How to get width and height of QScrollbars arrow widgets

[markus.liebe]

Hi there,

is it possible to get the height (for vertical scrollbars) and the width (for horizontal scrollbars) of the arrow widgets of a QScrollbar?

@+-+
|^| arrow widget top
+-+
| |
| | scrollbar
| |
+-+
|v| arrow widget bottom
+-+
@

In the example above I am interested in the height of "arrow widget bottom" and "arrow widget top".

In the docs for QScrollBar I did not find anything like that.

Regards,
Markus

[kibsoft]

I think it's impossible at least in standart way. See to the source code of QScrollBar, maybe it helps you.

[ogoffart]

using the style.

From memory:

QStyleOptionSlider newScrollbar;
newScrollbar.initFrom(scrollbar);
// fill other stuff in newScrollbar, see source code of QScrollBar::initStyleOption
h = scrollbar->style()->subControlRect(CC_ScrollBar, &option,SC_ScrollBarSubPage, scrollbar).height();

Good luck.

[markus.liebe]

Hi again.

I tried the approach using the style. But I had no luck. In the example below I try to get the height of the subcontrol (arrow widget) but I always get the height of the complete scrollbar:

(by the way: it seems as if the forum software gets confused by the parantheses even though I used the "code" icon to insert the code)

@#include <QtGui>
#include <QtGui>

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
MainWindow(QWidget *parent = 0)
: QMainWindow(parent),
m_textEdit(new QTextEdit())
{
setCentralWidget(new QWidget(this));
centralWidget()->setLayout(new QVBoxLayout());

    QPushButton *pb = new QPushButton("print info");
    connect(pb,SIGNAL(clicked()),this,SLOT(printInfo()));

    centralWidget()->layout()->addWidget(m_textEdit);
    centralWidget()->layout()->addWidget(pb);

    for(int counter = 0; counter < 200; counter++){
        m_textEdit->append(QString("Line %1").arg(counter));
    }

    resize(320,240);
}

~MainWindow(){

}

public slots:
void printInfo()
{
QScrollBar *scrollbar = m_textEdit->verticalScrollBar();
QStyleOptionSlider *option = new QStyleOptionSlider;
option->initFrom(scrollbar);

    // Print height and width for SC_ScrollBarAddLine,SC_ScrollBarSubLine,SC_ScrollBarAddPage and SC_ScrollBarSubPage

    qDebug() << "SC_ScrollBarAddLine: ";
    QRect rect = style()->subControlRect(QStyle::CC_ScrollBar,option,QStyle::SC_ScrollBarAddLine,scrollbar);
    qDebug() << "Height: " << rect.height();
    qDebug() << "Width: " << rect.width();
    qDebug() << "--------------------------------------------------------------------------------";

    qDebug() << "SC_ScrollBarSubLine: ";
    rect = style()->subControlRect(QStyle::CC_ScrollBar,option,QStyle::SC_ScrollBarSubLine,scrollbar);
    qDebug() << "Height: " << rect.height();
    qDebug() << "Width: " << rect.width();
    qDebug() << "--------------------------------------------------------------------------------";

    qDebug() << "SC_ScrollBarAddPage: ";
    rect = style()->subControlRect(QStyle::CC_ScrollBar,option,QStyle::SC_ScrollBarAddPage,scrollbar);
    qDebug() << "Height: " << rect.height();
    qDebug() << "Width: " << rect.width();
    qDebug() << "--------------------------------------------------------------------------------";

    qDebug() << "SC_ScrollBarSubPage: ";
    rect = style()->subControlRect(QStyle::CC_ScrollBar,option,QStyle::SC_ScrollBarSubPage,scrollbar);
    qDebug() << "Height: " << rect.height();
    qDebug() << "Width: " << rect.width();
    qDebug() << "--------------------------------------------------------------------------------";
}

private:
QTextEdit* m_textEdit;
};

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}

#include "main.moc"
@

In my case the output of the little program (after pressing the button) is:

@SC_ScrollBarAddLine:
Height: 185
Width: 16

SC_ScrollBarSubLine:
Height: 185
Width: 0

SC_ScrollBarAddPage:
Height: 185
Width: 0

SC_ScrollBarSubPage:
Height: 185
Width: 0

@

any hints?
Regards, Markus

[Guest]

One crazy workaround you can use is to set a stylesheet to your scroll bar. You can set some default height to "QScrollBar:horizontal" and also the width to "QScrollBar::add-line:horizontal" (or vertical) and to "QScrollBar::sub-line:horizontal" (or vertical). Now you can anytime retrieve this stylesheet as a QString using qscrollbar->stylesheet(). You can now also set some custom value by reconstructing this string and using qscrollbar->setStyleSheet() ...

Maybe not the most elagant solution, but I tried and it'll work ;)

[Guest]

The default size should be documented, anything custom (depending on your use case), my approach should work