Stop playing videos when they are no longer visible

This mimics Adobe Reader behaviour
BUGS: 286932
FIXED-IN: 4.8.0

ui/pageview.cpp

@@ -3832,6 +3832,7 @@ void PageView::slotRequestVisiblePixmaps( int newValue )
     QRect viewportRect( horizontalScrollBar()->value(),
                         verticalScrollBar()->value(),
                         viewport()->width(), viewport()->height() );
+    const QRect viewportRectAtZeroZero( 0, 0, viewport()->width(), viewport()->height() );
 
     // some variables used to determine the viewport
     int nearPageNumber = -1;
@@ -3862,6 +3863,10 @@ void PageView::slotRequestVisiblePixmaps( int newValue )
             vw->move(
                 qRound( i->uncroppedGeometry().left() + i->uncroppedWidth() * r.left ) + 1 - viewportRect.left(),
                 qRound( i->uncroppedGeometry().top() + i->uncroppedHeight() * r.top ) + 1 - viewportRect.top() );
+            
+            if ( vw->isPlaying() && viewportRectAtZeroZero.intersect( vw->geometry() ).isEmpty() ) {
+                vw->stop();
+            }
         }
 
         if ( !i->isVisible() )

ui/videowidget.cpp

@@ -219,6 +219,11 @@ Okular::NormalizedRect VideoWidget::normGeometry() const
     return d->geom;
 }
 
+bool VideoWidget::isPlaying() const
+{
+    return d->player->isPlaying();
+}
+
 void VideoWidget::play()
 {
     d->load();

ui/videowidget.h

@@ -27,6 +27,8 @@ class VideoWidget : public QWidget
 
         void setNormGeometry( const Okular::NormalizedRect &rect );
         Okular::NormalizedRect normGeometry() const;
+        
+        bool isPlaying() const;
 
     public slots:
         void play();