Allow message bar items to be dismissed from QgsMessageBarItem

python/gui/auto_generated/qgsmessagebaritem.sip.in

@@ -82,6 +82,17 @@ returns the duration in second of the message
     QString getStyleSheet();
 %Docstring
 returns the styleSheet
+%End
+
+  public slots:
+
+    void dismiss();
+%Docstring
+Dismisses the item, removing it from the message bar and deleting
+it. Calling this on items which have not been added to a message bar
+has no effect.
+
+.. versionadded:: 3.4
 %End
 
   signals:

src/gui/qgsmessagebar.cpp

@@ -267,6 +267,9 @@ void QgsMessageBar::showItem( QgsMessageBarItem *item )
 void QgsMessageBar::pushItem( QgsMessageBarItem *item )
 {
   resetCountdown();
+
+  item->mMessageBar = this;
+
   // avoid duplicated widget
   popWidget( item );
   showItem( item );

src/gui/qgsmessagebaritem.cpp

@@ -269,6 +269,14 @@ QgsMessageBarItem *QgsMessageBarItem::setDuration( int duration )
   return this;
 }
 
+void QgsMessageBarItem::dismiss()
+{
+  if ( !mMessageBar )
+    return;
+
+  mMessageBar->popWidget( this );
+}
+
 void QgsMessageBarItem::urlClicked( const QUrl &url )
 {
   QFileInfo file( url.toLocalFile() );

src/gui/qgsmessagebaritem.h

@@ -27,6 +27,7 @@
 
 class QTextBrowser;
 class QLabel;
+class QgsMessageBar;
 
 /**
  * \ingroup gui
@@ -91,6 +92,17 @@ class GUI_EXPORT QgsMessageBarItem : public QWidget
     //! returns the styleSheet
     QString getStyleSheet() { return mStyleSheet; }
 
+  public slots:
+
+    /**
+     * Dismisses the item, removing it from the message bar and deleting
+     * it. Calling this on items which have not been added to a message bar
+     * has no effect.
+     *
+     * \since QGIS 3.4
+     */
+    void dismiss();
+
   signals:
     //! emitted when the message level has changed
     void styleChanged( const QString &styleSheet );
@@ -112,6 +124,9 @@ class GUI_EXPORT QgsMessageBarItem : public QWidget
     QLabel *mLblIcon = nullptr;
     QString mStyleSheet;
     QTextBrowser *mTextBrowser = nullptr;
+    QgsMessageBar *mMessageBar = nullptr;
+
+    friend class QgsMessageBar;
 };
 
 #endif // qgsmessagebaritem_H