GraphicsView Class Reference

QGraphicsView class with event handling added. Typically the events are sent to the active digitizing state. More...

#include <GraphicsView.h>

Inheritance diagram for GraphicsView:

Collaboration diagram for GraphicsView:

Public Slots
void	slotDropRegression (QString)
	Receive drag and drop regression test url. More...

Signals
void	signalContextMenuEventAxis (QString pointIdentifier)
	Send right click on axis point to MainWindow for editing. More...
void	signalContextMenuEventGraph (QStringList pointIdentifiers)
	Send right click on graph point(s) to MainWindow for editing. More...
void	signalDraggedDigFile (QString)
	Send dragged dig file to MainWindow for import. This comes from dragging an engauge dig file. More...
void	signalDraggedImage (QImage)
	Send dragged image to MainWindow for import. This typically comes from dragging a file. More...
void	signalDraggedImageUrl (QUrl)
	Send dragged url to MainWindow for import. This typically comes from dragging an image from a browser. More...
void	signalKeyPress (Qt::Key, bool atLeastOneSelectedItem)
	Send keypress to MainWindow for eventual processing by DigitizeStateAbstractBase subclasses. More...
void	signalMouseMove (QPointF)
	Send mouse move to MainWindow for eventual display of cursor coordinates in StatusBar. More...
void	signalMousePress (QPointF)
	Send mouse press to MainWindow for creating one or more Points. More...
void	signalMouseRelease (QPointF)
	Send mouse release to MainWindow for moving Points. More...
void	signalViewZoomIn ()
	Send wheel event to MainWindow for zooming in. More...
void	signalViewZoomOut ()
	Send wheel event to MainWindow for zooming out. More...

Public Member Functions
	GraphicsView (QGraphicsScene *scene, MainWindow &mainWindow)
	Single constructor. More...
virtual	~GraphicsView ()
virtual void	contextMenuEvent (QContextMenuEvent *event)
	Intercept context event to support point editing. More...
virtual void	dragEnterEvent (QDragEnterEvent *event)
	Intercept mouse drag event to support drag-and-drop. More...
virtual void	dragMoveEvent (QDragMoveEvent *event)
	Intercept mouse move event to support drag-and-drop. More...
virtual void	dropEvent (QDropEvent *event)
	Intercept mouse drop event to support drag-and-drop. This initiates asynchronous loading of the dragged image. More...
virtual void	keyPressEvent (QKeyEvent *event)
	Intercept key press events to handle left/right/up/down moving. More...
virtual void	mouseMoveEvent (QMouseEvent *event)
	Intercept mouse move events to populate the current cursor position in StatusBar. More...
virtual void	mousePressEvent (QMouseEvent *event)
	Intercept mouse press events to create one or more Points. More...
virtual void	mouseReleaseEvent (QMouseEvent *event)
	Intercept mouse release events to move one or more Points. More...
virtual void	wheelEvent (QWheelEvent *event)
	Convert wheel events into zoom in/out. More...

Detailed Description

QGraphicsView class with event handling added. Typically the events are sent to the active digitizing state.

Definition at line 19 of file GraphicsView.h.

Constructor & Destructor Documentation

GraphicsView()

GraphicsView::GraphicsView	(	QGraphicsScene *	scene,
		MainWindow &	mainWindow
	)

Single constructor.

Definition at line 30 of file GraphicsView.cpp.

                                                   :
  QGraphicsView (scene)
{
  connect (this, SIGNAL (signalContextMenuEventAxis (QString)), &mainWindow, SLOT (slotContextMenuEventAxis (QString)));
  connect (this, SIGNAL (signalContextMenuEventGraph (QStringList)), &mainWindow, SLOT (slotContextMenuEventGraph (QStringList)));
  connect (this, SIGNAL (signalDraggedDigFile (QString)), &mainWindow, SLOT (slotFileOpenDraggedDigFile (QString)));
  connect (this, SIGNAL (signalDraggedImage (QImage)), &mainWindow, SLOT (slotFileImportDraggedImage (QImage)));
  connect (this, SIGNAL (signalDraggedImageUrl (QUrl)), &mainWindow, SLOT (slotFileImportDraggedImageUrl (QUrl)));
  connect (this, SIGNAL (signalKeyPress (Qt::Key, bool)), &mainWindow, SLOT (slotKeyPress (Qt::Key, bool)));
  connect (this, SIGNAL (signalMouseMove(QPointF)), &mainWindow, SLOT (slotMouseMove (QPointF)));
  connect (this, SIGNAL (signalMousePress (QPointF)), &mainWindow, SLOT (slotMousePress (QPointF)));
  connect (this, SIGNAL (signalMouseRelease (QPointF)), &mainWindow, SLOT (slotMouseRelease (QPointF)));
  connect (this, SIGNAL (signalViewZoomIn ()), &mainWindow, SLOT (slotViewZoomInFromWheelEvent ()));
  connect (this, SIGNAL (signalViewZoomOut ()), &mainWindow, SLOT (slotViewZoomOutFromWheelEvent ()));
 
  setMouseTracking (true);
  setAcceptDrops (true);
  setEnabled (true);
  setRenderHints(QPainter::Antialiasing);
  setBackgroundBrush (QBrush (QColor (Qt::gray)));
  verticalScrollBar()->setCursor (QCursor (Qt::ArrowCursor));
  horizontalScrollBar()->setCursor (QCursor (Qt::ArrowCursor));
 
  // Skip setStatusTip here since that will overwrite much more important messages, and trigger gratuitous showing of status bar
  setWhatsThis (tr ("Main Window\n\n"
                    "After an image file is imported, or an Engauge Document opened, an image appears in this area. "
                    "Points are added to the image.\n\n"
                    "If the image is a graph with two axes and one or more curves, then three axis points must be "
                    "created along those axes. Just put two axis points on one axis and a third axis point on the other "
                    "axis, as far apart as possible for higher accuracy. Then curve points can be added along the curves.\n\n"
                    "If the image is a map with a scale to define length, then two axis points must be "
                    "created at either end of the scale. Then curve points can be added.\n\n"
                    "Zooming the image in or out is performed using any of several methods:\n"
                    "1) rotating the mouse wheel when the cursor is outside of the image\n"
                    "2) pressing the minus or plus keys\n"
                    "3) selecting a new zoom setting from the View/Zoom menu"));
}

~GraphicsView()

GraphicsView::~GraphicsView ( )

virtual

Definition at line 69 of file GraphicsView.cpp.

{
}

Member Function Documentation

contextMenuEvent()

void GraphicsView::contextMenuEvent ( QContextMenuEvent *  event )

virtual

Intercept context event to support point editing.

Definition at line 73 of file GraphicsView.cpp.

{
  LOG4CPP_INFO_S ((*mainCat)) << "GraphicsView::contextMenuEvent"
                              << " selectedCount=" << scene()->selectedItems().count();
 
  GraphicsItemsExtractor graphicsItemsExtractor;
  const QList<QGraphicsItem*> &items = scene()->selectedItems();
  QStringList pointIdentifiers = graphicsItemsExtractor.selectedPointIdentifiers(items);
 
  if (pointIdentifiers.count() > 0) {
 
    if (graphicsItemsExtractor.allSelectedItemsAreEitherAxisOrGraph (items,
                                                                     GRAPH_POINTS)) {
 
      // One or more graph points are selected so edit their coordinates
      emit signalContextMenuEventGraph (pointIdentifiers);
 
    } else if (graphicsItemsExtractor.allSelectedItemsAreEitherAxisOrGraph (items,
                                                                            AXIS_POINTS) && pointIdentifiers.count() == 1) {
 
      // A single axis point is selected so edit it
      emit signalContextMenuEventAxis (pointIdentifiers.first());
 
    }
  }
 
  QGraphicsView::contextMenuEvent (event);
}

dragEnterEvent()

void GraphicsView::dragEnterEvent ( QDragEnterEvent *  event )

virtual

Intercept mouse drag event to support drag-and-drop.

Definition at line 102 of file GraphicsView.cpp.

{
  LOG4CPP_INFO_S ((*mainCat)) << "GraphicsView::dragEnterEvent " << (event->mimeData ()->hasUrls () ? "urls" : "non-urls");
 
  if (event->mimeData ()->hasImage () ||
      event->mimeData ()->hasUrls ()) {
    event->acceptProposedAction();
  }
}

dragMoveEvent()

void GraphicsView::dragMoveEvent ( QDragMoveEvent *  event )

virtual

Intercept mouse move event to support drag-and-drop.

Definition at line 112 of file GraphicsView.cpp.

{
  LOG4CPP_INFO_S ((*mainCat)) << "GraphicsView::dragMoveEvent";
 
  if (event->mimeData ()->hasImage () ||
      event->mimeData ()->hasUrls ()) {
    event->acceptProposedAction();
  }
}

dropEvent()

void GraphicsView::dropEvent ( QDropEvent *  event )

virtual

Intercept mouse drop event to support drag-and-drop. This initiates asynchronous loading of the dragged image.

Definition at line 122 of file GraphicsView.cpp.

{
  LOG4CPP_INFO_S ((*mainCat)) << "GraphicsView::dropEvent";
 
  // Urls from text/uri-list
  QList<QUrl> urlList = event->mimeData ()->urls ();
 
  const QString MIME_FORMAT_TEXT_PLAIN ("text/plain");
  QString textPlain (event->mimeData()->data (MIME_FORMAT_TEXT_PLAIN));
 
  QUrl urlFirst;
  if (event->mimeData ()->hasUrls () &&
      urlList.count () > 0) {
    urlFirst = urlList.at (0);
  }
 
  QImage image;
  if (event->mimeData()->hasImage()) {
    image = qvariant_cast<QImage> (event->mimeData ()->imageData ());
  }
 
  if (handleDropEvent (textPlain,
                       event->mimeData ()->hasUrls (),
                       urlFirst,
                       event->mimeData ()->hasImage (),
                       image)) {
 
    event->acceptProposedAction();
 
  } else {
 
    LOG4CPP_INFO_S ((*mainCat)) << "GraphicsView::dropEvent dropped";
    QGraphicsView::dropEvent (event);
  }
}

keyPressEvent()

void GraphicsView::keyPressEvent ( QKeyEvent *  event )

virtual

Intercept key press events to handle left/right/up/down moving.

Definition at line 203 of file GraphicsView.cpp.

{
  LOG4CPP_DEBUG_S ((*mainCat)) << "GraphicsView::keyPressEvent";
 
  // Intercept up/down/left/right if any items are selected
  Qt::Key key = static_cast<Qt::Key> (event->key());
 
  bool atLeastOneSelectedItem = (scene ()->selectedItems ().count () > 0);
 
  if (key == Qt::Key_Down ||
      key == Qt::Key_Left ||
      key == Qt::Key_Right ||
      key == Qt::Key_Up) {
 
    emit signalKeyPress (key, atLeastOneSelectedItem);
    event->accept();
 
  } else {
 
    QGraphicsView::keyPressEvent (event);
 
  }
}

mouseMoveEvent()

void GraphicsView::mouseMoveEvent ( QMouseEvent *  event )

virtual

Intercept mouse move events to populate the current cursor position in StatusBar.

Definition at line 227 of file GraphicsView.cpp.

{
//  LOG4CPP_DEBUG_S ((*mainCat)) << "GraphicsView::mouseMoveEvent cursor="
//                               << QtCursorToString (cursor().shape()).toLatin1 ().data ();
 
  QPointF posScreen = mapToScene (event->pos ());
 
  if (!inBounds (posScreen)) {
 
    // Set to out-of-bounds value
    posScreen = QPointF (-1.0, -1.0);
  }
 
  emit signalMouseMove (posScreen);
 
  QGraphicsView::mouseMoveEvent (event);
}

mousePressEvent()

void GraphicsView::mousePressEvent ( QMouseEvent *  event )

virtual

Intercept mouse press events to create one or more Points.

Definition at line 245 of file GraphicsView.cpp.

{
  LOG4CPP_DEBUG_S ((*mainCat)) << "GraphicsView::mousePressEvent";
 
  QPointF posScreen = mapToScene (event->pos ());
 
  if (!inBounds (posScreen)) {
 
    // Set to out-of-bounds value
    posScreen = QPointF (-1.0, -1.0);
  }
 
  emit signalMousePress (posScreen);
 
  QGraphicsView::mousePressEvent (event);
}

mouseReleaseEvent()

void GraphicsView::mouseReleaseEvent ( QMouseEvent *  event )

virtual

Intercept mouse release events to move one or more Points.

Definition at line 262 of file GraphicsView.cpp.

{
  LOG4CPP_DEBUG_S ((*mainCat)) << "GraphicsView::mouseReleaseEvent signalMouseRelease";
 
  QPointF posScreen = mapToScene (event->pos ());
 
  if (!inBounds (posScreen)) {
 
    // Set to out-of-bounds value
    posScreen = QPointF (-1.0, -1.0);
  }
 
  // Send a signal, unless this is a right click. We still send if out of bounds since
  // a click-and-drag often ends out of bounds (and user is unlikely to expect different
  // behavior when endpoint is outside, versus inside, the image boundary)
  int bitFlag = (unsigned (event->buttons ()) & Qt::RightButton);
  bool isRightClick = (bitFlag != 0);
 
  if (!isRightClick) {
 
    emit signalMouseRelease (posScreen);
 
  }
 
  QGraphicsView::mouseReleaseEvent (event);
}

signalContextMenuEventAxis

void GraphicsView::signalContextMenuEventAxis ( QString  pointIdentifier )

signal

Send right click on axis point to MainWindow for editing.

signalContextMenuEventGraph

void GraphicsView::signalContextMenuEventGraph ( QStringList  pointIdentifiers )

signal

Send right click on graph point(s) to MainWindow for editing.

signalDraggedDigFile

void GraphicsView::signalDraggedDigFile ( QString  )

signal

Send dragged dig file to MainWindow for import. This comes from dragging an engauge dig file.

signalDraggedImage

void GraphicsView::signalDraggedImage ( QImage  )

signal

Send dragged image to MainWindow for import. This typically comes from dragging a file.

signalDraggedImageUrl

void GraphicsView::signalDraggedImageUrl ( QUrl  )

signal

Send dragged url to MainWindow for import. This typically comes from dragging an image from a browser.

signalKeyPress

void GraphicsView::signalKeyPress ( Qt::Key  , bool  atLeastOneSelectedItem  )

signal

Send keypress to MainWindow for eventual processing by DigitizeStateAbstractBase subclasses.

signalMouseMove

void GraphicsView::signalMouseMove ( QPointF  )

signal

Send mouse move to MainWindow for eventual display of cursor coordinates in StatusBar.

signalMousePress

void GraphicsView::signalMousePress ( QPointF  )

signal

Send mouse press to MainWindow for creating one or more Points.

signalMouseRelease

void GraphicsView::signalMouseRelease ( QPointF  )

signal

Send mouse release to MainWindow for moving Points.

signalViewZoomIn

void GraphicsView::signalViewZoomIn ( )

signal

Send wheel event to MainWindow for zooming in.

signalViewZoomOut

void GraphicsView::signalViewZoomOut ( )

signal

Send wheel event to MainWindow for zooming out.

slotDropRegression

void GraphicsView::slotDropRegression ( QString  urlText )

slot

Receive drag and drop regression test url.

Definition at line 309 of file GraphicsView.cpp.

{
  // Regression test with local file or internet url specified
  QString emptyDigFileName;
  bool hasUrl = true;
  QUrl url (urlText); // Works as is for internet url
  if (!urlText.contains ("http")) {
    url = QUrl::fromLocalFile (urlText);
  }
  bool hasImage = false;
  QImage emptyImage;
 
  handleDropEvent (emptyDigFileName,
                   hasUrl,
                   url,
                   hasImage,
                   emptyImage);
}

wheelEvent()

void GraphicsView::wheelEvent ( QWheelEvent *  event )

virtual

Convert wheel events into zoom in/out.

Definition at line 328 of file GraphicsView.cpp.

{
  const int ANGLE_THRESHOLD = 15; // From QWheelEvent documentation
  const int DELTAS_PER_DEGREE = 8; // From QWheelEvent documentation
 
  QPoint numDegrees = event->angleDelta() / DELTAS_PER_DEGREE;
 
  LOG4CPP_INFO_S ((*mainCat)) << "MainWindow::wheelEvent"
                              << " degrees=" << numDegrees.y()
                              << " phase=" << event->phase();
 
  // Criteria:
  // 1) User has enabled wheel zoom control (but that is not known here so MainWindow will handle that part)
  //    in slotViewZoomInFromWheelEvent and slotViewZoomOutFromWheelEvent
  // 2) Angle is over a threshold to eliminate false events from just touching wheel
  if ((event->modifiers() & Qt::ControlModifier) != 0) {
 
    if (numDegrees.y() >= ANGLE_THRESHOLD) {
 
      // Rotated backwards towards the user, which means zoom in
      emit signalViewZoomIn();
 
    } else if (numDegrees.y() <= -ANGLE_THRESHOLD) {
 
      // Rotated forwards away from the user, which means zoom out
      emit signalViewZoomOut();
 
    }
 
    // Accept the event as long as Control key was used and we are capturing wheel event
    event->accept();
 
  } else {
 
    // Let non-Control events manage scrolling
    QGraphicsView::wheelEvent (event);
 
  }
}

---

The documentation for this class was generated from the following files:

• Graphics/GraphicsView.h
• Graphics/GraphicsView.cpp