HI,

I am trying to capture the mouse position relative to a graphicsscene. See code below, the X and Y values in the bottom right are for the view, I would like the values for the scene, I so when I hover ove the top right cross is says 250,250 etc.:

I am stumped any help would be appreciated.

Thanks,

Pete.

Qt Code: 
  1. #include <QApplication>
  2. #include <QMainWindow>
  3. #include <QStatusBar>
  4. #include <QGraphicsView>
  5. #include <QGraphicsScene>
  6. #include <QGraphicsSceneMouseEvent>
  7. #include <QGraphicsTextItem>
  8. #include <QMouseEvent>
  9. #include <QScrollBar>
  10. #include <QLabel>
  11. #include <math.h>
  12. #include <QtGui>
  13.  
  14.  
  15. class MapView : public QGraphicsView
  16. {
  17.  
  18. public:
  19. MapView(QWidget *parent = 0);
  20. QPoint sceneCoordinates;
  21. QLabel *coordinateDisplayLabel;
  22.  
  23. protected:
  24. void scaleView(qreal scaleFactor);
  25. void wheelEvent(QWheelEvent *event);
  26. void mousePressEvent(QMouseEvent *event);
  27. void mouseMoveEvent(QMouseEvent *event);
  28. void mouseReleaseEvent(QMouseEvent *event);
  29. void mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent);
  30. void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent);
  31.  
  32.  
  33. private:
  34. QString cursorXString;
  35. QString cursorYString;
  36. void storeMouseEvent(QMouseEvent *event);
  37. bool scrolling;
  38. QMouseEvent lastMouseEvent;
  39.  
  40. };
  41.  
  42. MapView::MapView(QWidget *parent)
  43. : QGraphicsView(parent), lastMouseEvent(QEvent::None,QPoint(),
  44. Qt::NoButton,Qt::NoButton,Qt::NoModifier)
  45.  
  46. {	
  48. setAttribute (Qt::WA_SetCursor);
  49. setCursor(Qt::CrossCursor); 
  50. scale(1,-1);
  51. coordinateDisplayLabel = new QLabel(0);
  52. setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  53. setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff) ;
  54. setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
  55. scrolling = false;
  56. }
  57.  
  58. void MapView::wheelEvent(QWheelEvent *event)
  59. {
  60. scaleView(pow((double)2, event->delta() / 240.0));
  61. }
  62.  
  63. void MapView::scaleView(qreal scaleFactor)
  64. {
  65. qreal factor = matrix().scale(scaleFactor, scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width();
  66. if (factor < 0.07 || factor > 100)
  67. return;
  68. scale(scaleFactor, scaleFactor);
  69. } 
  70.  
  71. void MapView::storeMouseEvent(QMouseEvent *event)
  72. {
  73. lastMouseEvent = QMouseEvent(event->type(), event->pos(), event->globalPos(),
  74. event->button(),event->buttons(),event->modifiers());
  75.  
  76. }
  77.  
  78. void MapView::mousePressEvent(QMouseEvent *event)
  79. {
  80. if(event->button() == Qt::MidButton) 
  81. {
  82. setCursor(Qt::ClosedHandCursor);
  83. scrolling = true;
  84. storeMouseEvent(event);
  85. event->accept();
  86. return;
  87. }
  88. }
  89. void MapView::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent)
  90.  {
  91. //QGraphicsScene::mousePressEvent(mouseEvent);
  92. qDebug() << mouseEvent->scenePos();
  93.  
  94. }
  95. void MapView::mouseMoveEvent(QMouseEvent *event)
  96. {
  97.  
  98. if(scrolling) 
  99. {
  100. QPoint delta = event->globalPos() - lastMouseEvent.globalPos();
  101. QScrollBar *hBar = horizontalScrollBar();
  102. QScrollBar *vBar = verticalScrollBar();
  103. hBar->setValue(hBar->value() - delta.x());
  104. vBar->setValue(vBar->value() - delta.y());
  105. storeMouseEvent(event);
  106. event->accept();
  107. return;
  108. }
  109.  
  110. sceneCoordinates = mapFromScene(event->pos());
  111. cursorXString.setNum(sceneCoordinates.x());
  112. cursorYString.setNum(sceneCoordinates.y());
  113. coordinateDisplayLabel->setText("x = " + cursorXString + " " + "y = " + cursorYString);	
  114. }
  115.  
  116. void MapView::mouseReleaseEvent(QMouseEvent *event)
  117. {
  118. if((event->button() == Qt::MidButton) && (scrolling == true))
  119. {
  120. setCursor(Qt::CrossCursor);
  121. scrolling = false;
  122. storeMouseEvent(event);
  123. event->accept();
  124. return;
  125. }
  126. event->ignore();
  127. }
  128.  
  129.  
  130. int main( int argc, char **argv )
  131. {
  132. QApplication a( argc, argv );
  134. MapView *view = new MapView;
  135. QStatusBar *statusbar = new QStatusBar;
  137.  
  138. scene->setSceneRect(-30000, -30000, 60000, 60000);
  139. scene->setBackgroundBrush(Qt::black);
  140.  
  141. scene->addLine ( -50, 0, 50, 0, (QPen(Qt::white, 0)));
  142. scene->addLine ( 0, -50, 0, 50, (QPen(Qt::white, 0)));
  143. QGraphicsTextItem item1("0,0");
  144. item1.setDefaultTextColor(Qt::white);
  145. item1.setPos(0,0);
  146. item1.scale(1,-1);
  147. scene->addItem(&item1);
  148.  
  149. scene->addLine ( 200, 250, 300, 250, (QPen(Qt::white, 0)));
  150. scene->addLine ( 250, 300, 250, 200, (QPen(Qt::white, 0)));
  151. QGraphicsTextItem item2("250,250");
  152. item2.setDefaultTextColor(Qt::white);
  153. item2.setPos(250,250);
  154. item2.scale(1,-1);
  155. scene->addItem(&item2);
  156.  
  157. view->setScene(scene);
  158. mw->setCentralWidget(view);
  159. statusbar->addPermanentWidget(view->coordinateDisplayLabel, 0);
  160. mw->setStatusBar(statusbar);
  161.  
  162. mw->show();
  163.  
  164. return a.exec();
  165. }
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