Qt代码实现上下左右布局

//实现在上下左右四个方向分别放置按钮
#include <QtWidgets>

#include "arrowpad.h"

ArrowPad::ArrowPad(QWidget *parent)
    : QWidget(parent)
{

upButton = new QPushButton(tr("&Up"));

downButton = new QPushButton(tr("&Down"));

leftButton = new QPushButton(tr("&Left"));

rightButton = new QPushButton(tr("&Right"));


QGridLayout *mainLayout = new QGridLayout;
mainLayout->addWidget(upButton, 0, 1);
mainLayout->addWidget(leftButton, 1, 0);
mainLayout->addWidget(rightButton, 1, 2);
mainLayout->addWidget(downButton, 2, 1);
setLayout(mainLayout);
}