Add QScrollArea to QDialog

[cpsmusic]

Hi,

Is it possible to create a Qdialog with a QScrollArea?

I've tried the following but neither method works:

QScrollArea scrollArea;
scrollArea.viewport()->setBackgroundRole(QPalette::Dark);
scrollArea.viewport()->setAutoFillBackground(true);
scrollArea.setWindowTitle(QObject::tr("Mixer Strip"));
scrollArea.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scrollArea.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scrollArea.setParent(this);
scrollArea.show();

QScrollArea scrollArea;
scrollArea.viewport()->setBackgroundRole(QPalette::Dark);
scrollArea.viewport()->setAutoFillBackground(true);
scrollArea.setWindowTitle(QObject::tr("Mixer Strip"));
scrollArea.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scrollArea.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scrollArea.setParent(this);
scrollArea.show();

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QScrollArea scroll;
scroll.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scroll.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
QWidget *viewport = new QWidget;
scroll.setWidget(viewport);
scroll.setWidgetResizable(true);
QVBoxLayout *l = new QVBoxLayout(viewport);
setLayout(l);
scroll.show();

QScrollArea scroll;
scroll.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scroll.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
QWidget *viewport = new QWidget;
scroll.setWidget(viewport);
scroll.setWidgetResizable(true);
QVBoxLayout *l = new QVBoxLayout(viewport);
setLayout(l);
scroll.show();

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Cheers,

Chris

[Rachol]

The second example seems to be correct, but what is the parent of QScrollArea?

[cpsmusic]

If I change the code to the following I still don't see the QScrollArea:

QScrollArea scroll;
    scroll.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll.setWidget(viewport);
    scroll.setWidgetResizable(true);
    QVBoxLayout *l = new QVBoxLayout(viewport);
    setLayout(l);
    scroll.setParent(this);
    scroll.show();

QScrollArea scroll;
    scroll.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll.setWidget(viewport);
    scroll.setWidgetResizable(true);
    QVBoxLayout *l = new QVBoxLayout(viewport);
    setLayout(l);
    scroll.setParent(this);
    scroll.show();

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[Santosh Reddy]

Create QScrollArea on heap

QScrollArea * scroll = new QScrollArea(this);

QScrollArea * scroll = new QScrollArea(this);

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[cpsmusic]

Hi,

I tried the following:

setWindowTitle("Mixer Strip");
    setMinimumSize(600, 350);
 
    QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
    QHBoxLayout *l = new QHBoxLayout(viewport);
    setLayout(l);

setWindowTitle("Mixer Strip");
    setMinimumSize(600, 350);

    QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
    QHBoxLayout *l = new QHBoxLayout(viewport);
    setLayout(l);

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Using this code the scrollbars are visible however they're positioned in the top left corner of the dialog and don't change position when the dialog is resized. I can just makeout the widgets that are added.

Cheers,

Chris

[Santosh Reddy]

If you are adding widgets to QHBoxLayout *l then

QHBoxLayout *l = new QHBoxLayout(viewport);
viewport->setLayout(l);

QHBoxLayout *l = new QHBoxLayout(viewport);
viewport->setLayout(l);

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[cpsmusic]

I tried the following:

QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
    QHBoxLayout *l = new QHBoxLayout(viewport);
    viewport->setLayout(l);

QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    QWidget *viewport = new QWidget;
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
    QHBoxLayout *l = new QHBoxLayout(viewport);
    viewport->setLayout(l);

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The scrollbars are visible however they're still not attached to the dialog.

I also tried removing the call to

scroll->setWidget(viewport)

scroll->setWidget(viewport)

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In this case, the scrollbars are visible (and the size of the area they contain is larger) but they're still not attached to the dialog.

[Santosh Reddy]

I think I got you problem, not sure how you are using QDialog, let me put both the ways, check which is applicable to you

1. If sub-classing QDialog, then in the constructor of the sub-calss

MyDialog::MyDialog(QWidget * parent) : QDialog(parent)
{
    QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
 
    QWidget *viewport = new QWidget(this);
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
 
    QHBoxLayout *l = new QHBoxLayout(viewport);
    viewport->setLayout(l);
 
    // add needed widgets to layout "l"
    for(int i = 0; i < 10; i++)
        l->addWidget(new QPushButton());
 
    // Add a layout for QDialog
    QHBoxLayout *dialog_layout = new QHBoxLayout(this);
    dialog_layout->addWidget(scroll); // add scroll to the QDialog's layout
    setLayout(dialog_layout);
 
    // show dialog
    show();
}

MyDialog::MyDialog(QWidget * parent) : QDialog(parent)
{
    QScrollArea *scroll = new QScrollArea(this);
    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
	
    QWidget *viewport = new QWidget(this);
    scroll->setWidget(viewport);
    scroll->setWidgetResizable(true);
	
    QHBoxLayout *l = new QHBoxLayout(viewport);
    viewport->setLayout(l);

    // add needed widgets to layout "l"
    for(int i = 0; i < 10; i++)
        l->addWidget(new QPushButton());

    // Add a layout for QDialog
    QHBoxLayout *dialog_layout = new QHBoxLayout(this);
    dialog_layout->addWidget(scroll); // add scroll to the QDialog's layout
    setLayout(dialog_layout);
    
    // show dialog
    show();
}

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1. If using QDialog directly, then

QDialog * dialog = new QDialog(this); //my be you already have this
 
QScrollArea *scroll = new QScrollArea(dialog);
scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
 
QWidget *viewport = new QWidget(dialog);
scroll->setWidget(viewport);
scroll->setWidgetResizable(true);
 
QHBoxLayout *l = new QHBoxLayout(viewport);
viewport->setLayout(l);
 
// add needed widgets to layout "l"
for(int i = 0; i < 10; i++)
	l->addWidget(new QPushButton());
 
// Add a layout for QDialog
QHBoxLayout *dialog_layout = new QHBoxLayout(dialog);
dialog->setLayout(dialog_layout);
dialog->layout()->addWidget(scroll); // add scroll to the QDialog's layout
dialog->show();

QDialog * dialog = new QDialog(this); //my be you already have this

QScrollArea *scroll = new QScrollArea(dialog);
scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);

QWidget *viewport = new QWidget(dialog);
scroll->setWidget(viewport);
scroll->setWidgetResizable(true);

QHBoxLayout *l = new QHBoxLayout(viewport);
viewport->setLayout(l);

// add needed widgets to layout "l"
for(int i = 0; i < 10; i++)
	l->addWidget(new QPushButton());

// Add a layout for QDialog
QHBoxLayout *dialog_layout = new QHBoxLayout(dialog);
dialog->setLayout(dialog_layout);
dialog->layout()->addWidget(scroll); // add scroll to the QDialog's layout
dialog->show();

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Edit: your actual problem is you are adding QScrollArea to QDialog, where as you should be adding QScrollArea to QDialog's layout

[cpsmusic]

Thanks, that fixed the problem.

[cpsmusic]

Although I've got the scrollbars showing now, I've run into another problem - the widgets are being spread too widely in the horizontal direction. What I'd like is for the widgets to bunch up on the left hand side of the layout. I tried using a QGridLayout however this didn't fix the problem. The code I'm using is below. One thing, the widget is a custom widget that has a fixed size. I'm implemented the sizeHint method returning the size of the widget.

MixerDialog::MixerDialog(QWidget *parent) :
    QDialog(parent) {
 
    setWindowTitle("Mixer");
    setMinimumSize(600, 350);
 
    QScrollArea *scrollArea = new QScrollArea(this);
    scrollArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scrollArea->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
 
    QWidget *viewport = new QWidget(this);
    scrollArea->setWidget(viewport);
    scrollArea->setWidgetResizable(true);
 
    QHBoxLayout *hlayout = new QHBoxLayout(viewport);
    hlayout->setMargin(0);
    hlayout->setSpacing(0);
    viewport->setLayout(hlayout);
 
    // add needed widgets to layout "hlayout"
    int numberOfChannels = 10;
    for(int i = 0; i < numberOfChannels; i++) {
        MixerStrip *strip = new MixerStrip;
        hlayout->addWidget(strip);
    }
    hlayout->addStretch();
 
    // Add a layout for QDialog
    QHBoxLayout *dialog_layout = new QHBoxLayout(this);
    dialog_layout->setMargin(0);
    dialog_layout->setSpacing(0);
    dialog_layout->addWidget(scrollArea); // add scrollArea to the QDialog's layout
    setLayout(dialog_layout);
 
    // show dialog
    show();
}

MixerDialog::MixerDialog(QWidget *parent) :
    QDialog(parent) {

    setWindowTitle("Mixer");
    setMinimumSize(600, 350);

    QScrollArea *scrollArea = new QScrollArea(this);
    scrollArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
    scrollArea->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);

    QWidget *viewport = new QWidget(this);
    scrollArea->setWidget(viewport);
    scrollArea->setWidgetResizable(true);

    QHBoxLayout *hlayout = new QHBoxLayout(viewport);
    hlayout->setMargin(0);
    hlayout->setSpacing(0);
    viewport->setLayout(hlayout);

    // add needed widgets to layout "hlayout"
    int numberOfChannels = 10;
    for(int i = 0; i < numberOfChannels; i++) {
        MixerStrip *strip = new MixerStrip;
        hlayout->addWidget(strip);
    }
    hlayout->addStretch();

    // Add a layout for QDialog
    QHBoxLayout *dialog_layout = new QHBoxLayout(this);
    dialog_layout->setMargin(0);
    dialog_layout->setSpacing(0);
    dialog_layout->addWidget(scrollArea); // add scrollArea to the QDialog's layout
    setLayout(dialog_layout);

    // show dialog
    show();
}

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[Santosh Reddy]

You code should work, hlayout->addStretch(); does the magic...Post a screenshot indicating the of the probelm