Scrolling 2 QGraphicsViews with 1 scrollbar

[dentist]

Hi, i have a scrolling issue. I read lots of docs, googled, etc - but couldn't figure it out. The idea is to scroll 2 QGraphicsViews with the scrollbar of one of them. This is what i did:

class QPianoRoll : public QWidget {
 
    Q_OBJECT
 
    public:
    QPianoRoll(){
 
        currentScrollPosition = 0;
 
        QHBoxLayout *layout = new QHBoxLayout;
 
        // both, QNoteEditor and QVerticalPiano are derived from QGraphicView
 
        piano = new QVerticalPiano();
        layout->addWidget(piano);
 
        QNoteEditorCore * editor = new QNoteEditorCore();
        wrapper = new QNoteEditor(editor);
        QScrollBar * scrollbar = wrapper->verticalScrollBar();
        connect(scrollbar, SIGNAL(valueChanged(int)),this,SLOT(scrollRoll(int)));
 
        layout->addWidget(wrapper,2);
        layout->setAlignment(Qt::AlignLeft);
        setLayout(layout);
 
    }
 
    private :
            QNoteEditor * wrapper;
            QVerticalPiano * piano;
            int currentScrollPosition;
 
    public slots :
            void scrollRoll(int value) {
                int relative = currentScrollPosition - value;
                piano->scroll(0,relative);
                currentScrollPosition = value;
            }
 
};

class QPianoRoll : public QWidget {

    Q_OBJECT

    public:
    QPianoRoll(){

        currentScrollPosition = 0;

        QHBoxLayout *layout = new QHBoxLayout;
        
        // both, QNoteEditor and QVerticalPiano are derived from QGraphicView

        piano = new QVerticalPiano();
        layout->addWidget(piano);

        QNoteEditorCore * editor = new QNoteEditorCore();
        wrapper = new QNoteEditor(editor);
        QScrollBar * scrollbar = wrapper->verticalScrollBar();
        connect(scrollbar, SIGNAL(valueChanged(int)),this,SLOT(scrollRoll(int)));

        layout->addWidget(wrapper,2);
        layout->setAlignment(Qt::AlignLeft);
        setLayout(layout);

    }

    private :
            QNoteEditor * wrapper;
            QVerticalPiano * piano;
            int currentScrollPosition;

    public slots :
            void scrollRoll(int value) {
                int relative = currentScrollPosition - value;
                piano->scroll(0,relative);
                currentScrollPosition = value;
            }

};

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It's quite the same implementation as introduced here, but unfortunately it doesn't work. The slot scrollRoll just moves the visible scene up and down and does not scroll any contents. What am I doing wrong ?

[JohannesMunk]

Hi!

Untested, but why don't you set the value of the pianos vertical scrollbar directly?

connect(wrapper->verticalScrollBar(), SIGNAL(valueChanged(int)),piano->verticalScrollBar(),SLOT(setValue(int)));

connect(wrapper->verticalScrollBar(), SIGNAL(valueChanged(int)),piano->verticalScrollBar(),SLOT(setValue(int)));

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This requires them to have the same ranges though. But if you want to move synchronize their scrolling they should have!

HIH

Johannes

[norobro]

I agree with Joh about connecting the scroll bars directly, but you might also try the following in your slot:

piano->viewport()->scroll(0,relative);

piano->viewport()->scroll(0,relative);

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