Show busy indicator while rendering in map canvas

python/gui/qgsmapcanvas.sip

@@ -363,15 +363,15 @@ class QgsMapCanvas : QGraphicsView
     //! - additional drawing shall be done directly within the renderer job or independently as a map canvas item
     void renderComplete( QPainter * );
 
+    // ### QGIS 3: renamte to mapRefreshFinished()
     /** Emitted when canvas finished a refresh request.
     \note Added in 2.0 */
-    //! @deprecated since 2.4 - anything related to rendering progress is not visible outside of map canvas
-    void mapCanvasRefreshed() /Deprecated/;
+    void mapCanvasRefreshed();
 
+    // ### QGIS 3: rename to mapRefreshStarted()
     /** Emitted when the canvas is about to be rendered.
       \note Added in 1.5 */
-    //! @deprecated since 2.4 - anything related to rendering progress is not visible outside of map canvas
-    void renderStarting() /Deprecated/;
+    void renderStarting();
 
     //! Emitted when a new set of layers has been received
     void layersChanged();

src/app/qgisapp.cpp

@@ -1670,6 +1670,10 @@ void QgisApp::createStatusBar()
   mProgressBar->setWhatsThis( tr( "Progress bar that displays the status "
                                   "of rendering layers and other time-intensive operations" ) );
   statusBar()->addPermanentWidget( mProgressBar, 1 );
+
+  connect( mMapCanvas, SIGNAL( renderStarting() ), this, SLOT( canvasRefreshStarted() ) );
+  connect( mMapCanvas, SIGNAL( mapCanvasRefreshed() ), this, SLOT( canvasRefreshFinished() ) );
+
   // Bumped the font up one point size since 8 was too
   // small on some platforms. A point size of 9 still provides
   // plenty of display space on 1024x768 resolutions
@@ -3196,11 +3200,6 @@ void QgisApp::addMssqlLayer()
 void QgisApp::addOracleLayer()
 {
 #ifdef HAVE_ORACLE
-  if ( mMapCanvas && mMapCanvas->isDrawing() )
-  {
-    return;
-  }
-
   // show the Oracle dialog
   QDialog *dbs = dynamic_cast<QDialog*>( QgsProviderRegistry::instance()->selectWidget( "oracle", this ) );
   if ( !dbs )
@@ -5730,10 +5729,6 @@ void QgisApp::addRing()
 
 void QgisApp::fillRing()
 {
-  if ( mMapCanvas && mMapCanvas->isDrawing() )
-  {
-    return;
-  }
   mMapCanvas->setMapTool( mMapTools.mFillRing );
 }
 
@@ -6147,6 +6142,16 @@ void QgisApp::refreshMapCanvas()
   mMapCanvas->refresh();
 }
 
+void QgisApp::canvasRefreshStarted()
+{
+  showProgress( -1, 0 ); // trick to make progress bar show busy indicator
+}
+
+void QgisApp::canvasRefreshFinished()
+{
+  showProgress( 0, 0 ); // stop the busy indicator
+}
+
 void QgisApp::toggleMapTips()
 {
   mMapTipsVisible = !mMapTipsVisible;
@@ -8342,6 +8347,23 @@ void QgisApp::showProgress( int theProgress, int theTotalSteps )
     }
     mProgressBar->setMaximum( theTotalSteps );
     mProgressBar->setValue( theProgress );
+
+    if ( mProgressBar->maximum() == 0 )
+    {
+      // for busy indicator (when minimum equals to maximum) the oxygen Qt style (used in KDE)
+      // has some issues and does not start busy indicator animation. This is an ugly fix
+      // that forces creation of a temporary progress bar that somehow resumes the animations.
+      // Caution: looking at the code below may introduce mild pain in stomach.
+      if ( strcmp( QApplication::style()->metaObject()->className(), "Oxygen::Style" ) == 0 )
+      {
+        QProgressBar pb;
+        pb.setAttribute( Qt::WA_DontShowOnScreen ); // no visual annoyance
+        pb.setMaximum( 0 );
+        pb.show();
+        qApp->processEvents();
+      }
+    }
+
   }
 }
 

src/app/qgisapp.h

@@ -1019,6 +1019,11 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     //! refresh map canvas
     void refreshMapCanvas();
 
+    //! start "busy" progress bar
+    void canvasRefreshStarted();
+    //! stop "busy" progress bar
+    void canvasRefreshFinished();
+
     /** Dialog for verification of action on many edits
      * @note added in 1.9 */
     bool verifyEditsActionDialog( const QString& act, const QString& upon );

src/app/qgsmaptooladdfeature.cpp

@@ -47,11 +47,6 @@ bool QgsMapToolAddFeature::addFeature( QgsVectorLayer *vlayer, QgsFeature *f )
 
 void QgsMapToolAddFeature::activate()
 {
-  if ( !mCanvas || mCanvas->isDrawing() )
-  {
-    return;
-  }
-
   QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( mCanvas->currentLayer() );
   if ( vlayer && vlayer->geometryType() == QGis::NoGeometry )
   {

src/gui/qgsmapcanvas.cpp

@@ -635,6 +635,8 @@ void QgsMapCanvas::refreshMap()
   mJob->start();
 
   mMapUpdateTimer.start();
+
+  emit renderStarting();
 }
 
 
@@ -695,6 +697,8 @@ void QgsMapCanvas::rendererJobFinished()
   // so the class is still valid when the execution returns to the class
   mJob->deleteLater();
   mJob = 0;
+
+  emit mapCanvasRefreshed();
 }
 
 void QgsMapCanvas::mapUpdateTimeout()

src/gui/qgsmapcanvas.h

@@ -443,15 +443,15 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! - additional drawing shall be done directly within the renderer job or independently as a map canvas item
     void renderComplete( QPainter * );
 
+    // ### QGIS 3: renamte to mapRefreshFinished()
     /** Emitted when canvas finished a refresh request.
     \note Added in 2.0 */
-    //! @deprecated since 2.4 - anything related to rendering progress is not visible outside of map canvas
-    Q_DECL_DEPRECATED void mapCanvasRefreshed();
+    void mapCanvasRefreshed();
 
+    // ### QGIS 3: rename to mapRefreshStarted()
     /** Emitted when the canvas is about to be rendered.
       \note Added in 1.5 */
-    //! @deprecated since 2.4 - anything related to rendering progress is not visible outside of map canvas
-    Q_DECL_DEPRECATED void renderStarting();
+    void renderStarting();
 
     //! Emitted when a new set of layers has been received
     void layersChanged();