+void QgsTaskManager::trigger( QgsTask *task )
+{
+  if ( task )
+    emit triggered( task );
+}
+
 void QgsTaskManager::taskProgressChanged( double progress )
 {
   QgsTask *task = qobject_cast< QgsTask * >( sender() );

src/core/qgstaskmanager.h

@@ -485,6 +485,14 @@ class CORE_EXPORT QgsTaskManager : public QObject
      */
     int countActiveTasks() const;
 
+  public slots:
+
+    /**
+     * Triggers a task, e.g. as a result of a GUI interaction.
+     * \see triggered()
+     */
+    void trigger( QgsTask *task );
+
   signals:
 
     /**
@@ -532,6 +540,14 @@ class CORE_EXPORT QgsTaskManager : public QObject
      */
     void countActiveTasksChanged( int count );
 
+    /**
+     * Emitted when a \a task is triggered. This occurs when a user clicks on
+     * the task from the QGIS GUI, and can be used to show detailed progress
+     * reports or re-open a related dialog.
+     * \see trigger()
+     */
+    void triggered( QgsTask *task );
+
   private slots:
 
     void taskProgressChanged( double progress );

src/gui/qgstaskmanagerwidget.cpp

@@ -33,6 +33,7 @@
 
 QgsTaskManagerWidget::QgsTaskManagerWidget( QgsTaskManager *manager, QWidget *parent )
   : QWidget( parent )
+  , mManager( manager )
 {
   Q_ASSERT( manager );
 
@@ -54,6 +55,8 @@ QgsTaskManagerWidget::QgsTaskManagerWidget( QgsTaskManager *manager, QWidget *pa
   mTreeView->header()->setStretchLastSection( false );
   mTreeView->header()->setSectionResizeMode( QgsTaskManagerModel::Description, QHeaderView::Stretch );
 
+  connect( mTreeView, &QTreeView::clicked, this, &QgsTaskManagerWidget::clicked );
+
   vLayout->addWidget( mTreeView );
 
   setLayout( vLayout );
@@ -97,6 +100,15 @@ void QgsTaskManagerWidget::modelRowsInserted( const QModelIndex &, int start, in
   }
 }
 
+void QgsTaskManagerWidget::clicked( const QModelIndex &index )
+{
+  QgsTask *task = mModel->indexToTask( index );
+  if ( !task )
+    return;
+
+  mManager->trigger( task );
+}
+
 ///@cond PRIVATE
 //
 // QgsTaskManagerModel

src/gui/qgstaskmanagerwidget.h

@@ -55,9 +55,11 @@ class GUI_EXPORT QgsTaskManagerWidget : public QWidget
   private slots:
 
     void modelRowsInserted( const QModelIndex &index, int start, int end );
+    void clicked( const QModelIndex &index );
 
   private:
 
+    QgsTaskManager *mManager = nullptr;
     QTreeView *mTreeView = nullptr;
     QgsTaskManagerModel *mModel = nullptr;
 };