第27课 - 应用程序中的主窗口（NotePad菜单栏）

1、主窗口的概念 

应用程序中的主窗口 

         －主窗口是与用户进行长时间交互的顶层窗口

         －程序的绝大多数功能直接由主窗口提供 

         －主窗口通常是应用程序启动后显示的第一个窗口

          - 整个程序由一个主窗口和多个对话框组成 

 

Qt中的主窗口 

         - Qt开发平台中直接支持主窗口的概念 

         - QMainWindow是Qt中主窗口的基类 

         - QMainWindow继承于QWidget是一种容器类型的组件 

                                                 

              开发主窗口与使用的类（如QWidget、QDialog等）

              没有关系，那么QMainWindow有什么优势呢？

 

QMainWindow中封装的秘密     

     
   

 

QMainWindow中的组件布局 

 

2、主窗口中的菜单 

在Qt中提供与菜单相关的类组件 

 

在Qt主窗口中创建菜单 

3、编程实验 

主窗口中创建菜单      NotePad.pro 

MainWindow.h

#ifndef _MAINWINDOW_H_
#define _MAINWINDOW_H_

#include <QtGui/QMainWindow>
#include <QKeySequence>
#include <QMenuBar>
#include <QAction>

class MainWindow : public QMainWindow
{
    Q_OBJECT

private:
    MainWindow();
    MainWindow(const MainWindow&);
    MainWindow& operator= (const MainWindow&);

    bool construct();
    bool initMenuBar();
    bool initFileMenu(QMenuBar* mb);
    bool makeAction(QAction*& action, QString text, int key);
public:
    static MainWindow* NewInstance();
    ~MainWindow();
};

#endif // _MAINWINDOW_H_

MainWindow.cpp

#include "MainWindow.h"
#include <QMenu>

MainWindow::MainWindow()
{

}

MainWindow* MainWindow::NewInstance()
{
    MainWindow* ret = new MainWindow();

    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }

    return ret;
}

bool MainWindow::construct()
{
    bool ret = true;

    ret = ret && initMenuBar();

    return ret;
}

bool MainWindow::initMenuBar()
{
    bool ret = true;
    QMenuBar* mb = menuBar();

    ret = ret && initFileMenu(mb);

    return ret;
}

bool MainWindow::initFileMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("File(&F)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "New(N)", Qt::CTRL + Qt::Key_N);

        if( ret )
        {
            menu->addAction(action);    // add Action item to Menu
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Exit(X)", Qt::CTRL + Qt::Key_X);

        if( ret )
        {
            menu->addAction(action);    // add Action item to Menu
        }
    }

    if( ret )
    {
        mb->addMenu(menu);    // add Menu to application Menu Bar
    }
    else
    {
        delete menu;
    }


    return ret;
}

bool MainWindow::makeAction(QAction*& action, QString text, int key)
{
    bool ret = true;

    action = new QAction(text, NULL);

    if( action != NULL )
    {
        action->setShortcut(QKeySequence(key));
    }
    else
    {
        ret = false;
    }

    return ret;
}

MainWindow::~MainWindow()
{
    
}

main.cpp

#include <QtGui/QApplication>
#include "MainWindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow* w = MainWindow::NewInstance();
    int ret = -1;

    if( w != NULL )
    {
        w->show();

        ret = a.exec();
    }

    delete w;

    return ret;
}

                       Alt+F快捷键

4、小技巧 

快捷键设置 

5、小结 

主窗口是与用户进行长时间交互的顶层窗口 

主窗口通常是应用程序启动后显示的第一个窗口 

QMainWindow是Qt中主窗口的基类 

QMainWindow是一种容器类型的窗口组件 

QMainWindow中封装了菜单栏，工具栏，状态栏等组件 

6、练习

实现如下界面

MainWindow.h

#ifndef _MAINWINDOW_H_
#define _MAINWINDOW_H_

#include <QtGui/QMainWindow>
#include <QKeySequence>
#include <QMenuBar>
#include <QAction>

class MainWindow : public QMainWindow
{
    Q_OBJECT

private:
    MainWindow();
    MainWindow(const MainWindow&);
    MainWindow& operator= (const MainWindow&);

    bool construct();

    bool initMenuBar();

    bool initFileMenu(QMenuBar* mb);
    bool initEditMenu(QMenuBar* mb);
    bool initFormatMenu(QMenuBar* mb);
    bool initViewMenu(QMenuBar* mb);
    bool initHelpMenu(QMenuBar* mb);

    bool initFileToolItem(QToolBar* tb);
    bool makeAction(QAction*& action, QString text, int key);
public:
    static MainWindow* NewInstance();
    ~MainWindow();
};

#endif // _MAINWINDOW_H_

MainWindow.cpp

#include "MainWindow.h"
#include <QMenu>

MainWindow::MainWindow()
{

}

MainWindow* MainWindow::NewInstance()
{
    MainWindow* ret = new MainWindow();

    if( (ret == NULL) || !ret->construct() )
    {
        delete ret;
        ret = NULL;
    }

    return ret;
}

bool MainWindow::construct()
{
    bool ret = true;

    ret = ret && initMenuBar();

    return ret;
}

bool MainWindow::initMenuBar()
{
    bool ret = true;
    QMenuBar* mb = menuBar();   

    ret = ret && initFileMenu(mb);
    ret = ret && initEditMenu(mb);
    ret = ret && initFormatMenu(mb);
    ret = ret && initViewMenu(mb);
    ret = ret && initHelpMenu(mb);

    return ret;
}


bool MainWindow::initFileMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("File(&F)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "New(&N)", Qt::CTRL + Qt::Key_N);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Open(&O)...", Qt::CTRL + Qt::Key_O);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Save(&S)", Qt::CTRL + Qt::Key_S);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Save As(&A)...", 0);

        if( ret )
        {
            menu->addAction(action);
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Print(&P)...", Qt::CTRL + Qt::Key_P);

        if( ret )
        {
            menu->addAction(action);
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Exit(&X)", 0);

        if( ret )
        {
            menu->addAction(action);
        }
    }

    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }

    return ret;
}

bool MainWindow::initEditMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Edit(&E)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "Undo(&U)", Qt::CTRL + Qt::Key_Z);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Redo(&R)...", Qt::CTRL + Qt::Key_Y);

        if( ret )
        {
            menu->addAction(action);
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Cut(&T)", Qt::CTRL + Qt::Key_X);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Copy(&C)...", Qt::CTRL + Qt::Key_C);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Paste(&P)...", Qt::CTRL + Qt::Key_V);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Delete(&L)", Qt::Key_Delete);

        if( ret )
        {
            menu->addAction(action);
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Find(&F)...", Qt::CTRL + Qt::Key_F);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Replace(&R)...", Qt::CTRL + Qt::Key_H);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Goto(&G)...", Qt::CTRL + Qt::Key_G);

        if( ret )
        {
            menu->addAction(action);
        }

        menu->addSeparator();

        ret = ret && makeAction(action, "Select All(&A)", Qt::CTRL + Qt::Key_A);

        if( ret )
        {
            menu->addAction(action);
        }
    }

    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }

    return ret;
}

bool MainWindow::initFormatMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Format(&O)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "Auto Wrap(&W)", 0);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Font(&F)...", 0);

        if( ret )
        {
            menu->addAction(action);
        }
    }

    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }

    return ret;
}

bool MainWindow::initViewMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("View(&V)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "Tool Bar(&T)", 0);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "Status Bar(&S)", 0);

        if( ret )
        {
            menu->addAction(action);
        }
    }

    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }

    return ret;
}

bool MainWindow::initHelpMenu(QMenuBar* mb)
{
    QMenu* menu = new QMenu("Help(&H)");
    bool ret = (menu != NULL);

    if( ret )
    {
        QAction* action = NULL;

        ret = ret && makeAction(action, "User Manual", 0);

        if( ret )
        {
            menu->addAction(action);
        }

        ret = ret && makeAction(action, "About NotePad...", 0);

        if( ret )
        {
            menu->addAction(action);
        }
    }

    if( ret )
    {
        mb->addMenu(menu);
    }
    else
    {
        delete menu;
    }

    return ret;
}


bool MainWindow::makeAction(QAction*& action, QString text, int key)
{
    bool ret = true;

    action = new QAction(text, NULL);

    if( action != NULL )
    {
        action->setShortcut(QKeySequence(key));
    }
    else
    {
        ret = false;
    }

    return ret;
}



MainWindow::~MainWindow()
{
    
}

main.cpp

#include <QtGui/QApplication>
#include "MainWindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow* w = MainWindow::NewInstance();
    int ret = -1;

    if( w != NULL )
    {
        w->show();

        ret = a.exec();
    }

    delete w;

    return ret;
}