Add method for preventing composer items from changing mouse cursor and workaround for qt bug 3732

Author: nyalldawson

src/core/composer/qgscomposermousehandles.cpp

@@ -28,6 +28,7 @@
 QgsComposerMouseHandles::QgsComposerMouseHandles( QgsComposition *composition ) : QObject( 0 ),
     QGraphicsRectItem( 0 ),
     mComposition( composition ),
+    mGraphicsView( 0 ),
     mBeginHandleWidth( 0 ),
     mBeginHandleHeight( 0 ),
     mIsDragging( false ),
@@ -47,6 +48,29 @@ QgsComposerMouseHandles::~QgsComposerMouseHandles()
 
 }
 
+QGraphicsView* QgsComposerMouseHandles::graphicsView()
+{
+  //have we already found the current view?
+  if ( mGraphicsView )
+  {
+    return mGraphicsView;
+  }
+
+  //otherwise, try and find current view attached to composition
+  if ( scene() )
+  {
+    QList<QGraphicsView*> viewList = scene()->views();
+    if ( viewList.size() > 0 )
+    {
+      mGraphicsView = viewList.at( 0 );
+      return mGraphicsView;
+    }
+  }
+
+  //no view attached to composition
+  return 0;
+}
+
 void QgsComposerMouseHandles::paint( QPainter* painter, const QStyleOptionGraphicsItem* itemStyle, QWidget* pWidget )
 {
   Q_UNUSED( itemStyle );
@@ -216,13 +240,11 @@ QRectF QgsComposerMouseHandles::selectionBounds() const
   return bounds;
 }
 
-double QgsComposerMouseHandles::rectHandlerBorderTolerance() const
+double QgsComposerMouseHandles::rectHandlerBorderTolerance()
 {
   //calculate size for resize handles
   //get view scale factor
-  QList<QGraphicsView*> viewList = mComposition->views();
-  QGraphicsView* currentView = viewList.at( 0 );
-  double viewScaleFactor = currentView->transform().m11();
+  double viewScaleFactor = graphicsView()->transform().m11();
 
   //size of handle boxes depends on zoom level in composer view
   double rectHandlerSize = 10.0 / viewScaleFactor;
@@ -357,7 +379,24 @@ QgsComposerMouseHandles::MouseAction QgsComposerMouseHandles::mouseActionForScen
 
 void QgsComposerMouseHandles::hoverMoveEvent( QGraphicsSceneHoverEvent * event )
 {
-  setCursor( cursorForPosition( event->pos() ) );
+  setViewportCursor( cursorForPosition( event->pos() ) );
+}
+
+void QgsComposerMouseHandles::hoverLeaveEvent( QGraphicsSceneHoverEvent * event )
+{
+  Q_UNUSED( event );
+  setViewportCursor( Qt::ArrowCursor );
+}
+
+void QgsComposerMouseHandles::setViewportCursor( Qt::CursorShape cursor )
+{
+  //workaround qt bug #3732 by setting cursor for QGraphicsView viewport,
+  //rather then setting it directly here
+
+  if ( !mComposition->preventCursorChange() )
+  {
+    graphicsView()->viewport()->setCursor( cursor );
+  }
 }
 
 void QgsComposerMouseHandles::mouseMoveEvent( QGraphicsSceneMouseEvent* event )
@@ -466,7 +505,7 @@ void QgsComposerMouseHandles::mouseReleaseEvent( QGraphicsSceneMouseEvent* event
 
   //reset default action
   mCurrentMouseMoveAction = QgsComposerMouseHandles::MoveItem;
-  setCursor( Qt::ArrowCursor );
+  setViewportCursor( Qt::ArrowCursor );
   //redraw handles
   resetTransform();
   updateHandles();

src/core/composer/qgscomposermousehandles.h

@@ -22,6 +22,7 @@
 
 class QgsComposition;
 class QgsComposerItem;
+class QGraphicsView;
 
 /** \ingroup MapComposer
  * Handles drawing of selection outlines and mouse handles. Responsible for mouse
@@ -84,6 +85,7 @@ class CORE_EXPORT QgsComposerMouseHandles: public QObject, public QGraphicsRectI
     void mouseReleaseEvent( QGraphicsSceneMouseEvent* event );
     void mousePressEvent( QGraphicsSceneMouseEvent* event );
     void hoverMoveEvent( QGraphicsSceneHoverEvent * event );
+    void hoverLeaveEvent( QGraphicsSceneHoverEvent * event );
 
   public slots:
 
@@ -96,6 +98,7 @@ class CORE_EXPORT QgsComposerMouseHandles: public QObject, public QGraphicsRectI
   private:
 
     QgsComposition* mComposition; //reference to composition
+    QGraphicsView* mGraphicsView; //reference to QGraphicsView
 
     QgsComposerMouseHandles::MouseAction mCurrentMouseMoveAction;
     /**Start point of the last mouse move action (in scene coordinates)*/
@@ -131,7 +134,7 @@ class CORE_EXPORT QgsComposerMouseHandles: public QObject, public QGraphicsRectI
 
     /**Returns the current (zoom level dependent) tolerance to decide if mouse position is close enough to the
     item border for resizing*/
-    double rectHandlerBorderTolerance() const;
+    double rectHandlerBorderTolerance();
 
     /**Finds out the appropriate cursor for the current mouse position in the widget (e.g. move in the middle, resize at border)*/
     Qt::CursorShape cursorForPosition( const QPointF& itemCoordPos );
@@ -169,6 +172,11 @@ class CORE_EXPORT QgsComposerMouseHandles: public QObject, public QGraphicsRectI
     bool nearestItem( const QMap< double, const QgsComposerItem* >& coords, double value, double& nearestValue ) const;
     void checkNearestItem( double checkCoord, const QMap< double, const QgsComposerItem* >& alignCoords, double& smallestDiff, double itemCoordOffset, double& itemCoord, double& alignCoord ) const;
 
+    //tries to return the current QGraphicsView attached to the composition
+    QGraphicsView* graphicsView();
+
+    //sets the mouse cursor for the QGraphicsView attached to the composition (workaround qt bug #3732)
+    void setViewportCursor( Qt::CursorShape cursor );
 };
 
 #endif // QGSCOMPOSERMOUSEHANDLES_H

src/core/composer/qgscomposition.cpp

@@ -69,6 +69,7 @@ QgsComposition::QgsComposition( QgsMapRenderer* mapRenderer )
     , mActiveItemCommand( 0 )
     , mActiveMultiFrameCommand( 0 )
     , mAtlasComposition( this )
+    , mPreventCursorChange( false )
 {
   setBackgroundBrush( Qt::gray );
   addPaperItem();
@@ -104,7 +105,8 @@ QgsComposition::QgsComposition()
     mSelectionHandles( 0 ),
     mActiveItemCommand( 0 ),
     mActiveMultiFrameCommand( 0 ),
-    mAtlasComposition( this )
+    mAtlasComposition( this ),
+    mPreventCursorChange( false )
 {
   loadSettings();
 

src/core/composer/qgscomposition.h

@@ -351,6 +351,10 @@ class CORE_EXPORT QgsComposition : public QGraphicsScene
     /**Convenience function to create a QgsAddRemoveItemCommand, connect its signals and push it to the undo stack*/
     void pushAddRemoveCommand( QgsComposerItem* item, const QString& text, QgsAddRemoveItemCommand::State state = QgsAddRemoveItemCommand::Added );
 
+    /**If true, prevents any mouse cursor changes by the composition or by any composer items
+      Used by QgsComposer and QgsComposerView to prevent unwanted cursor changes*/
+    void setPreventCursorChange( bool preventChange ) { mPreventCursorChange = preventChange; };
+    bool preventCursorChange() { return mPreventCursorChange; };
 
     //printing
 
@@ -462,6 +466,8 @@ class CORE_EXPORT QgsComposition : public QGraphicsScene
 
     static QString encodeStringForXML( const QString& str );
 
+    bool mPreventCursorChange;
+
   signals:
     void paperSizeChanged();
     void nPagesChanged();