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Thread: Left align the items on Zommout

  1. #1
    Join Date
    Nov 2009
    Posts
    9
    Qt products
    Qt4
    Platforms
    Windows

    Default Left align the items on Zommout

    When doing zoomIn, zoom happens on left aligned (item on top left is always visible) but on zoom out items going to the center of the view by leaving lot of space on left,

    I want all items should be left aligned on zoom out also.

    Code for LeftAigned ZoomIn.
    Qt Code:
    1. void csGuiView::wheelEvent(QWheelEvent *event)
    2. {
    3.  
    4. if ((event->modifiers()&Qt::ControlModifier) == Qt::ControlModifier
    5. && event->angleDelta().x() == 0)
    6. {
    7. QPoint pos = event->pos();
    8. QPointF posf = this->mapToScene(pos);
    9.  
    10. double angle = event->angleDelta().y();
    11.  
    12. double scalingFactor;
    13.  
    14. if(angle > 0)
    15. {
    16. scalingFactor = 1 + ( angle / 360 * 0.1);
    17. }else if (angle < 0)
    18. {
    19. scalingFactor = 1 - ( -angle / 360 * 0.1);
    20. } else
    21. {
    22. scalingFactor = 1;
    23. }
    24.  
    25. m_pvtData->m_scale = scalingFactor;
    26.  
    27. this->scale(scalingFactor, scalingFactor);
    28.  
    29. double w = this->viewport()->width();
    30. double h = this->viewport()->height();
    31.  
    32. double wf = this->mapToScene(QPoint(w-1, 0)).x()
    33. - this->mapToScene(QPoint(0,0)).x();
    34. double hf = this->mapToScene(QPoint(0, h-1)).y()
    35. - this->mapToScene(QPoint(0,0)).y();
    36.  
    37. double lf = posf.x() - pos.x() * wf / w;
    38. double tf = posf.y() - pos.y() * hf / h;
    39.  
    40. /* try to set viewport properly */
    41. this->ensureVisible(lf, tf, wf, hf);
    42.  
    43.  
    44. QPointF newPos = this->mapToScene(pos);
    45.  
    46.  
    47. this->ensureVisible(QRectF(QPointF(lf, tf) - newPos + posf,
    48. QSizeF(wf, hf)), 0, 0);
    49.  
    50. }
    51.  
    52. if ((event->modifiers()&Qt::ControlModifier) != Qt::ControlModifier) {
    53. QGraphicsView::wheelEvent(event);
    54. }
    55.  
    56. event->accept();
    57. }
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    Last edited by high_flyer; 8th December 2017 at 23:46. Reason: missing [code] tags

  2. #2
    Join Date
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    Qt products
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    Platforms
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    Default Re: Left align the items on Zommout

    I am not sure about this (years since I have done anything with QGraphicsView - but I'd try setting the view alignment to top left:
    http://doc.qt.io/qt-5/qgraphicsview.html#alignment-prop

    If this does not help, I'd experiment with the viewport anchor:
    http://doc.qt.io/qt-5/qgraphicsview....ionAnchor-prop

    Please share here if you have solved it and how.
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