Moving scroll bar inside QScroll Area

[gmahan]

Hi,

I need to use a custom scroll bar for the QScrollArea widget which I am setting using the setVerticalScrollBar() member function. However, my custom scroll bar is showing up complete, it's being cut. The custom scroll bar has a width of 48px.

MyScrollBar::MyScrollBar(QWidget *parent) :
QWidget(parent),
ui(new Ui::MyScrollBar)
{
scrollWidget = new ScrollWidget(this);
scrollBar = new ScrollBar(Qt::Vertical, this);

ui->setupUi(this);
scrollBar->setMaximumWidth(46);
scrollBar->setMinimumWidth(46);
ui->scrollArea->setVerticalScrollBar(scrollBar);

//ui->scrollArea->widget()->show();
}

See image below..

ScrollBarPushed.PNG

NormalScroll.PNG

[wysota]

I think that if the bar is wider than the standard bar, you will need to adjust the scroll area viewport's contents margins accordingly and maybe also position the new bar yourself inside a reimplemented resizeEvent.

[gmahan]

Thanks for the response. Could you elaborate on this : scroll area viewport's contents margins

Is the viewport a subcontrol of the scrollArea widget. I am unable to get any information on the subcontrols that belong to QScrollArea.

[wysota]

Look at QAbstractScrollArea api.

[gmahan]

I tried setting the margins using the setViewportMargins(), but it didn't work.

ScrollArea::ScrollArea(QWidget *parent, QScrollBar *scrollbar) :
QScrollArea(parent)
{
setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOf f);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
setVerticalScrollBar(scrollbar);
setViewportMargins(0, 0, 50, 0);
}

I am not familiar with the resize event so I have not tried it yet. I just wanted to make sure if I was on the correct path.

Scroll.PNG

[gmahan]

Tried to add the setViewportMargins in the resize event function, but that didn't work either. Any other hints? I've looked everywhere but haven't found anything. Looks like I might have to create a custom scroll bar and link the signals to the scrollarea widget.

[wysota]

How does "doesn't work" manifest itself?

[gmahan]

The scroll bar is still clipped off. I am unable to move it's position within QScrollArea Widget.

[wysota]

The scroll bar is still clipped off. I am unable to move it's position within QScrollArea Widget.

Can we see the code you have written to achieve this?

[gmahan]

#include "scrollarea.h"

ScrollArea::ScrollArea(QWidget *parent, QScrollBar *scrollbar) :
QScrollArea(parent)
{
setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
setVerticalScrollBar(scrollbar);
setViewportMargins(50, 50, 50, 50);
}

ScrollArea::~ScrollArea()
{

}

void ScrollArea::resizeEvent(QResizeEvent *event)
{
setViewportMargins(0, 0, 50, 0);

QScrollArea::resizeEvent(event);
}

#include "scrollbar.h"

ScrollBar::ScrollBar(Qt::Orientation orientation, QWidget *parent):
QScrollBar(orientation, parent)
{
setMaximumWidth(48);
setMinimumWidth(48);

/* Center Body */
this->setStyleSheet(QString("QScrollBar:vertical {"
"background: #333333;"
"margin: 46px 0 46px 0;"
"}"
/*Slider*/
"QScrollBar::handle:vertical {"
"border: none;"
"background: #4b4b4b;"
"}"

/* Down button */
"QScrollBar::add-line:vertical {"
"background: none;"
"height: 48px;"
"subcontrol-position: bottom;"
"subcontrol-origin: margin;"
"}"
/*Up-button*/
"QScrollBar::sub-line:vertical {"
"background: none;"
"height: 48px;"
"subcontrol-position: top;"
"subcontrol-origin: margin;"
"}"

/* add-page, sub-page subcontrol*/
"QScrollBar::add-page:vertical, QScrollBar::sub-page:vertical {"
"background: none;"
"}"

/*up arrow normal state*/
"QScrollBar::up-arrow:vertical {"
"image: url(:/Images/scroll-uparrow);"
"width: 48px;"
"height: 46px;"
"}"

/* down arrow normal state*/
"QScrollBar::down-arrow:vertical {"
"image: url(:/Images/scroll-downarrow);"
"width: 48px;"
"height: 46px;"
"}"

/* up arrow pressed*/
"QScrollBar::up-arrow:vertical:pressed {"
"image: url(:/Images/scroll-uparrow-hit);"
"width: 48px;"
"height: 46px;"
"}"

/* down arrow pressed*/
"QScrollBar::down-arrow:vertical:pressed {"
"image: url(:/Images/scroll-downarrow-hit);"
"width: 48px;"
"height: 46px;"
"}"));


}

ScrollBar::~ScrollBar()
{

}

#include "scrollbar.h"
#include "myscrollbar.h"
#include "scrollwidget.h"
#include "scrollarea.h"

#include <QApplication>
#include <QVBoxLayout>
#include <QSize>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget *mainWindow = new QWidget;
ScrollBar *scrollBar = new ScrollBar(Qt::Vertical, mainWindow);
ScrollArea *scrollArea = new ScrollArea(mainWindow, scrollBar);

QVBoxLayout *layout = new QVBoxLayout;

mainWindow->setWindowTitle("Scroll");
layout->addWidget(scrollArea);
mainWindow->setLayout(layout);
mainWindow->show();

return a.exec();
}



Sorry, for the annoying text format. What is the tag to insert code.

[wysota]

Ok, but in the resize event you were supposed to reposition the scrollbar to where you want it to be. Calling the base class implementation will position the bar exactly the same way as originally.

[gmahan]

Hmm, I guess that is the part I am tripping. What function call do you use to reposition the bar?

[wysota]

Setter of QWidget::geometry property.