Display cursor position in QGraphicsView

[dbrmik]

Hi

I need a bit of help displaying the cursor position of a pixel in a pixmap (4k x 1k pixels) using QGraphicsView . I have subclassed QGraphicsView

class viewWidget : public QGraphicsView
{
	Q_OBJECT;
public:
	viewWidget(QWidget* parent =0);
	virtual ~ viewWidget();
 
	void paintEvent(QPaintEvent* event);
	void mouseMoveEvent(QMouseEvent* event);
	void mousePressEvent(QMouseEvent* event);
 
signals:
	void grabPosition(const QPoint);
 
private:
	QPoint p;
	QString posString;
	float xScale;
	float yScale;
};

class viewWidget : public QGraphicsView
{
	Q_OBJECT;
public:
	viewWidget(QWidget* parent =0);
	virtual ~ viewWidget();

	void paintEvent(QPaintEvent* event);
	void mouseMoveEvent(QMouseEvent* event);
	void mousePressEvent(QMouseEvent* event);

signals:
	void grabPosition(const QPoint);

private:
	QPoint p;
	QString posString;
	float xScale;
	float yScale;
};

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viewWidget::viewWidget(QWidget* parent )
:QGraphicsView(parent),
xScale(1.0),
yScale(1.0)
{
	setMouseTracking(true);
}
 
viewWidget::~viewWidget(){};
 
void
viewWidget::paintEvent(QPaintEvent* event)
{
	QGraphicsView::paintEvent(event);
	QPainter paint(this);
	paint.setPen(QColor(Qt::yellow));
	paint.drawText(p,posString);
}
 
void
viewWidget::mouseMoveEvent(QMouseEvent* event)
{
	if (scene()==NULL)
		return;
 
	p=mapToScene(event->pos());
	posString = QString::number( (p.x() ) + "," + QString::number( p.y() );
 
	cout << qPrintable(posString) << endl;
	update();
}

viewWidget::viewWidget(QWidget* parent )
:QGraphicsView(parent),
xScale(1.0),
yScale(1.0)
{
	setMouseTracking(true);
}

viewWidget::~viewWidget(){};

void
viewWidget::paintEvent(QPaintEvent* event)
{
	QGraphicsView::paintEvent(event);
	QPainter paint(this);
	paint.setPen(QColor(Qt::yellow));
	paint.drawText(p,posString);
}

void
viewWidget::mouseMoveEvent(QMouseEvent* event)
{
	if (scene()==NULL)
		return;

	p=mapToScene(event->pos());
	posString = QString::number( (p.x() ) + "," + QString::number( p.y() );

	cout << qPrintable(posString) << endl;
	update();
}

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I create a QGraphicsScene from a pixmap and add it to the view as shown

view=new viewWidget(this); //Create a view widget
scene=new QGraphicsScene(view); 
scene->addPixmap(QPixmap::fromImage(*image));
view->setScene(scene);
view->show();

view=new viewWidget(this); //Create a view widget
scene=new QGraphicsScene(view); 
scene->addPixmap(QPixmap::fromImage(*image));
view->setScene(scene);
view->show();

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However the pixel position is not shown on the view, I get an error from the debugger

warning: QPainter::setPen: Painter not active

What am I doing wrong?

Thanks

[dbrmik]

Hi

Do I need to subclass QGraphicsScene and re-implement the painttEvent and mouseMoveEvent ? I can display the pixel positon in the status bar, bit I would like it attached the the cursor.

Thanks