Qt动态布局

动态布局无非就是打破原先的布局，然后再重新进行布局

清空布局

void MainWindow ::deleteAllitemsOfLayout(QLayout* layout)
{
    QLayoutItem *child;
    while ((child = layout->takeAt(0)) != nullptr)
    {
        ///setParent为NULL，防止删除之后界面不消失
        if(child->widget())
        {
            child->widget()->setParent(nullptr);
        }
        else if(child->layout())
        {
            deleteAllitemsOfLayout(child->layout());
        }
        delete child;
    }
}

#ifndef
#define

#include <QMainWindow>
#include <QDebug>
#include <QWidget>
#include <QLabel>
#include <QComboBox>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QGridLayout>
#include <QLayout>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

    void layout_1();
    void layout_2();
    void layout_3();
    void layout_4();
    void layout_5();
    void deleteAllitemsOfLayout(QLayout* layout);

    QWidget* L;
    QWidget* C;
    QComboBox* comboBox;
    QVector<QLabel* > vec_label;
    QVBoxLayout* mainLayout;
    QHBoxLayout* layout_L;

public slots:
    void slot_currentIndexChanged(int);

private:
    Ui::MainWindow *ui;
};
#endif// MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    this->setFixedSize(1080,720);
    L = new QWidget;
    L->setFixedSize(1080,600);
    C = new QWidget;
    C->setFixedSize(1080,120);
    mainLayout = new QVBoxLayout;
    mainLayout->addWidget(L);
    mainLayout->addWidget(C);
    mainLayout->setMargin(0);
    mainLayout->setSpacing(0);
    this->centralWidget()->setLayout(mainLayout);

    for(int i=0; i<9; i++)
    {
       vec_label.push_back(new QLabel(QString("通道 %1").arg(i+1)));
       vec_label[i]->setStyleSheet("background-color: rgb(66,66,66); color: rgb(221,221,221); font-size: 30px; text-align: center;");
    }

    layout_L = new QHBoxLayout(L);

    layout_1();

    comboBox = new QComboBox(C);
    comboBox->setGeometry(870,30,200,30);
    comboBox->addItem("布局1");
    comboBox->addItem("布局2");
    comboBox->addItem("布局3");
    comboBox->addItem("布局4");
    comboBox->addItem("布局5");
    connect(comboBox,SIGNAL(currentIndexChanged(int)),this,SLOT(slot_currentIndexChanged(int)));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::slot_currentIndexChanged(int n)
{
    switch(n)
    {
        case 0:
        {
            layout_1();
            break;
        }
        case 1:
        {
            layout_2();
            break;
        }
        case 2:
        {
            layout_3();
            break;
        }
        case 3:
        {
            layout_4();
            break;
        }
        case 4:
        {
            layout_5();
            break;
        }

    }
}

void MainWindow::layout_1()
{
    deleteAllitemsOfLayout(layout_L);

    QGridLayout * gridLayout = new QGridLayout;
    gridLayout->addWidget(vec_label[0],0,0);
    layout_L->addLayout(gridLayout);
}
void MainWindow::layout_2()
{
    deleteAllitemsOfLayout(layout_L);

    QGridLayout * gridLayout = new QGridLayout;
    gridLayout->addWidget(vec_label[0],0,0);
    gridLayout->addWidget(vec_label[1],0,1);
    layout_L->addLayout(gridLayout);
}
void MainWindow::layout_3()
{
    deleteAllitemsOfLayout(layout_L);

    QGridLayout * gridLayout = new QGridLayout;
    gridLayout->addWidget(vec_label[0],0,0);
    gridLayout->addWidget(vec_label[1],0,1);
    gridLayout->addWidget(vec_label[2],1,0);
    gridLayout->addWidget(vec_label[3],1,1);
    layout_L->addLayout(gridLayout);
}
void MainWindow::layout_4()
{
    deleteAllitemsOfLayout(layout_L);

    QGridLayout * gridLayout = new QGridLayout;
    gridLayout->addWidget(vec_label[0],0,0,2,2);
    gridLayout->addWidget(vec_label[1],0,2);
    gridLayout->addWidget(vec_label[2],1,2);
    gridLayout->addWidget(vec_label[3],2,0);
    gridLayout->addWidget(vec_label[4],2,1);
    gridLayout->addWidget(vec_label[5],2,2);
    layout_L->addLayout(gridLayout);
}
void MainWindow::layout_5()
{
    deleteAllitemsOfLayout(layout_L);

    QGridLayout * gridLayout = new QGridLayout;
    gridLayout->addWidget(vec_label[0],0,0);
    gridLayout->addWidget(vec_label[1],0,1);
    gridLayout->addWidget(vec_label[2],0,2);
    gridLayout->addWidget(vec_label[3],1,0);
    gridLayout->addWidget(vec_label[4],1,1);
    gridLayout->addWidget(vec_label[5],1,2);
    gridLayout->addWidget(vec_label[6],2,0);
    gridLayout->addWidget(vec_label[7],2,1);
    gridLayout->addWidget(vec_label[8],2,2);
    layout_L->addLayout(gridLayout);
}
void MainWindow::deleteAllitemsOfLayout(QLayout* layout)
{
    QLayoutItem *child;
    while ((child = layout->takeAt(0)) != nullptr)
    {
        ///setParent为NULL，防止删除之后界面不消失
        if(child->widget())
        {
            child->widget()->setParent(nullptr);
        }
        else if(child->layout())
        {
            deleteAllitemsOfLayout(child->layout());
        }
        delete child;
    }
}