Add Static area to QGraphicsView

[dubstar_04]

warning() is just a slot that prints the int value via std::cout.

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int value)));

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int value)));

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wont compile:



I dont know how to connect the ui->graphicsView->verticalScrollBar() to the slot or even if thats the correct object to connect.

Thanks,

Dubstar_04

[stampede]

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int /*no parameter name here*/ )));

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int /*no parameter name here*/ )));

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You can't give parameter name in SIGNAL or SLOT macro, only types.

[dubstar_04]

I added a screenshot of the build error. error is still the same with:

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int)));

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int)));

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[stampede]

I added a screenshot of the build error. error is still the same

Ok, I haven't seen the error before posting.
Maybe it's a stupid question, but - is the MainWindow a subclass of QObject (QWidget,QMainWindow,...) ? Does this class have Q_OBJECT macro in private section ?
QScrollBar is QObject-based for sure. Can you show the class header ?

[dubstar_04]

This is the MainWindow class header.

Normally when i am typing the connections, QTCreator offers a list of signals that can be emitted by the object. when i am typing this connection in nothing is offered.

class MainWindow : public QMainWindow
{
    Q_OBJECT
 
    QNetworkAccessManager manager2;
    QList<QNetworkReply *> currentDownloads;
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

class MainWindow : public QMainWindow
{
    Q_OBJECT

    QNetworkAccessManager manager2;
    QList<QNetworkReply *> currentDownloads;

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

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Thanks,

Dubstar_04

[stampede]

This is the MainWindow class header.

Well, I can agree that this could be a part of MainWindow class header

There should be nothing wrong in your code, my quick test looks very similar and works:

// test.h
#include <QtGui>
 
class MainW : public QMainWindow{
	Q_OBJECT
 
	QGraphicsView * view;
 
public:
	explicit MainW( QWidget * parent = NULL );
public slots:
	void warning( int value ){
		this->setWindowTitle(QString::number(value));
	}
};
 
// test.cpp
#include "test.h"
 
MainW::MainW( QWidget * parent ) : QMainWindow(parent){
	view = new QGraphicsView(this);
	QGraphicsScene * scene = new QGraphicsScene(this);
	scene->setSceneRect(0,0,1000,1000);
	view->setScene(scene);
	this->setCentralWidget(view);
	connect( view->verticalScrollBar(), SIGNAL(valueChanged(int)), this, SLOT(warning(int)) );
}
 
int main(int argc, char *argv[]){	
    QApplication a(argc, argv);
    MainW m;
    m.show();
    return a.exec();
}

// test.h
#include <QtGui>

class MainW : public QMainWindow{
	Q_OBJECT
	
	QGraphicsView * view;
	
public:
	explicit MainW( QWidget * parent = NULL );
public slots:
	void warning( int value ){
		this->setWindowTitle(QString::number(value));
	}
};

// test.cpp
#include "test.h"

MainW::MainW( QWidget * parent ) : QMainWindow(parent){
	view = new QGraphicsView(this);
	QGraphicsScene * scene = new QGraphicsScene(this);
	scene->setSceneRect(0,0,1000,1000);
	view->setScene(scene);
	this->setCentralWidget(view);
	connect( view->verticalScrollBar(), SIGNAL(valueChanged(int)), this, SLOT(warning(int)) );
}
 
int main(int argc, char *argv[]){	
    QApplication a(argc, argv);
    MainW m;
    m.show();
    return a.exec();
}

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Try to make a clean build ( make clean, qmake, make ). If this doesn't help, post full code (if you can).

[dubstar_04]

stampede,

I just made a new project and copied your example and i get the same error.

if i edit out the connect line it builds and runs as expected?

am using QT 4.7 on a mac.

any further suggestions?

Thanks,

Dubstar_04

[stampede]

That's really weird, I'm sorry but I can't help you more, because my experience with mac == 0
I see that you have Unix and Windows in your profile info, does all of this works on those systems, can you check that ?

[dubstar_04]

i am just uninstalling all the Qt stuff off my mac as i have loads of different versions. I will try and build it again once i have reinstalled everything.

I will try the linux and windows machines if that doesnt work.

Thanks for all your help.

update:
Reinstalled qt on mac. same error.
it wouldnt build on linux either. same issue.

[wysota]

I added a screenshot of the build error. error is still the same with:

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int)));

connect(ui->graphicsView->verticalScrollBar(), SIGNAL(valueChanged(int)),this,  SLOT(warning(int)));

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This usually means you forgot to #include <QScrollBar> or "mainwindow.h" and your compiler doesn't know QScrollBar or MainWindow are subclasses of QObject.

[dubstar_04]

Wysota,

Thanks for your reply. I thought i had included <QScrollBar>.

I will have a look later as i am back in work today

I wish i was a professional developer. its so interesting.

[dubstar_04]

SUCCESS !!!!

it was just missing a <QScrollBar> include.

I cant thank you guys enough for the help.

I have now drawn the timebar over the guide and it works beautifully!!

Thanks,

Dubstar_04

[stampede]

I don't understand something, dubstar_04 said that he couldn't compile my example with Qt 4.7, and that #include <QScrollBar> helped. But doesn't #include <QtGui> including all QtGui module classes definitions ? That's what documentation states:

To include the definitions of both modules' classes, use the following directive:
#include <QtGui>

It works without including separate header for QScrollBar on my side (Qt 4.5.2 on windows xp and Qt 4.7.2 on Ubuntu 9.02).