Hi!

I'm having problems with my QGraphicsView and some mouse events. Basically I want to zoom and pan my view and also handle the items events.

I want the following behavior: The graphics view should only receive the events while my space button is pressed. So if you want to pan/zoom you should press space and either the right or left mouse button (left = pan, right = zoom). Otherwise the items should receive the events.

My items don't implement any event handling at the moment so they are using the standard implementation.

The code for my view:

Qt Code: 
  1. //--------------------------------------------------------------------------------
  2. void GraphicsView::mousePressEvent(QMouseEvent *event)
  3. {
  4. 	if(_key != Qt::Key_Space)
  5. 	{
  6. 		QGraphicsView::mousePressEvent(event);
  7. 		event->ignore();
  8. 		return;
  9. 	}
  10.  
  11. 	//save mouse position
  12. 	_last_position = event->pos();
  13. }
  14.  
  15. //--------------------------------------------------------------------------------
  16. void GraphicsView::mouseReleaseEvent(QMouseEvent *event)
  17. {
  18. 	if(_key != Qt::Key_Space)
  19. 	{
  20. 		QGraphicsView::mouseReleaseEvent(event);
  21. 		event->ignore();
  22. 		return;
  23. 	}
  24.  
  25. 	setCursor(_default_cursor);
  26. }
  27.  
  28. //--------------------------------------------------------------------------------
  29. void GraphicsView::mouseMoveEvent(QMouseEvent *event)
  30. {
  31. 	if(_key != Qt::Key_Space)
  32. 	{
  33. 		QGraphicsView::mouseMoveEvent(event);
  34. 		event->ignore();
  35. 		return;
  36. 	}
  37.  
  38. 	int dx = event->x() - _last_position.x();
  39. 	int dy = event->y() - _last_position.y();
  40.  
  41. 	//save mouse position
  42. 	_last_position = event->pos();
  43.  
  44. 	qDebug() << "pos: " << event->pos().x() << " " << event->pos().y();
  45.  
  46. 	if (event->buttons() == Qt::LeftButton) 
  47. 	{
  48. 		setCursor(_move_cursor);
  49. 		pan(dx, dy);
  50. 	} 
  51. 	else if (event->buttons() == Qt::RightButton) 
  52. 	{
  53. 		zoom(dx);
  54. 	}
  55. }
  56.  
  57. //--------------------------------------------------------------------------------
  58. void GraphicsView::keyPressEvent(QKeyEvent *event)
  59. {
  60. 	_key = event->key();
  61. }
  62.  
  63. //--------------------------------------------------------------------------------
  64. void GraphicsView::keyReleaseEvent(QKeyEvent *event)
  65. {
  66. 	_key = 0;
  67. }
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Now my main problem is that I receive all events as expected but during my views mousMoveEvent which I handle only while space is pressed my events position isn't correct. It stays always the same. If I don't have space pressed the events position changes depending on the mouse position.

I have no idea what I'm doing wrong. If I uncomment all the QGraphicsView::mouseXEvent(event) it works fine. But if I deliver the events to my items if space is not pressed it doesn't work.