Qt中的布局管理器

1. 布局管理器提供相关的类对界面组件进行布局管理，能够自动排列窗口中的界面组件，窗口变化后能自动更新界面组件的大小。

2. QLayout是Qt布局管理器的抽象基类，通过继承QLayout实现了功能各异且互补的布局管理器。

①QBoxLayout: QVBoxLayout, QHBoxLayout

②QGridLayout:

③QFormLayout:

④QStackedLayout:

3. 综合实例（一个简单的安装向导模型）

Widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QtGui/QWidget>
#include <QPushButton>
#include <QLabel>
#include <QLineEdit>

class Widget : public QWidget
{
    Q_OBJECT
private:
    QPushButton PreBtn;
    QPushButton NextBtn;
    QLabel Lab0;
    QLabel Lab1;
    QLabel Lab2;
    QLabel Lab3;

    QPushButton PushButton1;
    QPushButton PushButton2;

    QLineEdit LineEdit;
    void InitControl();

    QWidget* GetFirstPage();
    QWidget* GetSecondPage();
    QWidget* GetThirdPage();

private slots:
    void PreBtnClicked();
    void NextBtnClicked();

public:
    Widget(QWidget *parent = 0);
    ~Widget();
};

#endif // WIDGET_H

Widget.cpp

#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QGridLayout>
#include <QFormLayout>
#include <QStackedLayout>
#include <QDebug>
#include "widget.h"

Widget::Widget(QWidget *parent): QWidget(parent), PreBtn(this), NextBtn(this)
{
    InitControl();
}

void Widget::InitControl()
{
    QVBoxLayout* vLayout = new QVBoxLayout();
    QHBoxLayout* hLayout = new QHBoxLayout();
    QStackedLayout* sLayout = new QStackedLayout();

    PreBtn.setText("Pre Button");
    PreBtn.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
    PreBtn.setMinimumSize(160, 30);

    NextBtn.setText("Next Button");
    NextBtn.setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
    NextBtn.setMinimumSize(160, 30);

    sLayout->addWidget(GetFirstPage());
    sLayout->addWidget(GetSecondPage());
    sLayout->addWidget(GetThirdPage());

    hLayout->setSpacing(10);
    hLayout->addWidget(&PreBtn);
    hLayout->addWidget(&NextBtn);

    vLayout->addLayout(sLayout);
    vLayout->addLayout(hLayout);

    setLayout(vLayout);

    connect(&PreBtn, SIGNAL(clicked()), this, SLOT(PreBtnClicked()));
    connect(&NextBtn, SIGNAL(clicked()), this, SLOT(NextBtnClicked()));

}

QWidget* Widget::GetFirstPage()
{
    QWidget* widget = new QWidget();
    QGridLayout* gLayout = new QGridLayout();

    Lab0.setText("This");
    Lab1.setText("is");
    Lab2.setText("First");
    Lab3.setText("Page");

    gLayout->addWidget(&Lab0, 0, 0);
    gLayout->addWidget(&Lab1, 0, 1);
    gLayout->addWidget(&Lab2, 1, 0);
    gLayout->addWidget(&Lab3, 1, 1);

    widget->setLayout(gLayout);

    return widget;
}

QWidget* Widget::GetSecondPage()
{
    QWidget* widget = new QWidget();

    QFormLayout* fLayout = new QFormLayout();

    LineEdit.setText("This is Second Page");

    fLayout->addRow("Name", &LineEdit);

    widget->setLayout(fLayout);

    return widget;
}

QWidget* Widget::GetThirdPage()
{
    QWidget* widget = new QWidget();
    QVBoxLayout* vLayout = new QVBoxLayout();

    PushButton1.setText("Third");

    PushButton2.setText("Page");

    vLayout->addWidget(&PushButton1);
    vLayout->addWidget(&PushButton2);

    widget->setLayout(vLayout);

    return widget;
}

void Widget::PreBtnClicked()
{

    QStackedLayout* sLayout =  dynamic_cast<QStackedLayout*>(((dynamic_cast<QVBoxLayout*>(layout()))->children())[0]);

    if(sLayout != NULL)
    {
        int currentIndex = sLayout->currentIndex();

        currentIndex = (currentIndex > 0) ? (currentIndex - 1) : currentIndex;

        sLayout->setCurrentIndex(currentIndex);
    }

    qDebug() << "PreBtnClicked()";
}

void Widget::NextBtnClicked()
{
    QStackedLayout* sLayout =  dynamic_cast<QStackedLayout*>(((dynamic_cast<QVBoxLayout*>(layout()))->children())[0]);

    if(sLayout != NULL)
    {
        int currentIndex = sLayout->currentIndex();

        currentIndex = (currentIndex < 3) ? (currentIndex + 1) : currentIndex;

        sLayout->setCurrentIndex(currentIndex);
    }

    qDebug() << "NextBtnClicked()";
}

Widget::~Widget()
{
    
}