Qt之setDefault切換焦點

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    button = new QPushButton("OK");
    button->setDefault(true);  //默認按鈕:當按下enter鍵時，會默認選中[點擊]button
    button->setParent(this);
    connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));
}
void Widget::slotButtonClicked()
{
    static int i = 0;  //局部靜態變量
    qDebug() << "slotButtonClicked" << i++;
}

通常狀況下，焦點在主窗口上，可是若是咱們須要處理子窗口，須要設置

#include "widget.h"
#include <QPainter>
#include <QDebug>
#include <QVBoxLayout>
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    QVBoxLayout *layout = new QVBoxLayout(this);
    QPushButton *button2, *button3;
    button = new QPushButton("OK");
    layout->addWidget(button);
    layout->addWidget(button2 = new QPushButton("cancel"));
    layout->addWidget(button3 = new QPushButton("quit"));
    button->setDefault(true);  //默認按鈕:當按下enter鍵時，會默認選中[點擊]button
    button2->setDefault(true);   //根據上下箭頭切換焦點[V]，默認焦點爲第一個設置的setDefault
    button3->setDefault(true);
    connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));
    connect(button2, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));
    connect(button3, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));
}
void Widget::slotButtonClicked()
{
    QPushButton *button = (QPushButton *)sender();
    qDebug() << button->text();
}