大多数复杂的程序，都使用MDI框架，在Qt designer中可以直接将控件MDI Area拖入使用。
QMdiArea一般使用于主窗口中，用于容纳多个子窗口QMdiSubWindow
代码如下：
mainwindow.h
1 #ifndef MAINWINDOW_H 2 #define MAINWINDOW_H 3 4 #include <QMainWindow> 5 #include <QTextEdit> 6 #include <QLabel> 7 #include <QMdiSubWindow> 8 9 namespace Ui { 10 class MainWindow; 11 } 12 13 class MainWindow : public QMainWindow 14 { 15 Q_OBJECT 16 17 public: 18 explicit MainWindow(QWidget *parent = 0); 19 ~MainWindow(); 20 21 private: 22 Ui::MainWindow *ui; 23 QMdiSubWindow *newwin; 24 25 private slots: 26 void on_btnCloseAll_clicked(); 27 void on_btnClose_clicked(); 28 void on_btnNext_clicked(); 29 void on_btnPrevious_clicked(); 30 void on_btnNewWindow_clicked(); 31 void on_btnRemoveWindow_clicked(); 32 33 }; 34 35 #endif // MAINWINDOW_H
mainwindow.cpp
1 #include "mainwindow.h" 2 #include "ui_mainwindow.h" 3 4 MainWindow::MainWindow(QWidget *parent) : 5 QMainWindow(parent), 6 ui(new Ui::MainWindow) 7 { 8 ui->setupUi(this); 9 10 //window1 11 QTextEdit *window1 = new QTextEdit; 12 window1->setHtml("C"); 13 ui->mdiArea->addSubWindow(window1); //将window1放进mdiArea框架 14 15 //window2 16 QTextEdit *window2 = new QTextEdit; 17 window2->setHtml("C++"); 18 ui->mdiArea->addSubWindow(window2); 19 20 //window3 21 QTextEdit *window3 = new QTextEdit; 22 window3->setHtml("Java"); 23 ui->mdiArea->addSubWindow(window3); 24 25 //window4 26 QTextEdit *window4 = new QTextEdit; 27 window4->setHtml("Hello World"); 28 ui->mdiArea->addSubWindow(window4); 29 30 ui->mdiArea->cascadeSubWindows(); //SubWindows重叠排列 31 32 connect(ui->pushButton_6,SIGNAL(clicked()),this,SLOT(on_btnPrevious_clicked())); 33 connect(ui->pushButton_7,SIGNAL(clicked()),this,SLOT(on_btnNext_clicked())); 34 connect(ui->pushButton_8,SIGNAL(clicked()),this,SLOT(on_btnClose_clicked())); 35 connect(ui->pushButton_9,SIGNAL(clicked()),this,SLOT(on_btnCloseAll_clicked())); 36 connect(ui->pushButton_10,SIGNAL(clicked()),this,SLOT(on_btnNewWindow_clicked())); 37 connect(ui->pushButton_11,SIGNAL(clicked()),this,SLOT(on_btnRemoveWindow_clicked())); 38 } 39 40 MainWindow::~MainWindow() 41 { 42 delete ui; 43 } 44 45 void MainWindow::on_btnCloseAll_clicked() 46 { 47 ui->mdiArea->closeAllSubWindows(); 48 } 49 50 void MainWindow::on_btnClose_clicked() 51 { 52 ui->mdiArea->closeActiveSubWindow(); 53 } 54 55 void MainWindow::on_btnNext_clicked() 56 { 57 ui->mdiArea->activateNextSubWindow(); 58 } 59 60 void MainWindow::on_btnPrevious_clicked() 61 { 62 ui->mdiArea->activatePreviousSubWindow(); 63 } 64 65 void MainWindow::on_btnNewWindow_clicked() 66 { 67 newwin = new QMdiSubWindow; 68 newwin->setWindowTitle("test"); 69 newwin->setWidget(&QLabel("hey")); 70 newwin->setAttribute(Qt::WA_DeleteOnClose); 71 newwin->resize(200,200); 72 ui->mdiArea->addSubWindow(newwin); 73 newwin->show(); //在非构造函数不加show()，，不显示 74 //setActiveSubWindow(QMdiSubWindow *window); 设置active窗口 75 } 76 77 void MainWindow::on_btnRemoveWindow_clicked() 78 { 79 ui->mdiArea->removeSubWindow(ui->mdiArea->currentSubWindow()); //remove 当前窗口 80 }
Demo：
上图中的子窗口就是QMdiSubWindow窗口
QMdiArea类的函数解析：
QMdiSubWindow *addSubWindow(QWidget *widget, Qt::WindowFlags flags = Qt::WindowFlags()); //在MDI区域中添加SubWindow子窗口。