ViewPreview Class Reference

Class that modifies QGraphicsView to automatically expand/shrink the view to fit the window, after resize events. More...

#include <ViewPreview.h>

Inheritance diagram for ViewPreview:

Collaboration diagram for ViewPreview:

Public Types
enum	ViewAspectRatio { VIEW_ASPECT_RATIO_VARIABLE , VIEW_ASPECT_RATIO_ONE_TO_ONE }
	Prevent aspect ratio distortion in certain previews by providing fixed 1:1 aspect ratio option. More...

Signals
void	signalMouseMove (QPointF pos)
	Forward the mouse move events.

Public Member Functions
	ViewPreview (QGraphicsScene *scene, ViewAspectRatio viewAspectRatio, QWidget *parent=0)
	Single constructor.
virtual void	mouseMoveEvent (QMouseEvent *event)
	Intercept cursor move events and forward them.
virtual void	resizeEvent (QResizeEvent *event)
	Intercept resize events so we can rescale to the graphics items just fit into the resized window.
virtual void	wheelEvent (QWheelEvent *event)
	Intercept wheel event and discard it so accidentally moving the wheel does not move drawn items out of view.

Detailed Description

Class that modifies QGraphicsView to automatically expand/shrink the view to fit the window, after resize events.

Definition at line 14 of file ViewPreview.h.

Member Enumeration Documentation

ViewAspectRatio

enum ViewPreview::ViewAspectRatio

Prevent aspect ratio distortion in certain previews by providing fixed 1:1 aspect ratio option.

Enumerator
VIEW_ASPECT_RATIO_VARIABLE
VIEW_ASPECT_RATIO_ONE_TO_ONE

Definition at line 21 of file ViewPreview.h.

                       {
    VIEW_ASPECT_RATIO_VARIABLE,
    VIEW_ASPECT_RATIO_ONE_TO_ONE
  };

Constructor & Destructor Documentation

ViewPreview()

ViewPreview::ViewPreview	(	QGraphicsScene *	scene,
		ViewAspectRatio	viewAspectRatio,
		QWidget *	parent = 0 )

Single constructor.

Definition at line 12 of file ViewPreview.cpp.

                                          :
  QGraphicsView (scene, parent),
  m_viewAspectRatio (viewAspectRatio)
{
  setMouseTracking(true);
}

Member Function Documentation

mouseMoveEvent()

void ViewPreview::mouseMoveEvent ( QMouseEvent * event )

virtual

Intercept cursor move events and forward them.

Definition at line 21 of file ViewPreview.cpp.

{
  QPointF pos = mapToScene (event->pos ());
 
  emit signalMouseMove (pos);
 
  // Normally we would need to call QGraphicsView::mouseMoveEvent at this point so that the mouse move event could be handled,
  // but this is unwanted since:
  // 1) Everywhere, except the pdf import preview, there is nothing to drag
  // 2) Dragging of PdfFrameHandle objects in the pdf import preview is handled indirectly by PdfCropping
  QGraphicsView::mouseMoveEvent (event);
}

resizeEvent()

void ViewPreview::resizeEvent ( QResizeEvent * event )

virtual

Intercept resize events so we can rescale to the graphics items just fit into the resized window.

Definition at line 34 of file ViewPreview.cpp.

{
  if (m_viewAspectRatio == VIEW_ASPECT_RATIO_ONE_TO_ONE) {
 
    fitInView (scene()->sceneRect(),
               Qt::KeepAspectRatio);
 
  } else {
 
    // Make image fit the new window size by using fitInView. This is needed since QGraphicsView ignores layout stretching.
    // If there is an image then we use its extent, so DlgSettingsGridDisplay with polar coordinates (which can extend well
    // outside of image) does not end up with tiny image with wasted space around it
    bool foundImage = false;
    for (int i = 0; i < scene()->items().count (); i++) {
      const QGraphicsItem *item = scene()->items().at (i);
      const QGraphicsPixmapItem *itemPixmap = dynamic_cast<const QGraphicsPixmapItem*> (item);
      if (itemPixmap != nullptr) {
        foundImage = true;
        fitInView (itemPixmap->boundingRect());
      }
    }
 
    if (!foundImage) {
      // Use the extent of everything
      fitInView (scene()->itemsBoundingRect ());
    }
 
    QGraphicsView::resizeEvent (event);
  }
}

signalMouseMove

void ViewPreview::signalMouseMove ( QPointF pos )

signal

Forward the mouse move events.

wheelEvent()

void ViewPreview::wheelEvent ( QWheelEvent * event )

virtual

Intercept wheel event and discard it so accidentally moving the wheel does not move drawn items out of view.

Definition at line 65 of file ViewPreview.cpp.

{
  event->accept ();
}

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

• View/ViewPreview.h
• View/ViewPreview.cpp