QVBoxLayout布局的两边留空如何修改？

[中才德创]

这个值是如何修改的？可以修改到0吗？

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui/QMainWindow>
#include <QGroupBox>
#include <QVBoxLayout>
#include <QPushButton>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    QGroupBox *m_pGroup0;
    QGroupBox *m_pGroup1;
    QGroupBox *m_pGroup2;
    QGroupBox *m_pGroup3;
    QPushButton *m_pBtn0;
    QPushButton *m_pBtn1;

    QVBoxLayout *m_pvLayoutMain;

public slots:
    void onClicked0();
    void onClicked1();
};

#endif // MAINWINDOW_H

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    m_pGroup0 = new QGroupBox("group0", this);
    m_pGroup1 = new QGroupBox("group1", this);
    m_pGroup2 = new QGroupBox("group2", this);
    m_pGroup3 = new QGroupBox("group3", this);
    m_pBtn0 = new QPushButton("hide group1", this);
    m_pBtn1 = new QPushButton("show group1", this);
    connect(m_pBtn0, SIGNAL(clicked()), this, SLOT(onClicked0()));
    connect(m_pBtn1, SIGNAL(clicked()), this, SLOT(onClicked1()));

    m_pvLayoutMain = new QVBoxLayout(this);
    m_pvLayoutMain->addWidget(m_pGroup0);
    m_pvLayoutMain->addWidget(m_pGroup1);
    m_pvLayoutMain->addWidget(m_pGroup2);
    m_pvLayoutMain->addWidget(m_pGroup3);
    m_pvLayoutMain->addWidget(m_pBtn0);
    m_pvLayoutMain->addWidget(m_pBtn1);
    m_pvLayoutMain->addStretch();    

    setCentralWidget(new QWidget);
    centralWidget()->setLayout(m_pvLayoutMain);
}

MainWindow::~MainWindow()
{
}

void MainWindow::onClicked0()
{
    m_pGroup1->hide();
}

void MainWindow::onClicked1()
{
    m_pGroup1->show();
}

[xinpo66]

注释掉这个：
m_pvLayoutMain->addStretch();

[中才德创]

是指垂直布局后，控件放在上面，它们的x轴方向，左右两边的那个“空白”。

[xinpo66]

运行结果贴出来 我看看

[lefttime]

......
    setCentralWidget(new QWidget);
    centralWidget()->setLayout(m_pvLayoutMain);
    m_pvLayoutMain->setContentsMargins(0,9,0,9); // 加这上一句即可~``
......