Method Arrow_widget

example/qt/qt4/hello/arrow.cpp:17–22

#include <math.h>

Arrow_widget::Arrow_widget(QWidget* parent) : QWidget(parent), color_(0)
{
    QPalette pal = palette();
    pal.setBrush(backgroundRole(), QBrush(Qt::white));
    setPalette(pal);
}

void Arrow_widget::slotChangeColor()
{